Jennifer Guohong Duan

Interests

Research

My research area is hydraulics and sediment transport focusing on experimental study of turbulence flow field and computational simulation of flow and sediment transport in rivers. My research objective is to advance the fundamental knowledge and develop the state-of-the-art computational models in the area of hydraulics and sediment transport through basic and applied research.

Teaching

Fluid Mechanics, Open Channel Flow, Computational Hydraulics, Sediment Transport Engineering

Courses

Scholarly Contributions

Chapters

• Duan, J. G. (2001).

  Simulation of Streambank Erosion Processes with a Two-Dimensional Numerical Model

  . In Landscape Erosion and Evolution Modeling. Springer, Boston, MA. doi:10.1007/978-1-4615-0575-4_13
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  Channel stabilization is critical for the success of channel restoration. A stable channel, from a geomorphic perspective, is one that has adjusted its width, depth, and slope such that there is no significant aggradation or degradation of the streambed or significant platform changes within an engineering time frame, generally less than 50 years (Biedenharn et al., 1997). Even though the bed of a stream in dynamic equilibrium is neither degrading nor aggrading, erosion may be occurring in stream banks and result in bank instability. Bank protection is often required even for a stream in dynamic equilibrium. Due to the lack of understanding of bank erosion mechanisms, the hydraulic and sediment transport models, including the series of U.S. Army Corps of Engineers Hydrologic Engineering Center models, CH3D-SED, etc., which have been widely applied to engineering projects to design stable channels, can only predict the vertical bed adjustments due to degradation and aggradation. Alluvial channels adjust themselves to reach regime conditions not only through bed elevation changes but also through platform evolution, for example, the migration of meandering channels.

Journals/Publications

• Duan, J. G. (2026). Closure to "quantification of Curve Numbers for Arid Watersheds". Journal of Hydrologic Engineering, 31(Issue 1). doi:10.1061/jhyeff.heeng-6765
• Duan, J. G., Arjmandi, A., Canfield, E., Demaria, E., Goodrich, D. C., & Qi, K. (2026). Erratum for “Quantification of Curve Numbers for Arid Watersheds” (Journal of Hydrologic Engineering DOI: 10.1061/JHYEFF.HEENG-6267). Journal of Hydrologic Engineering, 31(Issue 1). doi:10.1061/jhyeff.heeng-6778
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  The original paper incorrectly cited the reference Horton (1940) as the source of Horton's infiltration theory of surface runoff. While that paper was slated for publication in Eos, Transactions of the American Geophysical Union, it was never published. [See Horton (1940)forEos's explanation and Beven (2025) for further discus sion.] In fact, Dr. Horton initially presented this concept in Horton (1933) and later derived the original infiltration model [Eq. (5) in an original paper] in Horton (1939). Therefore, the reference for Horton (1940) should be replaced with Horton (1939). To preserve the published version of record, these details have been corrected only in this erratum.
• Arjmandi, A., Duan, J., Malusa, J., Demaria, E., & Canfield, E. (2025). Predicting Postfire Runoff Using Gridded Curve Number Map Generated from Vegetation Data: A Case Study. Journal of Hydrologic Engineering, 30(Issue 5). doi:10.1061/jhyeff.heeng-6448
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  Prediction of surface runoff immediately after a wildfire is challenging because it can significantly impact the hydrological parameters of the burned areas due to vegetation reduction. Still, there has been limited research focused on estimating the actual impact of vegetation reduction on increased surface runoff. This paper presents a novel approach to predict postfire surface runoff using the curve number (CN) method, in which the values of CNs were calculated based on the reduction of postfire vegetation. We illustrated the approach using a severely burned watershed after the 2020 Bighorn Fire in Southern Arizona. We developed prefire and postfire gridded CN maps using the latest vegetation map from the LANDFIRE database (LANDFIRE's 2022 map "Existing vegetation type"). We also analyzed and classified (cross-walked) the vegetation types corresponding to the CN values for the broader vegetation types listed in the USDA's 1986 technical release Urban hydrology for small watersheds (TR-55) and the Pima County Regional Flood Control District's 2019 technical report PC-Hydro user guide (PC-Hydro). Since only limited land use classifications for arid regions are available in both manuals, this study reclassified the vegetation types. We developed two new CN tables for more than 70 vegetation types in arid and semiarid regions. These tables quantify the CN values based on vegetation type, canopy cover, and soil hydrologic property. Postfire surface runoff was calculated for the 100 year rainfall event using these tables and the postfire vegetation reduction map. The results showed that areas with high burn severity experienced the most significant increase in CN values ranging from 8 to 20. In contrast, areas with low burn severity had the least increase in CN values (0-4). The peak discharges from the 100 year design rainfall increased at 21 of the 26 subbasin outlets, and the maximum increase is 22%. The comparison of runoff calculated using the grided CN map based on PC-Hydro with the predictions from the United States Geological Survey regression method and the field observations showed good agreements. Therefore, this approach and the revised CN value tables are valuable to hydrologic engineers for predicting postfire surface runoff from watersheds in arid and semiarid regions.
• Duan, J. G., Arjmandi, A., Canfield, E., Demaria, E., Goodrich, D. C., & Qi, K. (2025). Quantification of Curve Numbers for Arid Watersheds. Journal of Hydrologic Engineering, 30(Issue 1). doi:10.1061/jhyeff.heeng-6267
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  Although the curve number (CN) method has been widely used in rainfall and runoff models, the physical interpretation of the CN method is still challenging, for instance how to estimate the potential maximum retention. This paper analyzed the historical rainfall and runoff event data from 1975 to 2021 for two arid to semiarid watersheds, the Santa Rita and the Lucky Hills experimental watersheds in Tucson, Arizona. As is well known, a constant CN for a watershed can be back-calculated by fitting the observed rainfall and runoff. This study found this constant CN increase with the ratio of initial abstraction. On the other hand, CN can also be back-calculated for each event using the observed rainfall and runoff. The event-based CN depends on precipitation, land use, types and density of vegetation, as well as soil properties. If assuming the potential maximum retention is equal to the cumulative infiltrated water in each rainfall event, we applied the Green-Ampt infiltration model to estimate the CN for each historical event and compared with the back-calculated event-based CN. We found that 71% of the calculated CNs fell in the 10% margin of error, and 88% were within the 20% margin of error compared with the observed data. This indicated that the retention in CN can be considered as the cumulative infiltrated water in each event and calculated using the soil properties and rainfall duration. This is the first physical-based quantitative interpretation of retention in CN that will enable the determination of CN for ungauged watersheds in remote areas.
• Nookala, S. R., Duan, J. G., Qi, K., Pacheco, J., & He, S. (2025). Quantification of Suspended Sediment Concentration Using Laboratory Experimental Data and Machine Learning Model. Water (Switzerland), 17(Issue 15). doi:10.3390/w17152301
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  Monitoring sediment concentration in water bodies is crucial for assessing water quality, ecosystems, and environmental health. However, physical sampling and sensor-based approaches are labor-intensive and unsuitable for large-scale, continuous monitoring. This study employs machine learning models to estimate suspended sediment concentration using images captured in natural light, named RGB, and near-infrared (NIR) conditions. A controlled dataset of approximately 1300 images with SSC values ranging from 1000 mg/L to 150,000 mg/L was developed, incorporating temperature, time of image capture, and solar irradiance as additional features. Random forest regression and gradient boosting regression were trained on mean RGB values, red reflectance, time of captured, and temperature for natural light images, achieving up to 72.96% accuracy within a 30% relative error. In contrast, NIR images leveraged gray-level co-occurrence matrix texture features and temperature, reaching 83.08% accuracy. Comparative analysis showed that ensemble models outperformed deep learning models like Convolutional Neural Networks and Multi-Layer Perceptrons, which struggled with high-dimensional feature extraction. These findings suggest that using machine learning models and RGB and NIR imagery offers a scalable, non-invasive, and cost-effective way of sediment monitoring in support of water quality assessment and environmental management.
• Qi, K., Duan, J. G., Gerba, C. P., & Bright, K. R. (2025). Numerical Simulation of Bacteria and Virus Transport in Mobile Bed Channels. International Journal of Sediment Research.
• Qi, K., Al-Asadi, K., & Duan, J. G. (2024). Modeling Runoff and Sediment Load Using the HEC-HMS Model in an Arid Watershed. Journal of Hydrologic Engineering, 29(3). doi:10.1061/jhyeff.heeng-6070
• Qi, K., Al-Asadi, K., & Duan, J. G. (2024). Modeling runoff and sediment load using the HEC-HMS model in an arid watershed. Journal of Hydrologic Engineering, 29(3).
• Al-Asadi, K., Abbas, A. A., Dawood, A. S., & Duan, J. G. (2023).

  Calibration and Modification of the Hargreaves–Samani Equation for Estimating Daily Reference Evapotranspiration in Iraq

  . Journal of Hydrologic Engineering, 28(5). doi:10.1061/jhyeff.heeng-5877
• Al-Asadi, K., Abbas, A. A., Dawood, A. S., & Duan, J. G. (2023). Calibration and Modification of the Hargreaves-Samani Equation for Estimating Daily Reference Evapotranspiration in Iraq. Journal of Hydrologic Engineering, 28(5).
• Duan, J. G., & Arjmandi, A. (2023). Quantify Post Wildfire Curve Number for Arid Watersheds. AGU23.
• Duan, J. G., Engel, F. L., & Cadogan, A. (2023). Discharge Estimation Using Video Recordings from Small Unoccupied Aircraft Systems. Journal of Hydraulic Engineering, 149(11). doi:10.1061/jhend8.hyeng-13591
• Duan, J. G., Engel, F. L., & Cadogan, A. (2023). Discharge estimation using video recordings from small unoccupied aircraft systems. Journal of Hydraulic Engineering, 149(11), 04023048.
• Duan, J. G., Yu, C., & Ding, Y. (2023).

  Numerical Simulation of Sediment Transport in Unsteady Open Channel Flow

  . Water, 15(14), 2576. doi:10.3390/w15142576
• Duan, J. G., Yu, C., & Ding, Y. (2023). Numerical Simulation of Sediment Transport in Unsteady Open Channel Flow. Water (Switzerland), 15(14).
• Duan, J. G., & Al-Asadi, K. (2022). On bed form resistance and bed load transport in vegetated channels. Water, 14(23), 3794.
• Duan, J. G., & Al-Asadi, K. (2022). On bed form resistance and bed load transport in vegetated channels.. Water(Switzerland), 14(23). doi:doi:10.3390/w14233794
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  bed form and flow resistance in vegetated channel
• Gerba, C. P., Duan, J. G., Tousi, E. G., & Gundy, P. M. (2022). Resuspension and Attachment of PhiX174 in Sediment Laden Flow. Journal of Environmental Engineering, 148(6). doi:10.1061/(asce)ee.1943-7870.0001996
• Qi, K., Tousi, E. G., Duan, J. G., Gundy, P. M., Bright, K. R., & Gerba, C. P. (2022). Entrainment of E. coli and Listeria monocytogenes from sediment in irrigation canal. International Journal of Sediment Research, 37(6), 701--714.
• Tousi, E. G., Duan, J. G., Gundy, P. M., & Gerba, C. P. (2022). Resuspension and attachment of PhiX174 in sediment laden flow. Journal of Environmental Engineering, 148(6), 04022018.
• Boccelli, D. L., Lansey, K. E., Meixner, T., Scott, C. A., Crosson, C., Boccelli, D. L., Albrecht, T. R., Achilli, A., Shrestha, P. P., Pincetl, S., Zuniga-teran, A. A., Shrestha, P. P., Pincetl, S., Mack, E. A., Duan, J. G., Daigger, G. T., Crosson, C., Cath, T. Y., Albrecht, T. R., & Achilli, A. (2021). Net Zero Urban Water from Concept to Applications: Integrating Natural, Built, and Social Systems for Responsive and Adaptive Solutions. ACS ES&T Water, 1(3), 518-529. doi:10.1021/acsestwater.0c00180
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  Innovation in urban water systems is required to address drivers of change across natural, built, and social systems, including climate change, economic development, and aged infrastructure. Water ...
• Bright, K. R., Tousi, E. G., Gundy, P. M., Gerba, C. P., & Duan, J. G. (2021). Evaluation of E. coli in sediment for assessing irrigation water quality using machine learning.. The Science of the total environment, 799, 149286. doi:10.1016/j.scitotenv.2021.149286
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  Fresh produce irrigated with contaminated water poses a substantial risk to human health. This study evaluated the impact of incorporating sediment information on improving the performance of machine learning models to quantify E. coli level in irrigation water. Field samples were collected from irrigation canals in the Southwest U.S., for which meteorological, chemical, and physical water quality variables as well as three additional flow and sediment properties: the concentration of E. coli in sediment, sediment median size, and bed shear stress. Water quality was classified based on E. coli concentration exceeding two standard levels: 1 E. coli and 126 E. coli colony forming units (CFU) per 100 ml of irrigation water. Two series of features, including (FIS) and excluding (FES) sediment features, were selected using multi-variant filter feature selection. The correlation analysis revealed the inclusion of sediment features improves the correlation with the target standards for E. coli compared to the models excluding these features. Support vector machine, logistic regression, and ridge classifier were tested in this study. The support vector machine model performed the best for both targeted standards. Besides, incorporating sediment features improved all models' performance. Therefore, the concentration of E. coli in sediment and bed shear stress are major factors influencing E. coli concentration in irrigation water.
• Bright, K. R., Tousi, E. G., Gundy, P. M., Gerba, C. P., Duan, J. G., & Bright, K. R. (2021). Experimental Study of PhiX174 Resuspension from Mobile Bed Sediment. Journal of Irrigation and Drainage Engineering-asce, 147(5). doi:10.1061/(asce)ir.1943-4774.0001549
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  AbstractPhiX174 (or ΦX174) is a spherical single-stranded DNA bacteriophage used as a surrogate to study viral enteric pathogens in the environment. The resuspension of viral pathogen from bed sedi...
• Ghasemi Tousi, E., Duan, J., Gundy, P., Bright, K., & Gerba, C. (2021). Experimental Study of PhiX174 Resuspension from Mobile Bed Sediment. Journal of Irrigation and Drainage Engineering, 147(5). doi:10.1061/(ASCE)IR.1943-4774.0001549
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  PhiX174 (or φX174) is a spherical single-stranded DNA bacteriophage used as a surrogate to study viral enteric pathogens in the environment. The resuspension of viral pathogen from bed sediment in irrigation canals impairs the quality of overlaying water and can result in the contamination of produce. We conducted a series of laboratory experiments to evaluate the resuspension of PhiX174 from bed sediment in an open channel flume. Different flow conditions (e.g., flow rate, velocity, shear stress) and three types of sediment mixtures (i.e., loam, sand, sandy loam) were investigated. Results revealed that the resuspension rate increases with the dimensionless bed shear stress. Based on these results, for the first time, we proposed two models to correlate the concentration of PhiX174 with the dimensionless bed shear stress for different sediment. One model was proposed for sandy loam and loam, was verified favorably by the experimental data, and yielded a Nash-Sutcliffe efficiency coefficient (NSE) of 0.71 and R2 value of 0.72. The other model was proposed for sand, with NSE of 0.20 and R2 of 0.26. The application of these models also indicated viruses are more easily resuspended from sand than sandy loam or loam sediments. The models shed a light for studying the correlation between the viruses in water and sediment and will benefit the management of irrigation water quality.
• Ahamed, T., Duan, J. G., & Jo, H. (2020).

  Flood-fragility analysis of instream bridges – consideration of flow hydraulics, geotechnical uncertainties, and variable scour depth

  . Structure and Infrastructure Engineering, 17(11), 1494-1507. doi:10.1080/15732479.2020.1815226
• Ahamed, T., Duan, J. G., & Jo, H. (2021). Flood-fragility analysis of instream bridges-consideration of flow hydraulics, geotechnical uncertainties, and variable scour depth. Structure and Infrastructure Engineering, 17(11), 1494-1507. doi:doi:10.1080/15732479.2020.1815226
• Ahamed, T., Shim, J., Jeong, J., Jo, H., & Duan, J. G. (2020). An efficient outlier removal algorithm for sonar-based bridge scour monitoring. Flow Measurement and Instrumentation. doi:https://doi.org/10.1080/15732479.2020.1815226
• Sassi, H. P., van Ogtrop, F., Morrison, C. M., Zhou, K., Duan, J. G., & Gerba, C. P. (2020). Sediment re-suspension as a potential mechanism for viral and bacterial contaminants. Journal of Environmental Science and Health, Part A, 55(12), 1398-1405. doi:10.1080/10934529.2020.1796118
• Sassi, H., Ogtrop, F. v., Morrison, C. M., Zhou, K., Duan, J. G., & Gerba, C. (2020). Sediment re-suspension as a potential mechanism for viral and bacterial contaminants. Journal of Environmental Science and Health, Part A. doi:https://doi.org/10.1080/15732479.2020.1815226
• Zhou, K., Duan, J. G., & Bombardelli, F. A. (2020). Experimental and Theoretical Study of Local Scour around Three-Pier Group. Journal of Hydraulic Engineering, 146(Issue 10). doi:10.1061/(asce)hy.1943-7900.0001794
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  The prediction of bridge-pier scour has been mostly aimed for a single pier of various sizes, shapes, and alignments with flow. For the case of multiple piers, widely used manuals still recommend using single-pier scour formulas with an equivalent diameter, regardless of pier separation and angle of attack. In this paper, we present the results of a new set of laboratory experiments conducted to address the local scour around a group of three piers with different sizes, spacing, and attacking angles. Based on the phenomenological theory of turbulence, we also formulate a semitheoretical framework for calculating the maximum scour depth in the multipier condition, including the single-pier counterpart as a special case. The few coefficients in the final equation were determined by experimental data from this and other studies. Our results provide an understanding of the eddies responsible for the scour process, and show that pier diameter, pier spacing, actual pier width, flow depth, Froude number, and sediment size are all important variables that need to be considered in order to obtain an accurate prediction of the maximum scour depth. Therefore, these results shed new light on current engineering procedures based on using single-pier expressions in the case of multiple piers.
• Zhou, K., Duan, J. G., & Bombardelli, F. A. (2020). Experimental and theoretical study of local scour around three-pier group. Journal of Hydraulic Engineering, 146(10). doi:doi:10.1061/(ASCE)HY.1943-7900.0001794
• Meixner, T., Meixner, T., Pavao-zuckerman, M., Pavao-zuckerman, M., Duan, J. G., Duan, J. G., & Crosson, C. (2019). Advances in Green Infrastructure Research, Development, and Community Adoption II. AGU Fall Meeting 2019.
• Meixner, T., Meixner, T., Pavao-zuckerman, M., Pavao-zuckerman, M., Duan, J. G., Duan, J. G., & Crosson, C. (2019). Advances in Green Infrastructure Research, Development, and Community Adoption III Posters. AGU Fall Meeting 2019.
• Shim, J., & Duan, J. G. (2019). Experimental and theoretical study of bed load particle velocity. Journal of Hydraulic Research, 57(1), 62-74.
• Duan, J., & Shim, J. (2018). Experimental and theoretical study of bed load particle velocity. Journal of Hydraulic Research, 57(1), 62-74. doi:10.1080/00221686.2018.1434837
• Ahamed, T., Shim, J., Jeong, J., Jo, H., & Duan, J. G. (2017). Advanced Signal Processing of Sonar Measurement for Bridge Scour Monitoring. WORLD ENVIRONMENTAL AND WATER RESOURCES CONGRESS 2017: INTERNATIONAL PERSPECTIVES, HISTORY AND HERITAGE, EMERGING TECHNOLOGIES, AND STUDENT PAPERS, 93-100.
• Al-Asadi, K., & Duan, J. G. (2017). Assessing methods for estimating roughness coefficient in a vegetated marsh area using Delft3D. JOURNAL OF HYDROINFORMATICS, 19(5), 766-783.
• Al-Asadi, K., & Duan, J. G. (2017). Assessing methods for estimating roughness coefficient in a vegetated marsh area using Delft3D. Journal of Hydroinformatics, 19(5), 766-783. doi:10.2166/hydro.2017.064
• Duan, J. G., Bai, Y., Dominguez, F., Rivera, E., & Meixner, T. (2017). Framework for Incorporating Climate Change on Flood Magnitude and Frequency Analysis in the Upper Santa Cruz River. Journal of Hydrology.
• Duan, J. G., Bai, Y., Dominguez, F., Rivera, E., & Meixner, T. (2017). Framework for incorporating climate change on flood magnitude and frequency analysis in the upper Santa Cruz River. JOURNAL OF HYDROLOGY, 549, 194-207.
• Duan, J. G., Poteuck, M., Rosenberg, A., & Zhou, K. (2017). Simulating Watershed Erosion in BMGR Using AGWA Model. WORLD ENVIRONMENTAL AND WATER RESOURCES CONGRESS 2017: HYDRAULICS AND WATERWAYS AND WATER DISTRIBUTION SYSTEMS ANALYSIS, 335-344.
• LiGuo, Z., XuDong, F., & Duan, J. G. (2017). A surface-based hiding function linking flume and field data. SCIENCE CHINA-TECHNOLOGICAL SCIENCES, 60(10), 1560-1569.
• Shim, J., & Duan, J. G. (2017). Experimental study of bed-load transport using particle motion tracking. INTERNATIONAL JOURNAL OF SEDIMENT RESEARCH, 32(1), 73-81.
• Shim, J., & Duan, J. G. (2017). Experimental study of bed-load transport using particle motion tracking. International Journal of Sediment Research, 32(Issue 1). doi:10.1016/j.ijsrc.2016.10.002
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  A series of experiments were conducted in a flume to study bed-load transport. The motion of bed-load particles was captured by a series of images taken by a high-speed camera.A novelparticle motion tracking method was developed to automatically detect all the moving particles and calculate the instantaneous particle velocities. The instantaneous bed load transport rate was calculated based on particle velocity and the volume of moving particles. To verify this method, bed load transport rate based on the image processing technique was compared to the manually measured ones as well as data from other experiments. Results showed that the new technique made it possible to quantify the spatial and temporal variations of bed load transport rate at the individual particle scale.
• Yu, C., & Duan, J. (2017). Simulation of Surface Runoff Using Hydrodynamic Model. JOURNAL OF HYDROLOGIC ENGINEERING, 22(6).
• Yu, C., & Duan, J. (2017). Simulation of Surface Runoff Using Hydrodynamic Model. Journal of Hydrologic Engineering, 04017006.
• Yu, C., & Duan, J. (2017). Simulation of Surface Runoff Using Hydrodynamic Model. Journal of Hydrologic Engineering, 22(6). doi:10.1061/(asce)he.1943-5584.0001497
• Zhang, L. G., Fu, X. D., & Duan, J. G. (2017). A surface-based hiding function linking flume and field data. Science China Technological Sciences, 60(Issue 10). doi:10.1007/s11431-016-0535-x
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  The quantification of the sheltering and exposure effects of non-uniform sediments has been widely achieved through hiding function models. Big challenge exists so far in the model parameter that is highly variable and differs greatly between laboratory flumes and field streams. This paper presents an improved surface-based hiding function. The force balance for particle inception was formulated and the allocation of the overall bed shear stress into each group of sediments was mimicked. The new hiding function was examined against and agrees well with the documented field and flume data. It was shown that the hiding function is closely related to the relative flow depth and the reference elevation in the velocity profile in addition to the bed material gradation. The power law of velocity profile that applies to both flume flows and natural streams can link the flume and field data together. The hiding function with b = 1/6 and b = 1/2 is applicable to natural streams and laboratory flumes, respectively. The value of b = 0.263 also works well for gravel bed rivers. The range of the reference elevation, namely z0 = 0.4Dm–1.4Dm, is recommended for either the flume or field data. The new hiding function contributes to addressing clearer physical meanings and a useful perspective for further improvement.
• Zhou, K., Sassi, H. P., Morrison, C. M., Duan, J. G., & Gerba, C. P. (2017). Resuspension of Escherichia coli and MS2 Bacteriophage from Bed Sediment in Irrigation Canals. JOURNAL OF IRRIGATION AND DRAINAGE ENGINEERING, 143(6).
• Zhou, K., Sassi, H. P., Morrison, C. M., Duan, J. G., & Gerba, C. P. (2017). Resuspension of Escherichia coli and MS2 Bacteriophage from Bed Sediment in Irrigation Canals. Journal of Irrigation and Drainage Engineering, 04017005.
• Shim, J., & Duan, J. G. (2016). Experimental study of bed-load transport using particle motion tracking. International Journal of Sediment Research.
• Shim, J., Duan, J., & Jo, H. (2016). Simulating Sediment Transport around a Bridge Pier Using Open FOAM Software. WORLD ENVIRONMENTAL AND WATER RESOURCES CONGRESS 2016: HYDRAULICS AND WATERWAYS AND HYDRO-CLIMATE/CLIMATE CHANGE, 362-369.
• Yu, C., Rosenberg, A., Poteuck, M., & Duan, J. G. (2016). Modeling of Erosion and Sedimentation Impacts from off-Road Vehicles in Arid Regions. World Academy of Science, Engineering and Technology, International Journal of Environmental and Ecological Engineering, 3(11).
• Al-Asadi, K., & Duan, J. G. (2015). Three-Dimensional Hydrodynamic Simulation of Tidal Flow through a Vegetated Marsh Area. JOURNAL OF HYDRAULIC ENGINEERING, 141(12).
• Al-Asadi, K., & Duan, J. G. (2015). Three-dimensional hydrodynamic simulation of tidal flow through a vegetated marsh area. Journal of Hydraulic Engineering, 141(Issue 12). doi:10.1061/(asce)hy.1943-7900.0001052
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  Simulation of tidal flow in an estuarine marsh area is challenging because of resistance from spatially and temporally varied vegetation. This study simulated the tidal flow in the Davis Pond marsh area near New Orleans, Louisiana, using an open source program. To quantify the time-varying roughness coefficient, four empirical equations for calculating Manning's roughness coefficient were incorporated into the program in addition to two options offered by the program to calculate the Chezy's coefficient and one option to use the modified momentum equations and the k-ε turbulence model. Results showed that the time-varying roughness coefficient equations accounting for both the degree of submergence and the vegetation frontal area gave the closest matches with the observed data.
• Bai, Y., & Duan, J. G. (2015). Using a Two-dimensional Watershed Model to Estimate Flood Magnitude and Frequency under Changing Climate. World Environmental and Water Resources Congress 2015: Floods, Droughts, and Ecosystems, 1163-1172.
• Shim, J., & Duan, J. G. (2015). Stochastic Properties of Bed Load Transport. World Environmental and Water Resources Congress 2015: Floods, Droughts, and Ecosystems, 1841-1850.
• Bai, Y., & Duan, J. G. (2014). Simulating unsteady flow and sediment transport in vegetated channel network. JOURNAL OF HYDROLOGY, 515, 90-102.
• Bai, Y., & Duan, J. G. (2014). Simulating unsteady flow and sediment transport in vegetated channel network. Journal of Hydrology, 515(Issue). doi:10.1016/j.jhydrol.2014.04.030
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  This paper presents a one-dimensional model for simulating flood routing and sediment transport over mobile alluvium in a vegetated channel network. The modified St. Venant equations together with the governing equations for suspended sediment and bed load transport were solved simultaneously to obtain flow properties and sediment transport rate. The Godunov-type finite volume method is employed to discretize the governing equations. Then, the Exner equation was solved for bed elevation change. Since sediment transport is non-equilibrium when bed is degrading or aggrading, a recovery coefficient for suspended sediment and an adaptation length for bed load transport were used to quantify the differences between equilibrium and non-equilibrium sediment transport rate. The influence of vegetation on floodplain and main channel was accounted for by adjusting resistance terms in the momentum equations for flow field. A procedure to separate the grain resistance from the total resistance was proposed and implemented to calculate sediment transport rate. The model was tested by a flume experiment case and an unprecedented flood event occurred in the Santa Cruz River, Tucson, Arizona, in July 2006. Simulated results of flow discharge and bed elevation changes showed satisfactory agreements with the measurements. The impacts of vegetation density on sediment transport and significance of non-equilibrium sediment transport model were discussed. © 2014 Elsevier B.V.
• Duan, J. (2014). Impacts of River Restoration on Bridges.
• YU, C., DUAN, J., ERPICUM, S., PIROTTON, M., ARCHAMBEAU, P., & DEWALS, B. J. (2014). Two-dimensional depth-averaged finite volume model for unsteady turbulent flows. Journal of hydraulic research, 52(1), 148--150.
• Yu, C., & Duan, J. (2014). Closure to "Two-dimensional depth-averaged finite volume model for unsteady turbulent flow" by CHUNSHUI YU and JENNIFER DUAN, J. Hydraulic Res. 50(6), 2012, 599-611. JOURNAL OF HYDRAULIC RESEARCH, 52(1), 150-151.
• Yu, C., & Duan, J. (2014). Two-Dimensional Hydrodynamic Model for Surface-Flow Routing. JOURNAL OF HYDRAULIC ENGINEERING, 140(9).
• Yu, C., & Duan, J. (2014). Two-Dimensional Hydrodynamic Model for Surface-Flow Routing. Journal of Hydraulic Engineering, 140(9). doi:10.1061/(asce)hy.1943-7900.0000913
• Yu, C., & Duan, J. G. (2014). High resolution numerical schemes for solving kinematic wave equation. JOURNAL OF HYDROLOGY, 519, 823-832.
• Yu, C., & Duan, J. G. (2014). High resolution numerical schemes for solving kinematic wave equation. Journal of Hydrology, 519(Issue). doi:10.1016/j.jhydrol.2014.08.003
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  This paper compares the stability, accuracy, and computational cost of several numerical methods for solving the kinematic wave equation. The numerical methods include the second-order MacCormack finite difference scheme, the MacCormack scheme with a dissipative interface, the second-order MUSCL finite volume scheme, and the fifth-order WENO finite volume scheme. These numerical schemes are tested against several synthetic cases and an overland flow experiment, which include shock wave, rarefaction wave, wave steepening, uniform/non-uniform rainfall generated overland flows, and flow over a channel of varying bed slope. The results show that the MacCormack scheme is not a Total Variation Diminishing (TVD) scheme because oscillatory solutions occurred at the presence of shock wave, rarefaction wave, and overland flow over rapidly varying bed slopes. The MacCormack scheme with a dissipative interface is free of oscillation but with considerable diffusions. The Godunov-type schemes are accurate and stable when dealing with discontinuous waves. Furthermore the Godunov-type schemes, like MUSCL and WENO scheme, are needed for simulating surface flow from spatially non-uniformly distributed rainfalls over irregular terrains using moderate computing resources on current personal computers.
• Bai, Y., & Duan, J. G. (2013). 1D Unsteady Flow and Sediment Transport Model for Vegetated Channel Network. PROCEEDINGS OF THE 35TH IAHR WORLD CONGRESS, VOLS I AND II, 5080-5088.
• Duan, J. G., & Yu, C. (2013). Two-dimensional Finite Volume Model for Overland and Channel Flow Routing. PROCEEDINGS OF THE 35TH IAHR WORLD CONGRESS, VOLS III AND IV.
• Liu, L., Zhong, D., Duan, J., & Zhang, H. (2013). Experimental Study on Landslide Dam Break Due to Overtopping. PROCEEDINGS OF THE 35TH IAHR WORLD CONGRESS, VOLS I AND II, 5718-5726.
• Zhang, S., Duan, J. G., & Strelkoff, T. S. (2013). Grain-Scale Nonequilibrium Sediment-Transport Model for Unsteady Flow. JOURNAL OF HYDRAULIC ENGINEERING-ASCE, 139(1), 22-36.
• Zhang, S., Duan, J. G., & Strelkoff, T. S. (2013). Grain-Scale Nonequilibrium Sediment-Transport Model for Unsteady Flow. Journal of Hydraulic Engineering, 139(1), 22-36. doi:10.1061/(asce)hy.1943-7900.0000645
• He, L. i., Duan, J. G., Wang, G., & Fu, X. (2012). Numerical Simulation of Unsteady Hyperconcentrated Sediment-Laden Flow in the Yellow River. JOURNAL OF HYDRAULIC ENGINEERING-ASCE, 138(11), 958-969.
• He, L., Duan, J. G., Wang, G., & Fu, X. (2012). Numerical Simulation of Unsteady Hyperconcentrated Sediment-Laden Flow in the Yellow River. Journal of Hydraulic Engineering, 138(11), 958-969. doi:10.1061/(asce)hy.1943-7900.0000599
• Hummel, R., Duan, J. G., & Zhang, S. (2012). COMPARISON OF UNSTEADY AND QUASI-UNSTEADY FLOW MODELS IN SIMULATING SEDIMENT TRANSPORT IN AN EPHEMERAL ARIZONA STREAM. JOURNAL OF THE AMERICAN WATER RESOURCES ASSOCIATION, 48(5), 987-998.
• Liu, F., Fu, X., Wang, G., & Duan, J. (2012). Physically based simulation of dam breach development for Tangjiashan Quake Dam, China. ENVIRONMENTAL EARTH SCIENCES, 65(4), 1081-1094.
• Liu, F., Fu, X., Wang, G., & Duan, J. (2012). Physically based simulation of dam breach development for Tangjiashan Quake Dam, China. Environmental Earth Sciences, 65(Issue 4). doi:10.1007/s12665-011-1025-9
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  Physically based modeling approach has been widely developed in recent years for simulation of dam failure process resulting from overtopping flow. Due to the lack of field data, there exist few applications to natural quake dams with complex erosion mechanisms. This paper presents a physically based simulation of the failure process of the Tangjiashan Quake Dam formed as a result of the "May 12, 2008" Wenchuan earthquake in China. The one-dimensional model adopted features as cost saving but enables capturing the main characteristics of the failure process, where selective sediment transport and gravitational slope collapse are accounted for. The simulated flow hydrograph and breach progression process are generally in good agreement with the observed data. Unsteadiness and non-uniformity are found to be substantial characteristics of breach progression during the failure process of natural quake dams. Sensitivity analysis showed that the Manning resistance coefficient and the erodibility coefficient in Osman and Thorne's (J Hydraul Eng 114(2):134-150, 1988) model significantly influences the flow peak discharge but has less influence on its occurrence time, while the velocity lag coefficient associated with bed-load transport may affect the two breaching parameters substantially. © 2011 Springer-Verlag.
• Posner, A. J., & Duan, J. G. (2012). Simulating river meandering processes using stochastic bank erosion coefficient. GEOMORPHOLOGY, 163, 26-36.
• Yu, C., & Duan, J. (2012). Two-dimensional depth-averaged finite volume model for unsteady turbulent flow. JOURNAL OF HYDRAULIC RESEARCH, 50(6), 599-611.
• Yu, C., & Duan, J. (2012). Two-dimensional depth-averaged finite volume model for unsteady turbulent flow. Journal of Hydraulic Research, 50(6), 599-611. doi:10.1080/00221686.2012.730556
• Zhang, S., Duan, J. G., Strelkoff, T. S., & Bautista, E. (2012). Simulation of Unsteady Flow and Soil Erosion in Irrigation Furrows. JOURNAL OF IRRIGATION AND DRAINAGE ENGINEERING-ASCE, 138(4), 294-303.
• Zhang, S., Duan, J. G., Strelkoff, T. S., & Bautista, E. (2012). Simulation of Unsteady Flow and Soil Erosion in Irrigation Furrows. Journal of Irrigation and Drainage Engineering, 138(4), 294-303. doi:10.1061/(asce)ir.1943-4774.0000396
• Zhang, S., Hummel, R., & Duan, J. G. (2012). Comparison of Unsteady and Quasi-Unsteady Flow Models in Simulating Sediment Transport in an Ephemeral Arizona Stream1. Journal of The American Water Resources Association, 48(5), 987-998. doi:10.1111/j.1752-1688.2012.00663.x
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  Hummel, Ryan, Jennifer G. Duan, and Shiyan Zhang, 2012. Comparison of Unsteady and Quasi-Unsteady Flow Models in Simulating Sediment Transport in an Ephemeral Arizona Stream. Journal of the American Water Resources Association (JAWRA) 48(5): 987-998. DOI: 10.1111/j.1752-1688.2012.00663.x Abstract:  Hydrodynamic and sediment transport models are useful engineering tools for predicting unsteady flood flow and sediment transport. Many models such as HEC-RAS, HEC-6, and IALLUVIAL apply quasi-unsteady flow model, whereas others apply the unsteady flow model. It remains unknown if a quasi-unsteady flow model is sufficiently accurate for simulating sediment transport in rapidly varied unsteady flood events, especially in ephemeral rivers in arid and semiarid regions. This study compared the quasi-unsteady HEC-RAS 4.1 model with one-dimensional (1D) Finite Volume Method (FVM) based model in simulating flood flow and sediment transport in the Pantano Wash, a dryland river in the state of Arizona. The objective is to determine which sediment transport method is appropriate in predicting bed elevation changes in an ephemeral stream, Pantano Wash, and if an unsteady model is more accurate than a quasi-unsteady flow model in predicting sediment transport. Results showed that the quasi-unsteady HEC-RAS model and the 1D FVM yielded similar results of bed degradation and aggradation for this dryland stream, although the FVM model predicted better flood hydrographs. Among the seven sediment transport formulas embedded in HEC-RAS, Yang’s and Engelund-Hansen’s equations gave the best matches with the field measurements for this particular case study.
• Duan, J., He, L. i., Wang, G., & Fu, X. (2011). Turbulent burst around experimental spur dike. INTERNATIONAL JOURNAL OF SEDIMENT RESEARCH, 26(4), 471-+.
• Wu, W., Altinakar, M. S., Al-Riffai, M., Bergman, N., Bradford, S. F., Cao, Z., Chen, Q. J., Constantinescu, S. G., Duan, J. G., Gee, D. M., Greimann, B., Hanson, G., He, Z., Hegedus, P., van, H. T., Huddleston, D., Hughes, S. A., Imran, J., Jia, Y., , Jorgeson, J. D., et al. (2011). Earthen Embankment Breaching. JOURNAL OF HYDRAULIC ENGINEERING-ASCE, 137(12), 1549-1564.
• Zhang, S., & Duan, J. G. (2011). 1D finite volume model of unsteady flow over mobile bed. JOURNAL OF HYDROLOGY, 405(1-2), 57-68.
• Zhang, S., & Duan, J. G. (2011). 1D finite volume model of unsteady flow over mobile bed. Journal of Hydrology, 405(Issue 1-2). doi:10.1016/j.jhydrol.2011.05.010
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  A one dimensional (1D) finite volume method (FVM) model was developed for simulating unsteady flow, such as dam break flow, and flood routing over mobile alluvium. The governing equation is the modified 1D shallow water equation and the Exner equation that take both bed load and suspended load transport into account. The non-equilibrium sediment transport algorithm was adopted in the model, and the van Rijn method was employed to calculate the bed-load transport rate and the concentration of suspended sediment at the reference level. Flux terms in the governing equations were discretised using the upwind flux scheme, Harten et al. (1983) (HLL) and HLLC schemes, Roe's scheme and the Weighted Average Flux (WAF) schemes with the Double Minmod and Minmod flux limiters. The model was tested under a fixed bed condition to evaluate the performance of several different numerical schemes and then applied to an experimental case of dam break flow over a mobile bed and a flood event in the Rillito River, Tucson, Arizona. For dam break flow over movable bed, all tested schemes were proved to be capable of reasonably simulating water surface profiles, but failed to accurately capture the hydraulic jump. The WAF schemes produced slight spurious oscillations at the water surface and bed profiles and over-estimated the scour depth. When applying the model to the Rillito River, the simulated results generally agreed well with the field measurements of flow discharges and bed elevation changes. Modeling results of bed elevation changes were sensitive to the suspended load recovery coefficient and the bed load adaptation length, which require further theoretical and experimental investigations. © 2011 Elsevier B.V.
• Julien, P. Y., & Duan, J. G. (2010). Numerical simulation of meandering evolution. Journal of Hydrology, 391(1), 34-46. doi:10.1016/j.jhydrol.2010.07.005
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  A two-dimensional depth-averaged hydrodynamic model is developed to simulate the evolution of meandering channels from the complex interaction between downstream and secondary flows, bed load and suspended sediment transport, and bank erosion. The depth-averaged model calculates both bed load and suspended load assuming equilibrium sediment transport and simulates bank erosion with a combination of two interactive processes: basal erosion and bank failure. The mass conservation equation is solved to account for both vertical bed-elevation changes as well as lateral migration changes when sediment is removed through basal erosion and bank failure. The numerical model uses deformable elements and a movable grid to simulate the gradual evolution of a near-straight deformable channel into a highly sinuous meandering channel. The model correctly replicates the different phases of the evolution of free meandering channels in experimental laboratory settings including: (1) downstream and upstream migration; (2) lateral extension; and (3) rotation of meander bends.
• Julien, P. Y., Friesen, N., Duan, J. G., & Eykholt, R. (2010). Celerity and Amplification of Supercritical Surface Waves. JOURNAL OF HYDRAULIC ENGINEERING-ASCE, 136(9), 656-661.
• Julien, P. Y., Friesen, N., Duan, J. G., & Eykholt, R. (2010). Celerity and Amplification of Supercritical Surface Waves. Journal of Hydraulic Engineering, 136(9), 656-661. doi:10.1061/(asce)hy.1943-7900.0000220
• Duan, J. G. (2009). Mean Flow and Turbulence around a Laboratory Spur Dike. JOURNAL OF HYDRAULIC ENGINEERING-ASCE, 135(10), 803-811.
• Duan, J. G. (2009). Mean Flow and Turbulence around a Laboratory Spur Dike. Journal of Hydraulic Engineering, 135(10), 803-811. doi:10.1061/(asce)hy.1943-7900.0000077
• Duan, J. G., He, L. i., Fu, X., & Wang, Q. (2009). Mean flow and turbulence around experimental spur dike. ADVANCES IN WATER RESOURCES, 32(12), 1717-1725.
• Duan, J. G., He, L., Fu, X., & Wang, Q. (2009). Mean flow and turbulence around experimental spur dike. Advances in Water Resources, 32(Issue 12). doi:10.1016/j.advwatres.2009.09.004
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  An acoustic Doppler velocimeter was used to measure flow and turbulence around an experimental spur dike in a flat and a scoured bed. Differences of mean velocity, turbulent intensity and Reynolds stresses between these two flow fields were analyzed. Upon the formation of scour hole, mean flow velocities in the downstream and lateral directions were reduced, but increased in the vertical direction. The turbulence intensities (u′ and v′) are much larger, and the vertical component (w′) is smaller than that in the flat bed. Among three Reynolds stresses, the - ρ over(u′ w′, -) and - ρ over(v′ w′, -) components are much smaller than the - ρ over(u′ v′, -). Bed shear stress near the dike can be 6 to 8 times as large as that of the approaching flow so that a local scour is developed near the dike without the shear stress of approaching flow exceeding the critical shear stress of bed material. The local scour initiated at the upstream of the dike and then extends to downstream from the dike tip. These results indicated that the development of local scour synchronizes to high shear stresses resulted from the horseshoe vorticies on a mobile bed surface. © 2009 Elsevier Ltd.
• Barkdoll, B. D., & Duan, J. G. (2008). Sediment modeling: Issues and future directions. JOURNAL OF HYDRAULIC ENGINEERING-ASCE, 134(3), 285-285.
• Barkdoll, B. D., & Duan, J. G. (2008). Sediment modeling: Issues and future directions. Journal of Hydraulic Engineering, 134(Issue 3). doi:10.1061/(asce)0733-9429(2008)134:3(285)
• Chen, D., & Duan, J. G. (2008). Case Study: Two-Dimensional Model Simulation of Channel Migration Processes in West Jordan River, Utah. Journal of Hydraulic Engineering, 134(3), 315-327. doi:10.1061/(asce)0733-9429(2008)134:3(315)
• Chen, D., & Duan, J. G. (2008). Case study: Two-dimensional model simulation of channel migration processes in West Jordan River, Utah. JOURNAL OF HYDRAULIC ENGINEERING-ASCE, 134(3), 315-327.
• Duan, J. G., & Barkdoll, B. D. (2008). Surface-based fractional transport predictor: Deterministic or stochastic. JOURNAL OF HYDRAULIC ENGINEERING-ASCE, 134(3), 350-353.
• Zhong, D. Y., & Duan, J. G. (2008). Analytical approach to calculate rate of bank erosion - Closure. JOURNAL OF HYDRAULIC ENGINEERING-ASCE, 134(2), 281-282.
• Zhong, D. Y., & Duan, J. G. (2008). Closure to “Analytical Approach to Calculate Rate of Bank Erosion” by J. G. Duan. Journal of Hydraulic Engineering, 134(2), 281-282. doi:10.1061/(asce)0733-9429(2008)134:2(281)
• Duan, J. G., & Scott, S. (2007). Selective bed-load transport in Las Vegas Wash, a gravel-bed stream. JOURNAL OF HYDROLOGY, 342(3-4), 320-330.
• Chen, D., & Duan, J. D. (2006). Simulating sine-generated meandering channel evolution with an analytical model. JOURNAL OF HYDRAULIC RESEARCH, 44(3), 363-373.
• Chen, D., & Duan, J. D. (2006). Simulating sine-generated meandering channel evolution with an analytical model. Journal of Hydraulic Research, 44(Issue 3). doi:10.1080/00221686.2006.9521688
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  An analytical model to simulate the evolution of a meandering channel was developed based on the analytical solution of flow field in a sine-generated meandering channel and application of the bank erosion model by Duan et al. The flow-field solution was derived from two-dimensional, depth-averaged, steady-flow equations in channel-fitted, curvilinear orthogonal coordinates where the transverse bed slope was treated as a variable increasing with channel sinuosity. The flow-field solution indicated that the location where the shift of maximum velocity zone from the convex to concave banks in sine-generated channels varies with the transverse bed slope and the strength of secondary current. The rate of bank erosion was calculated as a gradient function of the longitudinal sediment transport rate and strength of the secondary flow rather than being proportional to the magnitude of excessive near-bank velocity or shear stress. This model replicated the evolution of meandering channels from mildly to highly sinuous ones. Simulation results showed the migration of meandering channel is a combination of downstream translation, lateral extension, expansion, and downstream and upstream rotation. Low-sinuous free meanders migrate rapidly toward downstream. As the sinuosity increases, downstream translation diminishes, and meandering loops expand laterally with its head rotating toward downstream and then upstream. The simulated results indicated the gradient of the longitudinal sediment transport rate is essential in modeling meandering evolution. © 2006 International Association of Hydraulic Engineering and Research.
• Duan, J. G. (2006). Closure to " simulation of flow and mass dispersion in meandering channels" by Jennifer G. Duan. Journal of Hydraulic Engineering, 132(3), 341-342. doi:10.1061/(asce)0733-9429(2006)132:3(341)
• Duan, J. G., & Chen, D. (2006). Modeling width adjustment in meandering channels. Journal of Hydrology, 321(1), 59-76. doi:10.1016/j.jhydrol.2005.07.034
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  Widening in sinuous channels occurs when the retreat of the outer bank exceeds the advance of the opposite bank. An analytical model is presented to simulate width adjustment in meandering channels of non-cohesive bank material resulting from bank erosion of two interactive processes: basal erosion and bank collapse. Bank collapse refers to the avalanche of non-cohesive material in the upper part of bank above water surface resulting from over-steepening of the bank surface due to basal erosion. The rate of basal erosion, including lateral erosion and bed degradation, is calculated as a function of the longitudinal gradient of sediment transport rate and strength of secondary flow. The transverse bed slope is treated as a variable that increases as channel sinuosity increases until the transverse bed slope reaches its maximum value. By simplifying the bank-collapse process for non-cohesive materials, the present study shows that the rate of bank-line retreat is determined by lateral erosion rate, near-bank bed-degradation rate, sediment grain size, and difference between flow depth and bank height. The time-dependent widening processes of two meandering channels in the laboratory are selected to test applicability of the model. The result shows that the simulated bank lines at individual time intervals closely match the experimental measurements. Whether the sinuosity of a meandering channel will increase or decrease is primarily determined by didtribution of the lngitudinal gradient of sediment transport rate along the channel.
• Duan, J. G., & Nanda, S. K. (2006). Two-dimensional depth-averaged model simulation of suspended sediment concentration distribution in a groyne field. JOURNAL OF HYDROLOGY, 327(3-4), 426-437.
• Duan, J. G., Barkdoll, B., & French, R. (2006). Lodging Velocity for an Emergent Aquatic Plant in Open Channels. Journal of Hydraulic Engineering, 132(10), 1015-1020. doi:10.1061/(asce)0733-9429(2006)132:10(1015)
• Duan, J. G., Barkdoll, B., & French, R. (2006). Lodging velocity for an emergent aquatic plant in open channels. JOURNAL OF HYDRAULIC ENGINEERING-ASCE, 132(10), 1015-1020.
• Duan, J. G., Chen, L. i., & Scott, S. (2006). Application of surface-based bed load transport equations to a desert gravel-bed stream. JOURNAL OF HYDRAULIC RESEARCH, 44(5), 624-630.
• Duan, J. G., Chen, L., & Scott, S. (2006). Application of surface-based bed load transport equations to a desert gravel-bed stream. Journal of Hydraulic Research, 44(5), 624-630. doi:10.1080/00221686.2006.9521712
• Duan, J. G. (2005). Analytical Approach to Calculate Rate of Bank Erosion. Journal of Hydraulic Engineering, 131(11), 980-990. doi:10.1061/(asce)0733-9429(2005)131:11(980)
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  Bank erosion consists of two processes: basal erosion due to fluvial hydraulic force and bank failure under the influence of gravity. Because bank resistance force varies with the degree of saturation of bank material, the probability of bank failure is the probability of the driving force of bank failure being greater than the bank resistance force. The degree of saturation of bank material increases with river stage; therefore, the frequency of bank failure is correlated to the frequency of flooding. Consequently, the rate of bank erosion is due to both basal erosion and bank failure, and bank failure is a probabilistic phenomenon. In this paper, for cohesive bank material experiencing planar bank failure, a deterministic approach was adopted for basal erosion analysis, whereas the probability of bank failure was included in the analysis of bank failure. A method for calculating the rate of bank erosion was derived that integrates both basal erosion and bank failure processes, and accounts for the effects of hydraulic force, bank geometry, bank material properties, and probability of bank failure.
• Julien, P. Y., & Duan, J. G. (2005). Numerical simulation of the inception of channel meandering. Earth Surface Processes and Landforms, 30(9), 1093-1110. doi:10.1002/esp.1264
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  The inception of channel meandering is the result of the complex interaction between flow, bed sediment, and bank material. A depth-averaged two-dimensional hydrodynamic model is developed to simulate the inception and development of channel meandering processes. The sediment transport model calculates both bedload and suspended load assuming equilibrium sediment transport. Bank erosion consists of two interactive processes: basal erosion and bank failure. Basal erosion is calculated from a newly derived equation for the entrainment of sediment particles by hydrodynamic forces. The mass conservation equation, where basal erosion and bank failure are considered source terms, was solved to obtain the rate of bank erosion. The parallel bank failure model was tested with the laboratory experiments of Friedkin on the initiation and evolution processes of non-cohesive meandering channels. The model replicates the downstream translation and lateral extension of meandering loops reasonably well. Plots of meandering planforms illustrate the evolution of sand bars and redistribution of flow momentum in meandering channels. This numerical modelling study demonstrates the potential of depth-integrated two-dimensional models for the simulation of meandering processes. Copyright © 2005 John Wiley & Sons, Ltd.
• Barkdoll, B., Duan, J., Fan, S., Klumpp, C., McAnnally, B., Papanicolaou, T., Scott, S., Wang, S., Wu, W., & Ying, X. (2004). Computational Modeling of Sediment Transport Processes. Journal of Hydraulic Engineering, 130(7). doi:10.1061/(ASCE)0733-9429(2004)130:7(597)
• Duan, J. G. (2004). Discussion of ''Three-Dimensional CFD Modeling of Self-Forming Meandering Channel'' by Nils Reidar B. Olsen. Journal of Hydraulic Engineering, 130(8), 837-838. doi:10.1061/(asce)0733-9429(2004)130:8(837)
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  The paper presented the computational simulation of a selfforming meandering channel from an initially straight channel with a three-dimensional computational fluid dynamics ~CFD! model. The simulated meandering channel wavelength and magnitude are closer to the experimental results ~Friedkin 1945! as compared to the simulated results with an enhanced 2D model ~Duan et al. 2001!. However, the discusser feels that the simulated results will be more convincing if the author explained in detail the approaches in calculating suspended sediment and bedload transport and plotted the simulated velocity vector field and bed topographic configurations shown in Fig. 7. In Eq. ~1!, the author set the suspended sediment diffusion coefficient equal to the eddy viscosity taken from the k‐« model. Studies have shown that the mass diffusion coefficient can be expressed as G5v t /s c , in which v t5eddy viscosity, and s c5turbulent Schmidt number, which represents the ratio of eddy viscosity to eddy diffusivity. A value of s c50.5 has been found suitable in previous calculations of pollutant spreading in an open channel ~Rastogi and Rodi 1978!. Ye and McCorquodale ~1997! have used s c50.15 in the simulation of pollutant dispersion with a depth-averaged 2D model. With respect to suspended sediments, the mass diffusion coefficient is equal to the eddy viscosity only when the Schmidt number equals 1.0, which is not true based on previous studies ~Rastogi and Rodi 1978; Ye and McCorquodale 1997!. In particular, the mass diffusion coefficient for suspended sediments in the vertical direction « z is much larger than that in the horizontal direction and relates to the fluid momentum diffusion ~van Rijn 1984! as follows:
• Duan, J. G. (2004). Simulation of flow and mass dispersion in meandering channels. Journal of Hydraulic Engineering, 130(10), 964-976. doi:10.1061/(asce)0733-9429(2004)130:10(964)
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  This paper reports the development of an enhanced two-dimensional (2D) numerical model for the simulation of flow hydrodynamics and mass transport in meandering channels. The hydrodynamic model is based on the solution of the depth-averaged flow continuity and momentum equations where the density of flow varies with the concentration of transported mass. The governing equation for mass transport model is the depth-averaged convection and diffusion equation. The dispersion terms arisen from the integration of the product of the discrepancy between the mean and the actual vertical velocity distribution were included in the momentum equations to take into account the effect of secondary current. Two laboratory experimental cases, flow in mildly and sharply curved channels, were selected to test the hydrodynamic model. The comparison of the simulated velocity and water surface elevation with the measurements indicated that the inclusion of the dispersion terms has improved the simulation results. A laboratory experiment study of dye spreading in a sine-generated channel, in which dye was released at the inner bank, centerline, and outer bank, respectively, was chosen to verify the mass transport model. The simulated concentration field indicated that the Schmidt number can be used as a calibration parameter when dispersion is computed using a 2D approach with a simplified turbulence model.
• Miller, J., French, R. H., & Duan, J. G. (2002). The Lodging Velocity for Emergent Aquatic Plants in Open Channels. Journal of The American Water Resources Association, 38(1), 255-263. doi:10.1111/j.1752-1688.2002.tb01549.x
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  : The growth of aquatic plants in open-channels has many adverse environmental effects including, but not limited to, impeding the transport of water, hindering navigation, increasing flood elevations, increasing sediment deposition, and degrading water quality. Existing control strategies include physical removal and chemical treatment. Physical removal is only a temporary solution and chemical treatment is unacceptable if the water will be consumed by humans. The hydrodynamic method can wash out the encroached aquatic plants by keeping flow velocity higher than the critical velocity required to bend and rupture (lodge) their stems. This approach is a promising, physically-based, efficient, economic, and permanent solution for this problem. However, the success of this approach requires the accurate prediction of the critical lodging velocity. This paper presents an analytic study of the lodging velocity for the submerged portion of aquatic plants of narrow leaved emergent stems that are wider at bottom than the top. Based on the principles of engineering materials and the theory of turbulent flow, a semi-empirical formula is derived for the prediction of the critical lodging velocity. It indicates that the lodging of aquatic plants is controlled not only by flow conditions but also the geometric and mechanical characteristics of the plants. These analytic results provide a satisfactory explanation of the lodging phenomena observed in the field and are verified by the available experimental data.
• Duan, J. G. (2001). Numerical Analysis of River Channel Processes with Bank Erosion. Journal of Hydraulic Engineering, 127(8), 702-703. doi:10.1061/(asce)0733-9429(2001)127:8(702)
• Duan, J., Wang, S., & Yafei, J. (2001). The applications of the enhanced CCHE2D model to study the alluvial channel migration processes. Journal of Hydraulic Research, 39(5). doi:10.1080/00221686.2001.9628272
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  This paper is to report a newly developed numerical-empirical model, the Enhanced CCHE2D (EnCCHE2D), and its application to simulating the alluvial channel migration phenomena. EnCCHE2D model is capable of predicting quasi-three-dimensional (3D) flow field and shear stress distribution on the bed, because a set of empirical functions of 3D flow characteristics formulated by results of a 3D model, CCHE3D, was integrated with CCHE2D, a depth-averaged hydrodynamic model, the predecessor of EnCCHE2D. The processes of sediment transport and meander migration were predicted based on these quasi-3D flow solutions. The advance or retreat of bank is calculated by considering not only the hydraulic erosion of bank surface and toe, but also the mass balance of sediment flux in the near-bank zone. As a result, the simulation of bank erosion, bar/pool formation and shifting, bank advance and retreat, channel widening and migration and meander evolution phenomena agree well with the available measurements of physical experiments.
• Wang, S. S., Jia, Y., & Duan, J. G. (2001). The applications of the enhanced CCHE2D model to study the alluvial channel migration processes. Journal of Hydraulic Research, 39(5), 469-480. doi:10.1080/00221686.2001.9628272
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  This paper is to report a newly developed numerical-empirical model, the Enhanced CCHE2D (EnCCHE2D), and its application to simulating the alluvial channel migration phenomena. EnCCHE2D model is ca...
• Duan, G., Jia, Y., & Wang, S. S. (1998). Bed shear stress in sine-generated channels. International Water Resources Engineering Conference - Proceedings, 2, 1374-1379.
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  Abstract: In this paper, shear stress on the bed of sine-generated channels is studied by using a three dimensional hydrodynamic model (CCHE3D). Predictions of the shear stress distribution from CCHE3D are compared with experimental data measured in sine-generated curved channels. Both the simulation and the measurement show that the distribution pattern of bed shear stress is strongly affected by channel sinuosity, while the magnitude of bed shear stress is a function of channel sinuosity and bed relative roughness.
• Duan, G., Ligeng, L. i., & Wang, S. S. (1998). Two-dimensional bank erosion model for noncohesive bank material. International Water Resources Engineering Conference - Proceedings, 2, 1398-1403.
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  Abstract: Bank erosion happens frequently in alluvial channels, which may cause serious economic and environmental problems, such as land loss, channel sedimentation and property damage. Due to its complexity, even though extensive research has been done in the past, it is still difficult to predict bank erosion. Therefore, a two dimensional numerical model has been developed to simulate the bank erosion processes by using computer. The model is based on a hydrodynamic model CCHE2D developed in the Center for Computational Hydroscience and Engineering, the University of Mississippi. In CCHE2D, depth averaged Navier-Stokes equations were solved by finite element method to obtain the depth averaged flow properties. Boundary shear stress is calculated by the flow model. From the boundary shear stress, bed load transport rate is computed. Assuming bed load only, the sediment continuity equation is solved numerically. Bank erosion is then related with the vertical erosion at the bank toe. The model has been validated against a physical experiment conducted by Ikeda (1981), and good agreements are observed.
• Duan, G., & Wang, G. (1995). Experimental study on bed forms and flow resistance of light-weight materials with different densities. Journal of Hydrodynamics, 7(1), 58-65.
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  Abstract: Experiments were conducted to investigate the bed form and flow resistance of the light-weight sediment in an open channel flow. Three different synthetic materials with specific gravity 1.055, 1.46 and with uniform sizes D50 1.25mm, 1.05mm, 1.40mm were used. Some conclusions were obtained from experimental results and the data of other reliable references. The conclusions indicate that the grain resistance is greatly affected by D50, and the bed form resistance is the function of the downstream slope and height of dune As well as natural sand, Y is not only the function of Y', but also affected by the relative roughness Rb/D50 and the size of used sediment.

Proceedings Publications

• Duan, J. G., & Qi, K. (2023, August). Case study: sediment transport simulation at Munds Draw watersheds. In 40th IAHR Congress, Vienna, Austria.
• Duan, J. G., & Zhou, K. (2023, August). Turbulence flow field and local scour around three-pier group. In Proceedings of 40th IAHR Congress, Vienna, Austria.
• Duan, J., & Zhou, K. (2023, August). Turbulence Flow Field and Local Scour around Three-Pier Group. In Proceedings of the 40th IAHR World Congress.
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  This paper presented the experimental results of flow field measurements using Acoustic Doppler Vectrino Profiler around a three-pier group. The piers were spaced at one and five times the pier diameter, and the attacking angles were set at 0 and 30o, respectively, to study the effect of pier spacing and attack angle on turbulence flow field. The distribution of flow velocity vectors and turbulence intensities were analyzed in both the horizontal and vertical planes. A strong sheltering effect from the upstream pier in a tandem alignment was observed when piers spacing is small. The horseshoe vortices around the middle and downstream piers were enhanced when the piers were in a staggered alignment. The distributions of bed shear stress showed that when the scour reached equilibrium, bed shear stress in the scour hole is smaller than that of the approaching flow.
• Qi, K., & Duan, J. G. (2023). Case Study: Surface Runoff Simulation Using HMS for Arid Watershed. In ASCE EWRI Congress 2023 In Las Vegas, Nevada.
• Qi, K., & Duan, J. G. (2023, May). Case Study: Surface Runoff Simulation using HMS for Arid Watershed. In 2023 EWRI World Environment and Water Resources Congress: Adaptive Planning and Design in an Age of Risk and Uncertainty., 1, 1242-1250.
• Shim, J., Shim, J., Jo, H., & Duan, J. G. (2019). APPLICATION OF SMOOTHED PARTICLE HYDRODYNAMICS MODEL TO SIMULATE PIER SCOUR IN LABORATORY DAM BREAK FLOW. In 38th IAHR World Congress - "Water: Connecting the World".
• Duan, J. G., Jo, H., Shim, J., & Ahamed, T. (2018, March). Flood fragility analysis of instream bridges. In SPIE Smart Structures/NDE.
• Zhou, K., Duan, J. G., Rosenberg, A., & Shim, J. (2018, Jan). Application of KINEROS2 for Simulating Surface Runoff and Sediment Yield in Desert Watershed. In 18th World Environmental and Water Resources Congress 2018, 489-497.
• Duan, J. G., Jo, H., Jeong, J., Shim, J., & Ahamed, T. (2017, May). Advanced signal processing of sonar measurement for bridge scour monitoring. In the World Environmental and Water Resources Congress.
• Duan, J. G., Poteuck, M., Rosenberg, A., & Zhou, K. (2017). Simulating Watershed Erosion in BMGR Using AGWA Model. In ASCE EWRI 2017 World Environment and Water Resources Congress.
• Ahamed, T., Shim, J., Jo, H., & Duan, G. (2016). Feasibility Test of Low-Cost Sonar Sensors for Bridge Scour Monitoring. In World Environmental and Water Resources Congress 2016.
• Jo, H., Duan, J. G., & Shim, J. (2016, Spring). Simulating Sediment Transport around a Bridge Pier Using Open FOAM Software. In World Environmental and Water Resources Congress.
• Touhid, A., Shim, J., Jo, H., & Duan, J. G. (2016, Spring). Feasibility Test of Low-cost Sonar Sensors for Bridge Scour Monitoring. In World Environmental and Water Resources Congress.
• Duan, J. G., & Bai, Y. (2015). Using a two-dimensional watershed model to estimate flood magnitude and frequency under changing climate. In World Environmental and Water Resources Congress 2015, 1163-1172.
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  A two-dimensional physical based hydrodynamic watershed model, HydroSed2D, was used to estimate the impact of climate change on flood magnitude and frequency in the Upper Santa Cruz River Watershed (USCRW) in the Southern Arizona. Hourly precipitation data from a Regional Climate Model (RCM), Weather Research and Forecasting model (WRF), for three periods, 1990-2000, 2031-2040 and 2071-2079, were used to quantify the impact of climate change on flood. Precipitation outputs from RCM-WRF model were bias-corrected using observed gridded precipitation data for three periods before directly used in the watershed model. The calibrated watershed model was applied to USCRW for simulating surface flow routing for the selected three periods. Simulated discharges are analyzed to obtain future flood magnitude and frequency curves. Results indicate that flood discharges for different return periods are increased: the discharges of 100-year and 200-year return period are increased by 3,000 and 4,000 cfs, respectively.
• Shim, J., & Duan, J. (2015). Stochastic properties of bed load transport. In World Environmental and Water Resources Congress 2015.
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  The fluctuation of bed-shear stress on moving bed load particle plays an important role in the particle velocity. Our theoretical model treated the instantaneous bed-shear stress as a log-normal distribution, and developed a theoretical model to calculate the spatially averaged particle velocity and its distribution. A series of experiments were conducted in an open channel flume to measure instantaneous bed load particle velocities using the image based bed load analyzer. The instantaneous bed load particle velocities were measured in both the streamwise and the transverse directions. A total of 26 experimental runs were performed, and over 1,000 instantaneous particle velocities in the horizontal plane were measured. Results showed that the bed load particle velocity relates to the instantaneous bed-shear stress, which satisfies a log-normal distribution. The spatially averaged streamwise mean velocity is a function of mean bed shear stress and particle size. The probability density function (PDF) of the streamwise particle velocity is an exponential function, and the PDF of transverse particle velocity is a normal distribution. Bed-shear stress affects both the particle velocity distribution and the peak intensity. At last, the measurements were used to verify a theoretical model for the particle velocity and its distribution. Reasonable agreements were found between model's predictions and the experimental measurements.
• Al-Asadi, K., & Duan, J. G. (2014). Three-Dimensional Simulation of Tidal Flow in Vegetated Marsh Area. In World Environmental and Water Resources Congress 2014.
• Yu, C., & Duan, J. G. (2014). Modeling Meandering Channel by Two-Dimensional Shallow Water Equations. In AGU Fall Meeting Abstracts, 1.
• Yu, C., & Duan, J. G. (2014). Two-Dimensional Finite Volume Model for Sediment Transport in Unsteady Flow. In World Environmental and Water Resources Congress 2014.
• Duan, J. G. (2013). A Simple Total Sediment Load Formula. In World Environmental and Water Resources Congress 2013, 1942-1950.
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  Prediction of total sediment load has been a challenge to river engineers for decades. Two approaches are typically used: One is to directly calculate the total sediment load from measured flow and sediment properties, and the other is to separate total sediment load into bed load and suspended load and calculate them independently. Because the criteria that separate bed load and suspended load is still a debatable subject, practical engineers prefer to use the total load equation for estimating sediment load. However, there are more than 31 equations for calculating total sediment load, and the discrepancies of those equations are in the orders of magnitude. To obtain a general equation, this study analyzed more than 4,000 sets of laboratory experimental and 3,000 sets of field measurements of total sediment load. Based on the dimensional analysis, eight new dimensionless parameters are formulated to quantify total sediment load. Correlations of dimensionless total sediment load with those new and other conventional parameters are calculated using the observed data. The highest correlation, 0.94, was found between the dimensionless total sediment load and a new dimensionless parameter, τ* (u* - u*c) / ω , in which u* is shear velocity, ω is settling velocity, and τ* is dimensionless shear stress. A simplified power-law relation is formulated from fitting the measured data. This new relation is compared with the commonly used total sediment load relation, such as Engelund-Hansen (1967), Ackers-White (1972), Yang (1973, 1979). Results showed the new simplified equation yielded the best matches of this set of total sediment load data.
• Duan, J. G., Yu, C., Duan, J. G., & Yu, C. (2013, Sept). Two Dimensional Finite Volume Model for Overland and Channel Flow Simulation. In Proceedings of 35th IAHR conference.
• Shim, J., Shim, J., & Duan, J. G. (2013). Experiment study of bed load particle velocity. In World Environmental and Water Resources Congress 2013, 1962-1970.
• Yu, C., & Duan, J. (2013, May). A surface flow routing algorithm based on shallow water equation with kinematic wave approximation. In World Environmental and Water Resources Congress 2013: Showcasing the Future.
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  A two-dimensional numerical model is developed to simulate turbulent shallow-water flow. The model is based on two-dimensional depth-averaged Navier-Stokes equations. A second-order Godunov-type upwind finite volume scheme with augmented HLLC Riemann solver is implemented. The conservative variables near the edges of cells are linearly reconstructed by the MUSCL scheme. The reconstructions are based on the primitive variables. The time marching scheme is a second-order TVD Runge-Kutta scheme, which can prevent the occurrence of oscillation in every intermediate stage. The model uses first-order approximations for the wet-dry fronts and boundaries, which make the solution as robust as possible. An additional flux is calculated to keep the scheme well balanced. To provide body-fitted mesh, the Cartesian cut-cell method is adopted. The κ - ε turbulence model is implemented as the turbulence model closure. The model is tested against several laboratory experiments and field measurements. In all test cases, the simulated results agree well with the observations. © 2013 American Society of Civil Engineers.
• Duan, J. G., & Acharya, A. (2011). Three dimensional simulation of flow field around series of spur dikes. In World Environmental and Water Resources Congress 2011, 2085-2094.
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  Erosion of the banks and bed of natural and manmade channels is a common problem in water resources management. Spur dikes in rivers and streams such as the Mississippi River are used to prevent bank erosion and to keep the main channel navigable. Scour around these dikes can be a serious problem, weakening structural stability. Three-dimensional models are often used in engineering design to determine mean and turbulence flow field around these dikes. However, a universal turbulent model that is valid for all cases of turbulent flow in open channels currently does not exist. Some turbulent closures offer advantages over others in specific turbulent flow fields depending on the nature of turbulence. Therefore, a three-dimensional numerical model, FLOW-3D, is used to simulate the turbulent flow field around a series of three spur dikes in flat and scoured bed. This study examined one equation mixing length model, standard two-equation e − k model, Renormalization Group (RNG) e − k model and Large Eddy Simulation (LES) model. Experimental data from a laboratory study of flow in a flat bed and scoured bed around a series of three dikes were used to verify the results from the numerical model. Although the simulated mean flow field is close to the experimental data, the simulated turbulence properties from different turbulent model deviate considerably. Modeling results using the standard e − k model showed over 50% discrepancy from the measured turbulent kinetic energy. The RNG e − k model yielded better results of both mean flow field and turbulence kinetic energy for the flat bed surface and scoured bed surface. Based on these results, this study recommends the use of RNG e − k model for simulating mean flow field around dikes. Further improvements of FLOW-3D model is needed for predicting turbulence properties (e.g. TKE) near this series of spur dikes under various flow conditions.
• Duan, J., & Yu, C. (2011, May). Depth-averaged two dimensional model using cartesian cut-cell approach. In World Environmental and Water Resources Congress 2011: Breaking Knowledge for Sustainability.
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  A two-dimensional numerical model was developed for simulating free surface flow. The model is based on the solutions of two-dimensional depth averaged Navier-Stokes equations. A finite volume method is applied such that mass conservation is satisfied both locally and globally. The model adopted the two-step, high resolution MUSCL-Hancock scheme. This Godunov type scheme is used together with the approximate Riemann solver. The boundary cells are treated as cut-cells in order to accommodate arbitrarily geometries of natural rivers. An automatic wet-cell cutting algorithm is incorporated into the model so that the wet areas cut out of the mesh have cut-cells representing their boundaries. There are sixteen types of cut-cells depending on the slope of the boundary intersection with the cell. A cell merging technique is incorporated in the model that combines small cells with neighboring cells to create a larger cell that helps satisfying the CFL condition. The cut-cells approach permits a fully boundary-fitted mesh without implementing a complex mesh generation procedure for irregular geometries. The model is verified by several laboratory experiments including unsteady flow passing through cylindrical piers and dam break flow in a rectangular channel. © 2011 ASCE.
• Hummel, R., & Duan, J. G. (2011). Modeling Sediment Transport in the Pantano Wash, Tucson. In World Environmental and Water Resources Congress 2011, 4246-4254.
• Fu, X., Wang, G., He, L., Fu, X., & Duan, J. G. (2010). Turbulent burst around experimental spur dike.. In World Environmental and Water Resources Congress 2010, 1702-1711.
• Yaeger, M., & Duan, J. (2010). Mean flow and turbulence around two series of experimental dikes. In World Environmental and Water Resources Congress 2010: Challenges of Change.
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  Scour around various structures obstructing flow in an open channel is a common problem; therefore a better understanding of how turbulent flow affects sediment transport is needed. Additionally, is it the mean flow or the turbulence properties that are more important in contributing to bed shear stress? To this end, an experimental study was conducted in a fixed-bed flume containing a series of dikes. Turbulence intensities and Reynold's stresses were calculated from 3-D velocity measurements gathered with a microADV. Results showed that the maximum shear stress was nearly 12-20 times that of the approach flow, while maximum turbulence intensities were about 3-5 times those of the incoming flow. Highest magnitudes of both were seen at the tip of the second dike in the three-dike series. The mean velocity appeared to have no relation to the formation of scour near the tips of the dikes but the turbulence intensities did. © 2010 ASCE.
• Zhang, S., Strelkoff, T. S., & Duan, J. G. (2010). Simulation of unsteady flow and soil erosion in irrigation furrows.. In World Environmental and Water Resources Congress 2010, 2080-2089.
• Duan, J., & He, L. (2009, May). Comparison of mean flow and turbulence around experimental spur dike. In World Environmental and Water Resources Congress 2009: Great Rivers.
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  An acoustic Doppler velocimeter was used to measure flow and turbulence around an experimental spur dike in a flat and a scoured bed. Differences of mean velocity, turbulent intensity and Reynolds stresses between these two flow fields were compared and analyzed. Upon the formation of scour hole, mean flow velocities in the downstream and lateral directions were reduced, but increased in the vertical direction. The turbulence intensities (u' and v') are much larger, and the vertical component (w') is smaller than that in the flat bed. Bed shear stresses determined from near-bed Reynolds stresses in the scoured bed were smaller than that in the flat bed. These results indicated that local scour has not only significantly reduced bed shear but also contributed to the increase of turbulence intensities in the scouring zone. © 2009 ASCE.
• Yeager, M., Duan, J. G., & Acharya, A. (2008). Sediment Sorting around Experimental Spur Dike. In World Environmental and Water Resources Congress 2008, 1-11.
• Zhang, S., Yaeger, M. A., Duan, J. G., & Acharya, A. (2008). Evaluation of Flow and Sediment Models for the Rillito River. In World Environmental and Water Resources Congress 2008, 1-10.
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  Hydrodynamic and sediment transport models are useful engineering tools for predicting flood flow. Many models such as HEC-RAS, HEC-6, IALLUVIAL, SRH-1D were developed for perennial rivers, and may not be suitable to ephemeral rivers in arid and semi-arid regions. This paper outlines a comparison study that examined the water surface and bed elevations of a flood event exceeding 100-year flood in the Rillito River at Tucson, Arizona. The result of IALLUVIAL2, HEC-RAS and GSTAR1D models were compared with field survey data. Results showed that IALLUVIAL2, which cannot compute bridge effects, predicted a flood similar to that of the more commonly used HEC-RAS model, which take bridges into account. Both models underestimated the flooding by about 2 to 4 feet, but accurately predicted the progression of each flood flow. This study also found the most appropriate sediment transport and roughness equations for this particular river are Laursen sediment equation and Manning's relation. The results indicated the need of an appropriate model for predicting flood flows in ephemeral streams for water resource managers, engineers, and urban planners.
• Chen, D., Zhang, Y., Duan, J., Stone, M., & Acharya, K. (2007, May). Two-dimensional simulation of hydrodynamic and sediment transport in a gravel bed channel: The Salt River. In World Environmental and Water Resources Congress 2007: Restoring Our Natural Habitat.
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  Flow hydraulics, sediment transport, and channel morphological changes of the Rio Salado, Salt River, Phoenix, Arizona were simulated using CCHE2D, a depth-averaged two-dimensional hydrodynamic and sediment transport model developed at the National Center for Computational Hydro-Science and Engineering at the University of Mississippi. The bed material was treated as multiple grain-sized sediment mixtures and simulated by a sediment transport module. Changes in bed elevation were calculated by solving the sediment mass conservation equation. The calculated results were compared with HEC-RAS results and field observation, which showed that the two-dimensional model was more applicable in simulating flood zone coverage, non-uniform sediment sorting and channel geomorphology changes. © 2007 ASCE.
• Duan, J., Chen, D., Jen, W., & Benoit, T. (2007, May). Two-dimensional simulation of flow hydraulics and bed-load transport in a mountain gravel-bed stream: The upper Spanish Creek. In World Environmental and Water Resources Congress 2007: Restoring Our Natural Habitat.
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  Sediment transport in a gravel-bed mountain stream, the Upper Spanish Creek, California, was simulated with a depth-averaged, two-dimensional hydrodynamic and sediment transport model. The hydrodynamic model is based on the solution of depth-averaged flow continuity and momentum equations with dispersion terms to account for the effect of secondary flow. The sediment transport model treats bed load and bed material as mixtures of multiple grain-size sediment. Changes in bed elevation are calculated by solving the sediment mass conservation equation. The model was applied to predict bed-load transport in the Upper Spanish Creek to identify areas of high-erosive potential that require bank protections. Results of this verification process demonstrated the applicability of the two-dimensional hydrodynamic and sediment transport model to assist river restoration designs for gravel-bed streams. © 2007 ASCE.
• Duan, J. G. (2006). Three-dimensional Mean Flow and Turbulence around a Spur Dike. In World Environmental and Water Resource Congress 2006, 1-9.
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  This paper presents an experimental study conducted at the St. Anthony Falls Laboratory, University of Minnesota. Flow field at the neighborhood of a spur dike was measured by using a SonTek 10 MHz Acoustic Doppler Velocimeter (ADV). Timehistory of velocities in all three spatial dimensions was recorded at 650 nodes near the dike. The time-averaged mean velocity and Reynolds stresses were calculated from the measurements. The results showed two counter-rotating secondary flow cells formed immediately downstream of the dike. The secondary flow cell at one side of the channel having the dike grows gradually, while the other cell decades until separated flows rejoin. These measurements clearly demonstrated the spatial distributions of turbulent normal stresses and Reynolds stresses. Additionally, bed shear stresses were calculated by using mean flow and turbulence Reynolds stresses. Bed shear stresses calculated by using Reynolds’ stresses are more accurate for approximating bed shear stresses field around the dike.
• Duan, J. G. (2006). Unsteady flow simulation of alternative bars in a semi-circle bend. In 4th IAHR Symposium on River, Coastal and Estuarine Morphodynamics, RCEM 2005, 2.
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  Non-uniform sediment transport through a semi-circle channel was simulated with a depthaveraged two-dimensional hydrodynamic and sediment transport model. The hydrodynamic model is based on the solution of depth-averaged flow continuity and momentum equations with dispersion terms to take the effect of secondary flow into account. The sediment transport model treats bed load and bed material as multiple grainsized sediment mixtures. Changes in bed elevation are calculated by solving the sediment mass conservation equation. Laboratory experiments on sand bar formation and transverse sediment sorting during an unsteady flow event were selected to test the sediment transport model. The comparison of the simulated bar/pool bed configurations and the distribution of surface bed material with the measurements indicated the developed flow model capable of simulating bed topography and non-uniform sediment sorting under unsteady flow. © 2006 Taylor & Francis Group.
• Duan, J. G., & Chen, D. (2006). Modeling Channel morphologic Change in the West Jordan River, Utah. In World Environmental and Water Resource Congress 2006, 1-10.
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  Many existing river morphological models are limited by their inability to account for erodible banks. In this study, the sediment continuity equation was solved to determine the rate of bed degradation and aggradation. The rate of bank erosion was calculated by determining bed degradation, lateral erosion, and bank failure. To be applicable to the West Jordan River, two layers in the bank surface were considered herein. This bank erosion model distinguishes itself from other models by relating bank erosion rate with not only flow but also sediment transport near the bank. Additionally, bank height, slope, vegetation, and thickness of each layer in the bank surface were considered. For the purpose of long-term simulation, decoupling technique is used among the flow, sediment transport, and bank erosion models. Furthermore, a new technique of computational mesh adjustment was also put forward. The developed model was then applied to simulate the processes of meandering migration in the study reach from 1981 to 1992. The reasonable agreements between simulated results and the available observations indicate the capability of this model in simulating channel morphologic change in the West Jordan River, Utah.
• Julien, P. Y., & Duan, J. G. (2006). Numerical simulation of meandering evolution. In World Environmental and Water Resource Congress 2006.
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  A two-dimensional depth-averaged hydrodynamic model is developed to simulate the evolution of meandering channels from the complex interaction between downstream and secondary flows, bed load and suspended sediment transport, and bank erosion. The depth-averaged model calculates both bed load and suspended load assuming equilibrium sediment transport and simulates bank erosion with a combination of two interactive processes: basal erosion and bank failure. The mass conservation equation is solved to account for both vertical bed-elevation changes as well as lateral migration changes when sediment is removed through basal erosion and bank failure. The numerical model uses deformable elements and a movable grid to simulate the gradual evolution of a near-straight deformable channel into a highly sinuous meandering channel. The model correctly replicates the different phases of the evolution of free meandering channels in experimental laboratory settings including: (1) downstream and upstream migration; (2) lateral extension; and (3) rotation of meander bends.
• Duan, J. G. (2005). Two-Dimensional Model Simulation of Flow Field around Bridge Piers. In Impacts of Global Climate Change, 1-12.
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  Two-dimensional (2D) depth-averaged hydrodynamic model was applied to simulate flow field around a circular pier in clear water. A correction factor was included in the friction term to take account of the effect of streamline curvature due to flow separation and vortex shedding. In this study, 2D model simulates not only the vortex shedding in the turbulence wake but also bed shear stress distribution. The simulated bed shear stress contours were close to experimental measurements and three-dimensional (3D) modeling results. Since 2D model is much simpler and requires significantly less computational time than three-dimensional model, these results demonstrated that an improved 2D model is a capable tool of simulating bed shear stress distribution around bridge piers. Research in enhancing and applying 2D model to simulating the initiation and development of local scour is still a challenging topic for hydraulic engineers.
• Chen, D., & Duan, J. G. (2004). Simulation of meandering channel evolution with an analytical model. In 2004 World Water and Environmental Resources Congress: Critical Transitions in Water and Environmental Resources Management.
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  Bank retreat rate, the receding rate of bank top-lines through basal erosion and bank failure, was calculated based on the analysis of bank stability and sediment mass conservation near banks. This study indicated that the gradient of sediment transport rate in the longitudinal direction and the strength of secondary flow determined the rate of bank retreat. An analytical model was developed based on this result and applied to simulating the evolution of sine-generated meandering channels. Not like the conventional methods which assumed that the rate of bank retreat was proportional to the magnitude of excessive near-bank velocity or shear stress, this approach in simulating bank retreat and meandering channel evolution has advantages by taking into account the gradient of longitudinal velocity and the strength of secondary flow, and will avoid the estimation of the erodibility coefficient in traditional bank erosion models.
• Schwar, M. T., & Duan, J. G. (2003). Modeling of Flow and Sediment Transport at a River Confluence with the EnSed2D model. In World Water & Environmental Resources Congress 2003, 1-10.
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  This paper summarized the results of computational modeling study for the confluence of the Kankakee and the Iroquois Rivers. This project aims to study the effectiveness of engineering alternatives on reducing sedimentation at the confluence. The hydraulics and sediment transport patterns of three management scenarios, which are keeping natural situation without engineering structures, constructing three short dikes at the left banks of the Kankakee River, and constructing three longer dikes at the left banks are studied by applying the EnSed2D model. The sediment transported in the Kankakee and the Iroquois Rivers are primarily suspended sediment. Channel bed has a thin layer of bed material, and occasionally bed rocks are exposed. Therefore, this study focused on the simulation of suspended sediment transport in the system. Two methods were applied to simulating suspended sediment deposition and erosion processes. One method assumes that bed material layer is too thin to allow suspended sediment concentration reach equilibrium at the bottom that only deposition occurs, the other method assumes there is a sufficient amount of sediment that can be entrained from channel bed so that the change of bed elevation is the difference between the rate of deposition and entrainment. The simulated results showed that if there is no entrainment, there is no scour in front of the dikes, while if there is an entrainment, the scouring in front of dikes are very apparent. In case of no construction methods, the deposition at the confluence will spread all over the confluence as well as its immediate downstream. The construction of three short dikes will reduce the deposition of suspended sediment at the confluence and facilitate the passage of suspended sediment from the Iroquois River to the Kankakee River. But, the increasing of dike lengths will potentially block flow from the Iroquois River to the Kankakee River, and worsen deposition at the confluence. Therefore, the results of this study recommended that dikes with a reasonable length could be the most cost-effective alternative to reduce sedimentation at the confluence. The locations, alignments, and dimensions of these dikes should be determined through another detailed computational modeling study. To insure the mechanical stability and minimize the negative environmental effect of these dikes, flow hydrodynamics and sediment transport at the near dike region should be investigated by applying an advanced computational model or conducting physical laboratory experiment.
• French, R. H., & Duan, J. G. (2001). Simulation of Meandering Channel Migration Processes with an Enhanced Two-Dimensional Numerical Model. In Bridging the Gap, 1-10.
• Duan, J. G. (2000). Assessment of non-point source sediment load from the California portion of the Truckee River watershed. In Building Partnerships, 1-9.
• Kuchnicki, J., Bullard, T., Duan, J., McGraw, D., & Minor, T. (2000). Truckee River basin assessment: Sediment source analysis in support of TMDL delineation. In Proceedings of the 8th Biennial Watershed Management Council Conference on Managing Watersheds in the New Century.
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  In accordance with Section 303(d) of the Clean Water Act, the Lahontan Regional Water Quality Control Board (LRWQCB) of the California Department of Environmental Protection has ascertained that the Truckee River and a number of its tributaries in California are water quality limited for sediment, nutrients, total dissolved solids and chloride. The water quality of the river system has been impacted by a variety of sources, including forest management, urban and recreational development, hydromodification and other alterations of wetland and fisheries habitat. The Desert Research Institute is actively conducting research to investigate the cumulative effects of management activities to watershed and channel conditions of the Truckee River basin. To determine chronic sediment sources, the study features aerial photographic analyses and utilization of a spatially-distributed. GIS-based model complemented by a field monitoring network. Analyzing and comparing historical and recent air photos allows for a gross estimation of the magnitude and rate of sediment discharges from sub-watersheds stemming from both natural and anthropogenic influences. Estimation of runoff and sediment from landscape units within sub-watersheds is accomplished through use of the Annual Agricultural Nonpoint Source (AnnAGNPS) model. Input to the model includes land use, topography and slope, soil type, vegetation type and density, and climate data; these parameters allow for estimation of actual and projected sediment loads within the basin. Field monitoring of suspended sediment conducted during the period of snowmelt runoff serve as a validation tool for the model. Results from the analyses facilitate the prioritization of restoration needs within the basin.

Presentations

• Duan, J. G., Xiaofeng, L., Kimberley, H., & Luke, M. (2024, 12). Breaking Barriers in Sediment Transport Research Across Science and Engineering III eLightning. American Geophysical Union 2024 Conference. Washington DC: American Geophysical Union.
• Duan, J. G., & Stahmer, G. (2023, May).

  Simulation of Post-fire Sediment Transport Using HEC-RAS Model

  . 2023 EWRI World Environment and Water Resources Congress: Adaptive Planning and Design in an Age of Risk and Uncertainty.. Henderson, NV: ASCE EWRI.
• Duan, J. G. (2020, 12/2020). Experimental and Computational Fluvial Hydraulics. Invited Web Seminar. Tucson, AZ: School of Civil Engineering, Tianjin University, Tianjin, P.R China.
• Duan, J. G. (2019, 6/2019). Experimental Study of Bed Load Particle Velocity Using Particle Tracking. Invited Seminar. Wuhan, PR China: State Key Laboratory of Water Resources and Hydropower Engineering Science, Wuhan University, Wuhan, P.R. China.

Poster Presentations

• Duan, J. G., Engel, F. L., Qi, K., & Asadi, K. A. (2024, 12). Evaluation of LSPIV and STIV Methods Uisng Public Domian Software. American Geophysical Union 2024 Conference. Washington DC: American Geophysical Union.
• Meixner, T., Zuckerman, M. P., Duan, J. G., & Crosson, C. (2019, 12/2019). Advances in Green Infrastructure Research, Development, and Community Adoption III. AGU Fall Meeting.

Case Studies

• Duan, J. G., Qi, K., & Stahmer, G. (2022. Watershed Erosion and Sedimentation Assessment of Munds Draw Watershed(p. 67).

Others

• Duan, J. G., & Stahmer, G. (2022, Feb). Sediment Transport Model for Canyon Del Oro Wash. Technical Report, Pima County Regional Flood Control District.