- Professor, Agricultural-Biosystems Engineering
Interested on water resources engineering that includes irrigation aminly microirrigation, hydraulics, hydrology, hydraulic structures, and transboundary river basin management. Additionally, recent interset includes climate change and development, sustainable development, and disaster risk sciences. My teaching interest goes along my research interest, mainly soila nd water resources engineering. Also, computer aiaded design and microcomputer application.
- Fulbright Scholar, Fulbright Program, US StateDepartment (2001 - 2003)
- Professor, ABE Department (1999 - Ongoing)
- Research Associate, University of California, Riverside, Riverside, California (1983 - 1984)
- National Water & Energy Conservation Award
- Irrigation Association, Fall 2017
- Microirrigation for SustainableWater Use
- Western Agricultural Experiment Directors, Summer 2014
Teach Soil and Water Resources Engineering, Hydraulics, Hydrology, Computer Aided Design, Microcomputer Application
Microirrigation, Water Conservation, Climate Change, Geospatial Analysis, Remote Sensing
Basic Comptr Skills Off AppsAGTM 120 (Spring 2019)
Basic Comptr Skills Off AppsBE 120 (Spring 2019)
Basic Comptr Skills Off AppsFCSC 120 (Spring 2019)
Basic Comptr Skills Off AppsNSC 120 (Spring 2019)
Basic Comptr Skills Off AppsPLS 120 (Spring 2019)
Engineering Graphics Auto CadBE 220 (Spring 2019)
Introduction To CadBE 221 (Spring 2019)
Basic Comptr Skills Off AppsABE 120 (Fall 2018)
Basic Comptr Skills Off AppsAGTM 120 (Fall 2018)
Basic Comptr Skills Off AppsFCSC 120 (Fall 2018)
Basic Comptr Skills Off AppsNSC 120 (Fall 2018)
Basic Comptr Skills Off AppsPLS 120 (Fall 2018)
Engineering Graphics Auto CadABE 220 (Fall 2018)
Introduction To CadABE 221 (Fall 2018)
Basic Comptr Skills Off AppsABE 120 (Summer I 2018)
Basic Comptr Skills Off AppsAGTM 120 (Summer I 2018)
Basic Comptr Skills Off AppsFCSC 120 (Summer I 2018)
Basic Comptr Skills Off AppsNSC 120 (Summer I 2018)
Introduction To CadABE 221 (Summer I 2018)
Basic Comptr Skills Off AppsABE 120 (Spring 2018)
Basic Comptr Skills Off AppsAGTM 120 (Spring 2018)
Basic Comptr Skills Off AppsFCSC 120 (Spring 2018)
Basic Comptr Skills Off AppsNSC 120 (Spring 2018)
Basic Comptr Skills Off AppsPLS 120 (Spring 2018)
Introduction To CadABE 221 (Spring 2018)
Basic Comptr Skills Off AppsABE 120 (Fall 2017)
Basic Comptr Skills Off AppsAGTM 120 (Fall 2017)
Basic Comptr Skills Off AppsFCSC 120 (Fall 2017)
Basic Comptr Skills Off AppsNSC 120 (Fall 2017)
Basic Comptr Skills Off AppsPLS 120 (Fall 2017)
InternshipABE 393 (Fall 2017)
Introduction To CadABE 221 (Fall 2017)
Introduction To CadENGR 221 (Fall 2017)
Basic Comptr Skills Off AppsABE 120 (Summer I 2017)
Basic Comptr Skills Off AppsAGTM 120 (Summer I 2017)
Basic Comptr Skills Off AppsFCSC 120 (Summer I 2017)
Basic Comptr Skills Off AppsNSC 120 (Summer I 2017)
Basic Comptr Skills Off AppsPLS 120 (Summer I 2017)
Introduction To CadABE 221 (Summer I 2017)
Introduction To CadENGR 221 (Summer I 2017)
Basic Comptr Skills Off AppsABE 120 (Spring 2017)
Basic Comptr Skills Off AppsAGTM 120 (Spring 2017)
Basic Comptr Skills Off AppsFCSC 120 (Spring 2017)
Basic Comptr Skills Off AppsNSC 120 (Spring 2017)
Basic Comptr Skills Off AppsPLS 120 (Spring 2017)
Introduction To CadABE 221 (Spring 2017)
Introduction To CadENGR 221 (Spring 2017)
Irrigation Systems DsgnABE 456 (Spring 2017)
Irrigation Systems DsgnABE 556 (Spring 2017)
Irrigation Systems DsgnCE 456 (Spring 2017)
Basic Comptr Skills Off AppsABE 120 (Fall 2016)
Basic Comptr Skills Off AppsAGTM 120 (Fall 2016)
Basic Comptr Skills Off AppsFCSC 120 (Fall 2016)
Basic Comptr Skills Off AppsNSC 120 (Fall 2016)
Basic Comptr Skills Off AppsPLS 120 (Fall 2016)
DissertationABE 920 (Fall 2016)
InternshipABE 693 (Fall 2016)
Introduction To CadABE 221 (Fall 2016)
Introduction To CadENGR 221 (Fall 2016)
Basic Comptr Skills Off AppsABE 120 (Summer I 2016)
Basic Comptr Skills Off AppsAGTM 120 (Summer I 2016)
Basic Comptr Skills Off AppsFCSC 120 (Summer I 2016)
Basic Comptr Skills Off AppsNSC 120 (Summer I 2016)
Basic Comptr Skills Off AppsPLS 120 (Summer I 2016)
Introduction To CadABE 221 (Summer I 2016)
Introduction To CadENGR 221 (Summer I 2016)
- Waller, P. M., & Yitayew, M. (2016). Irrigation and Drainage Engineering. http://www.springer.com/us/book/9783319056982: Springer. doi:10.1007/978-3-319-05699-9More infoThis textbook focuses on the combined topics of irrigation and drainageengineering. It emphasizes both basic concepts and practical applications of the latest technologies available. The design of irrigation, pumping, and drainage systems using Excel and Visual Basic for Applications programs are explained for both graduate and undergraduate students and practicing engineers. The book emphasizes environmental protection, economics, and engineering design processes. It includes detailed chapters on irrigation economics, soils, reference evapotranspiration, crop evapotranspiration, pipe flow, pumps, open-channel flow, groundwater, center pivots, turf and landscape, drip, orchards, wheel lines, hand lines, surfaces, greenhouse hydroponics, soil water movement, drainage systems design, drainage and wetlands contaminant fate and transport. It contains summaries, homework problems, and color photos. The book drawsfrom the fields of fluid mechanics, soil physics, hydrology, soil chemistry, economics, and plant sciences to present a broad interdisciplinary view of the fundamental concepts in irrigation and drainage systems design.
- Waller, P., & Yitayew, M. (2015). Irrigation and Drainage Engineering. Holland: Springer.
- Yitayew, M. -., & Kitaw, M. (2014). Water Governance in the Nile Basin for Hydropower Development. In Nile River Basin Ecohydrological Challenges, Climate Change and Hydropolitics Melesse et al. Editors(p. 17). Springer International Publishing Switzerland 2014.
- Nouri, I., Yitayew, M., Massmann, J., & Tarhouni, J. (2015). Multi-Objective Optimization Tool for Integrated Groundwater Management. Water Resources Management, 29(14), %353-5375 ( 23 pages).
- Yitayew, M. (2012). Discussion of "Simplified method for sizing laterals with two or more diameters". Journal of Irrigation and Drainage Engineering, 138(7), 697-702.
- Yitayew, M., & Melesse, A. (2011). Critical Water Resources Issues in the Nile River Basin. Nile River Basin Hydrology, Climate and Water Use.
- Stewart, D., Canfield, E., Yitayew, M., & Nichols, M. (2010). Estimating an impedance-to-flow parameter for flood peak prediction in semiarid watersheds. Journal of Hydrologic Engineering, 15(3), 182-190.More infoAbstract: The time of concentration equation used in Pima County, Arizona, includes a hydrologic parameter representing the impedance to flow for peak discharge estimation on small [typically less than 2.59 km2 (1 mi2)] semiarid watersheds. The impedance-to-flow parameter is similar in function to the hydraulic Manning's n roughness coefficient in the kinematic wave time of concentration equation; however, the impedance to flow is a hydrologic parameter representing all portions of a watershed rather than a hydraulic parameter representing friction loss during uniform flow. To relate the impedance-to-flow parameter to physical watershed characteristics, impedance-to-flow values were calculated for return period and observed events on five undeveloped rangeland watersheds and correlated with Manning's n roughness coefficients determined from particle size analysis and simulated flow conditions. Impedance to flow displayed a positive trend with observed peak discharge on each watershed. The results indicate that local impedance-to-flow values can be developed for time of concentration equations using observed rainfall and runoff data, as well as measurable field characteristics. The impedance-to-flow parameter allows for a physical basis in time of concentration estimation without the additional detail of a physically based model. © 2010 ASCE.
- Didan, K., & Yitayew, M. (2009). Prototype geographic information system for agricultural water quality management using cropsyst. Journal of Irrigation and Drainage Engineering, 135(1), 58-67.More infoAbstract: A prototype raster geographic information system (GIS) coupled with a decision support submodel for agricultural nitrogen nonpoint source pollution analysis is presented herein. This analysis is an extension of the one-dimensional approach used to simulate and analyze farm production systems and their impact on the environment. The farm system was rasterized into an aggregation of spatial units with homogeneous physical and management characteristics. A crop model to simulate the farm and the environmental response to management alternatives was integrated with this prototype GIS. The system coordinates the running of the crop model on each homogeneous unit and results are passed to a maximum expected utility decision analysis submodel. Only the crop yield and chemical leaching are considered in the decision model. Based on the utility of these two parameters and the probability of realization, the management alternative that potentially leads to the highest yield and lowest nitrogen leaching will be recommended. This prototype model was evaluated with field data from a controlled lettuce production with intense nitrogen application in Arizona. The results achieved compared well with the actual field data including the best management practice recommended for this farm production system. © 2009 ASCE.
- Melesse, A. M., Loukas, A. G., Senay, G., & Yitayew, M. (2009). Climate change, land-cover dynamics and ecohydrology of the Nile River Basin. Hydrological Processes, 23(26), 3651-3652.
- Yitayew, M. (2009). Simplified method for sizing laterals with two or more diameters. Journal of Irrigation and Drainage Engineering, 135(1), 111-114.More infoAbstract: The economic design of microirrigation and sprinkler laterals requires the use of a combination of diameters of different lengths. The present practice is to solve the basic hydraulic equations using a trial-and-error method for a given allowable head loss. This requires an iterative process that consumes time and limits the accuracy of the solution. Herein is presented a direct analytical approach that gives an exact solution. The method is compared with the trial-and-error approach and found to give the same result. © 2009 ASCE.
- Clark, G. A., Haman, D. Z., Prochaska, J. F., & Yitayew, M. (2007). 5. General system design principles. Developments in Agricultural Engineering, 13, 161-220.
- Hills, D. J., & Yitayew, M. (2007). 14. Bubbler Irrigation. Developments in Agricultural Engineering, 13, 553-573.
- Zerihun, D., Sanchez, C. A., Farrell-Poe, K., & Yitayew, M. (2005). Analysis and design of border irrigation systems. Transactions of the American Society of Agricultural Engineers, 48(5), 1751-1764.More infoAbstract: Application efficiency (Ea) is the primary criterion for border irrigation design and management. The objective of this study is to analyze the behavior of the application efficiency function of border irrigation with respect to border length (L) and unit inlet flow rate (qo), given a target minimum application depth. The results show that the application efficiency function is unimodal with respect to L and qo. Optimality conditions are derived for both the Ea(L) and Ea(q o) functions, based on which simple rules that reduce the design and management procedure into a series of one-dimensional optimization problems with respect to qo are developed. The proposed procedure has a variable bounding step in which the feasible ranges of L and qo are determined. This is then followed by a step wherein alternative approximate optimum values of Ea(qo) are calculated for each of the feasible values of L. Finally, the optimal Ea(qo) is selected from the available alternatives based on sensitivity analysis and other locally pertinent practical criteria. In addition, the advantages and limitations of advance-phase and post-advance-phase inflow cutoff options and their effects on system design and management are discussed. The distance-based (advance-phase) inflow cutoff option offers two main advantages over post-advance-phase cutoff: operational convenience, and a lower degree of sensitivity of design and management prescriptions to inaccuracies in inflow measurements and to non-uniformities in the distribution of inlet flow over the width of the border. However, the results of the study also show that, depending on the parameter set, there exist limiting conditions that preclude the applicability of the distance-based cutoff criterion in border irrigation management. Even when the distance-based inflow cutoff criterion is feasible, the corresponding design and management scenario can be sub-optimal, in which case a near-optimum operation scenario can be realized only with post-advance-phase inflow cutoff. © 2005 American Society of Agricultural Engineers.
- Holland, D. F., Yitayew, M., & Warrick, A. W. (2000). Measurement of subsurface unsaturated hydraulic conductivity. Journal of Irrigation and Drainage Engineering, 126(1), 21-27.More infoAbstract: Measurement of unsaturated hydraulic conductivity is needed for precise control of water and solutes in the vadose zone. Because of the spatial variation of soils, a large number of surface and subsurface measurements are needed to characterize a field. In this work, permeameters were developed and tested for estimating subsurface unsaturated hydraulic conductivity. The permeameters apply water under tension; they are easy to use and have adequate accuracy. Unsaturated hydraulic conductivity was determined by measuring the steady flow rates for various values of negative pressure. Tests using a soil of known hydraulic conductivity showed that the permeameters provided valid measurements. Two types were used, a porous cloth model that was inflated against the soil and a porous ceramic cup that was rigid. The field testing determined that a rigid design using a ceramic cup coupled to the soil by a layer of fine sand was easier to use, was reliable, and provided good results.
- Reynolds, C. A., Yitayew, M., Slack, D. C., Hutchinson, C. F., Huetes, A., & Petersen, M. S. (2000). Estimating crop yields and production by integrating the FAO Crop Specific Water Balance model with real-time satellite data and ground-based ancillary data. International Journal of Remote Sensing, 21(18), 3487-3508.More infoAbstract: An operational crop yield model was developed by introducing real-time satellite imagery into a Geographical Information System (GIS) and the Crop Specific Water Balance (CSWB) model of the Food and Agriculture Organization (FAO). Input databases were developed with three different resolutions; agro-ecological zone (AEZ) polygons, 7.6 km and 1.1 km pixels; from archived satellite data commonly used by Early Warning Systems (EWS) to simulate maize yield and production in Kenya from 1989 to 1997. Simulated production results from the GIS-based CSWB model were compared to historical maize production reports from two Government of Kenya (GoK) agencies. The coefficients of determination (r2) between the model and GoK district reports ranged from 0.86 to 0.89. The results indicated the 7.6 km pixel-by-pixel analysis was the most favorable method due to the Rainfall Estimate (RFE) input data having the same resolution. The GIS-based CSWB model developed by this study could also be easily expanded for use in other countries, extended for other crops, and improved in the future as satellite technologies improve.
- Yitayew, M., Didan, K., & Reynolds, C. (1999). Microcomputer based low-head gravity-flow bubbler irrigation system design. Computers and Electronics in Agriculture, 22(1), 29-39.More infoAbstract: Low-head bubbler irrigation systems are microirrigation systems that are based on gravity flow, operate at pressure heads as low as 1 m, and require no filtration or pumping. Despite their simplicity and advantages, low-head bubbler systems are not used in many countries. This is mainly due to lack of a well-defined design procedure to facilitate design and installation. A computer program called BUBBLER was developed for low-head gravity bubbler irrigation system design and analysis. It is a PC-based program that works under DOS environment. It takes minimal data input, and solves the hydraulics of low-head gravity distribution of water from multiple outlet pipe systems. The input includes elevation of the water source, crop and row spacing, field size, and elevation of the four corners of the field. The output includes the mainline, submain, and lateral sizes, delivery hose size, delivery hose elevations, and cost estimates. An example design is presented. The program can be used to evaluate alternative designs in minutes to decide the physical and economic feasibility of the system.
- Yitayew, M., Pokrzywka, S. J., & Renard, K. G. (1999). Using GIS for facilitating erosion estimation. Applied Engineering in Agriculture, 15(4), 295-301.More infoAbstract: Geographic Information System (GIS) combined with soil loss models can enhance the evaluation of soil erosion estimation. ARC/INFO geographic information system with the Revised Universal Soil Loss Equation (RUSLE) was used to estimate soil erosion on a portion of the Walnut Gulch experimental watershed in southeast Arizona. Spatial data from different sources provided input for four alternate GIS based procedures in computing the combined slope length and steepness factor in RUSLE for determining soil erosion estimates. Results of GIS based RUSLE erosion estimates from the four procedures are compared with actual sediment yield observed on the experimental watershed for the period 1973 through 1989. Results indicate GIS based RUSLE predicted soil erosion estimates are less than the observed measured sediment yield in most years. Application of a sediment delivery ratio which varies with watershed area is addressed as possible explanation for the differences in estimated erosion and measured sediment yield. GIS can be used with RUSLE to get a good estimate of soil erosion but care has to be taken in interpreting the result and comparing it to measured sediment yield. The results from this study clearly show the need for more work in using GIS and RUSLE for soil erosion estimation.
- Yitayew, M. (1998). Hydraulic design of drainage pipes: Simplified solution. Transactions of the American Society of Agricultural Engineers, 41(6), 1707-1709.More infoAbstract: A simple equation simulating flow in sub-surface drain pipe was developed and solved. The solution is based on the assumption that both velocity and pressure are continuous functions of distance along the drain length. The velocity head was also considered negligible. The solution was compared to results obtained from available design charts and procedures. The developed equation can be directly applied mainly to design drain laterals.
- Yitayew, M., Khan, A. A., & Warrick, A. W. (1998). In situ measurements of soil hydraulic conductivity using point application of water. Applied Engineering in Agriculture, 14(2), 115-120.More infoAbstract: A method for estimating hydraulic conductivity from in-situ measurements of soil's hydraulic parameters from a point application of water was tested for three soil types. The method is based on Wooding's (1968) and Warrick's (1985) solutions of water flow from a shallow circular pond and point source, respectively. Measurements of the saturated radii and the associated flow rates are used to determine the saturated hydraulic conductivity and a for the assumed Gardner's (1958) exponential relationship between hydraulic conductivity and soil matric head. Effects of flow rate on saturated and unsaturated surface wetted regimes were also observed. The surface wetted areas were found to be significantly affected by flow rate in all three soils. The results from the point application method were compared to those from ring infiltrometer measurements and gave consistent values for saturated hydraulic conductivity. The method's simplicity, repeatability and the ability to make rapid in-situ measurement makes it practical and applicable to use under varying conditions.
- Lamm, F. R., Clark, G. A., Yitayew, M., Schoneman, R. A., Mead, R. M., & Schneider, A. D. (1997). Installation issues for SDI systems. Paper - American Society of Agricultural Engineers, 2.More infoAbstract: Successful adoption of SDI technology will require durable, compatible, and user-friendly components; local support for design, installation, and service; and continuing educational programs on proper operational and management procedures. Success will depend on a heightened awareness and commitment to quality similar to those required in other advanced technologies.
- Yitayew, M., & Khan, A. (1997). Solute movement from point application of water. Paper - American Society of Agricultural Engineers, 2.More infoAbstract: In-situ evaluation of solute movement from a point application of water was made using gravimetric method. The result showed an increase in solute concentration with both higher input concentration, applied volume, and application rate up to about 25 and 30 cm depth and radial distance respectively beyond which, there was no significant difference. Results of this study may be used in chemigation recommendation for microirrigation.
- Yitayew, M., & Reynolds, C. (1997). Cost savings: The low-head gravity-flow bubbler irrigation system advantages. Paper - American Society of Agricultural Engineers, 2.More infoAbstract: Cost estimate for a typical orchard was made for low-head gravity-flow bubbler irrigation system. This was compared with micro-spray sprinkler system that is commonly used for tree crops. Bubbler system has a definite advantage in cost saving in addition to reduced water usage and an equal or better water distribution uniformity.
- Yitayew, M., & Yousaf, M. (1997). Solute transport under different irrigation systems. Paper - American Society of Agricultural Engineers, 2.More infoAbstract: Maximization of chemical utilization within the root zone of crops and minimization of groundwater contamination are the major objectives of chemigation under any irrigation system. Field evaluation of solute movement under drip, sprinkler and level basin irrigation systems was made using potassium bromide as a tracer. The results of the study indicate the temporal and spatial distribution of bromide to be more uniform under drip irrigation than under sprinkler or level basin systems. This implies that drip irrigation system has the potential for efficient utilization of chemicals and nutrients and minimization of groundwater pollution.
- Khan, A. A., Yitayew, M., & Warrick, A. W. (1996). Field evaluation of water and solute distribution from a point source. Journal of Irrigation and Drainage Engineering - ASCE, 122(4), 221-227.
- Yitayew, M. (1996). Low-head bubbler irrigation systems. Part I: Design. Agricultural Water Management, 29(1), 1-24.More infoAbstract: Low-head bubbler systems differ from other micro-irrigation systems because they are based on gravity-flow, can operate at pressures as low as 1 m (3.3 ft) and do not require elaborate filtration systems. Despite their simplicity and advantages, low-head bubbler systems lack a well-defined design procedure to facilitate design and installation. A comprehensive design procedure for low-head bubbler systems is presented and an example gradual slope design is given in detail. The design procedure utilizes head loss gradient charts based on the Darcy-Weisbach equation and the delivery hose elevations are calculated from the energy equation. ©1995 Elsevier Science B.V. All rights reserved.
- Reynolds, C., Yitayew, M., & Petersen, M. (1995). Low-head bubbler irrigation systems. Part I: Design. Agricultural Water Management, 29(1), 1-24.More infoAbstract: Low-head bubbler systems differ from other micro-irrigation systems because they are based on gravity-flow, can operate at pressures as low as 1 m (3.3 ft) and do not require elaborate filtration systems. Despite their simplicity and advantages, low-head bubbler systems lack a well-defined design procedure to facilitate design and installation. A comprehensive design procedure for low-head bubbler systems is presented and an example gradual slope design is given in detail. The design procedure utilizes head loss gradient charts based on the Darcy-Weisbach equation and the delivery hose elevations are calculated from the energy equation. © 1995.
- Tecle, A., & Yitayew, M. (1990). Preference ranking of alternative irrigation technologies via a multicriterion decision-making procedure. Transactions of the American Society of Agricultural Engineers, 33(5), 1509-1517.More infoAbstract: This article develops a preference ranking method for choosing a particular irrigation technology. The method uses a set of 23 criteria to evaluate the performances of 10 alternative irrigation technologies selected to achieve 12 objectives. The evaluation process is made using a distance-based multicriterion decision-making (MCDM) technique known as compromise programming (CP). The whole process resulted in a complete ranking of the 10 alternative technologies including the best and the worst irrigation technologies for the problem under consideration.
- Yitayew, M., & Brown, P. (1990). Predicting daily evapotranspiration (ETd) from short-term values. Journal of Irrigation and Drainage Engineering, 116(3), 387-398.More infoAbstract: Application of a remote sensing technique for estimating regional evapotranspiration requires extrapolation of instantaneous values to periods on the order of 1 day or more to be of practical use. A method for developing an extrapolation coefficient based on earth-sun geometry is presented. The validity of the method and applicability of the concept is evaluated using year-long regional values of measured Penman evapotranspiration. The results demonstrate that the use of an extrapolation coefficient for long-term regional evapotranspiration estimation has a potential for future use.
- Samani, Z. A., & Yitayew, M. (1989). Changes in soil properties under intermittent water application. Irrigation Science, 10(3), 177-182.More infoAbstract: A simple laboratory method was developed to measure changes in saturated hydraulic conductivity and bulk density as affected by intermittent saturating and draining of soil columns. Significant changes in soil properties were measured after intermittent wetting and draining. Laboratory experiments showed significant changes in bulk density and saturated hydraulic conductivity of soil samples during drainage period following saturation of initially dried samples. The rate of changes in soil properties during the drainage period was a function of soil type and degree of desaturation. The effect of intermittent application of water in reducing the soil hydraulic conductivity and subsequently the infiltration rate was verified in the field by measuring the changes in soil intake rate during intermittent (surge-flow) irrigation.
- Warrick, A. W., Hart, W. E., & Yitayew, M. (1989). Calculation of distribution and efficiency for nonuniform irrigation. Journal of Irrigation and Drainage Engineering, 115(4), 674-686.More infoAbstract: Nonuniform irrigation is considered along with an analysis of distribution, efficiency, and deep percolation. Analytical expressions are given for normal, lognormal, uniform, and 'specialized power' distributions. Numerical values of area fully irrigated, application efficiency, and deep percolation are tabulated for all distributions as a function of water applied and variability. Field distributions were successfully compared with theoretical results for two furrow and two sprinkler examples.
- Yitayew, M. (1989). Head loss in manifolds or trickle lateral. Simplified approach. Journal of Irrigation and Drainage Engineering, 115(4), 739-743.More infoAbstract: Head loss in manifolds or trickle laterals is an important consideration for optimum design of pressurized irrigation systems. Recently, Warrick and Yitayew presented analytical solutions to the nonlinear differential equation describing typical manifold problems. The solution yields a relationship between relative discharge and length, which, in turn, can be used to get the total head distribution along the manifold. They also presented applications to trickle irrigation design. In this paper is presented an extension to the anlaytical solutions, but with a much-simplified approach for calculating total head loss in manifolds.
- Brown, P. W., & Yitayew, M. (1988). Near-real time weather information for irrigation management in Arizona. Array, 708-715.More infoAbstract: The Arizona Meteorological Network (AZMET) is a near-real time ag-weather information system for Arizona. A single personal computer running inexpensive bulletin board software controls all phases of the AZMET system including data retrieval from remote weather stations, data management, and development and dissemination of weather-based information. The public gains access to AZMET information through a computer bulletin board system (BBS). Weather-based information for irrigation management is updated daily on the BBS in an ET report that summarizes raw data and estimates of actual evapotranspiration (ETa) for the most recent 14-day period. Applied research related to AZMET is presently focused on refining and/or developing new crop coefficients to convert Penman-based reference crop evapotranspiration values (ETb) to ETa.
- Fangmeier, D. D., & Yitayew, M. (1988). Border irrigation: dimensionless runoff curves and reuse system design.. Array.More infoAbstract: This chapter contains dimensionless runoff curves for irrigation borders and presents optional design procedures for reuse systems. The curves are based on runoff volume defined as a percentage of the total water applied at the head of the border. In border irrigation, end of field runoff can be saved by installing a reuse system. Application efficiencies can then be improved from 55% to over 70%. Field measurements of runoff are difficult due to the large number of variables, the most important one being quality of runoff, but data can be obtained through use of mathematical models. One such model discussed in this chapter is a design procedure based on dimensionless runoff curves. (from paper)
- Warrick, A. W., & Yitayew, M. (1988). TRICKLE LATERAL HYDRAULICS. I: ANALYTICAL SOLUTION.. Journal of Irrigation and Drainage Engineering, 114(2), 281-288.More infoAbstract: An important objective of any trickle system is a uniform distribution of water delivered through the emitters. Computation of flow distribution requires knowledge of the variables such as pressure, flow rate, length of lateral, characteristics of the orifices, and frictional loss in the system. Several studies have been reported that establish these relationships. In each study, the primary solution is based on a discharge that is uniform, although ramifications of the manufacturer's variability have been modeled based on the derived hydraulic profile. Herein, we present an alternative treatment that includes a spatially variable discharge function as part of the basic solution.
- Yitayew, M., & Warrick, A. W. (1988). TRICKLE LATERAL HYDRAULICS. II: DESIGN AND EXAMPLES.. Journal of Irrigation and Drainage Engineering, 114(2), 289-300.More infoAbstract: The trickle lateral analysis described in the companion paper is used to illustrate applications of a new analytical solution in system design. Examples are provided to point out the basic concepts and procedures based on this and related analytical solutions. Very simple and yet powerful design curves for different flow regimes are presented. Verification of the solution is also made by comparing the results with experimental measurements. The simplicity of the solution, coupled with the ease of including variable discharge, makes the analytical solution attractive for diversified uses in trickle system design.
- Emel, J. L., & Yitayew, M. (1987). Water duties: Arizona's groundwater management approach.. Journal of Water Resources Planning & Management - ASCE, 113(1), 82-94.More infoAbstract: This paper reviews the scientific determinants that the water duty conprises and describes the concept's implementation in Arizona's active management areas. The water duty is only one of several approaches to groundwater allocation. New Mexico, Oklahoma, and Nebraska employ approaches that differ considerably from Arizona's. Arizona's allocation varies per acre, depending upon a farm's cropping history. In the other 3 areas, the allocation is uniform per acre and is more dependent upon supply management goals.-from ASCE Publications Information Geog Dept, Clark Univ, Worcester, MA 01610, USA.
- Warrick, A. W., & Yitayew, M. (1987). An analytical solution for flow in a manifold. Advances in Water Resources, 10(2), 58-63.More infoAbstract: An analytical solution is developed for flow in a manifold. The interest is primarily for trickle irrigation laterals, but the solution has broader applications including those for which pressure increases in the direction of flow and for intake manifolds. Both velocity head losses and variable discharge along the manifold are considered in the fundamental analysis. The appropriate second order, nonlinear equation is solved for two flow regimes, laminar and fully turbulent. Results indicate that for most trickle irrigation laterals the velocity head loss is negligible, but for an example from a chemical processing system the effect is important. © 1987.
- Yitayew, M. (1987). Interrelationships of performance parameters for irrigation borders. Agricultural Water Management, 12(3), 221-230.More infoAbstract: The ability to determine irrigation performance parameters for a given set of hydralic variables facilitates optimum irrigation system design without requiring field trials. Relationships between several irrigation management parameters, specifically application efficiency, distribution uniformity, runoff and deep percolation, are presented. The field variables inflow, border length, time of cut-off, slope roughness and soil infiltration characteristics, are input variables for determining management parameters. They are applied through the use of dimensionless curves of runoff and equations of the ultimate distribution of infiltrated water. An example to illustrate the use of the developed relationships and dimensionless curves is included. © 1987.
- Warrick, A. W., Hart, W. E., & Yitayew, M. (1986). CALCULATION OF DISTRIBUTION AND EFFICIENCY FOR NON-UNIFORM IRRIGATION.. Paper - American Society of Agricultural Engineers.More infoAbstract: The analyses present closed formulas for calculating water distribution, the fraction of the area which receives the requirement, and the fraction of the applied water which contributes to meeting the requirement. Values are compared with the distributions from common types of irrigation systems.
- Yitayew, M., & Watson, J. (1986). FIELD METHODS FOR DETERMINING UNSATURATED HYDRAULIC CONDUCTIVITY.. Paper - American Society of Agricultural Engineers.More infoAbstract: Mathematical models have been developed which describe soil water movement under point and disc sources. Results of these models suggest the possibility of estimating unsaturated hydraulic conductivity if the variables K//o and alpha in the exponential function K( psi ) equals K//o exp( alpha psi ) are evaluated. Two approaches to evaluate these parameters in the field are proposed. Method 1 involves application of a constant flux from a simple constant flow device and measuring the steady state wetted radius for two different values of flux, and Method 2 makes use of a sorptivity tube type device - with a given potential at the soil surface and measurement of the steady flow rate and wetted radii. These measurements allow for the algebraic solution of the hydraulic conductivity function.
- Yitayew, M., & Emel, J. L. (1985). WATER DUTY FOR AGRICULTURE IN THE WESTERN UNITED STATES.. Array, 210-222.More infoAbstract: The agricultural water duty is a measure of the quantity of water reasonably required for use in agricultural crop production. For some time in the western United States, the agricultural water duty has been used in the settlement of allocational disputes, adjudication proceedings, canal sizing, for conservation programs, and irrigation scheduling. This paper presents a very brief inquiry into the definition and use of the water duty as an allocator of water to agriculture in the western United States. The objectives of the paper are threefold: (1) to examine the existing definitions of the water duty concept, (2) to analyze the scientific bases of the water duty, and (3) to describe the implementation of the concept by the Arizona Department of Water Resources within the Tucson Active Management Area.
- Yitayew, M., & Fangmeier, D. D. (1985). REUSE SYSTEM DESIGN FOR BORDER IRRIGATION.. Journal of Irrigation and Drainage Engineering, 111(2), 160-174.More infoAbstract: A procedure is presented for designing a system to reuse runoff from free outflow irrigation borders. Runoff volumes are obtained using four dimensionless variables and runoff curves developed with a zero-inertia mathematical model. An example of the design procedure includes different modes of reuse system operation.
- Yitayew, M., Letey, J., Vaux Jr., H. J., & Feinerman, E. (1985). FACTORS AFFECTING UNIFORMITY AND OPTIMAL WATER MANAGEMENT WITH FURROW IRRIGATION.. Irrigation Science, 6(3), 201-210.More infoAbstract: A kinematic wave mathematical model which simulates the hydraulics of continuous flow furrow irrigation was linked with a crop yield model and used in combination with an economic model to analyze the effects of inflow rate, water infiltration characteristics and furrow length on uniformity of infiltrated water, runoff, gross profits and optimal number of 12 hour irrigations for corn assuming other management practices to be constant. Higher uniformity of infiltrated water but more runoff and, in some cases, more deep percolation resulted from increased flow rates. Increases in uniformity of infiltrated water leads to greater profits, which are however offset by the associated increases in runoff and deep percolation.
- Yitayew, M., & Fangmeier, D. D. (1984). DIMENSIONLESS RUNOFF CURVES FOR IRRIGATION BORDERS.. Journal of Irrigation and Drainage Engineering, 110(2), 179-191.More infoAbstract: Nondimensional runoff curves useful in the design of reuse systems are presented for free outflow irrigation borders. Pertinent open channel variables affecting runoff in border irrigation, including inflow rate, surface resistance, border slope, soil infiltration characteristics, application time, and length of border, were studied and their effects presented. Maximum advance distance, which is of interest in designing border irrigation systems, is also given by the zero runoff curves. A zero-inertia mathematical model was used to develop the nondimensional predictive graphical solution in terms of four reduced variables.
- Flug, M., & Yitayew, M. (1979). PUMP CONSIDERATIONS FOR OPTIMUM CROP PRODUCTION.. Paper - American Society of Agricultural Engineers.More infoAbstract: A computer algorithm was employed to assist in the analysis of alternative pumps for selecting that one which maximizes farm profit for sorghum in Arizona. Farm profit is determined by predic yield from a production function and computing variable costs for the different pumping energy requirements. Pumps are characterized by quadratic equations fitted to manufacturer's performance skpecifications with a very high degree of correlation. Alternative pumps operate at different flow rates resulting in varying water deliveries and energy usage. These last two parameters effect, respectively, the crop yield and variable cost. Proper pump selection is shown to be most important as energy costs increase. Use of the algorithm enables the rapid analysis of several conditions including alternative pumps, farm sizes, crops, and static water levels.
- Rodriguez, J., Didan, K., Yitayew, M., & Slack, D. C. (2016, 04). Downscaling MOIS Evapotranspiration via Area-to-Point Kriging in Wellton-Mohawk Irrigation and Drainage District, Yuma, AZ. INNOVATION MATCH MX 2015 – 2016. 1er Foro International de Talento Mexicano. Articulanto Conocimento Global. April 4-8, 2016, Guadalajara, Mexico. Guadalajara, Mexico: INNOVATION MATCH MX 2015 – 2016.
- Yitayew, M. (2015, November). Scaling Microirrigation Technologies to Address the Global Water Challenge Report. Annual meeting of the Regional Research Project on Microirrigation. Long Beach, California.
- Yitayew, M. -. (2013, October). Prototype Climate Data Services in Support of Climate Change Studies. Climate Change and Development in Africa UN-ECA. UN-ECA, Addis Ababa, Ethiopia.
- Yitayew, M. -. (2013, Spring). Enhancing Energy Access and Security in the Nile River Basin. Enhancing Energy Access and Security in the Eastern Africa Sub-Region, Seventeenth Meeting of the Intergovernmental Committee of Experts (ICE). Kampala, Uganda: Unioted Nations Economic Commission for Africa.
- Yitayew, M. (2012, October). Water-agriculture-energy nexus under climate change. The second Climate Change and Development in Africa (CCDA-II) conference of the Climate for Development in Africa. Addis Ababa: ClimDev-Africa.
- Yitayew, M. -. (2012, February). Lecture Thesis and Dissertation requirement in ABE department and writing proposal for MS and PhD research. Graduate Program Requirement in ABE.
- Yitayew, M. -. (2011, February). Lecture Thesis and Dissertation requirement in ABE department and writing proposal for MS and PhD research. Graduate Program Requirement in ABE.
- Rodrigez, J., Diadan, K., Yitayew, M., Barreto, A., & Slack, D. (2015, October). Downscaling MODIS Evapotranspiration via Area-to-point Kriging in Wellton-Mohawk Irrigation and Drainage District, Yuma, AZ.. PHENOLOGY RESEARCH AND OBSERVATIONS OF SOUTHWEST ECOSYSTEMS SYMPOSIUM (PROSE). USGS Environment and Natural Resources Building (ENRB), Catalina Conference Room (Room 253), 520 N. Park Ave., Tucson,: Southwest U.S. Region, American Society of Photogrammetry & Remote Sensing (SW-ASPRS).
- Yitayew, M. (2014, December). Nile Basin Vegetation Response and Vulnerability to Climate Change: A multi-Sensor Remote Sensing Approach. AGU Annual meeting. San Francisco: American Geophysical Union.
- Barreto, A. -., & Didan, K. (2013, December). Nile Basin Vegetation Response and Vulnerability to Climate Change. American Geophysical Union Annual Meeting. San Fransicco, California.
- Yitayew, M., & Barreto, A. (2015, August). Design of Low-Head Gravity-Flow Bubbler Irrigation Systems for Trees, Vines and Orchard Crops. CALS Research. http://WWW.cals.arizona.edu/research/bubblerMore infoBubbler enables a user to design low-head bubbler irrigation systems for rectangular fields with level or gradual slopes. Low-head bubbler systems are based on gravity flow and a minimum head of approximately 1 meter (3.3 feet) must exist at the high end of the field for a bubbler system to be feasibleAn entire bubbler system can be designed if the following parameters are known: field dimensions (length and width) field elevation for each corner water source elevation and distance to highest corner of the field spacing of orchard cropWhen the above input data is suplied, Bubbler will determine the quantit, length, diameter, and field layout for all pipelines needed to install a bubbler irrigation system. In addition, the elevations for all delivery hoses are calculated for easy installation of a system.Bubbler sets default values for various design parameters such as maximum and minimum delivery hose elevations, depth of lateral burial, delivery hose flow rates, maximum number of tree rows per field, and available pipeline diamters. However, the user can specify different values for these design parameters if desired.