DESIGN OF LEVEL-BASIN IRRIGATION SYSTEMS FOR ROBUST PERFORMANCE

摘要

Level-basin irrigation is extensively used in South-Western United States where water isrnvery expensive. A well designed level-basin irrigation system is easy to manage, and hasrnsignificant potential for achieving higher application efficiency and improved salinity control,rnparticularly when the field is laser-leveled. Over the years, three different criteria have evolvedrnto design level-basin irrigation systems: the volume-balance design criterion proposed by thernSoil Conservation Service (SCS) of the United States Department of Agriculture (USDA), thernlimiting length design criterion, and the completion-of-advance criterion. Each one of thesernthree methods has its own advantages and disadvantages. For achieving higher applicationrnefficiency, in addition to proper design, a well-defined irrigation scheduling must be followedrnso that the soil-moisture deficit at the time of irrigation is close to the design depth of thernirrigation system. Otherwise, the actual application efficiency will be different (usually lower)rnthan the design application efficiency, and the actual water requirement efficiency achievedrnmay be significantly different (either under-irrigation or over-irrigation) from the design waterrnrequirement efficiency. However, if completion-of-advance design criterion is used, therndifference between actual and design efficiencies (application efficiency and water requirementrnefficiency) kept to a minimum. In addition, the actual performance of a level-basin irrigationrnsystem designed using the completion-of-advance criterion would be much closer to therndesign performance even when the inflow flow rate into level-basins fluctuates. This paper willrnpresent the results of a simulation study on the robust performance of level-basin irrigationrnsystems designed using the completion-of-advance criterion.