APPLICATION OF DRAINMOD AND SWAP IN SOUTH-WEST OF IRAN FOR OPTIMAL DESIGN OF DRAINAGE NETWORK

摘要

Land productivity in arid and semi-arid regions is a function of aeration and salt contents of thernsoil in root zone. An optimal design of drainage network can reduce the cost of constructionrnand increase the productivity by providing a better condition for plant growth. Drainagernsimulation models can be used to determine the combination of depth and spacing to optimizernthe performance of the system. In this research, two widely used drainage simulation models,rnDRAINMOD and SWAP, were used in a sugarcane farm in south-west of Iran (KhozestanrnProvince). Soil characteristics, climatological data, irrigation depths and schedules, and waterrntable information for 2000 and 2001 were used to calibrate and validate both the models.rnThe validated models were used to find the optimum drain spacing and depth based on croprnproduction and drainage water volume. Achieving maximum crop production and minimumrndrainage water were the objectives of the design.rnWater tables simulated by both the models were satisfactory with the R2 of 0.95 and 0.90rnand RMSE between simulated and observed water tables were 18.1 and 19.2 cm forrnDRAINMOD and SWAP, respectively. DRAINMOD under-estimated the drainage water butrnSWAP overestimated it. A relative yield of 80 % was achieved when drain spacing and depthrnwere set to 25 m and 1.60 m, respectively using SWAP. For DRAINMOD, these values werern15 m and 1.15 m, respectively.