Water reuse in sequential basin irrigation

Level basins, when properly designed and managed, often attain very high ir rigation efficiencies. Problems can arise when the infiltrated depth exceed s the soil water holding capacity or when the crops are sensitive to waterl ogging. Both cases could benefit from allowing part of the applied water to run off the basin. This water can be reused for on-farm irrigation of the subsequent basin. Such a setup will be referred to as the "runoff rescue" ( RR) system. In this work, an RR system composed of five adjacent terraced b asins is described and evaluated. The basins were connected by outflow poin ts located at the upstream and downstream ends of the fields. To provide te rms for comparison, the performance resulting from conventional irrigation (without RR) of each basin was estimated using a simulation model. The RR s ystem showed reductions of 14, 16, and 24% in irrigation time, infiltrated depth, and recession time, respectively. The average increments for distrib ution uniformity and application efficiency were 2 and 9%, respectively.