Agricultural drainage is the removal of excess water from the soil surface
and/or soil profile of cropland, by either gravity or artificial means. The two
main reasons for improving the drainage on agricultural land are for soil
conservation and enhancing crop production. The management goal of agricultural
drainage is to maintain a salt balance in the crop root zone in arid areas and
proper soil water balance in humid areas. Drainage water from different
locations and/or facilities will have different quality characteristics. Poor
quality water should be separated from good quality water. If drainage water is
unsuitable for reuse, it should be disposed of in a sink