Rethinking rational solutions for irrigation salinity

Abstract

Effective control of waterlogging and salinisation of irrigated landscapes in arid countries requires implementation of appropriate irrigation and drainage strategies at both the farm and irrigation area levels. These strategies need to be underpinned by a general understanding of the importance of managing groundwater abstraction from the deep aquifer in balance with recharge, to minimise salt mobilisation whilst controlling near-surface water table depth. A better understanding of the regional groundwater dynamics is required to quantify on-farm as well as regional impacts of drainage management options. This paper describes environmental concepts and modelling tools to develop and implement effective irrigation and drainage management options. Environmental concepts discussed include groundwater management zones, recharge quotas, hydraulic loading, tradeable crop area allocations and drainage reuse. These concepts can be formulated into effective management policies for providing optimum drainage service by using appropriate modelling tools such as the Salt Water And Groundwater MANagement (SWAGMAN) series. Case studies from Pakistan and Australia are included to illustrate the need for rational drainage design and future challenges for managing to achieve sustainability of irrigation areas.