A salinity managem ent model is developed for analysing an irrigation system (small or large), which consists of a hydro-salinity su bmodel, a soil m oistu re chemistry submodel, and a groundwater salinity submodel. The hydro-salinity submodel calculates water and salt budgets for an irrigation system in order to determine the recharge rate into the groundwater reservoir. The soil moisture chemistry submodel predicts soil moisture m ovemen t and transport of solutes in the unsaturated soil profile considerin g the cation exchan ge, precipitation an d dissolution of gypsu m and lime in the soil solution. The three-dimensional grou ndwater salinity submodel predicts the spatial and temporal changes in groun dwater salinity, as well as temporal variations in the salin ity of pumped water.