The Ganga basin in India has a serious problem of water availability. The basin, which is only one twelfth of the United States in area, has a population greater than the totalus population, and is increasing at a rate of 2·5% per annum. About 77% of the population is engaged in agriculture which is totally dependent on irrigation, as almost 85% of the rainfall comes down in 2–3 monsoon months. Surface storage possibility is extremely limited, but groundwater recharge appears feasible, since sedimentary alluvial formations extend to depths of thousands of metres. Three alternative schemes of groundwater recharge have been proposed. One involves pumping heavily along perennial rivers prior to the monsoon so as to lower the water-table and promote induced groundwater recharge. The second proposes a similar approach along nonperennial rivers. The third involves irrigation during the monsoon with groundwater lowered adequately in the non-monsoon period so that enough induced groundwater recharge takes place to provide adequate supplies for non-monsoon months. A simulation-optimization model has been developed to study the surface flow-groundwater interaction and has been applied to study comparative cost effectiveness of the three alternate approaches. Sensitivity analysis has also been carried out. It is shown that the third scheme is the most attractive.