Two-level optimization model for Lower Indus Basin

Abstract

The present study aims at the development of a model to schedule the sowing dates of the crops in such a manner that the peak water requirements of different crops are more uniformly distributed over different months and hence, more area can be irrigated for a given canal and tube well capacities. For this purpose, a two-level optimization model for optimal use of surface and groundwater has been developed. In the first level, the model gives optimal cropping patterns and monthly water withdrawals from canal and tube well for a given set of sowing dates to maximize the net economic returns. At second level, the sowing dates are varied within the allowable limits and the optimized sowing dates are obtained using an integer programming model. The sowing dates at the first level are then taken as the sowing dates obtained from the second level. The process is repeated until it converges. The sensitivity analysis for some of the parameters is also done. The model is applied to Dadu canal command of Lower Indus Basin. The results show an overall increase of 40% in the crop intensities and 38% in the benefits over the existing ones by using the two-level optimization model.