Optimization modeling for conjunctive use planning in Upper Damodar River basin, India

Abstract

Canal irrigated regions often suffer from twin problems of waterlogging and salinity as well as water scarcity in the absence of proper irrigation planning, particularly in developing nations. There is an urgent need to adopt the concept of ‘Conjunctive Use’ in practice for the sustainable management of land and water resources in canal commands. Considering real-world conditions, this study demonstrates a framework for conjunctive use planning using optimization modeling through a case study in the Upper Damodar River basin of Eastern India. A resource optimization model was developed taking into account spatial, seasonal and climatic variability of water supply, crop irrigation requirements and Dynamic Groundwater Reserve (DGWR) as well as considering DGWR as the available groundwater resource, which are unique in this study. The optimization model was solved for ‘Normal’ and ‘Dry’ climatic conditions considering four scenarios that represent optimal conjunctive use plans for four realistic situations. The results of optimization modeling indicated that it is possible to obtain the net annual benefits of Rs. 24818.00 million during ‘Normal’ years and Rs. 14679.00 million during ‘Dry’ years due to the efficient allocation of land and existing water supplies to current cropping patterns. If the available DGWR is fully utilized for irrigation along with the existing surface water supply, these net benefits can be increased by 197% during ‘Normal’ years and 267% during ‘Dry’ years. Thus, the developed optimal conjunctive use plans are promising and reasonable for significantly increasing farmers’ returns even during ‘Dry’ climatic condition. Based on the findings of this study, efficient management strategies could be formulated by the concerned planners/decision makers and practicing engineers to ensure sustainable management of land and water resources in the study area, which in turn can guarantee sustainable agricultural production and water security on a long-term basis.