Assessment of Water Supply-Demand Using Water Evaluation and Planning (WEAP) Model for Ur River Watershed, Madhya Pradesh, India

摘要

Many watersheds experience scarcity of water for agricultural and domestic use for most part of the year. Ur river watershed in Tikamgarh district of Madhya Pradesh, India, falls under a drought prone region of India. Water allocation and management are essential for sustainable agriculture for this region. Water Evaluation and Planning system (WEAP)-based decision support system can prove to be an effective tool for water allocation, supply and demand analysis. In the present study, spatially distributed model by using WEAP-MABIA method has been developed for analysis and simulation of agricultural water demands in the Ur river watershed. WEAP-MABIA method uses dual crop coefficient approach which helps in computing the separate soil evaporation and transpiration under various water availability situations. Year 2012-2013 is used as base year for customizing WEAP model for 8 subwatersheds. The model was calibrated using PEST tool, available in WEAP. The calibrated model was used for estimating future water demands and unmet demands by using future climate series, from 2015 to 2030, of IPCC scenario- RCP 4.5 of GDFL-ESM2M model. As per GFDLESM2M model (RCP4.5) predictions, rainfall is going to greatly vary in the coming years. The years 2020-2021 and 2028-2029 may experience very dry climatic conditions with 500 mm or less annual rainfall, while 2017-2018, 2023-2024 and 2025-2026 may experience heavy showers (1200 mm). Straight effects of this rainfall pattern could be seen in future water availability for agriculture and resultant crop yield. A high unmet demand exists in the case of agriculture since the first priority for water supply is meant to be for domestic purpose. Area under agriculture in Ur river watershed is large, while respective water supply is low. This gap puts an extra pressure on water resources leading to over extraction of groundwater and related problems. Looking at this scenario, water allocation requires great attention to narrow down the gap between existing demands and water supply. Since area under agriculture is large, water-efficient crops should be more emphasized. Also, efficient agricultural practices and rain water harvesting should be promoted in the study area. Since the watershed falls in semiarid condition and river flows are seasonal, different stress/deficit irrigation scenarios can be built using customized WEAP model to get higher yield.