INTEGRATED WATER MANAGEMENT IN SUNEI MEDIUM IRRIGATION PROJECT IN CHANGING CLIMATE

Abstract

The impact of climate change in the hydrology sector, often require fine scale spatial resolution climate information for studying present as well as future scenario. Global climate Models (GCMs) assess climate change scenarios on coarse partial resolution. There are different techniques to downscale to downscale coarser grid scale data to finer scale as coarse resolution of GCMs data cannot be used directly to asses climate impact for a particular area. Therefore downscaling of Global climate Models (GCMs) output is important to estimate regional climate change impacts. Precipitation is one of the important climate variables that is used as inputs in hydrologic models in many water resources studies. In this present study, Statistical Downscaling Model (SDSM) has been adopted to downscale daily precipitation to generate future climate outputs for Budhabalanga river basin in Odisha. Multiple linear regression (MLR) technique is used in SDSM. The daily precipitation data (1961-2001) representing Budhabalanga river catchment area (Sunei medium irrigation project) has been used as input of the SDSM Model. The model has been calibrated and validated with large-scale National Central for Environmental Prediction (NCEP) reanalysis data for the period 1961-1990 and 1991-2001 respectively. The prediction of future daily precipitation for the period 2025, 2050 and 2080 for the study area has been carried out corresponding to Hadley Centre Coupled Model version 3 (HadCM3 A2 and 132). The study results show that during the calibration and validation, confirm the SDSM model acceptability in regards to its downscaling performance for daily and annual rainfall. The results of the downscaled daily precipitation for future period indicates an increasing trend for the period 2025 and 2050 where as decrease in trend for the period 2080 for mean daily precipitation. It is noticed from the future climate precipitation scenario the rainfall shifted towards Month of April and May and sharp decreased in trend in month of August in the study area. Crop evapotranspiration (ET0 ) was calculated using mean monthly climate and rainfall data • with help of CROP WAT 8.0. Then crop water requirement (CWR) was determined for each crop of the project area of the study area. Results confirm the clear impact of climate change on crop water requirement of Kharif and Rabi crops. It observed that seasonal variation occurs in precipitation with decrease in trend in monsoon period. Due to constant mean annual temperature increases in both maximum and minimum temperature case and variation in precipitation, crop water requirements increases in both H3A2 and H3132 scenarios where as for some Rabi season crops like Dalua rice, Groundnut, Mustard crop water requirements decreases in future for H3132 scenario. The increase or decreases are considered compared to base period 2010. To meet the increase water demand and to increase yield for future, water resources can be increased by doing water conservation practices, small barrages and farm ponds near command area. Groundwater should be used as conjunctive use at peak requirement period. Considering future climate impact on agriculture sector, a suitable plan should be prepared within the command area to construct water storage structures like in-stream barrage, tail end reservoir, big farm ponds to restore excess surface runoff during monsoon period.