RAGHU BABU, MPRINCE, LITTLE2017-02-202017-02-202013http://krishikosh.egranth.ac.in/handle/1/5810001614D5106Human activities, primarily the burning of fossil fuels and changes in land cover and use, increases the atmospheric concentrations of greenhouse gases. This alters energy balances and tends to warm the atmosphere which will result in climate change. Being one of the very sensitive parameters, climate change can cause significant impacts on water resources by resulting changes in the hydrological cycle, and the spatial and temporal water resource availability can be significantly affected, which clearly amplifies its impact on sectors like agriculture, industry and urban development. The Soil and Water Assessment Tool (SWAT) was used in the study. This hydrologic model provides a link between climate changes and water yields through simulation of hydrologic processes within watersheds. The primary objective of this study is to determine quantitatively the expected changes of water availability and crop yield under changing climate scenarios in Krishna Western Delta located geographically at about 16.45 - 15.56 ˚N latitude and 79.85 - 80.83 ˚E longitude has a command area of 5275.214 km². The assumptions that have been made in the analysis are no land use change in future and there are no man-made changes in the river system. In this study the SWAT model was evaluated using five year (2005-2009) daily discharge at Returu gauging station collected from the A.P Hydrology Project. There is a good agreement between the observed and the simulated stream flow with a coefficient of determination of 0.91 and Nash-Sutcliffe (E) coefficient as 0.47. The present water balance in the study area indicated that 59.43 % of total water goes as surface and subsurface runoff, 38.13 %, as evapotranspiration, 2.3 % as change in aquifer storage and 0.14% as soil moisture storage change. The spatio-temporal water availability was determined in the study by changing major climatic parameters like rainfall and mean daily temperature without incorporating any man-made changes like dams, diversions etc. Based on the daily precipitation values and temperature values (1980-2010), considering a gradual decrease in precipitation by 10 % and 20 % (Gosain A. K. et al, 2006) and an increase in temperature by 1 °C and 2 °C (International Panel of Climate Change) considered to get the changed climate scenario in the study area for the period 2030 - 2060 was assessed. It is observed that the water availability in the system reduces in all climate scenarios. Both water yield and soil moisture storage decreases by 19 % under the scenario when rainfall decreases by 20 % and temperature increases by 2 °C. Average agriculture productivity in the study area decreases from 723 to 637 t ha-1 in different climate scenarios. From the simulation results, rice will be the most effected crop in the changing climate conditions. Rice crop yield decreases by 39 % followed by grams 19 %, sunflower 10 %, maize 7 % and cotton 4 %. Present study showed the potential of SWAT model to simulate the current and the future prospects of water balance and crop yield in Krishna Western Delta.en-USnullThesis