VARIABILITY OF RAINFALL, TEMPERATURE AND EVAPOTRANSPIRATION VARIABLES UNDER CLIMATE CHANGE IN FIVE SELECTED DISTRICTS OF CENTRAL PUNJAB BASED ON DATA DERIVED FROM IITM- REGCM4 BASED SIX MODEL ENSEMBLES

Rainfall, maximum air temperature and minimum air temperature data for the five critically ground water depleted districts of central Punjab viz., Barnala, Moga, Sangrur, Patiala and Ludhiana for the baseline period from 1983-2005 and the near future, 2030 under medium emission scenario RCP 4.5 was obtained from six climate model ensembles based on IITM- RegCM4 model. The potential evapotranspiration (PET) and actual evapotranspiration (AET) data were estimated using bias corrected climate data and validated SWAT model for the study districts. Modified Mann-Kendall trend test stastic (Mmk-Z) indicated a significant decrease in rainfall at p<0.05 during 2030 for all the study districts except Ludhiana and Patiala. Sens’s slope estimator indicated rate of decrease of rainfall by 3.4 mm/year, 3.3 mm/year, 2 mm/year, 1.9 mm/year and 1.2 mm/year for Moga, Patiala, Barnala, Sangrur and Ludhiana district, respectively and an increase in minimum air temperature by 0.02oC/year for the whole study region during 2030. The estimated PET vales showed an increase by 13.6 %, 11.7 %, 11.6 %, 10.6 % and 10.1 % for Ludhiana, Sangrur, Moga, Barnala and Patiala districts respectively, whereas, the estimated AET values showed a decrease by 33.5 %, 31.7%, 30.7 %, 28.6 % and 27.1 % for Patiala, Sangrur, Ludhiana, Barnala and Moga districts, respectively during 2030 over the base period. An increased irrigation water demand by 43%, 36%, 31%, 21% and 21% for Ludhiana, Patiala, Sangrur, Barnala and Moga districts, respectively during 2030 over the baseline period was observed indicating more dependency on ground water for meeting crop irrigation demand in the study districts.