IMPACTS OF CLIMATE CHANGE ON CROP WATER REQUIREMENT UNDER MULTI - REPRESENTATIVE CONCENTRATION PATHWAYS DURING MID-CENTURY: A CASE STUDY OF D. I. KHAN

Abstract

Climate change is a major problem which directly affects agricultural economy of a region as the crop water requirements of major crops is increased. This study was conducted to estimate evapotranspiration (ETo) and crop water requirements (CWR) of wheat and maize crops of the study area during mid (2040-2059) century under emission scenarios based on Representative Concentration Pathways (RCPs). The methodology employed here involves the comparison of temperature and precipitation data projected by different GCM with the observed data. The delta change and ratio method was used to obtain the corrected value of temperature and Precipitation (PPT) for the future. The ETo calculator of Food and Agriculture Organization was used to calculate evapotranspiration. The CWR of wheat and maize crops was computed using CROPWAT 8.0. Results showed that out of sixteen GCMs, only four models i.e., bcc_csm1_1_m, gfdl_cm3, miroc5 and noresm1_m, were considered suitable for simulating the present day climate for the study area. The Ensemble average of these four selected models showed an increase in mean temperature of 2.07 oC and 2.47 oC, and an increase in PPT of 8% and 10% under RCP 4.5 and 8.5, respectively. Similarly, ETo showed an increase of 17% and 21% under both scenarios. Ensemble seasonal CWR of wheat crop under RCP 4.5 is projected to be increased by 10%, while under RCP 8.5 it increased by 8%. The CWR of maize crop is projected to increase by 10% and 15% under RCP4.5 and RCP8.5, respectively.