PJB-2019-564
CROPWAT BASED PROJECTION OF WHEAT CROP UNDER CHANGING CLIMATIC CONDITIONS IN PUNJAB, PAKISTAN
Aftab Ahmad Khan
Abstract
The current study investigates the potential changes in Wheat crop Water Requirements (CWRs) and Net Irrigation Requirements (NIRs) and effective rainfall (Peff) in arid (Bahawalpur) and semi-arid Climatology (Faisalabad) of Pakistan. Future projections of precipitation and temperature data derived from four pre-validated Coupled Model of Inter comparison Project Phase 5 (CMIP5) of Global Climate Models (GCMs), namely, MIROC5, IPSL-CM5A_MR, NorESM1-M and CCSM4. Models data have been used as input to CROPWAT for simulation of CWR and NIR and Peff in historical period (1986-2005) and four consecutive future time series (2020-2039, 2040-2059, 2060-2079 and 2080-2099. Results exhibited a successive increase in CWR and NIR having indication of adverse impacts of climate change through increased consumptive use of crop and irrigation water need in wheat season. Wheat CWR is expected to increase by 3.01% and 6.86% in Faisalabad, and 2.46% and 5.64% in Bahawalpur by the end of 21st century for Representative Concentration Pathways (RCPs) 4.5 and 8.5 respectively. Wheat Actual Irrigation Requirements (NIR) will be increased by 5.49% and 10% in Faisalabad and 2.41% and 5.86% in Bahawalpur by 2099 for RCPs4.5 and 8.5, respectively. Mean seasonal effective precipitation in Rabi season will be declined by 9.79% and 10.07% in Faisalabad while in Bahawalpur effective rainfall will be increased by 3.16% and 2.81% over selected RCPs regimes. Faisalabad will be affected more than Bahawalpur due to changing climatic conditions threatening agriculture system. Wheat crop in Faisalabad will experiences more water stress in Faisalabad when effective rainfall is less than one fourth of crop water requirements which will yield to reduced crop growth and final yield. Inverse relation between seasonal effective rainfall and irrigation water requirement for wheat crop imply to formulate policy for sustainable irrigation water management and rain water harvesting solution under changing climatic conditions to ensure food security in the selected districts.
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