Impact of climate change on crop water and irrigation requirements over eastern Himalayan region

Due to climate change, the agricultural and socio-economic development over the eastern Himalayan region of India is greatly affected. The present study has been carried out to investigate the implications of climate change on regional crop water requirements (CWR) and crop irrigation requirement (CIR) of major crops (maize, wheat and, rice) over a Himalayan state, i.e., Sikkim. Daily climatic datasets such as rainfall, minimum temperature, maximum temperature, wind speed, sunshine hours, and relative humidity are used for this analysis along with crop and soil data. For future period (2021-2099), climatic datasets are collected from the four climate models (ACCESS1-0, CCSM4, CNRM-CM5 and MPI-ESM-LR) of CORDEX under two different scenarios, i.e., Representative Concentration Pathway (RCP) 4.5 and 8.5. CWR & CIR of maize, wheat and rice crops are projected for three-time windows, i.e. start term (2021-2046), mid-term (2047-2073), and end term (2074-2099) by taking 1998-2015 as baseline period. In addition, uncertainty and sensitivity analysis is carried out. The outcomes from the study suggest an increase in the CWR towards the end of the twenty-first century for rice and wheat over West (8% and 39%) and South (11% and 37%) Sikkim with respect to baseline period. In case of Maize, a decreasing trend is noticed over West (- 4%) and East (- 15%) Sikkim. For all the crops in East Sikkim, a declining trend is likely to occur. In most of the cases, the CIR has increased towards the end of the twenty-first century. The uncertainty analysis reveals RCP 4.5 as the possible scenario over the study area. The outcomes from the study facilitate the agricultural and water managers for adopting effective measures to ensure sustainability.