Impacts of climate change on groundwater level and irrigation cost in a groundwater dependent irrigated region

Abstract The objective of the present study was to assess the impacts of climate change on irrigation cost in a groundwater dependent irrigated region in northwest Bangladesh. An ensemble of general circulation model (GCMs) were used for the projection of climate, an empirical hydrological model based on support vector machine (SVM) was used to simulate groundwater level from climatic variables, and a multiple-linear regression (MLR) model was used to estimate the irrigation cost due to the changes in groundwater level. The results revealed a declination of average groundwater level in the study area in the range of 0.45 – 01.19 m, 0.55–1.79 m, and 0.76–2.71 m under three representative concentration pathways (RCP) scenarios namely, RCP2.6, RCP4.5 and RCP8.5, respectively and therefore, an average increase in irrigation cost in the range of 1.61 to 9.82 USD/hectare at 95% confidence level. The maximum declination of groundwater level was projected in the northeast part of the study area in the range of 2.23–4.12 m by the GCM MIROC-ESM-CHEM which might cause an increase of irrigation cost in the range of 8.07 to 14.79 USD/hector. The study concludes that the impact of climate change-induced fluctuations in groundwater level on crop production cost is much less compared to other costs, but it may be significant in locations where groundwater level is declining fast.