Appraising climate change impacts on future water resources and agricultural productivity in agro-urban river basins

• Published in: The Science of the total environment Vol. 788; p. 147717
• Main Authors: Aliyari, Fatemeh, Bailey, Ryan T., Arabi, Mazdak
• Format: Journal Article
• Language: English
• Published: Elsevier B.V 20.09.2021
• Subjects: Agricultural productivity; Climate change; Coupled SWAT-MODFLOW; Hydrological modeling; Large scale watershed; Water availability; Climate change; Agricultural productivity; Coupled SWAT-MODFLOW; Water availability; Hydrological modeling; Large scale watershed
• ISSN: 0048-9697; 1879-1026
• DOI: 10.1016/j.scitotenv.2021.147717

Climate change can have an adverse effect on agricultural productivity and water availability in semi-arid regions, as changes in surface water availability lead to groundwater depletion and resultant losses in crop yield. These inter-relationships necessitate an integrated management approach for surface water, groundwater, and crop yield as a holistic system. This study quantifies the future availability of surface water and groundwater and associated crop production in a large semi-arid agro-urban river basin in which agricultural irrigation is a leader consumer of water. The region of study is the South Platte River Basin (72,000 km2), Colorado, USA. The coupled SWAT-MODFLOW modeling code is used as the hydrologic simulator and forced with five different CMIP5 climate models downscaled by Multivariate Adaptive Constructed Analogs (MACA), each for two climate scenarios, RCP4.5, and RCP8.5, for 1980–2100. The hydrologic model accounts for surface runoff, soil lateral flow, groundwater flow, groundwater-surface water interactions, irrigation from surface water and groundwater, and crop yield on a per-field basis. In all climate models and emission scenarios, an increase of 3 to 5 °C in annual average temperature is projected. Whereas, variation in the projected precipitation depends on topography and distances from mountains. Based on the results of this study, the worst-case climate model in the basin is IPSL-CM5A-MR-8.5. Under this climate scenario, for a 1 °C increase in temperature and the 1.3% reduction in annual precipitation, the basin will experience an 8.5% decrease in stream discharge, 2–5% decline in groundwater storage, and 11% reduction in crop yield. These results indicate the significant effect of climate change on water and food resources of a large river basin, pointing to the need for immediate implementation of conservation practices. [Display omitted] •Water supply and crop production estimated in an agro-urban basin through 21st Century•SWAT-MODFLOW model applied to the South Platte River Basin, Colorado.•The model is stressed by 10 climate scenarios.•Climate change in the basin likely will reduce streamflow, groundwater storage, and crop yield.•The large spatial scale, extended study period, and number of climate models are vital in holistic assessments.