Department of Civil and Environmental Engineering, Colorado State University, 1372 Campus Delivery, Fort Collins, CO 80523-1372, United States.
Department of Civil and Environmental Engineering, Colorado State University, 1372 Campus Delivery, Fort Collins, CO 80523-1372, United States.
Sci Total Environ. 2021 Sep 20;788:147717. doi: 10.1016/j.scitotenv.2021.147717. Epub 2021 May 14.
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 km), 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.
气候变化会对半干旱地区的农业生产力和水资源供应产生不利影响，因为地表水供应的变化会导致地下水资源枯竭，从而导致作物产量下降。这些相互关系需要采用综合管理方法来管理地表水、地下水和作物产量，将其作为一个整体系统来考虑。本研究量化了一个大型半干旱农业城市流域中地表水和地下水的未来可利用情况，以及相关的作物产量，该流域中农业灌溉是主要的水资源消耗者。研究区域为美国科罗拉多州的南普拉特河流域（72000 平方公里）。该研究使用 SWAT-MODFLOW 耦合模型作为水文模拟器，该模型由 Multivariate Adaptive Constructed Analogs（MACA）进行降尺度，共使用了五个不同的 CMIP5 气候模型，每个模型都针对两个气候情景（RCP4.5 和 RCP8.5）进行了模拟，时间范围为 1980-2100 年。水文模型考虑了地表径流、土壤侧向流动、地下水流动、地下水-地表水相互作用、地表水和地下水灌溉以及逐田作物产量。在所有气候模型和排放情景中，预计年平均气温将增加 3 至 5°C。而预计的降水变化则取决于地形和与山脉的距离。根据本研究的结果，该流域中最恶劣的气候模型是 IPSL-CM5A-MR-8.5。在这种气候情景下，温度升高 1°C，年降水量减少 1.3%，流域的河流径流量将减少 8.5%，地下水位储量下降 2-5%，作物产量减少 11%。这些结果表明，气候变化对大型流域的水资源和粮食资源有重大影响，这表明需要立即实施保护措施。
