长江流域径流模拟及其对极端降雨的响应

研究流域径流量变化可为水资源科学调配、利用开发、水旱灾害防治、水环境污染整治和国民经济可持续发展等提供重要依据.但近年来受全球变暖影响,极端气候事件,尤其是极端降雨的发生频率和强度出现了变化,直接或间接影响径流量变化.运用SWAT模型模拟1965~2019年间长江流域径流时空变化规律,分析了不同极端降雨条件下径流对降雨的响应.结果表明,1965~2019年间长江流域径流变化并不显著,流域总径流和中下游径流均经历了"枯-丰-枯-丰"4个阶段.极端降雨情景模拟发现,50 a一遇极端降雨下,长江上、中和下游代表性子流域日均径流变化率分别为6200%、21%和15%,月均径流变化率为355%、5%和1.3%,年均变化率为78%、1%和0.24%.而100 a一遇极端降雨下,3个子流域日均径流变化率分别为8000%、25%和17%,月均径流变化率为437%、7%和1.5%,年均变化率为96%、1.2%和0.28%.研究结果可为流域水资源管理和利用及洪涝灾害预测与防控等提供理论依据.

Runoff Simulation and Its Response to Extreme Precipitation in the Yangtze River Basin

Studies on runoff are crucial for the scientific allocation, utilization, and development of water resources and can provide an important basis for the prevention and control of flood and drought disaster, as well as water environmental pollution management. Affected by global warming, the frequency and intensity of extreme climate events, particularly extreme precipitation, have significantly changed in recent years, which can directly or indirectly impact runoff changes. In this study, we used the SWAT model to simulate the spatiotemporal variations in runoff in the Yangtze River Basin from 1965 to 2019 and analyzed the response of runoff to precipitation under extreme conditions. The results showed that the changes in total runoff in the Yangtze River Basin were not significantly different from 1965 to 2019. The total runoff and the mid-lower runoff in the basin experienced four stages of "dry-wet-dry-wet." Simulations revealed that under the 50-year extreme precipitation event, the increase in daily average runoff was 6200%, 21%, and 15% for the typical sub-basins of the upper, middle, and lower reaches of the Yangtze River, respectively. Additionally, the increase in monthly and annual average runoff was 355%, 5%, and 1.3% and 78%, 1%, and 0.24%, for upper, middle, and lower reaches of the Yangtze River, respectively. Moreover, under the 100-year extreme precipitation, the average daily runoff increasing rates were 8000%, 25%, and 17% for upper, middle, and lower reaches of the Yangtze River, respectively, compared to the monthly increase of 437%, 7%, and 1.5% and annual increase of 96%, 1.2%, and 0.28%, respectively. Our findings may improve the understanding of hydrological responses to climate change and provide valuable inferences to decision-makers and water managers for better allocation and management of water resources.