降雨变化对东江流域径流的影响模拟分析

降雨变化对流域水文过程的影响是地理与环境科学领域关注的热点。应用流域水文模型HSPF建立了东江流域的径流模拟模型,并结合日降雨随机模拟模型,分析了降雨的长期变化对流域径流的影响。结果表明,降雨对东江流域的径流影响显著,径流量随降雨量均值与降雨量变差系数的增减而增减;相同的降雨量均值变化幅度条件下,径流增减的变化幅度相近;降雨量变差系数增加对径流的影响大于降雨量变差系数减小的影响,降雨强度的变化是影响径流量的重要因素,降雨量变化剧烈时,产生的径流更多;在同等的变化幅度内,降雨量均值变化对径流量的影响大于降雨量变差系数;由降雨情景变化引起的月径流的变化在6~8月最为明显。

The Impact of Variation in Rainfall on Runoff in the Dongjiang River Basin

The impact of rainfall variation on watershed hydrological process is an issue of great deliberation in geographical and environmental sciences. In this article, a comprehensive watershed model—The hydrological simulation program FORTRAN(HSPF) was set up and calibrated for the Dongjiang River basin in China, and was repeatedly run with various rainfall scenarios generated by the daily rainfall stochastic simulation model. The results indicated that: (1) The runoff changed in the same trend either with rise and fall in mean value or variation coefficient of rainfall; (2) In the four given scenarios (mean value of rainfall has increased by 20% and 40%, decreased by 20% and 40%, respectively), change magnitude of runoff was similar under same change magnitude of mean value of rainfall; (3) The average annual runoff raised by 24.93% when the variation coefficient of rainfall raised by 40%, and raised by 10.84% when the variation coefficient of rainfall raised by 20%. However, it fell by 3.84% and 5.35% respectively when the variation coefficient of rainfall fell by 20% and 40%, which presented that the increase of variation coefficient of rainfall has a greater impact on runoff than the decrease of variation coefficient of rainfall does. The intensity of rainfall change is an important factor affecting the runoff, and heavy rainfall has a great effect on the runoff; (4) Change of runoff due to fluctuation of variation coefficient of rainfall gradually decreased, when variation coefficient of rainfall gradually declined; (5) Average annual runoff raised by 33.99% as mean value of rainfall raised by 20%, and raised by 10.84% as variation coefficient of rainfall raised by 20%, which means change of mean value of rainfall has bigger impact on runoff change than variation coefficient of rainfall; (6) Variation of monthly runoff caused by different rainfall scenarios is more obvious in June, July and August than other months.