长江螺山站50年来基流演变趋势分析

基流是枯水期河川径流量的主要补给来源,合理确定基流过程及其演变趋势在水资源、水环境和水安全的管理中都有着重要的意义。本文选用HYSEP法对长江螺山站1965-2011年的逐日流量过程进行了基流分割,得到了螺山站基流过程,选用M-K趋势检验法分析了总径流量、基流量及基流指数(BFI)值的年际变化。结果表明:螺山站多年平均BFI为0.83;近50年来,年均径流和基流都呈现显著下降趋势;年均降水量和基流指数分别表现出下降和上升趋势,但趋势并不显著;径流年内分配不均,且主要集中在4-9月,基流表现为1-7月份增加,8-12月份减少;BFI年内则呈1-4月下降,10-12月上升的变化趋势;人类活动和上游洞庭湖的调蓄作用可能是影响螺山站基流过程的主要原因。

Analysis of evolution trend of base flow in Luoshan hydrology station of Yangtze river in past 50 years

Base flow is the main supply source of river runoff in dry season. The reasonable determination of baseflow process and its evolution trend is of great significance in water resources, water environment and water safety management. This paper used HYSEP to perform the base flow separation from 1965 to 2011 for the Luoshan station of Yangtze river,and got the base flow of Luoshan station.It chose M-K (Mann-Kendall) analysis method to identify the trend of interannual and annual average runoff, base flow and base flow index distribution. The results indicate that the base flow index is 0.83 at Luoshan station.During the past 50 years,the runoff and base flow decreased;the yearly average rainfall and BFI value show the falling and rising trend respectively but the trend is not significant;the runoff is uneven in a year and mainly concentrates from April to September. Base flow is increased from January to July and reduced from August to December;BFI decreases from January to April and ascends from October to December.The main reasons that impact the process of base flow at Luoshan station may be the human activities and storage function of upstream of Dongting lake.