三江平原典型湿地流域水文情势变化过程及其影响因素分析

Hydrological Regime Changing Process and Analysis of Its lnfluencing Factors in a Typical Wetland Watershed of the Sanjing Plain

湿地在流域中由于特殊的水理性质和地理位置而具有特殊的水文调节功能。但是流域水土资源的开发利用常常导致大量湿地丧失和退化,湿地水文调节功能遭到破坏。论文选择三江平原典型湿地流域为案例,详细分析了流域自20世纪60年代湿地开发以来河流流量的变化过程及其主要影响因素。结果显示,流域年均流量在1965～1999年间呈持续下降趋势,但在不同的季节月均流量、最大和最小流量变化出现差异,最小和最大流量向极端化方向发展。进一步分析主要影响因素发现,下垫面条件变化和水利工程对年均径流和流量的影响分别占76%和16%;而降水和水利工程用水对春季径流量减少的影响分别占47%和56%;下垫面条件改变和水利工程排水对秋季径流量增加、流量增大的影响分别占52%和37%。

Wetlands Rave peculiar hydrological regulating functions due to their peculiar soil hy-dro-physical properties and special geographical sites in a watershed. However,the water and land resources exploitation and utilization in a watershed often resulted in wetlands loss and degradation,thus destroying,wetland hydrological regulating functions. A case study on the changing processes of river flows and their influencing factors since wetland reclamation in a typical wetland watershed of the Sanjinag Plain in the 1960s has been conducted.The results indicated that annual mean flows showed a decreasing trend in 1965～1999.But,the changing processes were different in monthly mean,maximum and minimum flows,and the maximum flows increased and the minimum flows decreased in the study watershed.The main influencing factors leading to the above hydrological changes were estimated quantitatively.Further analysis indicated that land use/cover changes and water conservancy projects(WCP) were the main influencing factors,their effects accounted for 76% and 16% respectively;the effects of rainfall and WCP construction caused spring runoff decrease accounted for 47% and 56% respectively;also the land use/cover changes and WCP autumn runoff and river flow increase accounted for 52% and 37% respectively;and the effects of other factors such as evaporation and rainfall on watershed hydrological regime were very small.So human activities were the main factors affected hydrological regime in a wetland watershed.