北京山区植被恢复建设对流域径流量影响研究

植被恢复是山区保持水土资源、恢复生态环境的关键措施.为探究植被恢复对流域产水量的影响,以密云水库集水区红门川森林流域为研究对象,采用Mann-Kendall非参数趋势检验、基于分离评判原理的水文分析法、Zhang(2001)模型等方法,定量分析了1989－2009年间北京山区气候及森林变化对流域径流量的影响.研究结果表明:红门川流域年降水及产流性降水量在研究时段内均呈波动下降趋势(P>0.05);流域年径流呈显著性减少趋势,且年径流量在1998 年前后发生减少突变(P<0.01);气候变化对红门川流域径流减少贡献率为43%,植被恢复建设导致的森林数量及质量变化对流域径流减少贡献率为18.6%,其他人类活动影响贡献率为38.4%.综合比较得知,与植被恢复建设相比,降水减少对山区产水量减少影响更大.研究结果可为北京山区森林流域水土资源规划及管理提供参考.

Effect of vegetation rehabilitation and construction on runoff of watershed in Beijing Mountain Area

Vegetation rehabilitation is the key measures for maintaining the soil and water resources and restoring the ecological environment in mountain areas. To explore the impact of vegetation rehabilitation on annual runoff, Hongmenchuan watershed located in Miyun Reservoir of Beijing was selected as research object. Mann-Kendal Test, Hydrological analysis based on separation evaluation method, and Zhang (2001) model were applied to quantify the respective contribution of climatic change and forest change to annual runoff of the area from 1989 to 2009. The results indicated that the mean annual precipitation and of Hongmenchuan watershed showed a fluctuant decreasing but not remarkable trend from 1989 to 2009, while the runoff showed a significant decreasing trend. Combined with the results of cumulative runoff rate curve and independent sample t-test, the annual runoff had a significant decreasing trend with the change point occurred in 1998. Human activities were the strongest contributor to the reduction in mean annual streamflow of Hongmenchuan watershed, and the contribution rate reached 57%, while the remaining caused by climatic variations. Different types of human activities on the reduction in annual streamflow were quite different, for instance, the contribution rates of vegetation rehabilitation and construction on runoff was about 25.34%. In summary, compared with vegetation restoration, reduction in precipitation has a greater impact on the water yield. The results provide a theoretical reference for basin water resources management and land-use planning in Beijing Mountain areas.