生态保护和植树造林对黑河流域河川径流的影响

黑河流域是密云水库上游潮白河水系的重要组成部分。从20 世纪80 年代开始，国家在黑河流域开展了大 面积的生态保护和植树造林活动。为正确认识植树造林等活动对流域水资源的影响，本研究利用20 世纪80 年代 和2000 年两期土地利用数据和流域1959～2000 年降雨、径流资料，分析了生态保护和植树造林活动影响下的流域 河川径流量的变化情况。研究结果表明：1959～2000 年黑河流域年降水量和河川径流量年际变化较大，但整体变化 趋势性不显著；黑河流域以林地、草地和耕地面积为主，从20 世纪80 年代到2000 年林地面积增加了8x10²hm²，草 地和耕地面积分别减少了7x10²hm² 和1x10²hm²；1980～2000 年开展植树造林活动期较1959～1979 年多年平均径流 系数下降了4.1%；1980 年后20 年的生态保护和植树造林活动对河川径流量的影响为- 0.3mm/hm²，且有丰水年份 对流域河川径流量影响最大，平水年次之，在枯水年份对流域河川径流量影响最小的现象。

The Impact of Ecological Protection and Affor estation on Str eamflow in Heihe River Basin

Heihe basin is an important part of the Chaobai river system, which lies on the upstream of Miyun reservoir. Since 1980s, the government has launched many activities on ecological protection and afforestation. In order to understand the impact of these activities on water resource in Heihe basin, this paper analyzes the changes of streamflow by using land use data in the 1980s and 2000 and the precipitation-runoff data from 1959 to 2000. The results show: the interannual variation of precipitation and streamflow in Heihe basin from 1959 to 2000 is large, but has generally shown no obvious trend of rise or decline; and the heihe basin area is dominated by woodland, grasslands and farmland. From 1980s to 2000, the area of woodland had increased by 800 hectares while grassland and farmland had decreased, respectively, by 700 hectares and 100 hectares. During 1980 to 2000, when lots of ecological protection and afforestation activities were carried out, the average runoff coefficient got a reduction of 4.1%, compared to that in the control period of 1959~1979. According to the data of two periods in discussion, the impact of ecological protection and afforestation on streamflow is -0.308mm/hm2 and it indicates a phenomenon that the impact is the largest in wet years, smaller in normal years, and the smallest in dry years.