昕水河流域径流变化及其对气候和人类活动的响应

开展流域尺度气候变化和人类活动对径流的影响研究是科学制定流域综合管理规划,并实现流域可持续管理的基础。以黄土高原丘陵沟壑区的典型流域——昕水河流域为研究对象,结合流域多年(1958—2015年)气象水文数据,采用M-K趋势检验法分析年降水、年潜在蒸发散和年径流量的变化趋势,运用双累积曲线法分析年径流量序列的突变年份,并根据生态水文分析法与水量平衡原理定量解析流域尺度气候变化和人类活动对年径流的影响。结果表明:1958-2015年,流域年径流量变化呈显著下降趋势(Z=-5.84,p<0.0001),而降水(Z=-0.72,p=0.31)和潜在蒸散发(Z=-0.5,p=0.88)变化趋势不显著。双累积曲线法表明径流量突变点为1974年和2000年,其中,1975—2000年间影响径流减少的主要因素是气候变化,气候变化导致径流量减少的贡献率为73.14%,土地利用方式仅为26.86%;而2001—2015年土地利用变化是影响径流减少的主要原因,其贡献率高达103.81%,可见土地利用变化已成为昕水河流域径流量变化的主要驱动因素。在今后的流域治理中,需合理制定土地利用方案,实现昕水河流域水土资源协调发展。

Runoff Variation of Xinshui River Watershed and Its Response to Climate Change and Human Activities

Studying on the impacts of climate change and anthropogenic activities on runoff at the watershed scale is the basis for watershed management planning and achieving sustainable management of river basins.Xinshui river watershed, a typical watershed in the Loess Plateau, was selected as the study area. The M-K test method was used to analyze the trends of annual evapotranspiration, precipitation and runoff from 1958 to 2015. The double mass curve method was carried out to identify the abrupt point. Ecological hydrological analysis method and water balance principle were conducted to quantify the respective contribution of climate change and human activities on annual runoff. The annual runoff showed a significant decrease trend (Z=-5.84, p<0.000 1), however,nonsignificant trends were detected for precipitation (Z=-0.72, p=0.31) and potential evapotranspiration (Z=-0.5, p= 0.88). The muttionpoints of annual runoff were 1974 and 2000, respectively. Compared with the baseline period, the runoff reduction from 1975 to 2000 was mainly attributed to climate change. The contribution rate of climate change to runoff reduction was 73.14%, whereas the contribution rate of land use change was 26.86%. Contrarily, the runoff reduction from 2001 to 2015 was mainly ascribed to land use change. The contribution rate of land use change for runoff reduction was 103.81%,which indicated that land use change has become the main driving factor for the runoff variation in the Xinshui river watershed. It is necessary to develop land use plans rationally for realizing the coordinated development of water and soil resources in the Xinshui River Basin for river basin management in the future.