五台山区地形雨减少对水资源量的影响

海河流域水资源量减少的原因倍受关注,以五台山地区为例分析地形雨减少对水资源量的影响,分析五台山站与山下周边的5个站点年降水量之比——地形强化因子(R_o)的减少趋势以揭示地形雨的减少;并利用水热耦合平衡方程定量评估地形雨减少对该地区水资源量的影响。结果表明,近50年间R_o减少了0.53(27%),即地形雨大幅度减少;导致南庄水文站控制的五台山地区天然年径流量减少了1.9亿m3/a,占径流总减少量的70%,为多年平均年径流量的26%。中国很多地区的降水观测站网都缺少位于山上的雨量站,难以估计山区地形雨的减少,导致根据降水进行径流计算时,会低估水资源的减少量。

Impact of decreasing orographic precipitation on water resources in Wutai Mountain region, China

Much attention has been paid to the cause of declining water resources in the Haihe River basin In this study,the Wutai Mountain region is chosen to assess the impact of decreasing orographic precipitation on water resources The orographic precipitation enhancement factor R_o is defined as the ratio between the hilly precipitation from Wutaishan station and the low land precipitation from 5 stations around the Wutai Mountain.A coupled water energy balance equation is used to evaluate the impact of decreasing orographic precipitation on water resources in the region.Results show that the value of the factor R_o is down by 0.53 in the past 50 years,or a reduction of 27%,indicating a significant decline in orographic precipitation and leading to a reduction of 190 million m³/y,about 26% of the mean annual runoff, received in the region,which can even account for 70% of the total reduction of water resources.In addition,the hilly precipitation is often underestimated due to the current precipitation gauge networks suffers from a shortage of precipitation gauges at the peak of mountains in many regions of China.As a result,the impact of orographic precipitation on water resources may not be properly evaluated.The reduction of water resources cou ld thus be under-evaluated when runoff is calculated from the gauge precipitation.