永定河官厅水库下游河道内生态需水量研究

作为北京市母亲河的永定河自上个世纪80年代以来三家店以下一直处于断流,河床裸露、河道两岸土地沙化严重,是北京春季沙尘天气的主要沙源之一,由于地下水超采严重,加之无水补给地下水,使得北京西部地区第四纪地下水已经基本枯竭,永定河的生态系统已经受到严重破坏。要想恢复或治理受损的河道生态环境,作为生态系统中最活跃最重要的水分多少要先算清楚。本文采用湿周法计算了永定河官厅水库下游三个控制断面(官厅水库(坝下)、雁翅、卢沟桥)的河道内生态需水流量,计算结果为:官厅水库(坝下)站的河道内流量为3.7m~3 s~(-1)。(平水年P=50%,1978年),占年平均流量的20.7%,雁翅站的河道内流量为4.1m~3 s~(-1)(平水年P=50%,1981年),占年平均流量的20.1%,卢沟桥站的河道内流量为1.3m~3 s~(-1)(平水年P=50%,1978年),占年平均流量的22.1%。若能按照计算的流量来补充河道水量,即可使永定河恢复其基本的生态功能,按照Tennant法的标准,基本能使当地的河道生态系统处于较为良好的状态。

The Instream Ecological Water Flow Research at the Lower Reach of Guanting Reservoir on Yongdinghe River,Beijing

Yongding River, as the mother river of Beijing city, has been dried up from Sanjia Dian since 1980s. The naked riverbed and the desertification of its both sides play a main role of sandy weather in spring of Beijing. The Quaternary period underground water of the west Beijing has been drained off,because of the overload of the underground water plus with no supply pouring into. The ecological system of Yongding River has severely been devastated. If we want Yongding River to be recovered, we should clarify the quantity of the most active and the most important water. This paper calculated the instream ecological flow in three monitored sections of Yongding River Guanting Reservoir with wetted perimeter method. The three sections are Guanting Reservoir (under dam), Yanchi and Lugou Bridge. Respectively,the flows in the instream of each section are 3.7 m3s-1 (the normal flow year, P=50%, 1978) accounting for 20.7% of the average annual flow, 4.1 m3s-1(the normal flow year, P=50%, 1981)accounting for 20.1% of the average annual flow and 1.3 m3s-1(the normal flow year, P=50%,1978)accounting for 22.1% of the average annual flow. If the supplies are according to the calculated flows, Yongding River will return back from it. Still according to the Tennant method, the Yongding River will maintain a health situation.