密云水库集水区森林的水文作用——以北庄小流域为例

 从径流小区、天然坡面径流场及流域3个尺度,对试验流域内森林植被对水文特征的影响进行研究。结果表明:试验流域2004年年径流系数为0.43,2005年为0.10,流域内产沙均为0。有林与无林2个天然坡面径流场相比,降雨与径流系数之间呈二次曲线关系,有林坡面径流系数2003年最大,为0.72,无林坡面径流系数2003年最大,为0.97,有林坡面产沙模数明显低于无林坡面,2004年产沙削减率为18.7%,2005年产沙削减率为77.3%。不同树种组成的径流小区产流量排序为板栗>刺槐>油松。对流域水质抽样检验结果表明,超标指标主要是总氮和总磷,其余水质指标均达到一类水质标准。总体来看,流域内森林植被的增加,明显增强林地的调洪、蓄水、减沙和改善水质的功能。

Forest hydrology function of the Miyun Reservoir watershed: A case study of Beizhuang small watershed

This paper presents the effects of forest to the hydrological characteristics with three scales,including the runoff section,the natural slope runoff sites,and the watershed.The results show that:in the experimental watershed,annual runoff coefficient was 43.12% in 2004 and 10.43% in 2005 while sediment yields was zero.Runoff coefficient had significant correlation with rainfall and there was a relation of a conic curve.Comparing the natural slope runoff sites in the forest land and non-forest land,the maximum value of annual runoff coefficient in the forest land was 0.72 in 2003,while one in the non-forest land was 0.97 in 2004.The sediment modulus of natural slope runoff in the forest land significantly dropped.Sediment subduction in the forest land was 18.7% in 2004 and 77.3% in 2005.The order of runoff amount was Castanea mollissina>Robinia pseudoacacia>Pinus tabulaeformis in the runoff plot of different trees.By sampling inspection on water quality of watershed,the results show that most indexes of water quality achieved the national standards of Ⅰ class,while over-leveled indexes were total N content and total P content.In general,with the increasing the forest coverage in the watershed,the function of flood control,water retention,sediment reduction,and improvement of water quality could be strengthened obviously.