岷江上游的水沙变化及其与森林破坏的关系

森林与水之间的关系是当今林学和生态学领域研究的核心问题.岷江上游森林在水土保持和调节流域水量平衡等方面具有重要的生态功能,但20世纪以来森林被大量砍伐,生态功能遭到破坏,水沙条件发生改变.以岷江上游紫坪铺控制站长系列水文资料对岷江上游水文特征变化进行分析,并结合森林破坏对森林水文效应进行探讨.其结果表明,由于岷江上游森林破坏,使流域的蒸腾量减小,年径流量增大,枯枝落叶层减少,枯水期径流量减小,河流含沙量增大,洪峰流量减弱,大洪水发生的机率显著下降.

Flow-sediment variation and relation with deforest in the upstream of the Minjiang river

The relation between forest and water is a key problem of present researches on forestry and ecology.The forest in the upper Minjiang river area plays an important role in regulating the water balance and conserving the soil and water in this river basin.However,the forest there was largely cut down since the 20th century,the ecologic function was destroyed,so the water and sand condition was changed.Based on the long-term hydrometric records at Zipingpu hydrologic station on the upper Minjiang river,an analysis is conducted to reveal the effect of deforestation on the hydrologic regime.Analysis results show that the destroy of forest in the upper Minjiang river area makes the river basin's transpiration amount reduce,annual runoff amount increase,storey thickness of dead branches and fallen leaves decrease,runoff amount in dry seasons reduce,sediment content of river flow increase,peak flood flow reduce,and probability for large flood to occur remarkably decrease.