漓江流域旱涝拐点研究

Turning points of drought and flood in Lijiang river basin

漓江汛期和枯水期有明显的周期性,通过大量数据对漓江降雨量、植被变化和生态需水量与漓江径流量间的关系进行了分析。在相关图中出现了大量的拐点,其中漓江月平均流量与降雨量拐点重合,说明漓江是一条雨源性河流;分析了漓江年平均流量、最小流量及最枯月平均流量的拐点,其径流变异的主要因素除降水突变等气候变化,人类活动对漓江径流序列的突变影响也比较大。植被覆盖率倒U型拐点的出现,说明近些年植被破坏严重也是漓江旱涝的一个主要原因;生态需水量拐点出现的时间和月平均流量的时间基本一致,说明月平均流量对生态需水量的影响远远大于河流径流量的年际波动的影响。通过分析印证了漓江旱涝出现与降雨和径流的分布不均、补给区植被覆盖率、流域生态需水量的增加有关。

The flood and drought period of Lijiang river shows obvious periodicity.The analysis covers the rela-tionship between the Lijiang rainfall capacity,vegetation change,ecological water demand and the runoff vol-ume through mass data.There are many turning points in the related figures.The turning points of the average flow rate and the rainfall capacity coincide with each other in Lijiang which indicate that the source of the Li-jiang river is from the rain.Besides,the turning points of the average annual flow,minimum flow and maxi-mum average flow rate in the drainage basin are analyzed.Other than the runoff change climate like sudden rainfall change,human activity affects the runoff sequence change.The occurrence of reversal U-form turning point of the vegetation coverage presents that the serious vegetation deterioration in recent years is the main cause for the drought and flood.The occurrence time of the ecological water demand turning point is basically the same as the time of the average monthly flow,which shows that the influence of the average monthly flow on the ecological water demand is much greater than the influence of the inter-annual fluctuation of the river runoff. Through the analysis,it turns out that the drought and flood related to the uneven distribution of the rainfall and runoff increases the vegetation coverage in the recharge area and basin ecological water demand.