降雨过程中δ^(18)O时程变化规律及其对径流成分划分的影响

Temporal Variation of δ^(18)O in Rainfall and Its Impact on Hydrograph Separation

为分析降雨过程中δ18 O时程变化规律及其对径流划分的影响,分析了和睦桥流域2015年8月至2016年10月间七场降雨事件中林外降雨、穿透降雨、林外顺序降雨、穿透顺序降雨、河水的δ18 O变化规律,并利用二水源流量过程线分割模型,实时划分了径流成分。结果表明,林外降雨与穿透降雨的δ18 O均具有明显的时程变化,δ18 O时程变化导致径流划分所得旧水比例随时间的变化而变化;穿透降雨的δ18 O变化幅度小于林外降雨,但其δ18 O算术平均值和平均值整体上大于林外降雨,因此在进行径流成分划分时,需根据当地植被条件合理采样。研究结果为类似地区的径流划分提供借鉴。

To evaluate the temporal variation ofδ18 O in rainfall events and its impact on the hydrograph separation,seven flooding events from August 2015 to October 2016 were measured in Hemuqiao watershed.Samples include rainfall,throughfall,incremental rainfall and throughfall,and streamflow.All of them were used to separate hydrograph adapting two-component hydrograph separation method.The results show that theδ18 O of both incremental rainfall and thoughfall exhibits marked temporal variation.The variation of the former is higher,but the latter has higherδ18 O and meanδ18 O.The old water percentage vary with time due to the temporal variation ofδ18 O,illustrating the necessity of choosing a sampling method suitably in hydrograph separation.The result can be a reference for hydrograph separation in similar watershed.