以贵州荔波岩溶峰丛区表层岩溶泉为研究对象,采集同期大气降雨和泉水样品,根据它们的δ18O值和δD值以及水量特征,分析植被-土壤-表层岩溶带的调蓄功能.根据表层岩溶泉对降雨的响应特征,将植被-土壤-表层岩溶带分为慢速流域和快速流域,两域之间存在一定的水力联系.卷积积分理论的余弦模型计算结果表明,补给水体经慢速流域调蓄后,其氢氧同位素运移至泉水出水口的平均渡越时间不小于181 d,说明慢速流域具有较强的调蓄功能.通常,从水量特征上看,大的降雨事件易于引起快速流,而雨水和泉水的同位素特征表明,快速流不仅仅源于降雨通过植被冠层形成的穿透雨和树干径流,快速流域也可能具有一定的存储特征,但快速流暴涨暴落的特性显示其调蓄功能较差.因此,有必要采取相应措施,如改善生态环境,以防止水土流失,减少快速流的发生,提高水分的利用效率.%In Libo County of Guizhou Province, an epikarst spring catchment located in peak-cluster region, representative of a widely spreaded karst landform in Southwest China, was selected to study the water transfer and storage characteristics of forest-soil-epikarst system (FSES). From May 2008 to July 2009, samples of rainfall and the epikarst spring water in the study area were collected. The δ18O and δD of water samples were determined. According to the spring discharge, the FSES can be classified into slow flow domain (SFD) and rapid flow domain (RFD) to account for the generally continuous flow during rainy season. The two domains have hydraulic connections. The cosine-wave model of convolution integral was applied to calculate the mean transit times (MTTs) of 18O and D from rainfall input to slow flow output. The calculated MTTs were larger than 181 days. This suggests that the SFD has a relatively strong capacity to store and redistribute the inputting water into it. In general, rapid flow tended to occur in response to intense rainfall event. However, the δ18O and δD signatures of rapid flow differed considerably from those of throughfall and stemflow produced by the corresponding rainfall, indicating that the rapid flow didn't derive solely from the throughfall and stemflow that triggered the rapid response of spring discharge. So RFD might also have certain storage capacity. However, the dramatic increase of spring discharge in response to large and intense rainfall event as well as the very rapid decrease of springdischarge shortly after the rainfall event indicate that the regulation capacity of RFD was weak. Therefore, management strategies, such as improvement of eco-environment, should be carried out to prevent loss of water and soil, which minimizes the proportion of rapid flow, and improves the efficiency of water use in karst areas.
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