基于稳定同位素和水化学成分的西南喀斯特流域径流划分

针对喀斯特流域下垫面空间异质性强,地表、地下径流转化复杂的特点,本文选择贵州陈旗实验小流域,根据实地调查流域内水源位置以及同位素、水化学样品的采集,将流域内水源划分为地表水(仅当强降雨时发生)、表层岩溶带水和深层地下水,采用稳定同位素和水化学成分组合方法划分了流域出口径流的水源成分。结果表明:降雨期间,坡面地表径流所占比例较少,小于10%,表层岩溶带所占比例在28%～45%之间,地下径流所占比例在49%～62%之间;降雨过程中表层岩溶带径流比例增大,地下径流比例减少。降雨过后,表层岩溶带径流比例迅速减少、地下径流比例呈现增加趋势;地下径流是无雨期流域出口断面径流的主要组成部分,无雨期地下径流占地下暗河出口径流量68%～88%。

Separation of Runoff Components Based on the Stable Isotopes and Hydrochemical Composition in a Small Karstic Basin

Surface water and groundwater transfer is very complex in the karst region due to strong heterogeneity of land surface conditions.In this study,a small karstic basin of Chenqi in Guizhou Province was selected for the analysis of runoff components based on stable isotopes and hydrochemical composition during rainfall and non-rainfall periods.According to the characteristics of various water source positions by field investigations in the basin,we collected water samples at these positions for analyzing isotopic and geochemical composition.Watershed outflow was separated into surface water(only existing during rainfall),epikarst water and groundwater.The results showed that the proportion of epikarst water increased and the proportion of underground runoff decreased during the rainfall period.After the rainfall ceased,the proportion of epikarst water decreased significantly and underground runoff increased.During the rainfall,the proportion of surface water is less than 10%,epikarst water is within the range of 28%～45% and underground water,49%～62% of the total discharge.Underground runoff is a primary water resource of the entire basin during the non-rainfall periods,and the proportion is about 68%～88%.