岩溶地下河流域水循环方式的降水效应

The precipitation effect on the water cycle mode of karst subterranean stream catchment

岩溶水中锶元素来源于碳酸盐岩地层的溶解,其浓度受地层岩性及地下水径流条件的控制。通过对贵州荔波板寨地下河流域微量元素锶的水文地球化学特征分析,发现在纯碳酸盐岩流域范围内,岩溶水中锶浓度只受控于地下水径流条件,因而Ca/Sr值能良好的示踪岩溶区地下水循环。在本文中,以Ca/Sr值为判别依据,将板寨地下河流域7个水样点划分为3类,分别为管流带/饱水带水、地下河水及表层岩溶带水。通过对流域水文地质条件分析,地下河流域总排泄量由表层带岩溶水和管流带/饱水带岩溶水两个端元组成。径流切割结果表明,在2009年12月至2010年2月,虽然在地下河径流排泄量中饱水带岩溶水一直占有优势,但表层带岩溶水的贡献比也很可观,均大于40%。但受极端大旱气候的影响,2010年3月末表层岩溶带岩溶水几乎枯竭,其贡献比陡降至7.1%,说明降水对该流域岩溶水循环方式起着控制作用。

Strontium in karst water came from carbonate rocks, and its content is controlled by lithology of the formations and the runoff conditions of groundwater. In the area covered by pure carbonate rocks, the strontium content is only controlled by the latter based on the analyzing of strontium hydrochemical character of Banzhai subterranean stream located in Libo County, Guizhou Province. So, the Ca/Sr ratio can be used to discriminate the water circulation mode. In this paper, the 7 water sam- ple sites be divide two 3 types, which are epi-karst water sites, conduit flow zone/saturation zone water sites and subterranean stream debouchure. The total discharge in subteranean stream debouchure is madeup of other two end mumbers. Although the conduit flow zone/saturated zone water is dominated during Dec-2009 to Feb-2010, the contribution of epi-karst water quatity is also very important and more than 40% in total discharge. However, effected by the extremity dry season, the epi-karst water is almost exthaust and its contribution be droped to 7.1% sharply at the end of March 2010. It is shown that the kast water circulation mode is controlled by the precipitation in the study area.