我国南方表层岩溶带及其对岩溶水的调蓄功能

EPIKARST ZONE IN SOUTH CHINA AND ITS REGULATION FUNCTION TO KARST WATER

表层岩溶带是地表强烈岩溶化过程的产物 ,为表层碳酸盐岩各种岩溶个体形态和微形态组合构成的不规则带状的岩溶带 ,在我国南方岩溶区广泛分布。表层岩溶带对岩溶水的调蓄表现在两个方面 :一是增加入渗补给量 ;二是延缓降雨后雨水在岩溶水系统停留的时间 ,并形成了表层岩溶泉。表层岩溶带对岩溶水的调蓄功能大小主要与表层岩溶带的结构、岩层产状、地表覆盖情况和降雨性质有关。石漠化环境与森林环境的表层岩溶带对岩溶水的调蓄功能差异很大。石漠化地区 ,表层岩溶带泉的出流时间短 ,动态非常不稳定 ;表层岩溶带对岩溶管道泉调蓄能力弱 ,泉水动态与降雨动态一致。森林环境表层岩溶泉则多为常流泉 ,水文动态比较稳定。表层岩溶带形成的表层岩溶泉为开采深部岩溶水困难的峰丛山区的居民饮水提供了重要的水源 ,但只有恢复了岩溶石山区森林生态 ,才能实现表层岩溶泉应有的供水功能。

WT5BZ]Epikarst zone is an irregular karst zone occurring in surface carbonate rocks and consisting of various individual and micro karst forms, which result from strong karstification processes. It is wide spread in South China, but its size, landform and location are influenced by geological and climatic factors. Epikarst zone has two important regulation functions to karst water. Firstly, it can increase recharge of karst water with high intensity of fissure . Secondly, it may make rain water to store in karst water systems for a longer time and form epikarst springs somewhere. However, the regulation functions to karst water depend on the structure of the epikarst zone,occurrence of strata, land cover and rainfall intensity. The regulation of epikarst zone to water in rock desertification environments is quite different from that in forests. For example, in the rock desertification areas of Liupangshui, Guizhou, the water cycle time in epikarst zones is short, and the hydrologic behavior of epikarst springs is unstable and in correspondence with rainfall, and there is no water flow in dry seasons, showing that the regulation function of the epikarst zones is low. But the epikarst springs in forests, such as in Nongla, Guangxi, have a stable hydrologic behavior and are permanent. Therefore,the rehabilitation of forests in karst mountain areas of South China is very important to improve the regulation functions of epikarst zones to karst water. Epikarst springs in forests can provide local people with permanent drinking water, which also are important water sources in karst mountains, especially in karst peak cluster depressions where karst water in underground conduits is deep and difficult to exploit.