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选取桂林丫吉试验场硝盐洞为研究对象,通过示踪试验和高分辨率水文水化学监测,确定滴水补给来源,研究典型岩溶包气带洞穴滴水对降雨响应的水文过程。研究结果表明,硝盐洞XY5滴水主要受到两种径流成分补给,即集中补给的管道流和弥散流。硝盐洞上部包气带中可能存在表层岩溶带含水层,长期维持滴水流量。滴水流量、电导率和示踪剂浓度的峰值均出现在强降雨时段,表现出快速响应的管道流特征,存在降雨阈值引起硝盐洞滴水降雨响应。降雨前岩溶含水层水分条件是包气带水文响应差异的主要原因,雨季滴水对降雨响应迅速,XY5滴水对降雨响应的滞后时间为10 h;而旱季对降雨的响应滞后明显,滞后时间达9.8天,体现了土壤和表层岩溶带的调蓄作用。74.4 mm降雨量是旱季转雨季滴水响应的降雨阈值。借助于洞穴滴水的水文动态变化和示踪试验技术对于研究包气带水文过程,深入了解岩溶含水层结构及特征,揭示岩溶区降雨入渗补给机制具有重要作用。
Taking the salt cave in Yaji Experimental Site of Guilin as the research object, the source of drip supply was determined by tracer test and high-resolution hydrochemical monitoring, and the hydrological process of drip response to rainfall in typical karst aeration zone was studied. The results show that the drip of XY5 in the salt cave is mainly affected by the supply of two runoff components, namely, the concentrated supply of the pipe flow and the dispersed flow. There may be epikarst aquifers in the upper gas pool in the salt cave and long-term drip flow. The peak values of drip flow rate, conductivity and tracer concentration all appeared in the strong rainfall period, showing the characteristics of rapid response of the pipeline flow, and the existence of the rainfall threshold caused the drip rain response of the nitrate salt cave. Pre-rainfall karst aquifer is the main reason for the difference of hydrological response in aeration zone. Rapid drip irrigation in rainy season responds rapidly to rainfall, and the response time of XY5 drip irrigation to rainfall is 10 h. However, the response to rainfall in lag season lags behind with a lag time of 9.8 Day, reflecting the regulation of soils and epikarst zones. The rainfall of 74.4 mm is the rainfall threshold for drip response during the dry season. With the help of hydrologic dynamic change and tracer test technique of drip irrigation, it is of great significance to study the hydrological process of the aeration zone, understand the structure and characteristics of the karst aquifer and reveal the mechanism of rainfall infiltration and recharge in the karst area.