表层岩溶带土壤温度和体积含水率对夏季暴雨事件的响应

The effect of heavy rain event on soil temperature and soil volumetric water content in epikarst during summer

为揭示表层岩溶带土壤温度和体积含水率对暴雨事件的响应机制,利用HOBO土壤温度和体积含水率监测仪,连续监测2014年7-8月20cm和70cm土壤温度与体积含水率。结果表明:研究区域20cm土壤温度呈日变化,这种日变化格局主要受到大气温度日变化的影响,70cm土壤温度总体上呈上升趋势,主要受到夏季大气环流使气温升高的影响。夏季暴雨事件降低了20cm深度的土壤温度、增加其土壤体积含水率,并且导致70cm处土壤温度先增高后降低、土壤体积含水率升高。土壤体积含水率较低情况下,暴雨事件使得浅层较高温度土壤水快速向下移动引起升温,而后土壤体积含水率到达一定阈值后,便能够快速响应降水事件。研究表明,岩溶地区不同深度土壤温度和体积含水率受到夏季降水事件的影响存在差异。浅层土壤能够快速的响应暴雨事件,深层土壤温度和体积含水率对暴雨事件的响应不仅受到降水量阈值的影响,而且也受到表层土壤温度和体积含水率的制约。

To discover the carbon cycle in Guilin epikarst, the effect of heavy rain events on soil temperature and soil volumetric moisture has been studied. The HOBO equipment was used to monitor the the soil tem- perature and soil volumetric moisture content at depths of 20 cm and 70 cm in the summer of 2014 （July and August）. The results shows a daily variation at the depth of 20 cm in soil temperature, which is mainly dom-inated by the daily variation atmosphere temperature. Soil temperature shows a steady increase at the depth of 70 cm, which is dominated by the increased atmospheric temperature due to summer monsoon. At the depth of 20 cm, soil temperature generally decreased and soil volumetric moisture content generally increased during and after the heavy rain events. At the depth of 70 cm, soil temperature increased first and then de- creased, while soil volumetric moisture content increased during and after the heavy rain event. In the case of low soil moisture, the deep soil temperature can be elevated when the shallow high-temperature soil water in- filtrates down. When the soil volumetric moisture content reaches a certain threshold, it can respond to storm events quickly. The results show that heavy rain events have different effects on soil temperature and soil volumetric moisture content at different depths in the karst area. Shallow soil can quickly respond to the heavy rain events, while the deep soil temperature and soil volumetric moisture content is not only dominated by the rain amount, but also by shallow soil temperature and soil volumetric moisture content.