摘要:
为揭示岩溶石山山坡降雨入渗补给机制,选取典型岩溶石山山坡土壤剖面为研究对象,于2015年7-10月期间对不同深度土壤水分进行高分辨率连续监测,研究典型场雨条件下土壤剖面水分对降雨的响应过程,分析土壤剖面水分的动态变化规律及其可能影响因素.研究结果表明:土壤剖面水分对降雨的响应受前期土壤含水量、降雨量、降雨强度的影响,还与土壤所处的地形地貌有关;表层土壤水分对首次次降雨响应的滞后时间与前期土壤含水量有关,响应时间在0.5~4.75 h之间,旱季响应时间比雨季长;降雨阈值是引起土壤水分降雨响应的重要条件,旱季6 mm降雨量是土壤水分响应的降雨阈值.当降雨量补充土壤水分亏缺后,土壤剖面水分对降雨响应迅速,响应时间最小为0.25 h,不同深度土壤水分对降雨的响应时间一致,说明下层土壤水分可能受到优先流或侧向径流补给影响.土壤含水量的变化幅度随土层深度的增加而减小,不同深度土壤水分变化主要受土壤-大气界面、土壤-植被、土壤-基岩界面控制下的气候条件、植被蒸散发和介质渗透性差异影响.
Abstract:
To reveal the response processes of the moisture at soil profile to precipitation events,high-resolution monitoring has been conducted to estimate the dynamic change and the factors that affect the soil profile moisture.The purpose of this study was to identify the rainfall infiltration mechanisms in karst hillslope areas.The results indicate that the response of soil profile moisture to precipitation is influenced by previous soil moisture,rainfall amount,rainfall intensity and topographic condition.The resident time of the first soil moisture response is related to previous soil moisture content,which ranges from 0.5-4.75 h,characterized by significant seasonal differences.A threshold rainfall amount exists for producing an increase of soil moisture.The 6 mm threshold is required to activate soil moisture response in dry seasons.The response time is almost synchronous,approximately 0.25 h,when the soil moisture deficit is overcome.These results illustrate that the deeper soil moisture is probably recharged by preferential flow or lateral flow.The magnitude of soil moisture variation decreases with the increase of soil depth,which is related to the climate condition,evaporation and medium permeability differences controlled by communicating with the interfaces of soil-atmosphere,soil-vegetation,and soil-bedrock.
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