紫色土水分和壤中流对降雨强度的响应

为研究降雨强度对紫色土坡耕地不同深度土壤水分含量和壤中流的影响,初步揭示紫色土水分和壤中流之间的相互耦合关系,通过原位人工模拟降雨试验,在60,90,120 mm/h 3种降雨强度条件下,采用Minitrase TDR可埋式探头对紫色土坡耕地土壤剖面浅层(0—20cm)、中层(20—40cm)、深层(40—60cm)的土壤水分含量进行了实时连续测定,并在降雨过程中分层收集测量壤中流,开展了降雨—产流过程的观测试验。结果表明:(1)当雨强较小时,浅层土壤含水率变化曲线呈现上升期和稳定期,随着雨强和深度的增加则呈上升期、稳定期或始终处于稳定期;(2)随深度和降雨强度的增加,土壤含水率稳定时间增加,含水率变化越小,响应越不明显;(3)在不同降雨强度条件下,各土层均有壤中流产生,低雨强条件下壤中流都是单峰产流过程,中雨强和高雨强下为双峰产流过程;(4)壤中流产流时间随雨强增大而显著减小,随深度增加而显著增加;(5)降雨强度与土壤水分含量和壤中流参数三者间相互有显著相关性。

Response of Soil Water Content and Subsurface Flow to Rainfall Intensity in Purple Soil

Subsurface flow is an important form of water flow in slope cropland of purple soil area,while rain-fall intensity is the key factor to control subsurface flow and soil water content.In order to understand the impact of rainfall intensity on soil water and subsurface flow at different layers of purple soil depth and to discover the correlation between water content and interflow in purple soil area,Minitrase TDR probes were buried into purple soil profile,which included superficial layer (0-20 cm),middle layer (20-40 cm) and deep layer (40-60 cm),to continuously measure soil moisture content in situ under the conditions of three simulated rainfall intensities (60 mm/h,90 mm/h and 120 mm/h).During the simulated rainfall process,the precipitation-runoff-producing was observed by collecting different layers' interflow.The results indicated that:(1) When the simulated rainfall intensity was small,the changes of soil water content in superficial layer showed a trend of from rising to stability.Then along with the increasing rainfall intensity and soil depth,it presented rising,stable or always stable state.(2) As the soil depth and rainfall intensity increased,the response of soil water content to rainfall intensity was not obvious,with an increasing stabilization time and little change in soil water content.(3) The presence of various levels of interflow was observed in all layers under different rainfall intensities.Subsurface flow producing presented an unimodal process under low rainfall intensity conditions,otherwise,it had double peaks.(4) The producing time of interflow declined significantly with higher rainfall intensity,and increased with deeper layers.(5) It could be concluded that rainfall intensity had obvious correlations with soil water content and subsurface flow.