紫色土坡耕地土质埂坎分层入渗试验研究

以相邻田面为对照,利用双环入渗法对三峡库区紫色土坡耕地土质埂坎分层(地埂、坎腰和坎趾)的入渗特征进行研究。结果表明:(1)土质埂坎分层入渗与对照田面入渗均呈先陡降后趋于稳定的趋势,但达到稳定入渗的时间存在差异。地埂达到稳定入渗的时间最长(110min),坎腰、坎趾和田面达稳定入渗的时间分别比地埂少9%,82%,18%。从入渗性能看,土质埂坎各层均表现出初始入渗率平均入渗率稳定入渗率。平均入渗率与120min累积入渗量表现为地埂坎腰田面坎趾,初始入渗率为坎腰地埂田面坎趾,稳定入渗率为田面坎腰地埂坎趾。(2)采用4种模型进行拟合,其中通用经验模型是描述坡耕地土质埂坎入渗的较好模型,其后依次是Kostiakov模型、Horton模型和Philip模型。(3)土质埂坎入渗性能与土壤物理性质具有较好的相关性,初始入渗率与初始含水率、容重呈显著负相关(P0.05),平均入渗率、120min累积入渗量与粉粒体积分数、初始含水率呈显著负相关(P0.05),与砂粒体积分数和总孔隙度呈显著正相关(P0.05)。研究结果可为紫色土区坡耕地土壤侵蚀调控的埂坎措施优化提供依据。

Experimental Study of Different Layers Infiltration of Soil Bunds on Purple-soil Sloping Farmlands

An adjacent field was chose as a reference and soil infiltration rates of layered soil bunds (the upper,the central and the lower) were determined using double rings on the purple-soil sloping farmland.The results showed that:(1) The infiltration processes of all layered soil bunds and the field dropped steeply then decreased slowly till stable.However,there were differences on the duration to the stable infiltration.It cost a relatively longer time (110 minutes) for the upper bund to the stable state.The time for the central,the lower bund and the field was 9％,82％,and 18％ shorter than that of the upper bund.In perspective of infiltration performance,the soil permeability was sequenced as the initial infiltration rate,the mean infiltration rate,and then the steady infiltration rate.In view of layered soil bunds,the mean infiltration rate and the 120 minutes cumulative infiltration was sorted as the upper bund,the central bund,the field,and the lower bund.The initial infiltration rate was sequenced as the central bund,the upper bund,the field,and the lower bund,while the steady infiltration rate was sorted as the field,the central bund,the upper bund,and the lower bund.(2) Four models had been used to simulate the soil bund infiltrations.Among them,the general experience model was considered as the optimum one,and it was followed by the Kostiakov model,the Horton model and the Philip model.(3) The permeability of soil bunds had close relation with soil physical properties.The initial infiltration rate was significantly negative related to the initial water content and soil bulk density (P ＜ 0.05).The mean infiltration rate and the 120 minutes cumulative infiltration was significantly negative correlated with the silty particles volume and the initial water content (P＜0.05),and significantly positive correlated with the sandy particles volume and the total porosity (P＜0.05).The results of this study can provide a foundation for bunds construction as to control soil erosion on purple-soil farmlands.