黄土丘陵区小流域典型造林整地工程土壤水分特征曲线模拟

Simulation of a soil water retention curve of typical soil and water conservation engineering measures in the Loess hilly watershed

开展工程措施进行植被恢复是防治水土流失的有效方式。在黄土高原半干旱小流域,工程措施能够利用有限的降水资源,促进植被恢复。以甘肃定西龙滩小流域典型水土保持工程措施鱼鳞坑和反坡台为研究对象,采用配对实验设计,在实测土壤水分特征曲线基础上,分别利用Brooks-Corey、Gardner和van Genuchten模型对不同工程措施的土壤水分特征曲线进行模拟。研究结果发现:反坡台(10.63%)、鱼鳞坑(9.78%)粘粒含量显著高于对照样地(9.66%),粉粒含量反坡台(71.42%)与鱼鳞坑(70.74%)显著高于对照样地(67.85%)。较之对照样地,反坡台和鱼鳞坑饱和导水率分别提高53.5%和46.9%。3种模型均能够很好的拟合不同工程措施土壤水分特征曲线。较之对照,工程措施长期开展后,鱼鳞坑和反坡台的土壤有效水分分别提高15%和9%,且对表层土壤水分有效性的改善更为显著。

Soil and water conservation engineering is an effective measure to prevent water loss. In the semi-arid watershed of the Loess Plateau, reasonable soil and water engineering development can utilize the limited precipitation, thus promoting vegetation restoration. In the current study, typical soil and water engineering （e.g., fish scale pits and adversely graded tableland） in a small watershed located in Dingxi City, Gansu Province were selected, and natural slope with the same vegetation served as a control. Soil samples at each site were collected from depths of 0--20, 20--40, 40--60, and 60--80 cm. Soil particle size distribution was analyzed. Soil water retention curves were monitored and simulated by Brooks-Corey, Gardner and van-Genuchten models. The results indicated that, the effects of soil and water conservation engineering on soil particle size distribution varied with soil depth. For the soil particle size distribution, the clay content of adversely graded tableland （10.63%） and fish scale pits （9.78%） was significantly higher than that of the control （9.66%）. Meanwhile, the silt content of adversely graded tableland （71.42%） and fish scale pits （70.74%） also was significantly higher than that of the natural slope （67.85%）. Compared with control, soil saturated hydraulic conductivity can be improved by 53.5% and 46.9% in the adversely graded tableland and fish scale pits, respectively. The Brooks-Corey, Gardner, and van Genuchten model can well fit the soil water retention curve of different soil and water engineering approaches. Compared with control, soil available water in adversely graded tableland and in fish scale pits can be increased by 15% and 9%, respectively. The effects of soil and water engineering on the soil available water in the surface soil layer were more pronounced after long-term implemention of soil and water engineering.