摘要
土水势是直接反映土壤水能量和流向的指标,土壤水的流动对坡耕地产流有重要影响。胶体是农化物质(氮磷、农药)迁移的载体。【目的】研究紫色土坡耕地水分运移和胶体颗粒的输出特征。【方法】利用土壤含水率和土水势原位监测及径流收集系统,研究了紫色土坡耕地土壤剖面水分变化、产流及胶体颗粒迁移的动态。【结果】单次大暴雨或连续日降雨作用下,紫色土坡耕地易达到饱和,饱和土壤含水率>0.45 m3/m3。大雨强降雨事件有助于坡耕地中活塞流的产生,而连续降雨事件下坡耕地上部来水的沿程入渗能有效补给坡耕地中下部的深层土壤水,导致深层土壤含水率和土水势的响应有所滞后。坡耕地裂隙潜流流量的日变化介于0.11~36.56 L/min之间,具有强烈的时间变异性(变异系数为1.72)。潜流中胶体质量浓度的日变化介于0.20~15.41 mg/L之间。胶体质量浓度与潜流流量极显著正相关(相关系数为0.73)。【结论】土水势对紫色土水分运动的响应更灵敏,其与土壤含水率的结合能够更全面地揭示土壤水分运移机制。降雨入渗的水力剪切与裹携是胶体释放与迁移的主要机理,干湿交替会促进胶体颗粒的生成。
Soil water potential is the direct indicator of soil water energy and flow direction. Flow generation is greatly affected by the movementof soil water. Colloids usually act as the carrier for agro-chemicals（e.g. nutrients and pesticides）.【Objective】Explore the water movement and colloid transport characteristics of purple soil in slopory farmland.【Method】Dynamics of soil water, flow generation and colloid transport in a sloping farmland of purple soil were studied by the in-situ monitoring of soil water content and water potential as well as the subsurface fracture flow.【Result】Purple soil easily got saturated following single heavy storm or consecutive rainfall events with the saturated water content more than 0.45 m^3/m^3. Rainfall events of high intensities favored the generation of downward piston flow. While the infiltration of the mixture of rainwater and soil water from the upper slope toward to the middle and lower slope following consecutive rainfall events facilitated the supply of deep soil water content, resulting the delayed response of soil water content and water potential. The daily fracture flow discharge varied between 0.11 L/min to 36.56 L/min with an intense time variation（Cv=1.72）. Daily colloid concentration in the fracture flow varied between 0.20 mg/L to 15.41 mg/L and it was significantly positively correlated to flow discharge（R=0.73）.【Conclusion】Soil water potential shows a more sensitive response to the water movement in the purple soil as compared with soil water content. The combination of these two factors would better reveal the mechanism of water movement. Hydraulic shearing and scouring plays the dominant role in colloid release and transport in the subsurface, and dry-wet cycling would favor the dispersion and generation of soil colloids.
出处
《灌溉排水学报》
CSCD
北大核心
2018年第2期58-63,共6页
Journal of Irrigation and Drainage
基金
国家自然科学基金项目(41601539
41471268)
关键词
含水率
土水势
胶体
紫色土
water content
soil water potential
colloid
purple soil
