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【目的】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。【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】结果表明，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>0.45m3/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，导致该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 0.11~36.56L/min 之间，具有强烈的时间变异（变异系数为 1.72）。潜流中胶体质量浓度的日变化介于 0.20~15.41mg/L 之间。胶体浓度与潜流流量为极显著正相关关系（相关系数为0.73）。【结论】研究表明，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，湿干交替会促进胶体颗粒的生成。
【Objective】 Soil water potential is an index that directly reflects the energy and flow of soil water. The flow of soil water has an important influence on the runoff of arable land. Colloids are carriers of agrochemicals (nitrogen, phosphorus, pesticides) migration. 【Method】 Based on the in situ monitoring of soil water content and soil water potential and the system of runoff collection, the dynamic changes of soil water distribution, runoff and colloidal particle migration on purple soil sloping farmland were studied. 【Result】 The results show that purple soil slopes are easily saturated and the saturated soil moisture content> 0.45m3 / m3 under single heavy rain or continuous daily rainfall. Heavy rains during heavy rains contribute to the formation of plug flow in sloping arable land. Infiltration of incoming water along the sloped arable land during a continuous rainfall event can effectively replenish deep soil water in the lower part of the arable land, resulting in soil moisture content and soil Water potential has lagged in response. The diurnal variation of fissure subsurface flow in sloping arable land ranged from 0.11 to 36.56 L / min, with strong temporal variation (coefficient of variation was 1.72). The daily variation of colloidal mass concentration in underflow ranged from 0.20 to 15.41 mg / L. There was a significant positive correlation between colloid concentration and underflow (correlation coefficient of 0.73). 【Conclusion】 The results show that the soil water potential is more sensitive to the water movement of purple soil, and its combination with soil water content can reveal the mechanism of soil water movement more fully. Hydrostatic shearing and entrainment of rainfall infiltration are the main mechanism of the release and migration of colloid. Alternating wetting and drying will promote the formation of colloidal particles.