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Non-point source pollution of agriculture are defined that an effluence of nutrient and pollutant occurred in the nature are entering into the water body. Therefore, occurrence of nonpoint source pollution depends on the degree of precipitation and pollutant sources on the arable lands. It is always possibility of water contamination as an effluence of nutrient with soil erosion flowed into water system with intensive rainfall. Therefore, it is very meaningful to reduce the water contamination and to protect the nutrient loss and soil erosion with identifying characteristics of the effluence from farming land according to agricultural land use types in the environmental aspects.

To estimate the water quality of effluent from farming land according to agricultural land use types, a series of run-off samples were separately collected at paddy and upland with rainfall intensity. These samples were used for analyzing SS, EC and major nutrients such as nitrogen and phosphorus. Also, the purification effects of run-off quality with chain geomorphologic features were determined.

Rainfall intensity had influenced on SS contents in run-off from upland, which showed higher contents at high rainfall intensity. However, those of paddy didnt show its influence. According to the agricultural land use type, upland effluent had higher contents of SS than those of paddy. With geomorphologic feature, paddy, which was located at lowland of terraces, acts as sediment retention pond. It settled the settleable solids in run-off delivered from upland and reduced the delivery of sediment from agricultural lands to surface waters. With sedimentation of SS lost from cropland, water quality was purified. Nutrients contents such as nitrogen and phosphorus in upland run-off were decreased with passing paddy. This means that paddy has purification effects of run-off before it flows into water body.