Assessment of Water Quality and Pollutant Loads on Agricultural Watershed in Jeonbuk Province

This study was conducted to evaluate water quality and pollutant loads on small agricultural watershed in Jeonbuk province. The EC level of investigated watershed ranged from 0.07 to 0.52 dS/m, BOD level ranged from 0.1 to 5.0 mg/L, and level ranged from 0.6 to 17.7 mg/L. As above, contents of water quality indicators covered wide range, but each indicator was alike in mean content every other year. The contents of EC, were decreased in rainy season, but the contents of BOD, , T-N and T-P were not greatly different as compared to dry season. And high content of SS showed substantial sediments near the surface flow out and influence on water system in rainy season. The pollutant loads measured in terminal of watershed were kg/day for BOD, kg/day for T-N and kg/day for T-P. The pollutant loads of BOD, T-N and T-P in rainy season increased several times as compared to dry season. In rainy season, watershed with more than 30% in the proportion of paddy field to land showed relatively low discharge and pollutant loads in comparison to watershed with less than 30%. The discharge of watershed in rainy season increased 5.7times compared with the dry season in watershed with less than 30% in the proportion of paddy field to land, whereas was only 2.3times in watershed with more than 30%. The correlation coefficient() of regression between discharge and pollutant loads of T-N were higher than those of BOD and T-P.