• Journal of Wetlands Research
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• v.21 no.1
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• pp.9-15
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• 2019

The Daegi-cheon watershed is located in the upper part of the Han River, which has the representative highland vegetable growing complexes. This watershed has a large impact on the water quality and aquatic ecosystem in the upstream of the Han River by discharging a large amount of turbid water during rainfall season. For proposing an efficient turbid water management and policy, the analysis of the characteristics of flow rate and SS and its causes needs to be carried out preferentially. In this study, the relationship between flow rate and SS concentration was analyzed in the Daegi-cheon watershed, and in turn the turbidity characteristics were analyzed. As a result of the study, in the normal flood flow condition, it was shown that SS concentration changed arbitrarily due to various environmental factors. On the other hand, the SS concentration was considerably high in the very high flow condition. Based on the field survey, this could be the reason why the effects of the steep valley and slope collapse according to the very high flow rate as well as the source in the agricultural fields were greatly contributed. Therefore, it is necessary to develop a structural best management practice that can stabilize the steep slope and reduce river bed loss along with the typical source managements plans.

• Journal of The Korean Society of Agricultural Engineers
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• v.62 no.5
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• pp.15-26
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• 2020

There are fifteen non-point pollution management areas in Korea and three of them (Doam lake, Daegi district and Golji-cheon) are located in the upstream of the Namhan river watershed. Many efforts to reduce non-point sources (NPS) pollution have been conducted, however, water quality pollution in the watershed is still serious. To solve these problems, it is a priority to grasp water quality using statistical techniques. In this study, a trend analysis was conducted to evaluate the effect of NPS management in the watershed. The long-term trends from 1996 to 2018 of water quality properties were analyzed using data collected from the water environment information system. Seventeen monitoring stations were selected along the main stream in Namhan river basin. Monthly water quality properties (BOD, COD, TN, TP, TN/TP ratio, Conductivity, SS and Chlorophyll-a) were collected and analyzed by Mann-Kendall test and LOWESS. The results showed that the Conductivity tended to increase in all regions and was the highest level in Jijangcheon. Organic pollution such as BOD and COD tended to increase in the Jungseon area. SS did not show a large tendency, but it showed high concentration in the Doam watershed. In all regions, 40% of water quality properties showed a tendency to 'UP', 15% of water quality properties tended to 'DOWN', and 46% indicated no tendency. In order to determine the cause of this, additional research and measures for improvement are necessary. This study will be used for the establishment of water quality policy in the future.