In this study, K-CWQI (Korean-Comprehensive Water Quality Index) including five items such as pH, DO, BOD, SS and T-Coli developed by NIER (National Institute of Environmental Research) in 2006 is calculated by using the result of monitoring in the major tributaries of Gumho-River Basin from 2015 to 2016 and reviewed about applicability when evaluating water quality in the basin. The scope of calculated K-CWQI is from 70 to 90 points in five tributaries and water quality of major tributaries of Gumho-River Basin is evaluated above "slightly good grade". The highest value of K-CWQI is 88 points of Palgeacheon on the other hand, the lowest value of K-CWQI is 77 points of Namcheon. Also, the grade evaluated by K-CWQI and BOD is compared in order to apply K-CWQI to assessment of water quality. The results of this comparison are summarized as follows. The degree of agreement between the grade evaluated by K-CWQI and BOD is reached to 93% when including 1st grade difference as well as exact match and the monthly variation of K-CWQI is relatively lower than BOD. Therefore, K-CWQI not only can complement current water quality standard consisting of a single item, but also assess water environment of tributary comprehensively.

No abstract

As a response to climate change, South Korea has established its third National Climate Change Adaptation Plan (2021–2025) alongside the local governments’ plans. In this study, proxy variables in 22 sub-watersheds of the Nakdong River, Korea were used to investigate climate exposure, sensitivity, adaptive capacity, and non-point pollution in sub-watersheds, a climate change vulnerability index (CCVI) was established, and the vulnerability of each sub-watershed in the Nakdong River was evaluated. Climate exposure was highest in the Nakdong Estuary sub-watershed (75.5–81.7) and lowest in the Geumhogang sub-watershed (21.1–28.1). Sensitivity was highest (55.7) in the Nakdong Miryang sub-watershed and lowest (19.6) in the Habcheon dam sub-watershed. Adaptive capacity and the resulting CCVI were highest in the Geumhogang sub-watershed (96.2 and 66.2–67.9, respectively) and lowest in the Wicheon sub-watershed (2.61 and 18.5–20.4, respectively), indicating low and high vulnerabilities to climate change, respectively. The study revealed that the high CCVI sensitivity was due to adaptive capacity. These findings can help establish rational climate change response plans for regional water resource management. To assess climate change vulnerability more accurately, regional bias can be prevented by considering various human factors, including resources, budget, and facilities.

In this study, the major 38 tributaries in Nakdong River were monitored for flow rate and water quality in order to understand the characteristics of the watershed and to find improvement plan. The flow rate and water quality for each target tributary were evaluated based on the monitoring data in 2013∼2014 using a statistical package SPSS-22.0. In addition, the tributary grouping method was conducted using a BOD5 concentration/flowrate and TP concentration/flowrate monitoring data. The average values of BOD5, CODMn, TP and TOC concentrations in Gumicheon, Gyeonghocheon, Jincheoncheon, Gisegokcheon, Yonghacheon and Yonghocheon located at Nakdong Waegwan and Nakdong Goryung watershed were high and in the grade of III or IV (5∼8 mg/L). The Pearson correlation coefficients of TOC with BOD5, CODMn, and TP were greater (r=0.8, p<0.01) than those of the other water quality parameters (12 species). The tributaries with high values of water quality parameters (BOD5 > 3.0 mg/L, TP > 0.1 mg/L) and flowrate (Q > 0.1 m 3 /sec) were selected for improving water quality according to the stream grouping method. Five tributaries (Gumicheon, Gisegokcheon, Yonghacheon, Yeongsancheon, Mijeoncheon and Yonghocheon) were classified as Group I, which require polices and plans for water quality improvement.

This study has performed comparative analysis on characteristics of contaminated 35 tributaries on seasonal variation/point discharge load/pollutant distribution of water quality factors(8) in order to understand the effect of the watershed in Nakdong River Basin. As a results, the water quality of BOD 5 (Biochemical Oxygen Demand), Chl-a(Chlorophyll a) and Fecal E. Coli shows Ⅱ grade at tributaries of more than 50% without COD(Chemical Oxygen Demand), TP(Total Phosphate), TOC(Total Oxygen Carbon) and TN(Total Nitrogen) factors. The specific discharge(Q) were occupied about 54.4% (19 sites) as 0.05 m 3 /sec/km 2 value. Among these results, the contaminant level of Dalseocheon, Hyeonjicheon, Seokkyocheon 1, Uriyeongcheon and Dasancheon was also high, which has to consider a discharged pollutant load(kg/day). The 35 major tributaries of Nakdong River were included in 7 mid-watershed, such as Nakdong Waegwan, Geumho River, Nakdong Goryung, Nakdong Changnyung, Nam River, Nakdong Milyang, Nakdong River Hagueon. Especially, the discharged pollutant load of Nam River and Geumho River also was high according to the amount of discharge such as Kachang dam, Gongsan dam and Nam river dam. Seasonal difference of the water quality factors such as BOD 5 , TN, SS and Q was observed largely, on the other hand