• Journal of Wetlands Research
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• v.6 no.3
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• pp.83-93
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• 2004

The purpose of this study was to develop the environmental management strategy of streams based on the quantified evaluation method of the stream environment. The six streams in Jinju city flowing into the Nam-river were selected for the case study. The stream environment evaluation was performed considering the following three independent field surveys. First, the stream naturalnesses considering 20 evaluation elements were investigated for each unit section of the streams having the length of 500m and the width of 100m, and then were evaluated into 5 grades. Second, water qualities of the streams were evaluated into 5 grades based on the results of eight times water quality survey. Third, the landuse patterns in the stream basins were evaluated into 5 grades according to the residential area ratio. Finally, the stream environments were classified into 5 grades by integrating the above three subfactors - stream naturalness, water quality, and residential landuse. According to the evaluation results of stream environments, the three environmental management strategies of streams were suggested. As the results of the case study, Panmun stream and Ghajwa stream were evaluated to the forth grade that need active environmental restoration, and Nabul stream and Yonga stream were evaluated to the second grade that need partial environmental restoration while Youngchun river and Dogsan stream were evaluated to the first grade showing the desirable stream environmental condition. The above environmental evaluation results for each stream will be an important reference for the further stream restoration or management plan.

• Journal of Environmental Impact Assessment
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• v.23 no.5
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• pp.393-405
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• 2014

In this study, the nonpoint sources were evaluated by calculating the Nadonggang basin regional water quality and nonpoint source pollution load discharged. And were selected the banks of first administration based on the results and the direction of the next administration. As a results of estimating the water quality about BOD concentration in the mid influence area in the Nakdonggang basin, it was founded that 10 sites for 'Ia' water quality level, 6 sites for 'lb' water quality level, 5 sites for 'II' water quality level, 1 sites for 'I' water quality level. The estimation of COD concentration in the mid influence area, It showed that 9 sites for 'Ib' water quality level, 6 sites for 'II' water quality level, 6 sites for 'III' water quality level, 1 site for 'IV' water quality level. The assessment of water quality made Mid influence area of Gumhogang, Nakdong Goryung, Nakdong Milyang and Namgang selected as the mid influence area of high pollution. And delivery loads of nonpoint sources were calculated for mid influence area in Nakdonggang basin(max delivery load : 17,706.7 kg/day for Gumhogang influence area). As the result of calculating NPS(nonpoint sources) delivery load and water quality at influence area in Nakdonggang basin, Gumhogang influence area was selected as an area for management priority among nonpoint sources.

• Proceedings of the Korea Water Resources Association Conference
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• 2017.05a
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• pp.368-368
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• 2017

근대적 기상관측이 시작된 1905년 이후 우리나라의 연평균 강수량은 증가하고 있으나 강수량 변동폭 또한 커지면서 최갈수 기간의 영향을 받는 댐 등 대규모 수공구조물의 용수공급능력은 감소되고 있다. 또한 지역별 강수량과 인구 편차로 공간적으로 이용 가능한 수자원의 불균형이 발생하고 있어 지역적인 물 공급의 안정성과 형평성은 여전히 취약한 상황이다. 하지만 사회적 공감대 형성이 쉽지 않은 대규모 수자원개발 추진은 어려운 여건이며 국민들의 안전하고 맑은 물에 대한 수요 또한 지속적으로 증대되고 있어 이를 해소하기 위한 다각적인 대책 마련이 필요한 상황이다. 본 연구에서는 기 확보된 수자원의 효율적이고 공평한 활용을 위해 국내 용수공급의 중추적인 역할을 담당하고 있는 댐을 대상으로 댐간 연결을 통한 용수공급 방안을 제시하였다. 이를 위하여 소양강댐, 충주댐 등 다목적댐 16개 및 광동댐, 영천댐 등 용수댐 12개 총 28개댐의 용수공급능력 평가와 장래 용수수요량 조사를 실시하였으며 장래 용수부족 지역 해소를 위한 상시공급과 극한가뭄 등 재난 대처를 위한 비상시공급 방안을 검토하였다. 상시공급은 댐 용수공급능력 평가를 통하여 기본계획공급량 대비 여유수량을 갖는 댐에서 장래 용수수요 증가, 용수공급능력 감소 등으로 공급 용수가 부족한 인근 댐으로 공급하는 방식이며 용수 공급량은 저수지 모의운영을 통하여 양댐의 이수안전도(분석 기간중 1회에 한하여 물 부족 허용)를 충족시키는 수량을 산정하였다. 비상시공급은 타수계 및 근거리간 연결, 가뭄 예상지역을 기준으로 대상 댐을 검토하였으며 용수 공급량은 공급댐의 유지용수와 관개용수를 이용하여 공급받는 댐의 생 공용수 20% 공급가능시 공급량으로 산정하였다. 검토 결과 상시공급은 소양강댐에서 횡성댐으로 86천$m^3$/일, 장흥댐에서 주암본댐으로 127천$m^3$/일, 남강댐에서 수어댐으로 $140m^3$/일, 비상시 공급은 충주댐과 대청댐, 충주댐과 안동댐간 각각 500천$m^3$/일 공급을 통하여 장래 용수부족 지역의 물 부족 해소와 극한가뭄 등 비상상황의 대처가 가능한 것으로 분석되었다. 본 연구는 기후변화와 사회가치적으로 변화하고 있는 수자원 환경에 능동적으로 대처하기 위한 대책의 일환으로 고안된 것이며, 향후 유역간 물 이동에 따른 현행 수리권제도 및 어류, 수질변화에 따른 환경영향 등에 대하여 추가적인 연구가 필요할 것으로 판단된다.

• Journal of Korea Water Resources Association
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• v.55 no.12
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• pp.1065-1076
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• 2022

The purpose of this study was to investigate the effect of the expansion and withering of Salix subfragilis communities on the water quality in Namgang Dam reservoir. The distribution area of the Salix subfragilis communities was 0.12 km² in 2003 for the first time, but it was 3.58 km² in 2019, which has increased rapidly by about 30 times in 16 years. However, in 2013, the distribution area has decreased by 0.17 km² due to long-term immersion in high turbidity, and self-thinning in Salix subfragilis communities. The lake characteristics of reservoir showed a combination of lake type and river type in terms of average water depth, watershed area/lake surface area ratio, water residence time, flushing rate, and stratification. From the result of analyzing long-term changes in lake water quality, COD, TP, and chlorophyll-a in Salix subfragilis communities were significantly larger than those in the three points located in the central part of reservoir. In particular, the fact that the value of chlorophyll-a showed the maximum value in winter rather than summer, unlike the trend of the three points in the Namgang Dam water quality monitoring network, is thought to have occurred internally rather than externally. It can be estimated that one cause of this deterioration of the water quality in Namgang Dam reservoir is the huge amount of nutrients generated in the decomposition process of by-products such as fallen leaves, branches and withered trees in Salix subfragilis communities.

• Journal of Korea Water Resources Association
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• v.55 no.9
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• pp.687-700
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• 2022

For comprehensively assessment the water resources performance of multi-purpose dams and water supply dams in South Korea, a methodology was proposed to utilize the durational reliability along with the integrated auxiliary indicators including resiliency, dimensionless vulnerability, water resource efficiency, specific inflow, and specific water supply. In addition, for the purpose of sustainable dam operation in the future, a plan to grade the water resources performance was presented to periodically evaluate the performance and determine the priority of each dam's structural or non-structural planning according to the evaluation results. As major results, in the case of Sumjingang Dam, the durational reliability was 99.0%, but the integrated auxiliary index was the lowest of 44 points, which was 5th grade. This means that despite the current high reliability, hydrological changes due to future climate change or regional change of water demand-supply balance can have significant impacts on the water resources performances. In contrast, the Chungju Dam with a durational reliability of 93.0%, which is below the average among all multi-purpose dams, shows the 76 points of the integrated auxiliary index, which is 3^rd highest following the Soyanggang Dam and the Namgang Dam. Nevertheless, due to the size of the basin, the specific inflow is sufficiently high as 185%, so the actual performance could be evaluated relatively high. The water supply dams designed for a single purpose tend to be evaluated relatively high because they have a high proportion of industrial and municipal water supply and have enough room for the supply capacity.

• Journal of Korea Water Resources Association
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• v.55 no.11
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• pp.913-922
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• 2022

The purpose of this research is to propose the measurement of improving DEM by using the water surface range of SAR image analysis for river corridors and to suggest the construction of satellite-based 3D river spatial information of inaccessible regions such as North Korea. For this research, it has been progressed from the accessible area, watershed of Namgang river, the branch of Nakdonggang river. The satellite image was collected from SAR satellite image data for a year in 2021 which was provided by ESA from Sentinel-1A/B data and extracted from the seasonal water surface area. Ground gauge water level was collected from hourly intervals data by WAMIS. The DEM was improved by analysis of the river altitude of water surface area change by the combination of the ground water level of minimum to maximum water surface area data extracted from SAR image analysis. After the improvement of DEM, the altitude of the river varied that it is defined to comprise more natural form of river DEM than the existing DEM. The correction validation of improvement DEM was necessary in field survey elevation data; however, the correction validation was not progressed due to the absence of the data. Although, the purpose of this research is to provide the improvement of DEM by using the analyzed water surface by existing DEM data and SAR image analysis. After the progression of additional correction validation research, we would plan to examine the application in other places and to progress the additional methodological research to apply in inaccessible and unmeasured area including the North Korea.

• Korean Journal of Soil Science and Fertilizer
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• v.40 no.5
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• pp.383-391
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• 2007

This study was conducted for an assessment through the estimation of soil loss by each catchment classified by soil catena. Ten catchments, which are Geumgang21, Namgang03, Dongjincheon, Gapyongcheon01, Gyongancheon02, Geumgang16, Byongsungcheon01, Daesincheon, Bukcheon02, Youngsangang08, were selected from the hydrologic unit map and the detailed soil digital map (1:25,000) for this study. The catchments like Geumgang21, Namgang03, Dongjincheon, Gapyongcheon01 and Gyongancheon02 were mainly composed with soils originated from gneiss. The catchments like Geumgang16, Byongsungcheon01, Daesincheon, Bukcheon02 and Youngsangang08 were mainly composed with soils originated from granites. The grades, which are divided into seven grades with A(very tolerable), B(tolerable), C(moderate), D(low), E(high), F(severe), G(very severe), of soil erosion estimated by USLE in catchments were distributed in most A and B because of paddy land and forestry. In detailed, the soil erosion grade of catchments mainly distributing soils originated from gneiss showed more the distribution of B and C than it of catchments mainly distributing soils originated from granites. The reason of results would be derived from topographic characteristics of soils originated from gneiss located at mountainous. The soil loss according to soil catena linked with Songsan and Jigok series, which are soils originated from gneiss was calculated with $7.66ton\;ha^{-1}\;yr^{-1}$. The soil loss of Geumgang16, Byongsungcheon01, Daesincheon, Bukcheon02 which have the soil catena linked with Samgak and Sangju soil series originated from granite, was calculated with $5.55ton\;ha^{-1}\;yr^{-1}$. The soil loss of Youngsangang08 which have the soil catena linked with Songjung and Baeksan soil series originated from granite was calculated with $9.6ton\;ha^{-1}\;yr^{-1}$, but the conclusion on soil loss in this kind of soil catena would be drawn from the analysis of more catchments. In conclusion, the results of this study inform that the classification of soil catena by catchments and estimation of soil loss according to soil catena would be effective for analysis on the grade of non-point pollution by soil erosion in a catchment.

• Journal of the Korean Association of Geographic Information Studies
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• v.17 no.3
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• pp.175-194
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• 2014

This study attempts to identify the spatial distributions of Achnanthes convergens, and elucidate the environmental factors that affect the Periphyton diatom habitat. Data in 250 points of Nakdong river basin are collected between April(primary) and September(secondary) 2012, with the National Institute of Environmental Research's support. We define "clean area" over 10% of Achnanthes convergens appearance, and the others as "non-clean areas". Spatial statistics of Kriging, Hotspot, LISA are used in this study. Results show that 1) 56 points are identified as clean areas in the primary survey, while 41 points are discovered in the following survey; 2) using water quality variables, density of turbidity(clean $101.83{\mu}s/cm$; non-clean $598.48{\mu}s/cm$) and conductivity(clean 1.95 NTU; nonclear 5.58 NTU) are five-fold lower in clean-areas; 3) Habitat and Riparian Factors in Nakdong basin illustrate that natural sand bar, diversity of velocity, sediment condition, levee material, riverside land affect Achnanthes convergens; 4) Hotspots of Achnanthes convergens are located in watersheds, including upper Andong Dam, upper Imha dam, Wi-cheon, Miryang river, Nam river and Hwang river whereas mainstream/downstream of Nakdong river and Keumho river watershed are shown as coldspots.

• Journal of Korea Water Resources Association
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• v.52 no.5
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• pp.349-360
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• 2019

The purpose of this study is to evaluate the stream flow and water quality (SS, T-N, and T-P) behavior of Nakdong river basin ($23,609.3km^2$) by simulating the dam and weir operation scenarios using SWAT (Soil and Water Assessment Tool). The operation senarios are the simultaneous release for all dam and weirs (scenario 1), simultaneous release for all weirs (scenario 2), and sequential release for the weirs with one month interval from upstream weirs (scenario 3). Before evaluation, the SWAT was calibrated and validated using 11 years (2005-2015) daily multi-purpose dam inflow at 5 locations (ADD, IHD, HCD, MKD, and MYD), multi-function weir inflow at 7 locations (SHW, GMW, CGW, GJW, DSW, HCW, and HAW), and monthly water quality monitoring data at 6 locations (AD-4, SJ-2, EG, HC, MK-4, and MG). For the two dam inflow and dam storage, the Nash-Sutcliffe efficiency (NSE) was 0.56~0.79, and the coefficient of determination ($R^2$) was 0.68~0.90. For water quality, the $R^2$ of SS, T-N, and T-P was 0.64~0.79, 0.51~0.74, and 0.53~0.72 respectively. For the three scenarios of dam and weir release combination suggested by the ministry of environment, the scenario 1 and 3 operations were improved the stream water quality (for T-N and T-P) within the 3 months since the time of release, but it showed the negative effect for 3 months after compared to scenario 2.