Determination of standard target water quality in the Nakdong River basin for the total maximum daily load management system in Korea

The purpose of this study was to evaluate the streamflow and water quality (SS, T-N, and T-P) interaction of the Nakdong river basin (23,609.3 km2) by simulating dam and weir operation scenarios using the Soil and Water Assessment Tool (SWAT). The operation scenarios tested were dam control (Scenario 1), dam control and weir gate control (Scenario 2), dam control and sequential release of the weirs with a one-month interval between each weir (Scenario 3), dam control and weir gate full open (Scenario 4), dam control and weir gate sequential full open (Scenario 5), weir gate control (Scenario 6), weir gate full open (Scenario 7), and weir gate sequential full open (Scenario 8). Before evaluation, the SWAT was calibrated and validated using 13 years (2005–2017) of daily multi-purpose dam inflow data from five locations ((Andong Dam (ADD), Imha Dam (IHD), Hapcheon Dam (HCD), Namkang Dam (NKD), and Milyang Dam (MYD))multi-function weir inflow data from seven locations (Sangju Weir (SJW), Gumi Weir (GMW), Chilgok Weir (CGW), Gangjeong-Goryeong Weir (GJW), Dalseong Weir (DSW), Hapcheon-Changnyeong Weir (HCW), and Changnyeong-Haman Weir (HAW)), and monthly water quality monitoring data from six locations (Andong-4 (AD-4), Sangju (SJ-2), Waegwan (WG), Hapcheon (HC), Namkang-4 (NK-4), and Mulgeum (MG). For the dam inflows and dam storage, the Nash-Sutcliffe efficiency (NSE) was 0.59~0.78, and the coefficient of determination (R2) was 0.71~0.90. For water quality, the R2 values of SS, T-N, and T-P were 0.58~0.83, 0.53~0.68, and 0.56~0.79, respectively. For the eight dam and weir release scenarios suggested by the Ministry of Environment, Scenarios 4 and 8 exhibited water quality improvement effects compared to the observed data.

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Operational Water Quality Forecast for the Nakdong River Basin Using HSPF Watershed Model

Journal of Korean Society on Water Environment ◽

10.15681/kswe.2016.32.6.570 ◽

2016 ◽

Vol 32 (6) ◽

pp. 570-581

Author(s):

Chang Min Shin ◽

Kyunghyun Kim

Keyword(s):

Water Quality ◽

River Basin ◽

Watershed Model ◽

Nakdong River ◽

Nakdong River Basin ◽

The Nakdong River ◽

Water Quality Forecast ◽

Quality Forecast

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Assessment of Water Quality Target Attainment and Influencing Factors Using the Multivariate Log-Linear Model in the Nakdong River Basin, Republic of Korea

Sustainability ◽

10.3390/su131911094 ◽

2021 ◽

Vol 13 (19) ◽

pp. 11094

Author(s):

Mi-Ah Kim ◽

Eunhye Na ◽

Suyoung Park ◽

Taegu Kang ◽

Soyoung Lee

Keyword(s):

Water Quality ◽

River Basin ◽

Mean Squared Error ◽

Statistical Significance ◽

Main Stream ◽

Nakdong River ◽

Target Attainment ◽

Nakdong River Basin ◽

The Nakdong River ◽

Log Linear

Because identifying the factors affecting water quality is challenging, water quality assessment of an individual component based on the arithmetic mean method cannot adequately support management policies. Therefore, in this study, we assessed the water quality target attainment at 24 sites in the Nakdong River Basin by applying multivariate log-linear models to identify factors influencing water quality, including flow and season. The temporal and seasonal water quality trend and flow were also analyzed using the calculated model coefficients. Specifically, weekly data on biological oxygen demand (BOD), total phosphorous (TP), and flow during 2013–2018 were used to investigate the 2018 water quality target attainment level for this river. The significance and suitability of the models were analyzed using the F-test, root mean squared error (RMSE), mean absolute percent error (MAPE), and adjusted R2 values. All 24 models applied in this study showed statistical significance and suitability for the prediction of BOD and TP concentrations. Moreover, flow was identified as the main factor affecting water quality and had a predominant effect on BOD and TP concentrations in tributaries and the main stream, respectively. Furthermore, among the 24 sites, BOD and TP targets were evidently attained at 18 and 17 sites, respectively.

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Spatial patterning of chlorophyll a and water-quality measurements for determining environmental thresholds for local eutrophication in the Nakdong River basin

Environmental Pollution ◽

10.1016/j.envpol.2020.115701 ◽

2021 ◽

Vol 268 ◽

pp. 115701

Author(s):

Hyo Gyeom Kim ◽

Sungwon Hong ◽

Tae-Soo Chon ◽

Gea-Jae Joo

Keyword(s):

Water Quality ◽

Chlorophyll A ◽

River Basin ◽

Spatial Patterning ◽

Nakdong River ◽

Nakdong River Basin ◽

The Nakdong River ◽

Quality Measurements

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Linking trading ratio with TMDL (total maximum daily load) allocation matrix and uncertainty analysis

Water Science & Technology ◽

10.2166/wst.2008.604 ◽

2008 ◽

Vol 58 (1) ◽

pp. 103-108 ◽

Cited By ~ 4

Author(s):

H. X. Zhang

Keyword(s):

Water Quality ◽

Uncertainty Analysis ◽

Total Maximum Daily Load ◽

Scientific Uncertainty ◽

Preliminary Evaluation ◽

Load Reduction ◽

Trading Ratio ◽

Total Maximum ◽

Daily Load

An innovative approach for total maximum daily load (TMDL) allocation and implementation is the watershed-based pollutant trading. Given the inherent scientific uncertainty for the tradeoffs between point and nonpoint sources, setting of trading ratios can be a contentious issue and was already listed as an obstacle by several pollutant trading programs. One of the fundamental reasons that a trading ratio is often set higher (e.g. greater than 2) is to allow for uncertainty in the level of control needed to attain water quality standards, and to provide a buffer in case traded reductions are less effective than expected. However, most of the available studies did not provide an approach to explicitly address the determination of trading ratio. Uncertainty analysis has rarely been linked to determination of trading ratio. This paper presents a practical methodology in estimating “equivalent trading ratio (ETR)” and links uncertainty analysis with trading ratio determination from TMDL allocation process. Determination of ETR can provide a preliminary evaluation of “tradeoffs” between various combination of point and nonpoint source control strategies on ambient water quality improvement. A greater portion of NPS load reduction in overall TMDL load reduction generally correlates with greater uncertainty and thus requires greater trading ratio. The rigorous quantification of trading ratio will enhance the scientific basis and thus public perception for more informed decision in overall watershed-based pollutant trading program.

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