• 한국환경과학회지
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• 제23권7호
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• pp.1321-1332
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• 2014

The key objective of this study was to evaluate trophic state and empirical water quality models along with analysis of fish trophic guilds in relation to water chemistry (N, P). Trophic state index (TSI), based on total phosphorus (TP) and chlorophyll-a (CHL), ranged between oligotrophic and hypereutrophic state, by the criteria of Nurnberg(1996), and was lower than the trophic state of total nitrogen (TN). Trophic relations of Secchi depth (SD), TN, TP, and CHL were compared using an empirical models of premonsoon (Pr), monsoon (Mo), and postmonsoon (Po). The model analysis indicated that the variation in water transparency of Secchi depth (SD) was largely accounted (p < 0.001, range of $R^2$ : 0.76-0.80) by TP during the seasons of Mo and Po and that the variation of CHL was accounted (p < 0.001, $R^2=0.70$) up to 70% by TP during the Po season. The eutrophication tendency, based on the $TSI_{TP}$ vs. $TSI_{N:P}$ were predictable ($R^2$ ranged 0.85-0.90, p < 0.001), slope and y intercept indicated low seasonal variability. In the mean time, $TSI_{N:P}$ vs. $TSI_{CHL}$ had a monsoon seasonality in relation to values of $TSI_{N:P}$ during the monsoon season due to a dilution of reservoir waters by strong monsoon rainfall. Trophic compositions of reservoir fish reflected ambient contents of TN, TP, and CHL in the reservoir waters. Thus, the proportions of omnivore fish increased with greater trophic conditions of TP, TN and CHL and the proportions of insectivore fish decreased with greater trophic conditions.

• 한국물환경학회지
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• 제30권3호
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• pp.269-282
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• 2014

The objective of this study is to find out whether the developed semi-empirical biofilm model can be applicable to real BAF pilot-scale wastewater treatment. In addition, the optimum operating conditions of BAF as a function of process variables such as organic loading change can be drawn based on the simulation results of model. The results will provide the economic and efficient BAF process design and operating control. As a result, developed semi-empirical biofilm model which is relatively simple compared to mathematical model can simulate three BAF processes consisted of 25 layers within 1 seconds. When this model was used for simulating real pilot scale BAF process and the simulated water quality values were compared to experimental ones, simulated TCOD, SCOD, TN, $NH_4{^+}$-N, $NO_x{^-}$-N, alkalinity values were different to experimental ones within 21%, 20%, 8.1%, 48%, 10%, and 23%, respectively. Therefore, if the BAF system was equipped with automatic control, the BAF process can be better efficiently adapted under the condition of significant change of influent loading.

• 상하수도학회지
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• 제31권4호
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• pp.289-296
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• 2017

Pulp and paper industry produces large volumes of wastewater and residual sludge waste, resulting in many issues in relation to wastewater treatment and sludge disposal. Contaminants in pulp and paper wastewater include effluent solids, sediments, chemical oxygen demand (COD), and biological oxygen demand (BOD), which should be treated by wastewater treatment processes such as coagulation and biological treatment. However, few works have been attempted to predict the treatment efficiency of pulp and paper wastewater. Accordingly, this study presented empirical models based on experimental data in laboratory-scale coagulation tests and compared them with statistical models such as artificial neural network (ANN). Results showed that the water quality parameters such as turbidity, suspended solids, COD, and UVA can be predicted using either linear or expoential regression models. Nevertheless, the accuracies for turbidity and UVA predictions were relatively lower than those for SS and COD. On the other hand, ANN showed higher accuracies than the emprical models for all water parameters. However, it seems that two kinds of models should be used together to provide more accurate information on the treatment efficiency of pulp and paper wastewater.

• 한국환경과학회지
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• 제23권9호
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• pp.1537-1549
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• 2014

The objectives of this study were to analyze reservoir trophic state, based on Trophic State Index (TSI), spatial variation patterns of three zones (riverine, transition, and lacustrine zone), and empirical models through 20-years long-term data analysis. Trophic variables of TP and CHL-a were highest during the summer monsoon, and decreased along the main axis from the riverine to lacustrine zone. In the mean time, TN did not show the trend. Ratios of N:P and Secchi disc transparency (SD) increased from the riverine to lacustrine zone. The analysis of trophic state index (TSI) showed that mean TSI (TP) and TSI (CHL-a) were 62 and 57, respectively, and these values were highest in the transition zone during the summer. This zone should be managed well due to highest lake water pollution. The analysis of Trophic State Index Deviation (TSID) showed that algal growth was primarily limited by light penetration, and this was most pronounced in the monsoon season. The analysis of empirical models showed that the value of $R^2$, based on CHL-SD model, was 0.30 (p < 0.0001) in the transition zone and the $R^2$, based on TP-SD model, was 0.41 (p < 0.0001) in the transition zone.

• 한국물환경학회지
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• 제28권4호
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• pp.551-560
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• 2012

The objectives of this study were to elucidate spatio-temporal heterogeneity of water chemistry and develop empirical models using trophic variables in Daechung Reservoir during 2005-2010 along with in situ tests of nutrient enrichment bioassays (NEB). The relations of water quality parameters in regard to precipitation showed that seasonal and interannual fluctuations of biological oxygen demand (BOD), total nitrogen (TN) and pH were minor, whereas conductivity, suspended solids (SS), and total phosphorus (TP) were largely varied in response to the magnitude of rainfall. The CHL maxima occurred immediately after the spate of TP during the high flow, indicating that phytoplankton growth was directly controlled by phosphorus. Empirical linear models of CHL-TP indicated that the variation of CHL in premonsoon was accounted 60% ($R^2$ = 0.60, p < 0.05, n = 54) by TP. In the mean time, empirical models of annual CHL-TN showed that the variation of CHL was weakly accounted ($R^2$ = 0.16, p < 0.001) by TN and more strongly ($R^2$ = 0.44, p < 0.001) by TP. Thus, the variation of CHL was more explained by the variation of TP than TN. In situ tests of Nutrient Enrichment Bioassays (NEBs) showed that the growth of CHL was greater in the P-treatments (as $PO_4-P$) than the control and N-treatment (as $NO_3-P$). Overall, our results suggest that phosphorus was aprimary limiting nutrient controlling the seasonal phytoplankton growth, based on the in situ experiments of NEBs.

• 한국수자원학회:학술대회논문집
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• 한국수자원학회 2020년도 학술발표회
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• pp.172-172
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• 2020

In recent years, soil erosion has come to be regarded as an essential environmental problem in human life. Soil erosion causes various on- and off-site problems such as ecosystem destruction, decreased agricultural productivity, increased riverbed deposition, and deterioration of water quality in streams. To solve these problems caused by soil erosion, it is necessary to quantify where, when, how much soil erosion occurs. Empirical erosion models such as the Universal Soil Loss Equation (USLE) family models have been widely used to make spatially distributed soil erosion vulnerability maps. Even if the models detect vulnerable sites relatively well by utilizing big data related to climate, geography, geology, land use, etc. within study domains, they do not adequately describe the physical process of soil erosion on the ground surface caused by rainfall or overland flow. In other words, such models remain powerful tools to distinguish erosion-prone areas at the macro scale but physics-based models are necessary to better analyze soil erosion and deposition and eroded particle transport. In this study, the physics-based Surface Soil Erosion Model (SSEM) was upgraded based on field survey information to produce sediment yield at the watershed scale. The modified model (hereafter MoSE) adopted new algorithms on rainfall kinematic energy and surface flow transport capacity to simulate soil erosion more reliably. For model validation, we applied the model to the Doam dam watershed in Gangwon-do and compared the simulation results with the USLE outputs. The results showed that the revised physics-based soil erosion model provided more improved and reliable simulation results than the USLE in terms of the spatial distribution of soil erosion and deposition.

• 한국물환경학회지
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• 제24권1호
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• pp.7-18
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• 2008

The objective of this study was to develop and apply a water quality simulation model for the evaluation of ungaged watershed. The Modified WASP5 consisted of three sub-models, LOAD-M, DYN-M, and EUT-M. LOAD-M, an empirical model, estimates runoff loadings using point and non-point source data of villages. Daecheong Dam watershed was selected for the research to calibrate, verify and application of Modified-WASP5. LOAD-M model was established using field data collected from all items of water quality and water quantity gaging stations of the watersheds, and was applied to the ungauged watersheds, taking the watershed properties under consideration. The result of water quality simulation using ModifiedWASP5 shows that the observed BOD data of Yongpo and Daechong Dam in 1999 were 0.8 mg/L and 1.0 mg/L, and simulated data were 0.9 mg/L and 0.9 mg/L, respectively. In case of 1999, average BOD concentrations were 0.8 mg/L and 1.0 mg/L. Simulated concentration showed 1.1 mg/L and 1.5 mg/L, respectively. Generally, the simulation results were in good agreement with the observed data. This study was focused on formulating an integrated model for evaluating ungauged watersheds. Even though simulation results varied slightly due to limited availability of data, the model developed in this study would be a useful tool for the assessment and management of ungauged watersheds.

• 한국수자원학회:학술대회논문집
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• 한국수자원학회 2021년도 학술발표회
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• pp.150-150
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• 2021

Soil erosion due to climate change is one of the global environmental issues. Especially, Korea is vulnerable to soil erosion as the frequency of extreme rainfall events and rainfall intensity are increasing. Soil erosion causes various problems such as reduced farmlands, deterioration of water quality in rivers, etc. To these severe problems, understanding the process of soil erosion is the first process. Then, it is necessary to quantify and analyze soil ersoion using an erosion model. Soil erosion models are divided into empirical, conceptual, and physics-based models according to the structures and characteristics of models. This study used GSSHA (Gridded Surface Subsurface Hydrologic Analysis), the physics-based erosion model, running on WMS (Watershed Modeling System) to analyze soil erosion vulnerability of the CheonCheon watershed. In addition, we compared the six sediment transport capacity formulas provided in the model and evaluated the equations fir on this study site. Therefore, this result can be as a primary tool for soil conservation management.

• 환경생물
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• 제37권1호
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• pp.48-59
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• 2019

본 연구는 2004~2017년 동안 금강수계에서 백제보 건설 전 후의 화학적 수질 특성 및 경험적 모델 분석을 실시하였다. 4대강 사업 전후의 표층수의 수질에 대한 비교평가에 따르면, TP의 농도는 보 건설 후 급격히 감소하는 현상을 보였고, 총질소 역시 감소하는 것으로 나타났다. 반면, 식물성 플랑크톤의 1차 생산력의 지표인 CHL-${\alpha}$ 농도와 EC는 보 건설 후 증가한 것으로 나타났다. 즉, 보 구간에서 수체류 시간의 증가로 인해 N, P의 농도는 감소하였지만, CHL/TP 비는 크게 증가하였고, 이로 인해 단위 인(P) 농도 대비 1차생산력은 증가한 것으로 나타났다. 경험적 모델의 회귀분석에 따르면, 보 건설 전 기간에 CHL-${\alpha}$ 농도는 TP와 유의한 관계를 보이지 않았으나(r=0.068, p=0.860, n=58), 보 건설 이후에 두 변수 사이에는 유의한 관계(r=0.6102, p<0.05, n=56)를 보였다. TN 및 이온희석 현상의 지표로 이용된 EC는 계절별 분석에서 장마기에 크게 감소하는 현상을 보이며 강우와 역상관 관계(r=0.5378, p<0.01, n=163)를 보였으나, 계절별 TP과 부유물 농도(SS)는 갈수기에 비해 장마기에 증가하는 특성을 보여 강우와 정상관 관계(r>0.40, p<0.01, n=163)를 보였다. 2018년 현재 보 구간의 완전한 상시방류를 시행할 경우, 향후 수체의 하천화에 의해 TP 농도는 증가하며, 녹조 현상은 감소할 것으로 사료된다.

• 생태와환경
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• 제40권1호
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• pp.14-30
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• 2007

본 연구의 목적은 부영양화도 지수(TSI)를 이용하여 우리나라 호소의 영양 상태를 평가하고, 경험적 모델(Empirical model)에 의한 호소의 상태를 예측하기 위한 것이다. 연구에 사용된 수질 자료(2000, 2001)는 환경부 DB시스템에서 획득하였으며 이용된 변수는 용존산소(DO), 생물학적 산소 요구량(BOD), 화학적 산소 요구량(COD), 총인 (TP), 총질소 (TN), 부유물질 (SS), 투명도(SD), 엽록소-${\alpha}$ (CHL), 전기전도도 (Cond.)였다. 이런 수질 변수의 농도는 측정된 수계 및 계절에 따라 변이양상을 보였다. 일반적으로, 영양상태(Trophic state)는 상류로부터 댐으로 감소하는 경향을 보였으며, 계절적 변이는 여름 장마기 (7${\sim}$8월)동안 크게 발생했다. TP의 주된 유입은 장마기 (r=0.656, p=0.002)동안 일어났고, 이런 현상은 SS(r=0.678, p<0.001)와 유사한 경향을 보였다. CHL, TP, SD 및 TN을 포함한 수질변수는 계절에 따른 수계내의 영양상태를 평가하는 방법에 적용되었다. Carlson(1977)의 부영양화도지수(TSI)에 기초한 수계 내 TSI(CHL), TSI(TP)및 TSI(SD)는 중영양-부영양 상태를 보였다. 한편, TSI(TN)은 계절에 관계없이 전체 호소 내에서 TN농도가 풍부한 부영양-과영양 상태를 보였다. 따라서, 인은 호소 내 영양 상태를 조절하는 주요인자가 된다. CHL와 다른 수질 변수(TP, TN,그리고 SD)사이의 관계를 분석하기 위한 경험적 모델(Empirical model)이 개발되었다. 로그-전환 회귀분석에서 CHL-TP는 장마 전기 $R^2$ 값이 031(p=0.017)이었으나 장마 후기에는 0.69(p<0.017)로 장마 후기 인이 조류 성장에 큰 영향을 미치는 것으로 나타났다. 이와 대조적으로, SD는 TP, CHL증가에 대해 감소하는 경향을 보였고 TN은 모든 기간 동안 CHL와 약한 관계를 가졌다. 결과적으로, 경험적 모델(Empirical model)이 제시하듯이 TP는 CHL을 예측하는 핵심 인자로 사료되었다.