추계학적 계획모형을 이용한 하천수질관리

조재현,Cho, Jae Heon 대한토목학회 1994 대한토목학회논문집 Vol.14 No.1

A stochastic programming model for river water quality management was developed. River water quality, river flow, quality and flowrate of the wastewater treatment plant inflow were treated as random variables in the model. Withdrawal for water supply and submerged weir reaeration were included in the model itself. A probabilistic model was formulated to compute the expectation and variance of water quality using Streeter-Phelps equation. Chance constraints of the optimization problem were converted to deterministic equivalents by chance constrained method. Objective function was total annual treatment cost of all wastewater treatment plants in the region. Construction cost function and O & M cost function were derived in the form of nonlinear equations that are functions of treatment efficiency and capacity of treatment plant. The optimization problem was solved by nonlinear programming. This model was applied to the lower Han River. The results show that the reliability to meet the DO standards of the year 1996 is about 50% when the treatment level of four wastewater treatment plants in Seoul is secondary treatment, and BOD load from the tributary inflows is the same as present time. And when BOD load from Tanchon, Jungrangchon, and Anyangchon is decreased to 50%, the reliability to meet the DO standards of the year 1996 is above 60%. This results indicated that for the sake of the water quality conservation of the lower Han River, water quality of the tributaries must be improved, and at least secondary level of treatment is required in the wastewater treatment plants. 본 연구에서는 하천본류의 유량과 수질, 하수처리장 유입수량과 유입수질을 확률변수로 두고, 취수 문제와 수중보에 의한 재포기현상을 포함하는 추계학적 하천수질관리모형을 개발하였다. Streeter-Phelps식을 이용해서 각 구간 하천수질의 기대값과 분산을 계산하는 확률모형을 만들고, 최적화문제의 확률적 제약식은 chance constrained 방법을 이용해서 확정적 제약식으로 변환한다. 목적함수는 지역내 하수처리장의 년간처리비용으로 두었다. 건설비용함수와 유지관리비함수는 처리효율과 처리용량의 함수인 비선형의 단일식으로 유도되었다. 최적화문제는 비선형계획법으로 해를 구하였다. 본 모형을 한강하류부에 적용한 결과 서울시내 4개 하수처리장에서 2차처리를 하고, 지천유입수의 BOD부하량이 현재와 같을 때, 1996년 DO수질기준을 만족하는 신뢰도는 50% 정도였다. 그리고 탄천, 중량천, 안양천의 BOD부하량을 현재보다 50% 감소시켰을 때 1996년 DO수질기준을 만족하는 신뢰도는 60% 이상이었다. 따라서 한강하류부의 수질보전을 위해서는 유입지천의 수질개선과 2차처리 이상의 하수처리가 요구된다.

연구논문 : 오염총량관리지역내 소하천에 대한 BASINS 4.0 및 WinHSPF의 적용과 유전알고리즘을 이용한 매개변수의 보정

조재현 ( Jae Heon Cho ),윤승진 ( Seoung Jin Yun ) 한국환경영향평가학회 2012 환경영향평가 Vol.21 No.1

Recently various attempts have been made to apply HSPF model to calculate runoff and diffuse pollution loads of stream and reservoir watersheds. Because the role of standard flow is very important in the water quality modelling of Total Water Pollution Load Management, HSPF was used as a means of estimating standard flow. In this study, BASINS 4.0 and WinHSPF was applied to the Gomakwoncheon watershed, genetic algorithm(GA) and influence coefficient algorithm were used to calibrate the runoff parameters of the WinHSPF. The objective function is the sum of the squares of the normalized residuals of the observed and calculated flow and it is optimized using GA. Estimates of the optimum runoff parameters are made at each iteration of the influence coefficient algorithm. The calibration results showed a relatively good correspondence between the observed and the calculated values. The standard flow(Q275) of the Gomakwoncheon watershed was estimated using the ten years of weather data.

GIS를 이용한 동해안 하천유역의 토양유실량과 오염부하량 평가

조재현(Jae Heon Cho),연제철(Je Chul Yeon) 大韓環境工學會 2000 대한환경공학회지 Vol.22 No.7

고랭지 밭 밀집지역 다단계 침사지의 강우-유출 오염물질 제거 효율 - 소양호 상류의 자운지구를 중심으로 -

조재현 ( Jae Heon Cho ) 한국환경영향평가학회 2018 환경영향평가 Vol.27 No.2

홍천군 내면 자운지구에는 고랭지 채소밭이 밀집되어 있어서 우기에는 고랭지 밭에서 많은 토사가 유출되어 소양호 탁도와 수질에 큰 영향을 미치고, 하류의 수도권 상수원에도 악영향을 준다. 본 연구에서는 고랭지밭 지역의 토사유출 저감을 위한 여러 BMPs 시설 중에서 많은 비용이 들지만 우리나라에서의 실측 조사 결과가 거의 없는 다단계 침사지에 대해서 강우시 유출입수를 실측 조사하고, 비점원오염물질 삭감효율을 분석하였다. 자운지구의 자운리 786번지와 자운리 628-2번지 다단계 침사지에서 2차례 강우에 대해서 침사지의 SS 제거효율을 분석한 결과 35%~62%의 삭감율을 보였다. BOD는 약 24%~55%, TP는 약 35%~58%의 오염부하가 삭감되었다. 이 지역 다단계 침사지의 실측 효율은 이론적인 효율보다 다소 낮지만 현재 설치되어 있는 침사지를 적절하게 관리하면 효율을 더 높일 수 있고, 추가적인 침사지 설치를 통해 흙탕물 관리를 효과적으로 할 수 있다. Highland fields are concentrated in the Jaun area of Hongcheong-gun, a large amount of sediments are discharged from the highland fields. The sediment runoff affect the turbidity and water quality of the Soyang Lake, furthermore adversely affect water supply source of the capital region. There are several kinds of BMPs(Best management practices) to decrease the sediment runoff from the highland fields. Although construction cost of multistage sedimentation basins is very high, there is no actual survey data for the removal efficiency of suspended sediments and water quality in our country. In this study, stormwater inflow and outflow of the multistage sedimentation basins were surveyed, and the removal efficiency of nonpoint source pollutants were analyzed. The stormwater survey results for two rainfall events show that removal efficiencies of SS, BOD and TP loads in the multistage sedimentation basins are 35%~62%, 24%~55%, 35%~58%, respectively. Although the measured efficiencies of the basins were lower than the theoretical efficiency, the proper operation and management can improve the removal rate of the basins. Turbid water problem in the upper parts of the Soyang River can be managed effectively through the additional installation of multistage sedimentation basins.

연구논문 : 오염부하량 할당에 있어서 다목적 유전알고리즘의 적용 방법에 관한 연구

조재현 ( Jae Heon Cho ) 한국환경영향평가학회 2013 환경영향평가 Vol.22 No.6

In terms of waste load allocation, inequality of waste load discharge must be considered as well as economic aspects such as minimization of waste load abatement. The inequality of waste load discharge between areas was calculated with Gini coefficient and was included as one of the objective functions of the multi-objective waste load allocation. In the past, multi-objective functions were usually weighted and then transformed into a single objective optimization problem. Recently, however, due to the difficulties of applying weighting factors, multi-objective genetic algorithms (GA) that require only one execution for optimization is being developed. This study analyzes multi-objective waste load allocation using NSGA-II-aJG that applies Pareto-dominance theory and it`s adaptation of jumping gene. A sensitivity analysis was conducted for the parameters that have significant influence on the solution of multi-objective GA such as population size, crossover probability, mutation probability, length of chromosome, jumping gene probability. Among the five aforementioned parameters, mutation probability turned out to be the most sensitive parameter towards the objective function of minimization of waste load abatement. Spacing and maximum spread are indexes that show the distribution and range of optimum solution, and these two values were the optimum or near optimal values for the selected parameter values to minimize waste load abatement.

연구논문 : 영향계수법과 유전알고리즘을 이용한 QUAL2K 모형의 매개변수 최적화

조재현 ( Jae Heon Cho ),이창훈 ( Chang Hun Lee ) 한국환경영향평가학회 2009 환경영향평가 Vol.18 No.2

연구논문 : 수질오염총량관리제 대상 오염심화 하천에 대한 오염부하량 할당방법

조재현 ( Jae Heon Cho ) 한국환경영향평가학회 2013 환경영향평가 Vol.22 No.2

수질오염총량관리제 시행 하천에 대해서는 객관적이고 과학적 방법으로 유역내 각 지역의 오염 부하량을 할당할 필요가 있다. 본 연구에서는 대도시에서 배출되는 오염부하의 영향을 크게 받는 영산강수계의 중상류부를 대상으로 오염부하량 할당 방법에 대해 검토하였다. 오염부하량 할당을 위한 수질모델링은, 수질관리에 흔히 적용되어온 QUAL2E의 최근 판인, QUAL2Kw를 이용해서 수행하였다. 모델 적용 대상 지역의 각 reach의 수질매개변수는 QUAL2Kw의 자동보정 기능을 이용해서 추정하였다. 오염부하량 할당의 최적화는 유전알고리즘(genetic algorithm)을 이용하였고, 최소부하량 삭감법(least waste load removal allocation), 일정 부하량 이상 최소부하량 삭감법(least waste load removal over a certain value), 동일삭감률 할당법(equal removal rate)의 세가지 방법을 적용하고 비교 검토하였다. 동일삭감률 할당법은 다른 방법보다 유역 전체 부하량 삭감량이 훨씬 크기 때문에 효과적이지 않았고, 이 방법을 쓰기 위해서는 부하량 삭감대상인 각 소유역과 하수처리장을 그 규모와 특성에 따라 세분화할 필요가 있다. 동일삭감률 할당법의 적용시 세가지 범주로 나누어서 삭감률을 적용하였다. 오염부하량 삭감의 효율성을 감안할 때 최소 부하량 삭감법보다 일정 부하량 이상 최소부하량 삭감법이 더 적절한 것으로 검토되었다.

QUAL2Kw 모형을 이용한 자동보정 방법 비교분석과 섬강의 수질관리 대안 평가

조재현 ( Jae Heon Cho ) 한국환경영향평가학회 2016 환경영향평가 Vol.25 No.5

본 연구에서는 GA와 QUAL2K를 통합한 QUAL2Kw 모형을 이용해서 수질모형 매개변수의 자동보정 방법을 비교 분석하였다. 발전 속도가 빠른 원주시의 배출 오염부하의 영향을 크게 받는 섬강에 QUAL2Kw 모형을 적용하였고, 전 구간 단일 매개변수를 적용하는 방법과 구간별 매개변수를 적용하는 두가지 방법으로 자동보정 방법을 비교 분석하였다. CV(RMSE)의 오차와 GA의 적합도 분석결과 구간별매개변수 방법이 단일 매개변수 방법보다 정밀도가 다소 높은 것으로 나타났으므로 본 연구에서는 구간별매개변수 방법으로 계산한 자동보정 결과를 채택하였다. 검보정된 QUAL2Kw 모형을 섬강 수질관리를 위한 세가지 시나리오에 대해 적용해서 수질 개선 효과를 분석하였다. 원주하수처리장 방류수질을 개선하는 시나리오 1에서는 중권역 대표지점인 섬강 4-1지점의 BOD와 TP 농도가 각각 17.7%, 29.1% 감소되었고, 원주천 유입직후 섬강에서는 BOD와 TP 농도가 각각 50.4%, 40.5% 감소하여 섬강 수질 개선효과가 크다. 원주취수장을 폐쇄하고 섬강 이외의 수계에서 원주 일대에 광역상수도를 공급하는 시나리오 2에서는 섬강 중하류부의 유량이 증가함에 따라 섬강 본류의 수질이 소폭 개선된다. 원주천 합류 직후 섬강에서 BOD가 0.18mg/L, TP가 0.0063mg/L 감소하였다. 시나리오 3에서는 시나리오 1과 시나리오 2의 대안을 동시에 계획하는 것으로서 시나리오 1보다 섬강 수질이 소폭 더 개선된다. 시나리오별 수질 예측결과 원주하수처리장의 방류수질을 개선하는 것이 섬강 수질개선에 가장 효과적인 것으로 나타났다. 특히 원주천 합류직후 섬강 수질이 크게 개선된다. 원주취수장을 폐쇄하고 타 수계에서 광역상수도를 통해 원주 지역에 상수도를 공급하는 방안도 섬강 수질을 소폭 개선할 수 있다. In this study, auto-calibration method for water quality model was compared and analyzed using QUAL2Kw, which can estimate the optimum parameters through the integration of genetic algorithm and QUAL2K. The QUAL2Kw was applied to the Sum River which is greatly affected by the pollution loads of Wonju city. Two auto-calibration methods were examined: single parameter application for the whole river reach and separate parameter application for each reach of multiple reaches. The analysis about CV(RMSE) and fitness of the GA show that the separate parameter auto-calibration method is better than the single parameter method in the degree of precision. Thus the separate parameter auto-calibration method is applied to the water quality modelling of this study. The calibrated QUAL2Kw was used for the three scenarios for the water quality management of the Sum River, and the water quality impact on the river was analyzed. In scenario 1, which improve the effluent water quality of Wonju WWTP, BOD and TP concentrations of the Sum River 4-1 station which is representative one of Mid-Watershed, are decreased 17.7% and 29.1%, respectively. And immediately after joining the Wonjucheon, BOD and TP concentrations are decreased 50.4% and 40.5%, respectively. In scenario 2, Wonju water supply intake is closed and multi-regional water supply, which come from other watershed except the Sum River, is provided. The Sum River water quality in scenario 2 is slightly improved as the flow of the river is increased. Immediately after joining the Wonjucheon, BOD and TP concentrations are decreased 0.18mg/L and 0.0063mg/L, respectively. In scenario 3, the water quality management alternatives of scenario 1 and 2 are planned simultaneously, the Sum River water quality is slightly more improved than scenario 1. Water quality prediction of the three scenarios indicates that effluent water quality improvement of Wonju WWTP is the most efficient alternative in water quality management of the Sum River. Particularly the Sum River water quality immediately after joining the Wonjucheon is greatly improved. When Wonju water supply intake is closed and multi-regional water supply is provided, the Sum River water quality is slightly improved.

해수유입을 고려한 석호의 수질모델링

조재현 ( Jae Heon Cho ) 한국물환경학회 1997 한국물환경학회지 Vol.13 No.2

EUTRO5 model of WASP5 was applied to Lake Gyungpo which has characteristics of a lagoon. Lake Gyungpo has freshwater and seawater input. EUTRO5 model was calibrated with the measured water quality data of 1996. Sensitivity analysis was done to determine the NH, flux, PO₄ flux, and SOD from the bottom sediment. NH, flux used in this model was 30.0㎎/㎡-day, PO₄ flux was 2.l㎎/㎡-day, and SOD was 0.5g/㎡-day. Sensitivity analysis of seawater boundary showed that water quality of Lake Gyungpo was significantly affected by seawater boundary concentration. When the water quality of seawater boundary concentration is reduced to one-eighth of present condition, 0.067㎎/L of TP, 0.791㎎/L of TN, 2.3㎎/L of BOD are decreased compared with the present lake water quality. Water quality prediction of the year 2006 was done with the 3 case of water quality management alternatives. After constructing sewer system of the Gyungpo area and Gangrung wastewater treatment plant, 0.066㎎/L of TP, 0.58㎎/L of TN, 3.5㎎/L of BOD are decreased in comparison with the present lake water quality.

연구논문 : 오염하천의 자동보정을 위한 QUAL2Kw 모형의 적용과 유전알고리즘의 매개변수에 관한 민감도분석

조재현 ( Jae Heon Cho ) 한국환경영향평가학회 2011 환경영향평가 Vol.20 No.3

The QUAL2K has the same basic characteristics as the QUAL2E model, which has been widely used in stream water quality modeling; in QUAL2K, however, various functions are supplemented. The QUAL2Kw model uses a genetic algorithm(GA) for automatic calibration of QUAL2K, and it can search for optimum water quality parameters efficiently using the calculation results of the model. The QUAL2Kw model was applied to the Gangneung Namdaecheon River on the east side of the Korean Peninsula. Because of the effluents from the urban area, the middle and lower parts of the river are more polluted than the upper parts. Moreover, the hydraulic characteristics differ between the lower and upper parts of rivers. Thus, the river reaches were divided into seven parts, auto-calibration for the multiple reaches was performed using the function of the user-defined automatic calibration of the rates worksheets. Because GA parameters affect the optimal solution of the model, the impact of the GA parameters used in QUAL2Kw on the fitness of the model was analyzed. Sensitivity analysis of various factors, such as population size, crossover probability, crossover mode, strategy for mutation and elitism, mutation rate, and reproduction plan, were performed. Using the results of this sensitivity analysis, the optimum GA parameters were selected to achieve the best fitness value.