• 산업기술연구
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• 제28권B호
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• pp.175-183
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• 2008

This study reviewed and compared the measured value with the calculated sediment loads value by the existing theory equation, after actually measuring the suspended load, focusing on locality river in Gangwon province. Next, it suggested the application problems of the existing sediment loads calculation equation in case of rivers in Gangwon province, and suggested the proper sediment loads calculation equation to rivers in Gangwon province, after implementing the statistical regression analysis by using the measured data for 5 rears, 2003 ~ 2007.

• 한국물환경학회지
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• 제33권6호
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• pp.744-753
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• 2017

The sediment delivery ratio (SDR) is widely used to estimate sediment loads by multiplying soil loss through the Revised Universal Equation (RUSLE). In this study, the SDR equation was developed for the Lake Imha watershed using soil loss calculated by RUSLE and sediment loads by the calibrated Hydrological Simulation. Program Fortran (HSPF). The ratio of watershed relief and channel length ($R_f/L_{ch}$), the ratio of watershed relief and watershed length ($R_f/L_b$), curve number (CN), area (A), and channel slope ($SLP_{ch}$) demonstrated strong correlations with SDR. SDR equations were developed by a combination of subwatershed parameters by referring to the correlation analysis. The area based power functional SDR developed in this study showed significant errors at the point right after entering major tributaries, because SDR was unrealistically reduced when the watershed area increased significantly. The $SLP_{ch}$-based power functional SDR also showed extraordinary values when the channel slope was gradual. The SDR equation that showed the highest value of the coefficient of determination also presented unrealistic changes in the sediment loads within a relatively short river distance. The SDR equation $SDR=0.0003A^{0.198}R_f/L{_w}^{1.167}$ was recommended for application to the Lake Imha watershed. Using this equation, sediment loads at the outlet of the Lake Imha watershed were calculated, and the HSPF parameters related to sediment in the uncalibrated subwatersheds were determined by referring to the sediment loads calculated with the SDR equation.

• 대한토목학회논문집
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• 제43권3호
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• pp.321-335
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• 2023

자연하천에서의 유사량 계측은 하천공학적으로 중요한 의미를 가지지만 계측 방법의 비용 문제로 유사량 실측에 어려움이 따른다. 특히 소류사량 계측의 어려움으로 인해 주기적인 유사량 모니터링의 대부분이 부유사 농도 계측에만 제한되어 있는 실정이다. 본 연구에는 자동유량관측소에 설치된 횡방향 도플러 유속계(H-ADCP)의 후방산란값과 부유사 농도의 상관관계를 이용해 실시간으로 부유사 농도를 산정하고 총유사량을 산정하는 서포트벡터회귀 모형을 제안한다. 제안하는 실시간 총유사량 모니터링 시스템은 부유사 농도 모형과 수정 아인슈타인 방법을 모사하는 총유사량 산정 모형으로 구성된다. 각 모형의 매개변수와 입력변수는 K겹 교차검증 기반 격자검색 방법과 재귀적 특징 제거법을 이용해 결정되었다. 교차검증에서 부유사 농도 모형과 총유사량 산정 모형의 R²가 각각 0.885와 0.860으로 유사량-유량 관계곡선에 비해 정확한 것으로 나타났다. 시계열 유사량 관측을 통해 새로 제시되는 실시간 총유사량 관측 시스템이 자연하천에서 발달하는 유사량-유량 이력관계와 미세한 유량 변화에서 나타나는 유사량 변화를 성공적으로 관측할 수 있음을 확인했다. 본 연구에서 제안하는 방법은 마찰경사나 부유사 입도 등의 수리 조건을 가정할 필요 없이 H-ADCP의 원시자료만으로 부유사 농도와 총유사량을 산정할 수 있어 기존 방법에 비해 불확도가 적으며 경제적이다. 본 방법은 H-ADCP가 설치된 유사량 관측소에 광범위하게 적용 가능해 유사량 모니터링의 시간적 해상도를 경제적으로 크게 줄일 수 있을 것으로 기대된다.

• 한국농공학회논문집
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• 제54권2호
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• pp.27-35
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• 2012

Various Best Management Practices (BMPs) have been suggested to reduce Nonpoint source pollutant loads from agricultural fields. However, very little research regarding water quality improvement with sediment trap has been performed in Korea. Thus, effects of sediment trap were investigated in this study. Three sediment traps were installed at the edge of six plots and flow and water quality of inflow and outflow were monitored and analyzed. It was found that approximately 64.1 % of flow reduction was observed. In addition, pollutant concentration of outflow was reduced by 39.0 % for $BOD_5$. For SS, $COD_{Mn}$, DOC, T-N, T-P, approximately 62.1 %, 43.4 %, 43.5 %, 40.0 %, and 41.2 % reduction were observed, respectively. Over 80 % and 90 % of pollutant loads were reduced from sediment trap #2 and #3 because of less outflow from plots covered with rice straw/straw mat. In case of intensive rainfall events occurred from July 26~29, 2011, over 60 % of pollutant and 88.9 % of sediment reduction were observed from sediment trap #3. As shown in this study, small sediment traps could play important roles in reducing pollutant loads from agricultural fields. If proper management practices, such as rice straw/straw mat, are used to protect surface from rainfall impacts and rill formation, much pollutant reduction could be expected.

• 한국농공학회논문집
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• 제56권5호
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• pp.21-27
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• 2014

Sediment-laden water is problematic in aquatic ecosystem and for hydraulic structures in a watershed, and agriculture area in a watershed is one of source areas of nonpoint source (NPS), since soil surface typically exposures due to agricultural activities. Especially, severe sediment might flow into stream when agricultural area is located near stream like the Imha-dam watershed. Soil erosion is affected by precipitation, therefore there is a need to consider precipitation characteristics in soil erosion and best management practices (BMPs) simulation. The Web-based Spreadsheet Tool for the Estimation of Pollutant Load (STEPL WEB) allows estimating long-term sediment loads and the impact of best management practices to reduce sediment loads. STEPL WEB and predicted precipitation data by MIROC-ESM model was used to estimate sediment loads and its reduction by filter strip and conversion of agricultural area to forest in the future 30 years. The result indicates that approximately 70 % of agricultural area requires filter strip installation or that approximately 50 % of agricultural area needs to be converted to forest, for 41 % of sediment load reduction.

• 한국농공학회논문집
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• 제55권2호
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• pp.47-57
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• 2013

This study is to assess the reduction of non-point source pollution loads for rice straw mulching of upland crop cultivation at a watershed scale. For Byulmi-cheon watershed (1.21 $km^2$) located in the upstream of Gyeongan-cheon, the HSPF (Hydrological Simulation Program-Fortran) and SWAT (Soil and Water Assesment Tool), physically based distributed hydrological models were applied. Before evaluation, the model was calibrated and validated using 9 rainfall events. The Nash-Sutcliffe model efficiency (NSE) for streamflow using the HSPF was 0.62~0.76 and the determination coefficient ($R^2$) for water quality (sediment, total nitrogen T-N, and total phosphorus T-P) were 0.72, 0.62, and 0.63 respectively. The NSE for streamflow using the SWAT were 0.43~0.81 and the $R^2$ for water quality (sediment, T-N, and T-P) were 0.54, 0.87, and 0.64 respectively. From the field experiment of 16 rainfall events, the rice straw cover condition reduced surface runoff average 10.0 % compared to normal surface condition. By handling infiltration capacity (INFILT) in HSPF model, the value of 16.0 mm/hr was found to reduce about 10.0 % reduction of surface runoff. For this condition, the reduction effect of sediment, T-N, and T-P loads were 87.2, 28.5, and 85.1 % respectively. By handling soil hydraulic conductivity (SOL_K) in SWAT model, the value of 111.2 mm/hr was found to reduce about 10.0 point reduction of surface runoff. For this condition, the reduction effect of sediment, T-N, and T-P loads were 80.0, 83.2, and 78.7 % respectively. The rice straw surface covering was effective for removing surface runoff dependent loads such as sediment and T-P.

• 한국관개배수논문집
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• 제14권1호
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• pp.50-56
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• 2007

In this study, the Soil and Water Assessment Tool (SWAT) model was used to assess spatiotemporal effects on watershed runoff and sediment characteristics due to land uses changes from 1999 to 2002 at the small watershed, located in Chuncheon-si, Gangwon province. The annual average flow rate of Scenario I (long-term simulation using land use of 1990), II (long-term simulation using land use of 1996), III(long-term simulation using land use of 200) and IV(simulation using land use of 1990, 1995, and 2000) in long-term simulation) using the SWAT model were 29,997,043 m3, 29,992,628 m3, 29,811,191 m3 and 29,931,238 m3, respectively. It was shown that there was no significant changes in estimated flow rate because no significant changes in land uses between 1990 and 2000 were observed. The annual average sediment loads of Scenarios I, II, III and IV for 15 year period were 36,643 kg/ha, 45,340 kg/ha , 27,195 kg/ha and 35,545 kg/ha, respectively. The estimated annual sediment loads from Scenarios I, II, and III, were different from that from the scenario IV, considering spatio-temporal changes in land use and meterological changes over the years, by 10%, 127%, and temporal changes in land use and meterological changes over the years, by 10%, 127%, and 77%. This can be explained in land use changes in high soil erosion potential areas, such as upland areas, within the study watershed. The comparison indicates that changes in land uses upland areas, within the study watershed. The comparison indicates that changes in land uses can affect on sediment yields by more than 10%, which could exceed the safety factor of 10% in Total Maximum Daily Loads (TMDLs). It is, therefore, recommended that not only the temporal analysis with the weather input data but also spatial one with different land uses need to be considered in long-term hydrology and sediment simulating using the SWAT model

• 한국물환경학회지
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• 제37권2호
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• pp.103-113
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• 2021

In this study, an Excel-based model (ROADMOD) was developed to estimate pollutant loading from the road and evaluate BMPs. ROADMOD employs the Chezy-Manning equation and empirical expression for estimating surface runoff, and power function for pollutant buildup, and exponential function for pollutant washoff in SWMM. The results of model calibration for buildup and washoff using observed data revealed a good match between the simulation results and the observed data. The long-term surface runoff and sediment simulated by ROADMOD demonstrated a good match with those by SWMM with 2 ~ 14% of relative error. The shorter sweeping interval (within 8 days) remarkably decreased sediment loads from the road. It was found that the effect of reducing sediment loads from the road was greatly affected not only by the sweeping interval but also by sweeping on the day before a rainfall event. The 48% of removal efficiency of sediment loads from the road was achieved with 26 times of road sweeping per year when sweeping was performed on the day before the rainfall event. A 4-day sweeping interval showed similar removal efficiency (48%) with 96 times of sweeping per year. It is considered that the road sweeping on the day before a rainfall event could maximize the effect of reducing the non-point source pollution from the road with minimization of the number of road sweeping. So, the road sweeping on the day before a rainfall event can be considered as one of the useful and best management practices (BMPs) on road.

• Smart Structures and Systems
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• 제26권6호
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• pp.781-796
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• 2020

Prediction of total sediment load is essential in an extensive range of problems such as the design of the dead volume of dams, design of stable channels, sediment transport in the rivers, calculation of bridge piers degradation, prediction of sand and gravel mining effects on river-bed equilibrium, determination of the environmental impacts and dredging necessities. This paper is aimed to investigate and predict the total sediment load of the Wadi Arbaat in Eastern Sudan. The study was estimated the sediment load by separate total sediment load into bedload and Suspended Load (SL), independently. Although the sediment records are not sufficient to construct the discharge-sediment yield relationship and Sediment Rating Curve (SRC), the total sediment loads were predicted based on the discharge and Suspended Sediment Concentration (SSC). The turbidity data NTU in water quality has been used for prediction of the SSC in the estimation of suspended Sediment Yield (SY) transport of Wadi Arbaat. The sediment curves can be used for the estimation of the suspended SYs from the watershed area. The amount of information available for Khor Arbaat case study on sediment is poor data. However, the total sediment load is essential for the optimal control of the sediment transport on Khor Arbaat sediment and the protection of the dams on the upper gate area. The results show that the proposed model is found to be considered adequate to predict the total sediment load.

• 대한환경공학회지
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• 제33권1호
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• pp.9-15
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• 2011

농업 및 위락용으로 유지용수를 공급받는 군산 미제저수지의 수질 및 퇴적물 오염현황을 파악하고 퇴적물용출, 비점 오염원 및 외부공급수 등 세가지 영양염 유입경로별 오염부하를 비교 분석하였다. 수질분석결과 하절기에 수질이 크게 저하되고 부영양화에 따른 녹조현상이 가장 활발히 나타났으며, 부영양화지수 TSI (secchi depth)는 53.6, TSI (chlorophyll-a)은 57.7 및 TSI (TP)도 56.7로 모두 50 이상의 부영양호 상태를 보였다. 퇴적물오염도 조사결과 조사시기(계절)별 퇴적물 총질소(T-N)함량, 총인(T-P)함량 및 유기물함량의 각 평균은 통계학적으로 유의한 차이가 없는 것으로 나타났으나 시료채취 지점별 평균은 유의한 차이를 나타내 공간적 변화가 뚜렷하였다. 반면, T-N 및 T-P 퇴적물용출율결과는 공간적변화보다 시기별 변화가 뚜렷하였다. 수질 및 퇴적물 데이터의 상관성분석결과, 수질 T-N은 퇴적물 T-N함량 및 퇴적물 유기물함량과 통계학적으로 유의한 상관관계가 있었으나 수질 T-P는 통계학적으로 상관성을 보이는 인자가 확인되지 않았고 퇴적물 영양염 용출율 역시 수질과 통계학적으로 상관성을 보이는 인자가 확인되지 않았다. 미제저수지내 유입경로별 영양염오염부하 산정결과, T-N의 경우 외부 공급수에 의한 오염부하가 월등히 높게 나타났고 T-P의 경우 퇴적물용출부하와 외부 공급수 유입부하는 유사하고 비점유입부하가 상대적으로 적게 나타났다. 미제저수지의 수질개선을 위해서는 영양염오염부하가 상대적으로 높은 외부 공급수(금강호 양수)에 대한 대책이 우선적으로 수립되어야 하며 아울러, 퇴적물로부터 T-P용출을 저감시키는 수질오염저감대책이 필요한 것으로 판단된다.