• Journal of Korean Society on Water Environment
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• v.34 no.4
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• pp.382-390
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• 2018

In this study, the LIDMOD3 was developed to design and evaluate low impact development (LIDMOD). In the same fashion, the LIDMOD3 employs a curve number (NRCS-CN) method to estimate the surface runoff, infiltration and event mean concentration as applicable to pollutant loads which are based on a daily time step. In these terms, the LIDMOD3 can consider a hydrologic soil group for each land use type LID-BMP, and the applied removal efficiency of the surface runoff and pollutant loads by virtue of the stored capacity, which was calculated by analyzing the recorded water balance. As a result of Model development, the LIDMOD3 is based on an Excel spread sheet and consists of 8 sheets of information data, including: General information, Annual precipitation, Land use, Drainage area, LID-BMPs, Cals-cap, Parameters, and the Results. In addition, the LIDMOD3 can estimate the annual hydrology and annual pollutant loads including surface runoff and infiltration, the LID efficiency of the estimated surface runoff for a design rainfall event, and an analysis of the peak flow and time to peak using a unit hydrolograph for pre-development, post-development without LID, and as calculated with LID. As a result of the model application as applied to an apartment, the LIDMOD3 can estimate LID-BMPs considering a well spatical distributed hydroloic soil group as realized on land use and with the LID-BMPs. Essentially, the LIDMOD3 is a screen level and simple model which is easy to use because it is an Excel based model, as are most parameters in the database. This system can be expected to be widely used at the LID site to collect data within various programmable model parameters for the processing of a detail LID model simulation.

• Proceedings of the Korea Water Resources Association Conference
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• 2016.05a
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• pp.600-600
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• 2016

기후변화로 인한 가뭄 및 홍수 등의 이상 현상은 유역의 수자원에 미치는 영향이 크기 때문에 이에 대한 예측 및 적응방안을 마련하는 부분이 대두되고 있다. 따라서 본 연구에서는 유역의 수자원 관리를 위하여 단위유역에서의 수자원 취약성을 평가하고자 하였다. 평가 지표는 기후 및 사회 경제 환경적 측면을 고려하여 선정하였으며, 취약성 정의에 따라 수량 및 수질/수생태에 대하여 각각 노출, 민감도, 적응능력으로 구성하였다. 이후 다기준 의사결정기법(Multi-criteria Decision Making, MCDM) 중 TOPSIS(Technique for Order Performance by Similarity to Ideal Solution)를 적용하여 각각의 통합 취약성을 도출하였다. 지표 자료는 2010년을 기준으로 국가 통계 자료를 통해 수집하였으며, 유출량과 증발산량 자료는 준분포형 장기유출모형인 SWAT(Soil and Water Assessment Tool) 모형의 모의 자료(2005~2014)를 활용하였다. 또한, 지표에 대한 가중치는 전문가 설문조사를 통해 산정한 주관적 가중치(Subjective weight)와 수집된 자료를 통하여 산정한 객관적 가중치(Objective weight)로 구분하여 적용하였다. 인구 및 산업의 밀집도가 높은 한강권역에 대하여 표준단위유역(평균 $145km^2$)의 취약성을 평가하였으며, 각각의 취약성 우선 순위를 확인하였다. 수량 취약성의 경우에는 경기 강원북부와 충정도 일부 지역이 높은 것으로 나타났으며, 수질/수생태는 수도권 등 비교적 하류에 위치한 지역의 취약성 순위가 좀 더 높았다. 가중치 적용 방법에 따른 공간분포의 차이는 수질/수생태 취약성이 더 크게 나타나는 것을 확인할 수 있었다.

• Proceedings of the Korea Water Resources Association Conference
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• 2019.05a
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• pp.114-114
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• 2019

최근 들어 집중호우 및 토지이용 변화로 인한 고탁수 문제가 빈번히 발생하고 있다. 이러한 탁수 및 수질오염 문제를 해결하기 위해 환경부는 비점오염원 관리지역을 선정하였으며, Best Management Pratices(BMPs), Low Impact Development(LID) 등 다양한 저감 대책을 시행하고 있다. 비점오염원의 발생원인과 발생위치를 정확하게 증명할 수 없으므로 유역 내 수문 및 수질을 모의할 수 있는 Soil and Water Assessment Tool(SWAT) 모델이 다양한 비점오염원 연구에 널리 활용되고 있다. 그러나 SWAT 모델은 Hydrologic Response Unit(HRU)의 경사도와 경사장을 산정할 때 소유역 내 평균 경사도를 이용하여 토양유실량 및 유출특성을 모의에 필요한 매개변수들을 산정한다는 한계점이 있다. 본 연구에서는 이러한 SWAT 모형의 단점을 보완하기 위하여 실제 경작지를 기준으로 HRU를 생성하고, 실측 경사도와 경사장을 적용하기 위한 기술을 개발하였다. 본 연구에서 개발한 기술을 고탁수로 인해 비점오염원 관리지역으로 지정된 도암호 유역에 적용하여 실측 경사도와 경사장을 적용하여 모의한 유출량과 기존의 SWAT 모델을 통해 모의한 유출량을 비교 분석하였다. 기존 모델의 결과와 본 연구에서 개발한 기술을 적용하여 모의한 결과를 비교하였을 때 수문 컴포넌트 중 중간유출과 기저유출에 있어서 차이가 발생한 것을 알 수 있었다. 또한 본 연구에서 개발된 기술을 적용함으로써 도암호 유역에서 비교적 정확한 토양유실과 Suspended Solids(SS) 모의 결과를 나타냈다. 하지만 본 연구는 도암호 유역만을 대상으로 수행되었기 때문에 다른 비점오염 관리지역에 확대 적용하여 본 연구의 결과를 재검토할 필요가 있다.

• Journal of Korean Society on Water Environment
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• v.34 no.6
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• pp.591-601
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• 2018

Optimized BMP plans for controlling water quality using the Pareto trade-off surface curve in upper basin of Namgang Dam is proposed. The proposed alternatives consist of BMP installation scenarios in which the reduction efficiency of non-point pollutants is maximized in a given budget. The multi-objective optimization process for determining the optimal alternatives was performed without direct implementation of a watershed model such as SWAT analysis, thereby reducing the time taken. The shortening of the calculation time further enhances the applicability of the multi-objective optimization technique in preparing regional water quality management alternatives. In this study, different types of BMP are applied depending on the land use conditions. Fertilizer input control and vegetative filter strip are considered as alternatives to applying BMP to the field but only control of fertilizer input can be applied to rice paddies. Fertilizer input control and vegetative filter strip can be installed separately or simultaneously in a hydrologic response unit. Finally, 175 BMP application alternatives were developed for the water quality management of the upper river basin of Namgang dam. The proposed application alternative can be displayed on the map, which has the advantage of clearly defining the BMP installation location.

• Journal of Korean Society on Water Environment
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• v.27 no.4
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• pp.509-515
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• 2011

For this study the 4 sub-watersheds Okdong A, Hankang B, Jecheon A and Hankang C which are the main streams of the Han River within the mid-level region of Chungju Dam are selected and the analysis of soils has been carried out through the soil basic survey. When it comes to the soil erosion amount the soil nutrient load has been calculated by utilizing the RUSLE erosion equation. In case of the data related to the measurement of water flow and quality the information available from the "Water Information System" one of the websites run by the Ministry of Environment has been used to calculate the water pollution load. The correlation between the soil nutrient load and the water pollutant load has been analyzed through making comparison. According to the results related to the soil nutrient load of each sub-watershed the Hankang C shows the highest values TOC 29,986.92 ton/yr, TN 3,860.33 ton/yr and TP 973.97 ton/yr respectively. Even when it comes to the loads related to water quality the Hankang C shows also comparatively high values TOC 6,625.64 ton/yr, TN 7,335.01 ton/yrand TP 145.49 ton/yr respectively. The soil nutrient loads of the sub-watersheds are shown to increase towards the lower stream meaning the load increases in the order of Hankang CHankang B and Okdong A. When it comes to the water pollutant load the value goes up along down the water system meaning the load gets higher in the order of Hankang C, Hankang B and Okdong A while utilizing the mainstream within the mid-level region of Chungju Dam as the basis. The correlation study showed that the nutrient content of soil is proportional to the pollutant load in water with the strongest positive correlation with TOC.

• Journal of the Korean Society of Environmental Restoration Technology
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• v.25 no.3
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• pp.97-111
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• 2022

This study was conducted as restoration work to improve the discharge in forested wetlands where there is a concern of damage and observed changes in the discharge and groundwater level. The monthly changes showed that during the wet season, the amount of discharge decreased after restoration and GWL increased. It showed that during the dry season, the GWL and discharge increased. The increased discharge after restoration seems to be the difference in the number of days with no rainfall duration. The change in discharge for each unit of rainfall showed a tendency to increase the baseflow and decrease the direct discharge after restoration. The recharge ratio of GWL showed a decreasing tendency as rainfall was higher. After restoration, it showed a higher tendency under rainfall with less than 20mm. It has been confirmed that the restoration implemented by the study caused such an effect as the increased baseflow and increased GWL. It would be an effective restoration method to maintain water resources in forested wetlands. In the initial rainfall, it demonstrated a certain level of effect, but it is necessary to develop a restoration technology that can decrease the amount of water discharged after the end of rainfall or during the period of no rainfall to protect and maintain the forested wetlands. Streamflow should be identified by each type of terrain of wetlands and a proper restoration countermeasure should be devised for the site where the discharge frequently occurs.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.26 no.3B
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• pp.241-251
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• 2006

This study analyzed the topographical characteristics by extracting property factors of stream (stream order, number of stream, stream length, mean stream length) and property factors of basin (basin area, basin length, total stream length, total number of stream, basin mean width, form factor, maximum stream order, basin density, stream frequency, relief ratio, mean elevation, mean, slope, maximum elevation) from DEM (digital elevation model) and stream network generated by 1:5,000 NGIS (national geographical information system) data for the Bukhan-river basin. In addition, topographical factors for upper, mid stream and lower stream were analyzed and the mutuality of the factors by linear and nonlinear regression curve was identified.

• Journal of the Korean Association of Geographic Information Studies
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• v.17 no.1
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• pp.91-106
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• 2014

This study tries to cluster the 795 standard watersheds of Korea Water Resources Unit Map using multivariate statistical analysis technique. The 30 factors of watershed characteristics related to topography, stream, meteorology, soil, land cover and hydrology were selected for comprehensive analysis. From the factor analysis, 16 representative factors were selected. The significant factors in order were the pedological feature, scale and geological location and meteorological and hydrological features of the watershed. As a next step, the 73 gauged watersheds were selected for cluster analysis. They are scattered properly to the whole country and the discharge data were within a confidential level. Based on the 73 watersheds, the other ungaged watersheds were clustered by applying the 16 factors and calculating Euclidian distances. The clustering results showed that the similarity between standard watersheds within the same river basin were 87%, 69%, 41%, 52%, and 27% for Han, Nakdong, Geum, Seomjin, and Yeongsan river basins respectively.

• Journal of Korean Society on Water Environment
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• v.24 no.2
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• pp.147-155
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• 2008

Because of increased nonpoint source runoff potential at highland agricultural fields of Kangwon province, effective agricultural management practices are required to reduce the inflow of sediment and other nonpoint source pollutants into the water bodies. The watershed-scale model, Soil and Water Assessment Tool (SWAT), model has been used worldwide for developing effective watershed management. However, the SWAT model simulated sediment values are significantly affected by the number of subwatershed delineated. This result indicates that the SWAT estimated watershed characteristics from the watershed delineation process affects the soil erosion and sediment behaviors. However, most SWAT users do not spend time and efforts to analyze variations in sediment estimation due to watershed delineation with various threshold value although topography falsification affecting soil erosion process can be caused with watershed delineation processes. The SWAT model estimates the field slope length of Hydrologic Response Unit (HRU) based on average slope of subwatershed within the watershed. Thus the SWAT ArcView GIS Patch, developed by using the regression relationship between average watershed slope and field slope length, was utilized in this study to compare the simulated sediment from various watershed delineation scenarios. Four watershed delineation scenarios were made with various threshold values (700 ha, 300 ha, 100 ha, and 75 ha) and the SWAT estimated flow and sediment values were compared with and without applying the SWAT ArcView GIS Patch. With the SWAT ArcView GIS Patch applied, the simulated flow values are almost same irrespective of the number of subwatershed delineated while the simulated flow values changes to some extent without the SWAT ArcView GIS Patch applied. However when the SWAT ArcView GIS Patch applied, the simulated sediment values vary 9.7% to 29.8% with four watershed delineation scenarios, while the simulated sediment values vary 0.5% to 126.6% without SWAT ArcView GIS applied. As shown, the SWAT estimated flow and sediment values are not affected by the number of watershed delineation significant compared with the estimated flow and sediment value without applying the SWAT ArcView GIS Patch.

• Journal of Korea Water Resources Association
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• v.43 no.11
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• pp.995-1009
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• 2010

Accelerated soil erosion due to extreme climate change, such as increased rainfall intensity, and human-induced environmental changes, is a widely recognized problem. Existing soil erosion models are generally based on the gross erosion concept to compute annual upland soil loss in tons per acre per year. However, such models are not suitable for event-based simulations of erosion and deposition in time and space. Recent advances in computer geographic information system (GIS) technologies have allowed hydrologists to develop physically based models, and the trend in erosion prediction is towards process-based models, instead of conceptually lumped models. This study aims to propose an effective and robust distributed rainfall-sediment yield-runoff model consisting of basic element modules: a rainfall-runoff module based on the kinematic wave method for subsurface and surface flow, and a runoff-sediment yield-runoff model based on the unit stream power method. The model was tested on the Cheoncheon catchment, upstream of the Yongdam dam using hydrological data for three extreme flood events due to typhoons. The model provided acceptable simulation results with respect to both discharge and sediment discharge even though the simulated sedigraphs were underestimated, compared to observations. The spatial distribution of erosion and deposition demonstrated that eroded sediment loads were deposited in the cells along the channel network, which have a short overland flow length and a gentle local slope while the erosion rate increased as rainfall became larger. Additionally, spatially heterogeneous rainfall intensity, dependant on Thiessen polygons, led to spatially-distinct erosion and deposition patterns.