• Journal of The Korean Society of Agricultural Engineers
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• v.66 no.3
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• pp.39-51
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• 2024

To effectively implement the integrated water management policy outlined in the National Water Management Act, it is essential to analyze agricultural water supply and demand at both basin and water district levels. Currently, agricultural water is primarily distributed through open canal systems and controlled by floodgates, yet the utilization-to-supply ratio remains at a mere 48%. In the case of agricultural water, when analyzing water balance through existing national basin water resource models (K-WEAP, K-MODISM), distortion of supply and regression occurs due to calculation of regression rate based on the concept of net water consumption. In addition, by simplifying the complex and diverse agricultural water supply system within the basin into a single virtual reservoir, it is difficult to analyze the surplus or shortage of agricultural water for each field within the basin. There are limitations in reflecting the characteristics and actual sites of rural water areas, such as inconsistencies with river and reservoir supply priority sites. This study focuses on the development of a model aimed at improving the deficiencies of current water balance analysis methods. The developed model aims to provide standardized water balance analysis nationwide, with initial application to the Anseo standard watershed. Utilizing data from 32 facilities within the standard watershed, the study conducted water balance analysis through watershed linkage, highlighting differences and improvements compared to existing methods.

• Proceedings of the Korea Water Resources Association Conference
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• 2018.05a
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• pp.106-106
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• 2018

Ecosystem service valuation is a crucial step for the sustainable management of watershed. In the context of various ecosystem services provided by watershed, this study, particularly deals with water yield computation in Bagmati Basin of Nepal. The water availability per population in Bagmati Basin is lowest compared to other basins in Nepal. Also, the rate of urbanization is rapidly growing over a decade. In this regard, the objectives of this study are 1) to compute the total water yield of the basin along with computation on a sub-watershed scale, and 2) Study the impacts of land use change on water yield based on CLUE-S model. For the study, Integrated Valuation of Environmental Services and Tradeoffs (InVEST), a popular model for ecosystem service assessment based on Budyko hydrological method is used to compute water yield. As well, CLUE-S model is used to study land use change, which is further related to study variation on water yield. The sub-watershed wise outcome of the study is expected to provide the guidelines for the effective and economic management of a watershed on a regional scale.

• KCID journal
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• v.14 no.2
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• pp.207-213
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• 2007

For sustainable development at a watershed, environment friendly site-specific management practices need to be developed and implemented. The soil and Water Assessment Tool(SWAT)model has been world-wide used to estimate stream flow, sediment, and nonpoint source pollutant loads, and effects on water quality of different management practices. In this study, the SWAT model was used to estimate the flow resources at Hwacheon areas using Digital Elevation Model(DEM),Land use, precipitation ,wind ,maximum and minimum temperature, solar radiation, humidity of watershed The R2 value and EI value for the comparison of SWAT estimated flow and measured flow were 0.87 and 0.67 respectively for calibration period, and the R2 value and E1 value for validation were 0.75 and 0.67 respectively. The comparison results show what the SWAT model is applicable to simulate hydrology behaviors at this study watershed.

• Spatial Information Research
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• v.10 no.2
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• pp.263-273
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• 2002

This paper presents desirable water environmental management to a closed watershed. In order to obtain spatially distributed environmental information, GIS data have been used. Elevation data are used to extract stream channels automatically and to divide networks of a watershed. A Digital Elevation Model (DEM) has been developed, validated, and adopted to estimate the runoff of total nitrogen pollutant from watershed. This GIS-linked model can be applied effectively to the watersheds with many sub-streams, and for the estimation of pollutant runoff considering land use change.

• Journal of Korean Society of Environmental Engineers
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• v.36 no.8
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• pp.521-527
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• 2014

The objectives of study are 1) to enhance the filed scale BMPs model of HRSM4BMP for simulation of watershed scale and 2) to evaluate the enhanced HRSM4BMP model. Thus pre-process and post-process module were developed and HRSM4BMP was linked to SWAT routing module. After enhancement of model, enhanced HRSM4BMP model was applied to Heaan watershed in Kangwon province with Vegetative filter strip (2 m) in subwatershed #14 and reduction of sediment load was evaluated by watershed scale in outlet. The results of simulation, sediment load was reduced by 4 percent during 3 years in outlet. The result of this study is expected to be used Long-term BMPs establishing plan in South Korea.

• Spatial Information Research
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• v.3 no.2
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• pp.135-146
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• 1995

The purpose of this study is to develop a GIS application and interface model (GISCELWAB) for the temporal and spatial simulation of surface runoff from a small watershed. The model was constituted by three sub - models : The input data extraction model (GISINDATA) which prepares cell-based input data automatically for a given watershed, the cell water balance model(CELWAB) which calculates the water balance for a cell and simulates surface runoff of watershed simultaneously by the interaction of cells, and the output data management model(GISOUTDISP) which visualize the results of temporal and spatial variation of surface runoff. The input data extraction model was developed to solve the time-consuming problems for the input-data preparation of distributed hydrologic model. The input data for CELWAB can be obtained by extracting ASCII data from a vector map. The output data management model was developed to convert the storage depth and discharge of cell into grid map. This model ean-bles to visualize the temporal and spatial formulation process of watershed storage depth and surface runoff wholly with time increment.

• Journal of Korean Society on Water Environment
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• v.24 no.1
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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.

• Spatial Information Research
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• v.13 no.2 s.33
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• pp.167-183
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• 2005

Wetlands are a transitional zone between aquatic and terrestrial ecosystems, and a habit for the various biospheres. The main purpose of this study is to suggest a new technique that establishes the management districts of inland wetlands. To establish management districts of sub-watershed units, this study used the BurnDEM techniques. The management district resulted form this study are assessed its effectivity using an overlap of inland wetland map and sub-watershed maps classified by 18 sub-watershed. The result of this study could be applied to build a national inland wetland database.

• Proceedings of the Korean Society of Agricultural Engineers Conference
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• 2005.10a
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• pp.241-246
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• 2005

Doam watershed is located at alpine areas in the Kangwon province. The annual average precipitation, including snow accumulation during the winter, at the Doam watershed is significantly higher than other areas. Thus, pollutant laden runoff and sediment discharge from the alpine agricultural fields are causing water quality degradation at the Doam watershed. To estimate soil erosion from the agricultural fields, the Universal Soil Loss Equation (USLE) has been widely used because of its simplicity to use. The USLE rainfall erosivity (R) factor is responsible for impacts of rainfall on soil erosion. Thus, use of constant R factor for the Doam watershed cannot reflect variations in precipitation patterns, consequently soil erosion estimation. In the early spring at the Doam watershed, the stream flow increases because of snow melt, which results in erosion of loosened soil experiencing freezing and thaw during the winter. However, the USLE model cannot consider the impacts on soil erosion of freezing and thaw of the soil. Also, it cannot simulate temporal changes in USLE input parameters. Thus, the Soil and Water Assessment Tool (SWAT) model was investigated for its applicability to estimate soil erosion at the Doam watershed, instead of the widely used USLE model. The SWAT hydrology and erosion/sediment components were validated after calibration of the hydrologic component. The $R^2$ and Nash-Sutcliffe coefficient values are higher enough, thus it was found the SWAT model can be efficiently used to simulate hydrology and sediment yield at the Doam watershed. The effects of snow melt on SWAT estimated stream flow and sediment were investigated using long-term precipitation and temperature data at the Doam watershed. It was found significant amount of flow and sediment in the spring are contributed by melting snow accumulated during the winter. Thus, it is recommend that the SWAT model capable of simulating snow melt and long-term weather data needs to be used in estimating soil erosion at alpine agricultural land instead of the USLE model for successful soil erosion management at the Doam watershed.

• Journal of Environmental Impact Assessment
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• v.17 no.4
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• pp.235-242
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• 2008

To develop a watershed management plan for protection of the lake water quality, the linkages among land use activities, stream water quality, and lake water quality must be understood. This study conducted to develop a Decision Support System(DSS) for the reservoir water quality managers and a comprehensive watershed management plan. This DSS has three main components; database, interactive decision model, and data delivery interface system. Graphic User Interface(GUI) was developed as the interface medium to deliver the data and modeling results to the end users. Water quality management scenarios in Yongdam reservoir consist of two parts. One is the watershed management, and the other is water quality management in the reservoir. The watershed management scenarios that were evaluated include as follows : a removal of point sources, control of waste water treatment plant, reductions in nonpoint sources, and the management of developed land. Water quality management scenarios in the reservoir include to install a curtain wall and to operate an algae removal system. The results from the scenario analysis indicate that the strategy of the reservoir water quality management can promise the best effectiveness to conserve the quality of reservoir water. It is expected that many local agencies can use this DSS to analyze the impact of landuse changes and activities on the reservoir watershed and can benefit from making watershed management decisions.