• Journal of Korean Society of Water and Wastewater
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• v.34 no.6
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• pp.503-512
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• 2020

Identifying the water circulation status is one of the indispensable processes for watershed management in an urban area. Recently, various water circulation models have been developed to simulate the water circulation, but it takes a lot of time and cost to make a water circulation model that could adapt the characteristics of the watershed. This paper aims to develop a water circulation state estimation model that could easily calculate the status of water circulation in an urban watershed by using multiple linear regression analysis. The study watershed is a watershed in Seoul that applied the impermeable area ratio in 1962 and 2000. And, It was divided into 73 watersheds in order to consider changes in water circulation status according to the urban characteristic factors. The input data of the SHER(Similar Hydrologic Element Response) model, a water circulation model, were used as data for the urban characteristic factors of each watershed. A total of seven factors were considered as urban characteristic factors. Those factors included annual precipitation, watershed area, average land-surface slope, impervious surface ratio, coefficient of saturated permeability, hydraulic gradient of groundwater surface, and length of contact line with downstream block. With significance probabilities (or p-values) of 0.05 and below, all five models showed significant results in estimating the water circulation status such as the surface runoff rate and the evapotranspiration rate. The model that was applied all seven urban characteristics factors, can calculate the most similar results such as the existing water circulation model. The water circulation estimation model developed in this study is not only useful to simply estimate the water circulation status of ungauged watersheds but can also provide data for parameter calibration and validation.

• Journal of the Korean Society of Hazard Mitigation
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• v.11 no.2
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• pp.157-161
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• 2011

Although many researches have been carried out concerning the watershed division in natural areas, it has not been researched for the urban watershed division. If the boundary between two urban areas is indistinct because no natural distinction or no administrative division is between the areas, the boundary between the urban areas that have the different outlets (multi-outlet urban watershed) is determined by only designer of sewer system. The suggested urban watershed division model (UWDM) determines the watershed boundary to reduce simultaneously the peak outflows at the outlets of each watershed. Then, the UWDM determines the sewer network to reduce the peak outflow at outlet by determining the pipe connecting directions between the manholes that have the multi-possible pipe connecting directions. In the UWDM, because the modification of the sewer network changes the superposition effect of the runoff hydrographs in sewer pipes, the optimal sewer layout can reduce the peak outflow at outlet, as much as the superposition effects of the hydrographs are reduced. Therefore, the UWDM can optimize the watershed distinction in multi-outlet urban watershed by determining the connecting directions of the boundary-manholes using the genetic algorithm. The suggested model was applied to a multi-outlet urban watershed of 50.3ha, Seoul, Korea, and the watershed division of this model, the peak outflows at two outlets were decreased by approximately 15% for the design rainfall.

• Journal of Korea Water Resources Association
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• v.37 no.7
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• pp.599-612
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• 2004

The continuous long-term rainfall-runoff simulation model SWAT has the advantage of being able to account for various land use, however, SWAT lacks the capability of simulating the drainage characteristics of urban area. On the other hand, SWMM, which is the most popular model for runoff analysis of urban watershed, has the advantage of being capable of considering surface and drainage characteristics in urban area, but SWMM cannot easily account for land use other than urban area within a watershed. In this study, SWAT-SWMM model, which builds on the strengths of SWAT and SWMM, has been applied to the Osan River Watershed which is a tributary watershed to the Gyung-Ahn River. From the application, the results from coupled SWAT-SWMM model has been compared to the ones from SWAT for each hydrologic component such as evapotranspiration, surface runoff, groundwater flow, and watershed and channel discharge, and the runoff characteristics of two models for each hydrologic component has been discussed.

• Journal of Environmental Impact Assessment
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• v.16 no.1
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• pp.79-87
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• 2007

The performance of a stream water quality analysis model depends upon many factors attributed to the geological characteristics of a watershed as well as the distribution behaviors of pollutant itself on a surface of watershed. Because the model run has to import the pollution load from the watershed as a boundary condition along an interface between a stream water body and a watershed, it has been used to introduce a pollution delivery coefficient to behalf of the boundary condition of load importation. Although a nonlinear regression model (NRM) was developed to cope with the limitation of a conventional empirical way, this an up-to-date study has also a limitation that it can't be applied where the pollution load washed off (assumed at a source) is less than that delivered (observed) in a stream. The objective of this study is to identify what causes the limitation of NRM and to suggest how we can purify the process to evaluate a pollution delivery coefficient using many field observed cases. As a major result, it was found what causes the pollution load delivered to becomes bigger than that assumed at the source. In addition, the pollution load discharged to a stream water body from a specific watershed was calculated more accurately.

• Journal of Korea Water Resources Association
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• v.38 no.11
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• pp.907-916
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• 2005

For an urban watershed modeling, the ILLVDAS and SWMM model were the popular rainfall-runoff models using in Korea. However, combined sewerage systems in urban area produce some problems when a flood event happens because of the surcharged precipitation amounts which drain to streams directly. Also, rack of pipe line data and difficulties of modeling yield inappropriate modeling results in urban runoff analysis. In addition, rainfall-runoff models in an urban which using channel routing could be inaccurate and complicated processes. In this paper, the MIKE SWMM model has been applied for a stable urban area runoff analysis. Watershed and pipe line data were established by using past inundated records, DEM data and numerical pipe line data. For a runoff modeling, the Runoff block was adapted to a basin and the Extran block using dynamic equation was applied for sewerage system. After a comparisons against existing models yield that the MIKE SWMM model produce reliable and consistence results without distorting parameter of the model.

• Journal of Korea Water Resources Association
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• v.37 no.7
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• pp.589-598
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• 2004

From the continuous long-term rainfall-runoff standpoint, the urbanization within a watershed causes land use change due to the increase in impervious areas, the addition of manmade structures, and the changes in river environment. Therefore, rainfall-runoff characteristics changes drastically after the urbanization. Due to these reasons, there exists the demand for rainfall-runoff simulation model that can quantitatively evaluate the components of hydrologic cycle including surface runoff, river flow, and groundwater by considering urban watershed characteristics as well as natural runoff characteristics. In this study, continuous long-term rainfall-runoff simulation model SWAT-SWMM is developed by coupling semi-distributed continuous long-term rainfall-runoff simulation model SWAT with RUNOFF block of SWMM, which is frequently used in the runoff analysis of urban areas in order to consider urban watershed as well as natural watershed. The coupling of SWAT and SWMM is described with emphasis on the coupling scheme, model limitations, and the schematics of coupled model.

• Journal of Korean Society on Water Environment
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• v.22 no.2
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• pp.349-357
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• 2006

Nowadays, the discharges of urban streams during dry season are depleted because the hydrologic cycle in the watershed has been destroyed due to the expansion of the impermeable area, the excessive groundwater pumping, climate change, and so forth. The streamflow depletion may bring out severe water quality problems. This research are to investigate the hydrologic characteristics and to develop a technology to restore sound hydrologic cycle of Anyangcheon watershed. For the hydrological cycle analysis of the Anyangcheon watershed, continuous simulations of urban runoff were performed for the upstream basin of Gocheok bridge whose basin area covered 4/5 of the whole catchment area. The increase of impervious area by urbanization was analysed and its effect on urban runoff was evaluated. The SWMM 5 (Storm Water Management Model 5) was used for the continuous simulation of urban runoff. The analysis results of urbanization effect on runoff are as follows: the surface runoff in 2000 increases to 65% of the whole precipitation whereas the surface runoff in 1975 amounts to 50% of the precipitation; the groundwater runoff in 2000 amounts to 7% and shows 6% decrease during the period from 1975 to 2000.

• Proceedings of the Korea Water Resources Association Conference
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• 2005.05b
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• pp.862-866
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• 2005

For urban watershed models, the ILLUDAS and SWMM are the popular rainfall-runoff models used in Korea. However, combined sewage systems in urban areas produced problems when a flood occured because of the surcharged precipitation amount which drained to the streams directly. Also, the lack of pipe line data and the difficulties of modeling yield inappropriate modeling results in urban runoff analysis. In addition, rainfall-runoff models in urban areas which use channel routing could have inaccurate and complicated processes. In this paper, the MIKE SWMM model has been applied for the stable runoff analysis of urban areas. Watershed and pipe line data were established by using past inundated records, DEM data, and the numerical pipe line data. For runoff modelings, the runoff block was adapted to a basin and the Extran block using dynamic equations was applied to the sewage system. After comparing to models that exist, it is concluded that the MIKE SWMM model produces reliable and consistence results without distorting the Parameters of the model.

• Environmental Engineering Research
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• v.18 no.3
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• pp.199-208
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• 2013

This study intended to develop an integrated governance model and find measures to manage nonpoint source (NPS) pollutions in watershed management. To reach this goal, this study has analyzed NPS pollution management policies in Korea and has employed statistical methods such as expert Delphi survey, analysis of variance, and factor analysis. As a result, this study has found that the favored basic organization form was a private-public cooperative council. The necessary governance-based NPS pollution management measures determined through this study are as follows: to build collaboration mechanisms including those related to motivation provision, trust building, capacity building, and making optimal regulations; to employ financial resources based on principles such as 'polluter-pays', 'recipient-pays', and 'general-tax-source'; and to develop several programs, including system improvement, pilot and management projects, and publicity.

• Magazine of the Korean Society of Agricultural Engineers
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• v.31 no.1
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• pp.45-57
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• 1989

The hydrologic model FESHM was introduced and its applicability was investigated in an attempt to analyze the rainfall-runoff relationships of urban small watersheds and to hereafter predict the envi-ronmental changes. Basic data on rainfall, water level, geomorphological characterisitics and land use were obtained from Yeonwha stream watershed located in Chonju-si Dukjin-dong. WL-5 for simulation o subshed WS# 1(136.7 ha) with urban district and WL-1 for total watershed WS#5 (278.78 ha) we'e selected as gaging points. The main results gained through applications were summarized as follows. 1. Direct runoff ratio caalculated from a simple separation method for WS#5 WS# 1 was 2O~39%, 38~62%, respectively. 2. Simulations for the runoff estimation were carried out for each watershed using 5 rainfall events, the simulation errors had the range of 2~ 30%, O~ 63% and O 120 minutes for the runoff volume, peak flow and peak time, respectively. 3. The effect of landuse change by urbanization was tested to WS# 1, runoff volume before development was estimated as from tenth to twentieth against after development.