• Journal of Korea Water Resources Association
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• v.37 no.2
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• pp.163-172
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• 2004

In this paper, the sub-soil storage system for utilizing urban instream flow of rainfall runoff was developed and examined through experiments. The artificial rainfall facility and sub-soil storage were installed in the experimental area. The effect of the water qualify improvement and the storage effect were analyzed through the several experiments. Through the experiments of rainfall intensity variation, which are the rainfall intensity of 20mm/hr, 30mm/hr, 40mm/hr, 50mm/hr was indicated SS concentration can be reduction until 68％. Also, the ration of the storage volume is varied from 42.8％∼79.9％ based on the rainfall intensity. The reduction rate of the BOD, CO $D_{Mn}$, SS, T-N, T-P was 30％, 42％, 68％, 39％, 26％. As the result, water quality of runoff and efficient of runoff reduction by the system are much improved. The rainfall runoff with the installation of sub-soil storage could be used for instream flow.

• Journal of Korea Water Resources Association
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• v.36 no.5
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• pp.851-861
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• 2003

Snow accumulation and snow melt was simulated and included in the computation of the watershed runoff for Soyanggang Dam and Chungju Dam. A modified Tank Model was used for the simulation, which has three serial tanks and a pulse response function. The model parameters were estimated through the global optimization method of Shuffled Complex Evolution-University of Arizona (SCE-UA). A watershed was divided into four zones of elevation. The temperature decrease of the zones was a rate of -0.6$^{\circ}C$/100m. Almost all precipitation from December to February become accumulated as snow, and then the snow melts and runs off from March to April. The average runoff with snow melt was greater than the average runoff without snow melt during the period from March to April. The improved amount from snow melt simulation was about one fifth of the observed one for Soyanggang Dam. The increased amount for Chungju Dam was about one fourth of the observed average runoff during the same period. Although the watershed runoff was simulated including snow melt, it was less than the observed one for both of the dams.

• Journal of Korean Society on Water Environment
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• v.26 no.1
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• pp.61-70
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• 2010

The increase of impervious cover (IC) in a watershed is known as an important factor causing alteration of water cycle, deterioration of water quality and biological communities of urban streams. The study objective was to assess the impact of IC changes on the surface runoff characteristics of Kap Stream basin located in Geum river basin (Korea) using the Storm Water Management Model (SWMM). SWMM was calibrated and verified using the flow data observed at outlet of the watershed with 8 days interval in 2007 and 2008. According to the analysis of Landsat satellite imagery data every 5 years from 1975 to 2000, the IC of the watershed has linearly increased from 4.9% to 10.5% during last 25 years. The validated model was applied to simulate the runoff flow rates from the watershed with different IC rates every five years using the climate forcing data of 2007 and 2008. The simulation results indicated that the increase of IC area in the watershed has resulted in the increase of peak runoff and reduction of travel time during flood events. The flood flow ($Q_{95}$) and normal flow ($Q_{180}$) rates of Kap Stream increased with the IC rate. However, the low flow ($Q_{275}$) and drought flow ($Q_{355}$) rates showed no significant difference. Thus the subsurface flow simulation algorithm of the model needs to be revisited for better assessment of the impact of impervious cover on the long-term runoff process.

• Journal of Wetlands Research
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• v.19 no.3
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• pp.279-286
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• 2017

In this study, the characteristics of non-point source pollution runoff and the possibility of using new unit load were investigated by using pollutant load based on monitoring data considering baseflow. For this purpose, the components of hydrograph were separated by using digital filter method and the numerical integration method was applied to calculate the non-point source pollutant load for nine rainfall events in Juwon river in the Geum River basin. As a result of this study, the mean contribution rate of non-point pollutant was 31.34% for BOD, 58.94% for T-N, and 50.42% for T-P and BOD was more influenced by baseflow pollutant. Also, it was analyzed the pollutant load using the new unit load is closer to the observation load than the old unit load. This result implies that it is necessary to manage not only pollutant load due to direct runoff but also pollutant load due to baseflow runoff for efficient water quality management of the watershed.

• Journal of Korea Water Resources Association
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• v.47 no.6
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• pp.513-522
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• 2014

Climate change and urbanization have affected a increase of peak discharge and water pollution etc. In a view of these aspects, the LID(Low Impact Development) technology has been highlighted as one of adjustable control measures to mimic predevelopment hydrologic condition. Many LID technologies have developed, but there is a lack of studies with verification of LID technology efficiency. Therefore this study developed a rainfall-runoff simulator could be possible to verify LID technology efficiency. Using this simulator, this study has experimented the rainfall verification through the rainfall distribution experiment and the experiment to show the relation between inflow and effective rainfall in order to sprinkle the equal rainfall in each unit bed. As a result, the study defined the relation between allowable discharge range and RPM by nozzle types and verified the hydrologic cycle such as the relation between infiltration rate, surface runoff and subsurface runoff at pervious area and impervious area through the rainfall-runoff experiment.

• Journal of Wetlands Research
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• v.11 no.1
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• pp.91-97
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• 2009

The fowls manure is using as fertilizers for farmland because of enough nutrients. However, excess nutrients can be washed off during a storm and affected on nearby waterbodies. In this paper, the runoff characteristics from farmland were studied to determine the washoff mass. A lab-scale reactor was designed to estimate the surface runoff and infiltration rates according to the rainfall intensity. Surface runoff water did not occur at 10mm/hr rainfall intensity, but some runoff occurred at 20mm/hr rainfall intensity. At 32.4mm/hr rainfall intensity, it shows the highest pollutant concentrations such as 686mg/L for $BOD_5$ and at 630mg/L $COD_{Mn}$. The pollutant as based on fowls manure compost was highly washed-off by subsurface water at 32.4mm/hr rainfall intensity, however the concentration was largely decreased at 43.2mm/hr rainfall intensity. The summary of the results is that the highest wash-off concentrations value shows at 32.4mm/hr rainfall intensity for $BOD_5$ and at 67.1mm/hr for T-N and T-P.

• Proceedings of the Korea Water Resources Association Conference
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• 2021.06a
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• pp.130-130
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• 2021

The increasing effect of urbanization has been more apparent through flooding and downstream water quality especially from heavy rainfalls. In response, stormwater runoff management solutions have focused on runoff volume reduction and treatment through infiltration. However, there are areas with low infiltration soils or are experiencing more dry days and even drought. In this study, a lab-scale infiltration system was used to compare the applicability of two types of soil as base layer in gravel-filled infiltration systems with emphasis on runoff capture and suspended solids removal. The two types of soils used were sandy soil representing a high infiltration system and clayey soil representing a low infiltration system. Findings showed that infiltration rates increased with the water depth above the gravel-soil interface indicating that the available depth for water storage affects this parameter. Runoff capture in the high infiltration system is more affected by rainfall depth and inflow rates as compared to that in the low infiltration system. Based on runoff capture and pollutant removal analysis, a media depth of at least 0.4 m for high infiltration systems and 1 m for low infiltration systems is required to capture and treat a 10-mm rainfall in Korea. A maximum infiltration rate of 200 mm/h was also found to be ideal to provide enough retention time for pollutant removal. Moreover, it was revealed that low infiltration systems are more susceptible to horizontal flows and that the length of the structure may be more critical that the depth in this condition.

• Journal of Korean Society on Water Environment
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• v.29 no.3
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• pp.309-316
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• 2013

The Non-Point Sources shows different characteristics over a wide area depending on basin situation and rainfall events etc. In addition, Among various land uses in the urban areas, runoff appears high in the paved area, though small in its size, during a heavy rain than in other land use owing to its high impervious rate, and pollutants become severly accumulated owing to continual transportation of vehicles, characteristically showing high concentrations of runoff in the early stage. As a result, several advanced countries including USA give a special emphasis on the paved area as a target for supervision. In view of these aspects, the research is not only required to consider separated sub-basins which are distributed according to land uses, but also needed to develop a suitable monitoring which is reflected rainfall-runoff relation. The on-site monitoring has been performed to collect data in object watershed as well.

• Journal of Korea Water Resources Association
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• v.32 no.5
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• pp.515-524
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• 1999

A methodology to resolve a TOPMODEL problem has been suggested, which is associated with the spatial distribution of soil moisture behaviour in a runoff mechanism. A procedure to integrate the spatial information of saturation deficit in the TOPMODEL reflects the connectivity of saturated area in a watershed. The developed algorithm includes an improved basis in tracing the runoff path without increasing the number of parameters. The performance of the developed algorithm has been tested to an upland subwatershed, namely Dongok, which is the IHP watershed located at Wichon, Korea. Comparing with the original statistical version of the TOPMODEL, it has been found that the suggested algorithm can relax an overestimation of peak rate in the runoff simulation.

• Water for future
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• v.10 no.2
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• pp.101-111
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• 1977

The analysis performed here is aimed to increase the familiarity of hydrologic process especially for the small basins which are densely gaged. Kyung An and Mu Shim river basins are selected as a represectative basin according to the criteria which UNESCO has establisheed back in 1964 and being operated under the auspice of Ministry of Construction. The data exerted from these basins is utilized for the determination of the characteristics of precipitation and runoff phenomena for the small basin, which is considerred as a typical Korean samll watershed. The methodology developed by Soil Conservation Service, USA for determination of runoff value from precipitation is applied to find the suitability of the method to Korean River Basin. The soil cover complex number or runoff curve number was determined by considering the type of soil, soil cover, land use and other factor such as antecent moisture content. The averag values of CN for Kyung An and Mushim river basins were found to be 63.9 and 63.1 under AMC II, however, the values obtained from soil cover complex was less than those from total precipitation and effective precicpitation by 10-30%. It may be worth to note that an attention has to be paid in the application of SCS method lo Korean river basin by adjusting 10-30% increase to the value obtained from soil cover complex. Finally, the design flood hydrograph was consturcted by employing unit hydrograph technique to the dimensionless mass curve. Also a stepwise multiple regression was performed to find the relationship between runoff and API, evapotranspiration rate, 5 days antecedent precipitation and daily temperature.