• KSCE Journal of Civil and Environmental Engineering Research
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• v.8 no.4
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• pp.23-32
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• 1988

The rates of infiltration contributed to the flow fo water in an unconfined aquifer under the partially penetrated stream at an ungaged station and the corresponding base flow in channel are coupled by using the hydraulic and/or hydrologic characteristics obtained from the geomorphologic and soil maps. For the determination of groundwater flow, the linearized model which is originally Boussinesq's nonlinear equation is applied in this study. Also, a stream flow routing model for base flow in channel is based on a simplification of the Saint-venant. The distributed runoff model with piecewise spatial uniformity is presented for obtaining its solution based on a finite difference technique of the kinematic wave equations. The method developed in this study was tested to the Bocheong watershed(area : $475.5km^2$) of the natural stream basin which is one of tributaries in Geum River basin in Korea. As a result, it is suggested that the rationality of hydro-graph separation according to a wide variability in hydrogeologic properties be worked out as developing the physically based subsurface model. The results of the present model are shown to be possible to simulate a base flow due to an arbitrary rate of infiltration for ungaged basins.

• Korean Journal of Ecology and Environment
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• v.34 no.3 s.95
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• pp.215-222
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• 2001

A statistical analysis was performed to evaluate relationships among the pollutant concentrations in non-urban area. The data obtained from two subcatchments in Hwa-Ong watershed during 1999 was used for correlation and regression analyses. Strong correlations were observed among the SS, COD, and TP, while it was not significant with TN. The reason fer weak correlation with TN might be that TN was high in dry-days and runoff in wet-days could not increase enough to change it substantially like in other pollutants. The correlations were stronger for the data in wet-days than in dry-days, and it was influenced by watershed characteristics. While TP-COD showed linear relationship from the regression analysis, SS-TP and SS-COD shelved intrinsically linear relationship between log-transformed TP and COD data and non-transformed SS data. The TP-COD showed strong relationship for all the combinations of monitored data, which implies that these two constituent concentrations varied in a similar pattern. The regression equations reported in the paper might be used to estimate one pollutant concentration from the other in pollutant loading estimates, and its application could be expanded to other non-urban watersheds if their characteristics are not significantly different from the study area. In water quality management projects, rigorous monitoring and its thorough evaluation are recommended to develop more reliable relationships among the pollutant concentrations which could be used in other area.

• Korean Journal of Soil Science and Fertilizer
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• v.37 no.4
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• pp.245-250
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• 2004

Farmers typically apply the dressed soil (coarse saprolite) for various reasons in the sloped upland with high altitude in Kangwon province. However, little researches on the impacts of application of dressed soil in uplands were conducted. Therefore, it is necessary to assess soil quality in this area and to study adverse effects on soil and water due to application of dressed soil. Coarse saprolite itself showed signiScantly poor chemical properties, Particularly P and organic matter contents were not enough for crops to grow. With respect to biological qualities such as enzyme activity and microbial population, coarse saprolite itself showed poor qualities. For example, bacterial population in coarse saprolite contains six times or ten times smaller populations. Based on survey at Jawoon-ri in Hongchon-gun, this region is susceptible for soil erosion due to massive amounts of coarse saprolite application, undesirably long slope length, etc. When weestimated soil loss, more than 40% of farming field in this region exceeded $11.2MT\;ha^{-1}\;yr^{-1}$. According to experiment by installing sediment basins. the sediment basin with up-down tillage and application with dressed soil had the highest soil loss and runofT, while the sediment basin with contour tillage and without soil dressing showed the lowest soil erosion and runoff.

• Journal of Wetlands Research
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• v.22 no.2
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• pp.145-152
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• 2020

Highways are characterized by high non-point pollutant emissions due to high traffic volumes and sections that cause abrupt change in driving speed (i.e. rest stations, ticketing office, etc.). Most highways in Korea were constructed with layers that do not allow adequate infiltration. Moreover, non-point pollution reduction facilities were not commonly installed on domestic highways. This study was conducted to evaluate a facility treating highway runoff and develop a cost-effective design for infiltration facilities by using soil amendment techniques. Performing soil amendment increased the hydraulic retention time (HRT) and infiltration rate in the facility by approximately 30% and 20%, respectively. The facility's efficiency of removing non-point pollutants (Total Suspend Soiled (TSS), Chemical Oxygen Demand(COD), Biological Oxygen Demand(BOD), Total Nitrogen (TN) and Total Phosphorus, (TP) were also increased by 20%. Performing soil amendment on areas with low permeability can increase the infiltration rates by improving the storage volume capacity, HRT, and infiltration area. The application of infiltration facilities on areas with low permeability should comply with the guidelines presented in the Ministry of Environment's Standards for installation of non-point pollution reduction facilities. However, soil amendment may be necessary if the soil infiltration rate is less than 13 mm/hr.

• Journal of Environmental Impact Assessment
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• v.19 no.5
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• pp.475-481
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• 2010

Lots of pollutants typically originating from urban transportation are accumulating on the paved surfaces during dry periods and are washed-off directly to the river during a storm. Also, paved surfaces are contributing to increase in peak flows and volume of stormwater flows. These are the main reasons why the water quality of rivers and lakes remain polluted and still below standards. Currently, several management practices are being applied in developed countries but the design standards are still lacking. This research was conducted to develop a treatment technology that can be useful to address the problems concerning runoff quality and quantity. A lab scale infiltration device consisting of a pretreatment tank and media zone was designed and tested for various flow regimes characterizing the low, average and high intensity rainfall. Based on the experiments, the high intensity flow resulted to increase in outflow event mean concentration (EMC) of pollutants, about twice as much as the average outflow EMC. However, 78 to 88% of the total suspended solids were captured and retained in the pretreatment tank because of sedimentation. The removal of heavy metals such as zinc and lead was greatly affected by the vertical placement of woodchip layer prior to the media zone. It was observed that the high carbon content (almost 50%) in the woodchip provided opportunity for enhancing its uptake of metal by adsorption. The findings implied that the reduction of pollutants can be greatly achieved by means of proper pretreatment to allow for settling of particles with a combination of using high carbon source media like woodchip and a geotextile mat to reduce the flow before filtering into the media zone and finally discharging to the drainage system.

• Korean Journal of Soil Science and Fertilizer
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• v.30 no.3
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• pp.265-271
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• 1997

The salt accumulation, and chemical properties of 90 samples of the plastic film house soil in the area of Cheongju and Chungju were surveyed. Soil textural distribution of soil samples was 30% for sandy loam, 27% for loam and 43% for silty loam. Percentage distribution of electrical conductivity(EC) of surface soil was 23% below $2dS\;m^{-1}$, 30% for $2{\sim}4dS\;m^{-1}$, 25% for $4{\sim}6dS\;m^{-1}$ and 22% over $6dS\;m^{-1}$. Salt affected soil, which EC was higher than $4dS\;m^{-1}$, covered nearly 50% of all field surveyed. However subsoils(20~30cm) below $2dS\;m^{-1}$ was 68%. Salts in plastic film house soil was accumulated by increasing the cultivation period. After 5 years of cultivation electrical conductivity in plastic house soil was generally higher than $4.47dS\;m^{-1}$ in EC that was 2.8~5.6 times higher than that in the field soil in the outside of plastic film house. As the result of temporary removal of plastic film cover from the house during the rainy summer season, salt content in soil was decreased from $3.54{\sim}7.36dS\;m^{-1}$ to $0.71{\sim}2.92dS\;m^{-1}$ in EC due to the desalinization by runoff and percolating water. Contents of $NO_3-N$, $SO_4-S$ and Cl in plastic film house soil were 2.5. 7.0 and 3.4 times higher than those of open field respectively.

• Journal of the Korean GEO-environmental Society
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• v.13 no.10
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• pp.15-23
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• 2012

A numerical model and field monitoring data are used to estimate a change in groundwater level at a borrow site, which will be constructed at the mountainous area with a large ground excavation in the study area, Hwaseong city. Lithologic data and hydraulic coefficients are collected at 9 boreholes and also groundwater levels are measured at these boreholes and existing wells in the study area. Additionally, groundwater recharge rate for the type of land cover is estimated using water budget analysis; 133.34mm/year for a mountainous area, 157.68mm/year for a farming area, 71.08mm/year for an urbanized area, and 26.06mm/year for a bedrock exposure area. The change in groundwater level in and around a borrow site is simulated with Modflow using these data. The result of a transient model indicates that a removal of high ground (over 40El.m) by an excavation will produce a decrease in groundwater levels, up to 1 m, around a borrow site in 10 years. It also explains that this ground excavation will bring about the decreases of 9.4% and 7.0% for groundwater recharge and surface runoff, respectively, which are the factors causing groundwater level's change. This study shows that it is required to construct the groundwater monitoring wells to observe the change of groundwater near a borrow site.

• Fire Science and Engineering
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• v.29 no.2
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• pp.79-83
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• 2015

The fire accident is a representative type of disaster that can largely impact on business. Therefore, precautionary measures and rapid initial response is very important when a disaster occurs. The storage of porous combustibles is inevitable in coal yard, plywood processing industry, and others that are currently operating. Initial fire fighting of fire and identifying the ignition point in such a porous combustible storage space are so difficult that if the initial response is failed, being led to deep-seated fire, surface fire is likely to result in secondary damage. In addition, deep-seated fire can cause personal injuries and property damage due to a large amount of toxic gases and reignition. Therefore damage reduction measures is required around the storage space to handle a porous flammable. Improving the penetration performance of the concentration of the surfactant is carried out as underlying study, which is about an deep-seated fire extinguishing efficiency augmentation when using wetting agents. The porous materials used in the experiments is radiata pine wood flour, which occupies more than 75% of the domestic wood market. Fire fighting water is selected as Butyl Di Glycol (BDG), which is being used for infiltration extinguishing agent, and the experiment was carried out by producing a standard solution. The experiment was carried out on the basis of the Deep-Seated Fire Test of NFPA 18. The amount of watering, porous material to the internal amount of penetration, and runoff measurement out of the porous material was conducted. According to experimental results, as the surface tension is reduced, the surfactant concentration macroscopic penetration rate decreases, but infiltration to a porous material is shown to have growth characteristics.

• Journal of the Korean Society of Hazard Mitigation
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• v.6 no.3 s.22
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• pp.69-76
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• 2006

An hydraulic and hydrologic analysis procedure was proposed to reduce the inundation damage of highway in urban stream, that could contribute the EAP and Traffic control planning of Dongbu highway in the Jungrang stream basin which is one of the representative urban area in Korea. We performed the HEC-HMS runoff analysis, and the UNET unsteady flow modeling to decide the inundation reaches and their characteristics. The high inundation risk areas were of Emoon railway bridge and the Wollueng bridge, which are inundated in the case of 10 year and 20 year frequency flood respectively. We also analyze the inundation characteristics under the various conditions of the accumulation rainfall and the duration. Flood elevation at the Wolgye-1 bridge exceed over Risk Flood Water Level(EL.17.84 m) when the accumulation rainfall is over 250 mm and shorter duration than 7 hr. When neglecting backwater effect from the Han river, inundation risk are highly at the reach C2(Wolgye-1 br. ${\sim}$Jungrang br., left bank), C1(Wolgye-1 br. ${\sim}$Jungrang br., right bank), D(Jungrang br. ${\sim}$Gunja br.) in order, but when consider the effect, the inundation risk are higher than the others at the reach D2(Jungrang br. ${\sim}$Gunja br., left bank) and E(Gunja br. ${\sim}$Yongbi br.), which are located downstream near confluence.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.38 no.5
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• pp.671-683
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• 2018

The flood damage caused by heavy rains in urban watershed is increasing, and, as evidenced by many previous studies, urban flooding usually exceeds the water capacity of drainage networks. The flood on the area which considerably urbanized and densely populated cause serious social and economic damage. To solve this problem, deterministic and probabilistic studies have been conducted for the prediction flooding in urban areas. However, it is insufficient to obtain lead times and to derive the prediction results for the flood volume in a short period of time. In this study, IDNN, TDNN and NARX were compared for real-time flood prediction based on urban runoff analysis to present the optimal real-time urban flood prediction technique. As a result of the flood prediction with rainfall event of 2010 and 2011 in Gangnam area, the Nash efficiency coefficient of the input delay artificial neural network, the time delay neural network and nonlinear autoregressive network with exogenous inputs are 0.86, 0.92, 0.99 and 0.53, 0.41, 0.98 respectively. Comparing with the result of the error analysis on the predicted result, it is revealed that the use of nonlinear autoregressive network with exogenous inputs must be appropriate for the establishment of urban flood response system in the future.