• Journal of Korean Society on Water Environment
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• v.22 no.4
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• pp.648-657
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• 2006

Characteristics of water quantity and quality of the Anyangcheon were analyzed through many field measurements and the distributed hydrologic simulation model, Soil and Water Assessment Tool (SWAT). Event mean concentrations (EMCs) and baseflow mean concentrations were calculated from the data and the daily runoff were simulated by SWAT. The runoff was divided into the direct runoff and the baseflow. Using those values and quantity and quality data of release from the wastewater treatment plant (WWPT), unit loads of BOD, COD, SS, $NO_2-N$, $NO_3-N$, $NH_3-N$, and Dis-P were derived. EMCs of BOD and SS were even higher than the baseflow mean concentrations. The total runoff from October to April (7 months) of 2004 was just 13.5%, since the rainfall usually is concentrated in summer season. Futhermore BOD and SS were loaded during the event by 50.9% and 70.9%, respectively and over three quarters of total COD, $NO_2-N$, $NO_3-N$, $NH_3-N$, and Dis-P were flowed into the Anyangcheon during the remaining period. Therefore, the efficiency of WWPT for COD, $NO_2-N$, $NO_3-N$, $NH_3-N$, and Dis-P should be intensified from Oct. to Apr. and the runoff quality management of BOD and SS should be planned during the summer season.

• Journal of Korea Water Resources Association
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• v.38 no.2
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• pp.167-177
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• 2005

In this study, the PRMS(Precipitation and Runoff Modeling System), developed by USGS(United States Geological Survey), was applied to the Yongdam dam watershed in the Geum River basin. The efficiency for runoff simulation and spatial characteristics of PRMS were evaluated. The runoff changes with the changes of subcatchments and HRUs were estimated. As results, the size of the subcatchment and HRV did not significantly affect the runoff at the exit of watershed. Consequently, the spatial characteristic of PRMS was shown as lumped type rather than semi-distributed. The geographical input data for Yongdam dam watershed were converted to the USGS Input type, and the parameters were calibrated using Rosenbrock optimization method, validated with the observed runoff data. The PRMS showed resonable agreements in the long-term continuous runoff simulation, if the accuracy of observed data is ensured.

• Journal of Korea Water Resources Association
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• v.46 no.2
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• pp.183-193
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• 2013

Selecting the evaluation index to determine water resources system design yield is an important problem for water resources engineers. Reliability, resilience and vulnerability are three widely used indices for yield analysis. However, there is an overlap region between indices as well as resilience and vulnerability can show improvement in non-monotonic phenomena although yield condition becomes worse. These problems are usually not recognized and the decisions are made according to calculated estimates in real situation. The reason for this is caused by a diverse characteristics of water resources system such as seasonal variability of hydrologic characteristics and water demands. In this study, the applicability of resilience and vulnerability for multi indices application in addition to reliability which is applied generally is examined. Based on highly seasonal irrigation water demand ratio, the correlation and non-monotonic phenomena of each index are analyzed for seven selected reservoirs. Yongdam reservoir which supplies constant water supply showed the general tendency, but Chungju, Andong, Namgang and other reservoirs which supplies irrigation water showed clear non-monotonic phenomena in resilience and vulnerability.

• Magazine of the Korean Society of Agricultural Engineers
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• v.33 no.2
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• pp.51-60
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• 1991

The main objective of this study is to examine the adaptability for the large watershed of the storage tank model which can be applied for the analysis of both long and short terms runoff developed on the basis of hydrologic data for a smaH mountaineous watershed. The results obtained in this study are summarized as follows ; 1. Areal rainfalls of the Dae Chong watershed were calculated by Thiessen method composed of 9 Thiessen networks. 2. Optimal parameters for two types, Model A and Model B of tank models were derived through calibration procedure by standardized Powell method. 3. Monthly simulated flows of Model B are seemed to be closer to the monthly observed than those of Model A during calibration period in the long terms runoff. 4. Relative errors for the simulated flood flows of Model B were apperaed as lower percentage to the observed than those of Model A during calibration period in the short terms runoff. 5. Daily simulated hydrographs of Model B are seemed to be closer to the daily observed than those of Model A during verification period in the long terms runoff. Significance of Model B was highly acknowledged in comparison with Model A in the correlation analysis between annual observed and annual simulated runoff. 6. Reproducibility of simulated flows for Model B is generally seemed to be better than that of Model A during calibration period in the short terms runoff. 7. It can be concluded that reproducibility of Model B is superior to that of Model A in the long and short terms runoff even a large watershed like the result of the small one. 8. It was verified that adaptability for the large watershed of Model B is superior to that of Model A between the two models which were developed by a small watershed characteristics for both long and short terms runoff. 9. Further study for getting a suitable tank model is desirable to be established by the decision, calibration method of initial parameters of tank model and by additional application of another watershed with different watersheds and meterological characteristics.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.15 no.2
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• pp.1149-1156
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• 2014

In order to reduce flood damages, there should demand an appropriate design such as enlarging a bank, dredging a river bottom, building a hydraulic structure and so on. The installation locations about the Watergate are listed of the seven provisions in the river design standard, but it is not detailed. In order to compute proper place considering landuse and basin characteristics of inlands, internal inundation modeling that should be performed is regarded with quantitative evaluation. Anyway, that is very complex and taking a long time because that has to consider hydraulic and hydrologic characteristics. In the current study, therefore, the simple and convenient method for internal inundation modeling was proposed to overview the Watergate location.

• Journal of Soil and Groundwater Environment
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• v.7 no.1
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• pp.3-14
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• 2002

We analyzed hydrologic time-series data obtained from a fractured aquifer in Wonju and a porous shallow aquifer in Uiwang area. Auto-correlation, spectral density, and cross-correlation functions were used for the analyses. Water level at a shallow well in Wonju was weakly auto-correlated and it was sensitive to direct infiltration from rainfall through soil zone while that at a well screened in the fractured zone showed a relative stability to an outer stress (rainfall), which was derived from a delayed transmission of recharge stress through a fracture network from a remote area. Characteristics of time-series data in Uiwang area were similar to those in the fractured zone in Wonju. This was caused by a regional recharge from a distant area rather than a direct infiltration. This study demonstrated a usefulness of time series analyses for identification of recharge mechanism.

• Korean Journal of Remote Sensing
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• v.18 no.1
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• pp.1-12
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• 2002

Landslide prediction modeling has been regarded as one of the important environmental applications in GIS. While, landslide stability in a certain area as collateral process for prediction modeling can be characterized by DEM-based hydrological features such as flow-direction, flow-accumulation, flow-length, wetness index, and so forth. In this study, Slope-Area plot methodology followed by stability index mapping with these hydrological variables is firstly performed for stability analysis with actual landslide occurrences at Boeun area, Korea, and then Landslide prediction modeling based on likelihood ratio model for landslide potential mapping is carried out; in addition, KOMPSAT EOC imagery is used to detect the locations and scalped scale of Landslide occurrences. These two tasks are independently processed for preparation of unbiased criteria, and then results of those are qualitatively compared. As results of this case study, land stability analysis based on DEM-based hydrological variables directly reflects terrain characteristics; however, the results in the form of land stability map by landslide prediction model are not fully matched with those of hydrologic landslide analysis due to the heuristic scheme based on location of existed landslide occurrences within prediction approach, especially zones of not-investigated occurrences. Therefore, it is expected that the resets on the space-robustness of landslide prediction models in conjunction with DEM-based landslide stability analysis can be effectively utilized to search out unrevealed or hidden landslide occurrences.

• 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 regional geographers
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• v.4 no.1
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• pp.121-134
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• 1998

In this study, the satellite images and the GIS technique are used to select the basin characteristics parameters as the basis of water resources management of river basin. The study area is Geum-ho river basin and the hydrologic characteristics data are computed through the database of the basin characteristics parameters classified by subjects with 35 maps correspond to the study basin of 1:25,000 scale as the basic map. As the result, the drawing up of land use map through satellite image processing that provides the quantitative informations for the land is very efficient to analysis the extensive land use information of the basin, and exact analysis of mass surface data is possible and the feasibility of statistic computation between spatial subjects as it superpose on other subject map is ascertained. It is thought also that the analysis of the basin characteristics data can be utilized very effectively for the basin management and the analysis of basin surface area, once it is expressed numerically for database, since the superposition analysis with different subject map and the correlative analysis with the property data are possible although the tracing process of each subject in the basic map is not efficient. Especially, modification and renewal of the data for the change of land surface become easy, therefore more rapid and exact selection of the basin characteristics data and the construction of more efficient basin management plan are possible.

• Proceedings of the Korean Society of Soil and Groundwater Environment Conference
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• 2004.04a
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• pp.472-472
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• 2004

Numerous studies on urban groundwater have been carried out in many other countries. Urban groundwater shows a unique hydrologic system because of complex urban characteristics such as road pavement, sewers and public water supply systems. These urban facilities may change the characteristics of groundwater recharge but contaminate its quality as well. There have been several researches on urban groundwater in Seoul. Seoul has been industrialized very rapidly so that the city has large population. The recent population in Seoul amounts to more than ten millions, corresponding to a very high density of about 17, 000 people/km$^2$. Therefore, many factors affect the groundwater quality and quantity in Seoul. Nowadays, groundwater in Seoul is being extracted for construction, industrial use, and drinking and so on. There are 15, 714 wells in Seoul and its annual usage is 41, 425, 977m$^3$(in 2001). Therefore, systematic studies are needed to properly manage and use the groundwater in Seoul. The purposes of this study in progress are to identify geochemical characteristics of groundwater in Seoul and to determine the extent of groundwater contamination and its relationship with urban characteristics. For this study, groundwater was sampled from more than 400 preexisting wells that were randomly selected throughout the Seoul area. For all samples, major cations together with Si, Al, Fe, Pb, Hg For 200 samples among them, TCE, PCE, BTEX were also analyzed by GC. Our study shows that groundwater types of Seoul are distributed broadly from Ca-HCO$_3$ type to Ca-Cl＋NO$_3$ type. The latter type indicates anthropogenic contamination. Among cations, Ca is generally high in most samples. In some samples, Na and K are dominant. The dominant anions change widely from HCO$_3$ to Cl＋NO$_3$. The anion composition is considered to effectively indicate the contribution of distinct anthropogenic sources. In addition, major ions are positively proportional to total dissolved solid (TDS) except K and NO$_3$. Thus, we consider that TDS may be used as an effective indicator of the extent of pollution. However, the increase of TDS may result from increased water-rock interaction. To determine the extent of groundwater contamination, it is needed to figure out the baseline water quality in Seoul. Furthermore, detailed geochemical studies are required to find out pollution sources and their corresponding hydrochemical parameters.