Jeong-Kon Kim

Assessment of Riverine Health Condition and Estimation of Optimal Ecological Flowrate Considering Fish Habitat in downstream of Yongdam Dam

금강수계중 용담댐하류 앞섬 지점에서 생태유량을 산정하기 위한 생태 모니터링을 실시하여 어류종별 서식환경 특성조사를 포괄적으로 실시하였다. 이를 바탕으로 어류상, 상대풍부도 및 생물다양도 분석 등을 포함한 하천의 건강성 평가를 실시하고, 쉬리, 피라미 및 감돌고기 등에 대하여 작성한 서식처적합도 지수(HSI)...

Impacts of GIS data quality on determination of runoff and suspended sediments in the Imha watershed in Korea

Excessive soil loss during heavy rainfall results in serious turbid water problem in the reservoir. For the purpose of efficient turbid water management in the upland area of the Imha watershed in Korea, this study applied SWAT (Soil and Water Assessment Tools) for assessment of the soil erosion and attempted to evaluate the impact of GIS data on model response to test the model efficiency. First, the outputs of runoff and suspended sediment were investigated corresponding to the various DEM grid sizes (i.e., 30, 60, 90, 120, and 150 m). Further analysis was based on the 8 different scenarios combining with different scales of land use (i.e., 1:25,000 and 1:50,000) and soil type maps (i.e., 1:50,000 and 1:250,000) associated with two different DEM grid sizes. Statistical analysis of the simulated results revealed that model efficiency improved with 30 m resolution DEMs for estimation of runoff and suspended sediment. However, no significant improvement was expected associated with detailed scales of land cover and soil maps. The findings of this study will contribute to select the quality of GIS data, with no expense of the accuracy of model prediction to simulate runoff and suspended sediments.

Multi-variable and Multi-site Calibration and Validation of SWAT for the Gap River Catchment

Hydrological models with many parameters and complex model structures require a powerful and detailed model calibration/validation scheme. In this study, we proposed a multi-variable and multi-site calibration and validation framework for the Soil Water Assessment Tool (SWAT) model applied in the Gap-cheon catchment located downstream of the Geum river basin. The sensitivity analysis conducted before main calibration helped understand various hydrological processes and the characteristics of subcatchments by identifying sensitive parameters in the model. In addition, the model`s parameters were estimated based on existing data prior to calibration in order to increase the validity of model. The Nash-Sutcliffe coefficients and correlation coefficient were used to estimate compare model output with the observed streamflow data: ranged 0.41-0.84 and 0.5-0.86, respectively, at the Heuduck station. Model reproduced baseflow estimated using recursive digital filter except for 2-5% overestimation at the Sindae and Boksu stations. Model also reproduced the temporal variability and fluctuation magnitude of observed groundwater levels with of 0.71 except for certain periods. Therefore, it was concluded that the use of multi-variable and multi-site method provided high confidence for the structure and estimated parameter values of the model.

Evaluation of eco-hydrological changes in the Geum River considering dam operations: II. Hydraulic fish habitat condition analysis.

A quantitative analysis was conducted to study the impacts of artificial flow alteration on fish habitate condition change in the Geum River downstream the Daechung Multi-purpose Dam (DMD). River Analysis Package (RAP) was employed for the analysis and three fish species of black shiner, long nose barbel and Korean shinner were selected as icon species. The results of the analysis showed enhaced fish habitat conditions during low flow seasons in spring and fall after DMD construction, while the impact of the Youngdam Multipurpose Dam located upstream the DMD was insignificant. This result could be attributed to the fact that the increased flow during dry seasons helped create preferable habitat conditions for the fish species tested in this study.

Evaluation of Urbanization Effect and Analysis of Hydrological Characteristics in the Gap River Catchment using SWAT

Hydrological characteristics and urbanization effects in the Gap river catchment were investigated employing the SWAT model. The hydrological characteristics analysis showed that total runoff in the whole catchment from 2001 to 2004 consists of 44% of groundwater flow, 6% of lateral flow and 50% of surface flow under year 2000 landuse conditions. The analysis of urbanization effect using different landuse maps for year 1975 and 2000 indicated that although 5% increase in urbanized areas did not significantly impact on the total runoff in the whole catchment, a sub-basin where urbanized area increased by 32% over the past 30 years showed decrease in groundwater flow and increase in surface flow. It was found that urbanization decreased overall soil moisture and percolation rate except for some increase in soil moisture during dry season. Urbanization effect was found more sensitive during a dry year which has less rainfall and higher evapotranspiration than during a wet year. Therefore, from the results of this study we could infer increased flood damage during wet season and dried stream during dry season due to urbanization. To conclude, the results of this study can provide fundamental information to the eco-friendly restoration project for the three major rivers (Gap-cheon, Yudeung-cheon and Daejeon-cheon) in Daejeon Metropolitan City.

Improvement of Mid/Long-Term ESP Scheme Using Probabilistic Weather Forecasting

In hydrology, it is appropriate to use probabilistic method for forecasting mid/long term streamflow due to the uncertainty of input data. Through this study, it is expanded mid/long term forecasting system more effectively adding priory process function based on PDF-ratio method to the RRFS-ESP system for Guem River Basin. For implementing this purpose, weight is estimated using probabilistic weather forecasting information from KMA. Based on these results, ESP probability is updated per scenario. Through the estimated result per method, the average forecast score using ESP method is higher than that of naive forecasting and it confirmed that ESP method results in appropriate score for RRFS-ESP system. It is also shown that the score of ESP method applying revised inflow scenario using probabilistic weather forecasting is higher than that of ESP method. As a results, it will be improved the accuracy of forecasting using probabilistic weather forecasting.

Evaluation of Groundwater Flow for the Kap-cheon Basin

Groundwater flow in a basin is greatly affected by many hydrogeological and hydrological characteristics of the basin. A groundwater flow model for the Kap-cheon basin (

Evaluation of Spatio-Temporal Water Shortage in Sapgyo Catchment Employing Total Water Right Survey and Water Balance Analysis

area

Assessment of hydraulic fish habitat condition using integrated toolkit: a case study of the Geum river basin, Republic of Korea

The objective of this study was to evaluate spatio-temporal water shortage distribution in the Sapgyo catchment considering both permitted and non-permitted water rights obtained from the total water right survey conducted in 2010. The results showed that the agricultural water accounted for 98% of the total water uses with 83% being the non-permitted agricultural water uses. During the 11-year (2001~2011) simulation period, water shortage was shown only in the upper Gokgyo stream sub-catchment with the highest water stress from April to May in 2009, particularly because of the large demand for rice cultivation associated with low precipitation. As water shortage was not expected to happen when the permitted water rights were not considered, it was concluded that a proper management of non-permitted water rights would be urgent.

Development of Downstream Turbid Water Management System Using SWAT and KoRiv1 Dynamic Water Quality Simulation Model

Artificial changes of rivers, including construction and operation of dams, inevitably lead to physical and ecological changes throughout waterways and their floodplains. In this study, a conceptual model coupled with integrated numerical modeling is presented for hydraulic fish habitat assessment of the Geum River basin, Republic of Korea. Based on the major events which might have affected the ecological system, a conceptual model was formulated to guide desktop and field studies, modeling and scenario evaluations. The result of hydraulic fish habitat assessment indicated that the construction of the Daecheong Multipurpose Dam (DMD) in the Geum River basin has altered flow magnitudes and reduced the rivers flow variability. Changes are evident in the magnitude of medium and small flows and the river experiences increased low flows during the dry season. Black shiner, an endangered fish species in Korea, was selected and analyzed to explore relationships between flow regime change by dams and changes to its preferred habitats. As a result, fewer sensitive riffle-benthic species were observed in the reaches downstream of DMD due to the reduction of suitable habitat conditions such as riffle-pool sequences. The proposed conceptual model and integrated toolkit would allow river managers to isolate the physical and biological effects associated with dam operation and could be useful for developing river management strategies.