• The Journal of Engineering Geology
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• v.24 no.1
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• pp.91-98
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• 2014

This paper aims to calculate the increase in groundwater quantity following groundwater dam construction, and to assess its impact on surface water. In the study area of Osib-cheon, Yeongdeok, we estimated groundwater quantity, groundwater level, and effective porosity, and examined surface water fluctuations with respect to the increased groundwater quantity based on the flow duration. The results reveal that the increased groundwater quantity was at most $91,746m^3$ in the total drainage basin of the groundwater dam, and the reduced groundwater quantity was at most $11,259m^3$ in the lower zone of the groundwater dam. Therefore, the total groundwater resources secured was $80,487m^3$ and the decrease in groundwater quantity was just 12.27% of the amount of increase. There were changes in discharge rate by up to $3.00{\times}10^{-2}m^3/s$, as deduced from an analysis offlow duration as a result of groundwater dam construction. The overall difference between before and after construction of the dam was almost insignificant compared with the previous dam. The present results indicate that dammed groundwater can serve as an alternative water resource with sufficient quantity.

• Journal of Wetlands Research
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• v.25 no.1
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• pp.14-25
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• 2023

Floodplain in a reservoir is defined as the area naturally formed between the design flood level and the normal pool level. Located around the dam reservoir, floodplain has been damaged in many different ways including cultivation. As it is impossible to restore all the damaged floodplain at once, it is necessary to determine their order of priority. This process considers various factors, among which the flooding frequency is an important hydrologic characteristic, Different from the floodplains in a river, all the floodplains around the given dam reservoir have the same flooding frequency. To overcome this problem, this study proposes to use the cumulative flooding area curve, which represents the cumulative flooding area corresponding to the reservoir water level. Especially, this study evaluates the flooding frequency of those water levels corresponding to the cumulative flooding area of 30%, 50% and 70%. As application examples, this study considers the five restoration candidates each selected in the Andong Dam, Imha Dam, Youngju Dam and Nam river Dam of the Nakdong River Basin. As a result, the cumulative flooding area curve was found to well represent the overall shape of the floodplain (i.e., steep-to-mild slope or mild-to-steep slope). Also, the flooding frequency of those water levels corresponding to the cumulative flooding area of 30%, 50% and 70% was found to be so effective to quantify the hydrologic characteristics of a floodplain.

• Journal of Korea Water Resources Association
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• v.56 no.1
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• pp.11-21
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• 2023

This study suggests the drought resilience index as S-day as a means of preparing for the recent extreme drought, allowing for the actual operational identification of each drought countermeasure's priority as well as the vulnerability of water resource facilities to drought. Although each dam's drought measures are unique in this case, the representative examples include adjusting the water supply, linking the functioning of various facilities, and considering emergency capacity. Here, 15 multipurpose dams and water supply dams in Korea were inspected. Under the return period of 20-year drought, most of dams showed stable by adjusting the water supply overall. The measures, however, did not seem to be able to resist a multi-year drought lasting more than two years. Besides, Hoengseong and Anodong-Imha Dam only lasted a year under the 100-year drought return period with other measures. Without the deployment of drought mitigation strategies, it is expected that the Hoengseong Dam, Andong-Imha Dam, Gunwi Dam, Unmun Dam, Daecheong Dam, and Juam Dam would not be able to meet the all water demand for a year under the 20-year drought condition. The ideal capacity for each drought measure was then suggested. Additionally, by increasing or decreasing the current supply contract by 10% in order to account for demand changes resulting from socio-economic instability, the drought response capacity of all 15 dams was re-evaluated. By lowering the supply contract amount by 10%, it was possible to endure a severe drought.

• Water for future
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• v.35 no.5
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• pp.31-43
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• 2002

This study describes results of numerical simulations on river flow response due to global warming. Forecasts of changes in climatic conditions are required to estimate the hydrologic effects of increasing trace gas concentratrions in the atmosphere. However, reliable forecasts of regional climate change are unavailable. In there absense various approaches to the development of scenarios of furture climatic conditions are used. The approach in this study is to prescribe climatic changes for a river basin in a simplified manner. As a rule, such scenarios apecify air temperature increases from $0^{\circ}C$ to $4.0^{\circ}C$ and precipitation change (increase or decrease) in the range of 0% to 15%. On the basis of acceptable supposition of warming scenarios, furute daily stream flow is simulated using rainfall-runoff model in the Andong Dam basin. The numerical experiments have quantitatively revealed the change of discharge at 2010, 2020, 2030 and 1050 for each warming scenarios and compared it with the results for a non-worming scenario.

• Journal of Environmental Science International
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• v.16 no.5
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• pp.623-632
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• 2007

The objective of this study is analysis of Andong-Dam lake water quality with water quality model. Model parameters of the WASP applied to Lake Andong-Dam were estimated. The methodology is based on grouping water quality constituents and relevant parameters and successively estimating parameters by a trial-and-error procedure. Water qualify system for modeling consisted of BOD, DO, T-N, T-P. The results of water quality modelling using WASP. T-N was maximum affected by K71C(Organic nitrogen mineralization rate) parameter. T-P was maximum affected by K83C(Dissolved organic phosphorus mineralization) parameter, and It did not show a difference almost from the parameter of others and it omitted. BOD was maximum affected by Temperature parameter, it was visible of the reaction due to the KDC(Deoxygenation rate) in afterwords, and it did not show a difference from the parameter of others and it omitted. DO was maximum affect by Temperature parameter, and It did not show a difference almost from the parameter of others and it omitted. The parameter which it presumes from the this study uses a water quality modeling and Actual value and the result with which it compares, error rate the parameter presumption which is appropriate with 1% interior and exterior is investigated, It will reach and it uses and it will be able to apply to the suitable parameter in water quality modelling of the objective area which can be feeded by it becomes.

• Journal of the Korean Society of Hazard Mitigation
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• v.9 no.1
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• pp.123-133
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• 2009

In this study, we developed the GIS-based Geomorpho-hydrological Watershed Modeling System($G^{2}WMS$) which could consider both nonlilear rainfall-runoff relationship based on Geomorpho-Climatic Unit Hydrograph(GCUH) as well as watershed system inducing river routing. The developed new model was calibrated at the gaged rainfall events at natural watersheds and previewed to apply at the ungaged mountain basins, such as Sulma basin for small mountain basin and Andong-Dam basin for large scale basin, compared single with partitioned basin in the observed unit hydrographs and rainfall-discharge events. Finally, at the large scale Andong dam basin, we concluded that partitioned basin cases which including th nonlinear GCUH and river routing methods were superior to single basins which including the traditional methods in rainfall-discharge simulation at the mountain basins.

• Journal of Climate Change Research
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• v.8 no.2
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• pp.125-143
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• 2017

This study is conducted to estimate potential evapotranspiration of 10 weather observing systems in Andong Dam watershed with FAO56 Penman-Monteith (FAO56 PM) methodology using the meteorological data from 2013 to 2014. Also, assuming that there is no solar radiation data, humidity data or wind speed data, the potential evapotranspiration was estimated by FAO56 PM and the results were evaluated to discuss whether the methodology is applicable when meteorological dataset is not available. Then, the potential evapotranspiration was estimated with Hargreaves method and compared with the potential evapotranspiration estimated by FAO56 PM only with the temperature dataset. As to compare the potential evapotranspiration estimated from the complete meteorological dataset and that estimated from limited dataset, statistical analysis was performed using the Root Mean Square Error (RMSE), the Mean Bias Error (MBE), the Mean Absolute Error (MAE) and the coefficient of determination ($R^2$). Also the Inverse Distance Weighted (IDW) method was performed to conduct spatial analysis. From the result, even when the meteorological data is limited, FAO56 PM showed relatively high accuracy in calculating potential evapotranspiration by estimating the meteorological data.

• Journal of Korean Society on Water Environment
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• v.36 no.3
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• pp.229-244
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• 2020

Hydrologic models, as a useful tool for understanding the hydrologic phenomena in the watershed, have become more complex with the increase of computer performance. The hydrologic model, with complex configurations and powerful performance, facilitates a broader understanding of the effects of climate and soil in hydrologic partitioning. However, the more complex the model is, the more effort and time is required to drive the model, and the more parameters it uses, the less accessible to the user and less applicable to the ungauged watershed. Rather, a parsimonious hydrologic model may be effective in hydrologic modeling of the ungauged watershed. Thus, a semi-distributed hydrologic partitioning model was developed with minimal composition and number of parameters to improve applicability. In this study, the validity and performance of the proposed model were confirmed by applying it to the Namgang Dam, Andong Dam, Hapcheon Dam, and Milyang Dam watersheds among the Nakdong River watersheds. From the results of the application, it was confirmed that despite the simple model structure, the hydrologic partitioning process of the watershed can be modeled relatively well through three vertical layers comprising the surface layer, the soil layer, and the aquifer. Additionally, discussions were conducted on antecedent soil moisture conditions widely applied to stormwater estimation using the soil moisture data simulated by the proposed model.

• Spatial Information Research
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• v.9 no.1
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• pp.125-135
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• 2001

Ground failure such as landslide, rock fall land subsidence by heavy rainfall have damaged to people and property. Especially, the damage to important facility such as dam, bridge, tunnel and industrial complex may be possible. Therefore the ground failure must be assessed and counter plan must be prepared. So, the object of this study is to develop the spatial information system for regional ground stability assessment. For this, the topographic, geologic, soil, forest, land use, rainfall frequency map, and satellite image near 40 dams were collected and constructed to the spatial information system. The spatial information system was developed using Avenue in ArcView 3.2 environment and consists of pull down menus and icons. For application of the spatial information system, regional ground stability was assessed in Andong dam. The assessment was ground failure susceptibility and possibility. The spatial information can be used for regional ground stability assessment, prevention and mitigation of hazard, and management of ground as basic data.

• Journal of Korean Society on Water Environment
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• v.23 no.4
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• pp.467-473
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• 2007

Although the dominant land use at the Imha-dam watershed is forest areas, soil erosion has been increasing because of intensive agricultural activities performed at the fields located along the stream for easy-access to water supply and relatively favorable topography. In addition, steep topography at the Imha-dam watershed is also contributing increased soil erosion and sediment loads. At the Imha-dam watershed, outflow has increased sharply by the typhoons Rusa and Maemi in 2002, 2003 respectively. In this study, the Soil and Water Assessment Tool (SWAT) model was evaluated for simulation of flow and sediment behaviors with long-term temporal and spatial conditions. The precipitation data from eight precipitation observatories, located at Ilwol, Subi and etc., were used. There was no significant difference in monthly rainfall for 8 locations. However, there was slight differences in rainfall amounts and patterns in 2003 and 2004. The topographical map at 1:5000 scale from the National Geographic Information Institute was used to define watershed boundaries, the detailed soil map at 1:25,000 scale from the National Institute of Highland Agriculture and the land cover data from the Korea Institute of Water and Environment were used to simulate the hydrologic response and soil erosion and sediment behaviors. To evaluate hydrologic component of the SWAT model, calibration was performed for the period from Jan. 2002 to Dec. 2003, and validation for Jan. 2004 to Apr. 2005. The $R^2$ value and El value were 0.93 and 0.90 respectively for calibration period, and the $R^2$ value and El value for validation were 0.73 and 0.68 respectively. The $R^2$ value and El value of sediment yield data with the calibrated parameters was 0.89 and 0.84 respectively. The comparisons with the measured data showed that the SWAT model is applicable to simulate hydrology and sediment behaviors at Imha dam watershed. With proper representation of the Best Management Practices (BM Ps) in the SWAT model, the SWAT can be used for pre-evaluation of the cost-effective and sustainable soil erosion BMPs to solve sediment issues at the Imha-dam watershed. In Korea, the Universal Soil Loss Equation (USLE) has been used to estimate the soil loss for over 30 years. However, there are limitations in the field scale mdel, USLE when applied for watershed. Also, the soil loss changes temporarily and spatially, for example, the Imha-dam watershed. Thus, the SW AT model, capable of simulating hydrologic and soil erosion/sediment behaviors temporarily and spatially at watershed scale, should be used to solve the muddy water issues at the Imha-dam watershed to establish more effective muddy water reduction countermeasure.