• Journal of Korea Water Resources Association
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• v.38 no.7 s.156
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• pp.517-526
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• 2005

In Korea, the methods of estimating groundwater recharge can categorized into two groups. One is baseflow separation method by means of groundurater recession curve, the other is water level fluctuation method by using the data from groundwater monitoring wells. Baseflow separation method is based on annual recharge and lumped concept, and water-table fluctuation method is largely dependent on monitoring wells rather than water budget in watershed. However, groundwater recharge rate shows the spatial-temporal variability due to climatic condition, land use and hydrogeological heterogeneity, these methods have various limits to deal with these characteristics. For this purpose, the method of estimating daily recharge rate with spatial variability based on distributed rainfall-runoff model is suggested in this study. Instead of representative recharge rate of large watershed, the subdivided recharge rate with heterogeneous characteristics can be computed in daily base. The estimated daily recharge rate is an advanced quantity reflecting the heterogeneity of hydrogeology, climatic condition, land use as well as physical behaviour of water in soil layers. Therefore, the newly suggested method could be expected to enhance existing methods.

• Journal of the Korean Association of Geographic Information Studies
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• v.10 no.1
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• pp.10-21
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• 2007

The Doam-dam watershed, located at Kangwon Province, Korea, has been experiencing significant changes in land uses, conversion from forest to agricultural/urban areas, with human involvements. However, no thorough investigation of the landscape impacts of land use changes was performed at this watershed using the scientific analytical tool. Thus, the FRAGSTATS model was utilized to quantitatively analyze the landscape impacts of forest fragmentation in this study. To provide the detailed explanations for 11 landscape indices considered in this study, two artificial and simplified landscapes, before and after fragmentations, were constructed. Using these 11 indices, the landscape impacts of forest fragmentation in 19 subwatersheds of the Doam-dam watershed were analyzed. The S1 subwatershed, one of 19 subwatersheds of the Doam-dam watershed, was found to have experienced the significant forest fragmentation from 1985 to 2000 based on landscape analysis using the FRAGSTATS model. The results obtained in this study can be used to evaluate the water quality impacts of forest fragmentations/land use changes at watershed scale level, and establish environment-friendly land use planning based on the results obtained using landscape analytical tool, FRAGSTATS.

• Journal of Korean Society on Water Environment
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• v.25 no.3
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• pp.441-451
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• 2009

To evaluate the soil erosion best management practices, many computer models has been utilized over the years. Among those, the USLE and SWAT models have been widely used. These models estimate the soil erosion from the field using empirically-based USLE/MULSE in it. However, these models are not good enough to estimate soil erosion from highland agricultural watershed where severe storm events are causing soil erosion and muddy water issues at the receiving watersheds. Thus, physically-based WEPP watershed version was applied to a watershed, located at Jawoon-ri, Gangwon with very detailed rainfall data, rather than daily rainfall data. Then it was validated with measured sediment data collected at the sediment settling ponds and through overland flow. In this study, very detailed rainfall data, crop management data, soil data reflecting soil reconditioned for higher crop production were used in the WEPP runs. The $R^2$ and the EI for runoff comparisons were 0.88 and 0.91, respectively. For sediment comparisons, the $R^2$ and the EI values were 0.95 and 0.91. Since the WEPP provides higher accuracies in predicting runoff and sediment yield from the study watershed, various slope scenarios (2%, 3%, 5.5%, 8%, 10%, 13%, 15%, 18%, 20%, 23%, 25%, 28%, 30%) were made and simulated sediment yield values were analyzed to develop appropriate soil erosion management practices. It was found that soil erosion increase linearly with increase in slope of the field in the watershed. However, the soil erosion increases dramatically with the slope of 20% or greater. Therefore special care should be taken for the agricultural field with slope greater than 20%. As shown in this study, the WEPP watershed version is suitable model to predict soil erosion where torrential rainfall events are causing significant amount of soil loss from the field and it can also be used to develop site-specific best management practices.

• Journal of Korea Water Resources Association
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• v.49 no.8
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• pp.673-683
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• 2016

An Idea to estimate flexible criteria for river water use permits was proposed that takes the spatio-temporal flow variation along the river into account, which was applied to the Keumho River, one of the tributary of the Nakdong River in Korea. This idea implies the temporal division of four periods with different criteria, combining flood/non-flood seasons and irrigation/non-irrigation periods, while a single one has been applied throughout the year in the current practice. Through flow regime analysis of daily natural flow simulations at Dongchon and Seongseo, the control points of the study area, Q355 and 1Q10 for non-flood and non-irrigation period, Q275 for non-flood and irrigation period, Q185 for flood and irrigation period were suggested respectively. So, those values that subtract instream flow were determined as the flexible criteria in each season. From the comparison of current practice and the proposed method, it was estimated that $10.6\;million\;m^3/year$ is available for more water use permits without additional development of water storage. Therefore, it is conceived that flexible criteria for river water use permission suggested in this study can contribute to improve the national policies for more efficient water resources management in the future.

• Journal of The Korean Society of Agricultural Engineers
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• v.62 no.5
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• pp.105-119
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• 2020

Although there have been a lot of efforts to improve water quality in the estuarine reservoir, overall the water quality problems of the estuarine reservoirs remain. So, it is essential to establish water quality management plans under a comprehensive understanding of the environmental characteristics of the estuarine reservoir. Therefore, in this study, a resilience analysis framework for evaluating the estuarine reservoir's water quality was suggested for improving existing assessment method for water quality management plan. First, as a result of analyzing the static resilience to each scenario, it was found that from the S3 scenario in which dredging was conducted considerably, the resilience of about 30% more than the current estuarine reservoir system was restored. Second, as a result of analyzing the dynamic resilience, if cost and time are considered, there is no significant difference in robustness and resourcefulness, so it can be seen that the resilience of the estuarine reservoir can be efficiently improved by simply performing dredging up to the level of Scenario 3. Finally, as a result of comparing static and dynamic resilience, since static resilience is only presented as a single value, the differences and characteristics of the resilience capacity of the estuarine reservoir might be overlooked only by the static resilience analysis. However, in the aspect that it is possible to interpret the internal recovery capacity of the estuarine reservoir in multiple ways with various indicators (robustness, redundancy, resourcefulness, rapidity), evaluating water quality based on dynamic resilience analysis is useful.

• Journal of Korean Society for Geospatial Information Science
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• v.22 no.3
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• pp.11-19
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• 2014

This study is analyze future climate and land cover change affects behaviors for amount of streamflow and sediment discharge within basin. We used the climate forecast data in RCP 4.5 and 8.5 (2011-2100) which is opposite view for each other among RCP scenarios that are discussed for 5th report for IPCC. Land cover map built based on a social economic storyline in RCP 4.5/8.5 using Logistic Regression model. In this study we set three scenarios: one scenario for climate change only, one for land cover change only, one for Last both climate change and land cover change. It simulated amount of streamflow and sediment discharge and the result showed a very definite change in the seasonal variation both of them. For climate change, spring and winter increased the amount of streamflow while summer and fall decreased them. Sediment showed the same pattern of change steamflow. Land cover change increases the amount of streamflow while it decreases the amount of sediment discharge, which is believed to be caused by increase of impervious Surface due to urbanization. Although land cover change less affects the amount of streamflow than climate change, it may maximize problems related to the amount of streamflow caused by climate change. Therefore, it's required to address potential influence from climate change for effective water resource management and prepare suitable measurement for water resource.

• Journal of Wetlands Research
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• v.16 no.2
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• pp.173-185
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• 2014

Climate change has caused detrimental phenomena such as heavy rainfall which could aggravate soil erosion. Accordingly, it is needed to evaluate the groundwater recharge, baseflow, and soil erosion for the efficient management of water resources and quality. In this study, future climate change scenarios were applied to the H aean-myeon watershed which is a steep sloping watershed in South Korea to analyze groundwater recharge, baseflow, sediment. Also, the variation of groundwater recharge, baseflow, sediment was analyzed according to the change of slope (5 %). Simulated periods were divided into three terms (2013 ~ 2040 years, 2041 ~ 2070 years, 2071 ~ 2100 years). As a result of this study, average groundwater recharge and baseflow increased by 50 %, 42 %, and sediment decreased by 72 %, respectively. In these regards, the suggested method will positively contribute to hydro-ecosystem and reduction of muddy water at a steep sloping watershed.

• Proceedings of the Korea Water Resources Association Conference
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• 2010.05a
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• pp.273-277
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• 2010

This research was performed to examine changes in the timing of the growth of crops along with changes in temperatures due tochanges and to analyze the change of water-supply-reliability by adding an analysis of the change of agricultural water supply patterns in the basin area of Miryang dam in Korea. Had-CM3 model from U.K. was the tool adopted for the GCM model, a stochastic, daily-meteorology-generation-model called LARS-WG was alsoused for downscaling and for the climate change scenario (A1B) which represents Korea's circumstances best. First of all, to calculate changes in the timing of the growth of crops during this period, the theory of GDD was applied. Except for the period of transplanting and irrigation, there was no choice but to find the proper accumulated temperature by comparing actual temperature data and the supply pattern of agricultural use due to limited temperature data. As a result, proper temperatures were found for each period. $400^{\circ}C$ for the preparation period of a nursery bed, $704^{\circ}C$ for a nursery bed's period, $1,295^{\circ}C$ for the rice-transplanting period, $1,744^{\circ}C$ for starting irrigation, and $3,972^{\circ}C$ for finishing irrigation. To analyze future agricultural supply patter changes, the A1B scenario of Had-CM3 model was adopted, and then Downscaling was conducted adopting LARS-WG. To conduct a stochastical analysis of LARS-WG, climate scenarios were generated for the periods 2011~2030, 2046~2065, 2080~2099 using the data of precipitation andMax/Min temperatures collected from the Miryang gauging station. Upon reviewing the result of the analysis of accumulated temperatures from 2011~2030, the supply of agricultural water was 10 days earlier, and in the next periods-2046~2065, 2080~2099 it also was 10 days earlier. With these results, it is assumed that the supply of agricultural water should be about 1 month ahead of the existing schedule to meet the proper growth conditions of crops. From the results of the agricultural water supply patterns should be altered, but the reliability of water supply becomes more favorable, which is caused from the high precipitation change. Furthermore, since the unique characteristics of precipitation in Korea, which has high precipitation in the summer, water-supply-reliability has a pattern that the precipitation in September could significantly affect the chances of drought the following winter and spring. It could be more risky to make changes to the constant supply pattern under these conditions due to the high uncertainty of future precipitation. Although, several researches have been conducted concerning climate changes, in the field of water-industry, those researches have been solely dependent on precipitation. Even so, with the high uncertainty of precipitation, it is difficult for it to be reflected in government policy. Therefore, research in the field of water-supply-patterns or evapotranspiration according to the temperature or other diverse effects, which has higher reliability on anticipation, could obtain more reliable results in the future and that could result in water-resource maintenance to be safer and a more advantageous environment.

• Korean Security Journal
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• no.45
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• pp.161-189
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• 2015

As the terrorist act inflicted on the American Ambassador to Korea, Mark Lippert on March 5, 2015, the hunting rifle case in Sejong-si in which 3 persons were killed on February 25, and the hunting rifle murder case in Hwaseong-si Namyang-dong on February 27 occurred in succession, there is growing concern that our country is no long safe from firearm violence. Internationally, there is growing concern that our country is no longer safe from international terrorist organizations such as Islamic State (IS), the Sunni Muslims fundamentalists' Islamic militia group, which an 18-year old Korean boy Kim voluntarily joined in January 2015. The police crisis negotiation of our country was established and operated to prepare for the 1988 Olympic Games mainly for counter-terrorism purposes, and due to the characteristics of the prohibition of the use of guns, not a counter-terrorism incident has occurred, so the skepticism about its existence and the development directions are actively being discussed. Our country still prefers the traditional use of force such as SWAT team to resolve crisis case, such as such as murder, terrorism, robbery, and is reinforcing tactical capabilities. However, to perform the primary mission of the police to protect the people's lives and properties, it is necessary to establish the system in which crisis negotiations are possible in the initial stages no matter what incidents may occur by expanding the education for crisis negotiations techniques which are emphasized in the advanced countries such as the United States. In this research, the police department's internal education materials and media are analyzed so that the new police officers who work hardest on the forefront can carry out the roles as basic negotiators of crisis negotiations, and the measures for the development directions of the police crisis negotiations are presented.

• Proceedings of the Korea Water Resources Association Conference
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• 2015.05a
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• pp.238-238
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• 2015

There are demands for water environmental analysis of discharge processes in paddy fields, however, it is not fully understood in nutrients discharge process for watershed modeling. As hydrological processes both surface and ground water and agricultural water managements are so complex in paddy fields, the development of lowland paddy fields watershed model is more difficult than upland watershed model. In this research, the improvement of SWAT (Soil and Water Assessment Tool) model for a paddy watershed was conducted. First, modification of surface inundated process was developed in improved pot hole option. Those modification was evaluated by monitoring data. Second, the monitoring data in river and drainage channel in lowland paddy fields from 2012 to 2014 were analyzed to understand discharge characteristics. As a case study, Imbanuma basin, Japan, was chosen as typical land and water use in Asian countries. In this basin, lowland paddy fields are irrigated from river water using small pumps that were located in distribution within the watershed. Daily hydrological fluctuation was too complex to estimate. Then, to understand surface and ground water discharge characteristics in irrigation (Apr-Aug) and non-irrigation (Sep-Mar) period, the water and material balance analysis was conducted. The analysis was composed two parts, watershed and river channel blocks. As results of model simulation, output was satisfactory in NSE, but uncertainty was large. It would be coming from discharge process in return water. The river water and ground water in paddy fields were exchanged each other in 5.7% and 10.8% to river discharge in irrigation and non-irrigation periods, respectively. Through this exchange, nutrient loads were exchanged between river and paddy fields components. It suggested that discharge from paddy fields was not only responded to rainfall but dynamically related with river water table. In general, hydrological models is assumed that a discharge process is one way from watershed to river. However, in lowland paddy fields, discharge process is dynamically changed. This function of paddy fields showed that flood was mitigated and temporally held as storage in ground water. Then, it showed that water quality was changed in mitigated function in the water exchange process in lowland paddy fields. In future, it was expected that hydrological models for lowland paddy fields would be developed with this mitigation function.