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Yanggu, South Korea

Kang M.G.,Future Resources Institute | Park S.W.,Seoul National University
Environmental Management | Year: 2015

The aim of this study was to assess the states of watersheds in South Korea and to formulate new measures to improve identified inadequacies. The study focused on the watersheds of the Han River basin and adopted an adaptive watershed management framework. Using data collected during watershed investigation projects, we analyzed the management context of the study basin and identified weaknesses in water use management, flood management, and environmental and ecosystems management in the watersheds. In addition, we conducted an interview survey to obtain experts’ opinions on the possible management of watersheds in the future. The results of the assessment show that effective management of the Han River basin requires adaptive watershed management, which includes stakeholders’ participation and social learning. Urbanization was the key variable in watershed management of the study basin. The results provide strong guidance for future watershed management and suggest that nonstructural measures are preferred to improve the states of the watersheds and that consistent implementation of the measures can lead to successful watershed management. The results also reveal that governance is essential for adaptive watershed management in the study basin. A special ordinance is necessary to establish governance and aid social learning. Based on the findings, a management process is proposed to support new watershed management practices. The results will be of use to policy makers and practitioners who can implement the measures recommended here in the early stages of adaptive watershed management in the Han River basin. The measures can also be applied to other river basins. © 2015, Springer Science+Business Media New York. Source

Kang M.G.,Future Resources Institute | Park S.W.,Seoul National University
Journal of Irrigation and Drainage Engineering | Year: 2014

This paper presents a combined simulation-optimization model for simulating reservoir operations without any detailed operation rules; it features the integration of a nonlinear, multiple-objective function and a heuristic search method, the Shuffled Complex Evolution method, developed at the University of Arizona. The model is applied to optimal water allocations from both Balan Reservoir and Seomjingang Dam in South Korea, an irrigation reservoir and a multipurpose, multioutlet reservoir, respectively, that primarily supply irrigation water. In the case of the optimal operation of Balan Reservoir, the simulation results show that the optimal release patterns are similar to those of historical operations because the demands for irrigation water are accurately predicted and guide optimal reservoir operations. In addition, the model is successfully applied to establishing a long-term reservoir operation plan. As for the optimal operation of Seomjingang Dam, the reservoir operations are affected by the target water stages, and the model provides reasonable results, irrespective of inflow conditions. Moreover, the model is employed to create a new operation rule that is necessary to adapt to changes in the circumstances related to water management. Consequently, it is concluded that the model is useful for assessing reservoirs irrigation water supply capacities when establishing operation plans and providing feasible alternatives for new operation rules, and it could be applied to real-time reservoir operations. © 2014 American Society of Civil Engineers. Source

Kang M.G.,Future Resources Institute | Maeng S.J.,Chungbuk National University
Journal of Irrigation and Drainage Engineering | Year: 2016

This study presents two gray models with which to forecast groundwater levels at two study sites; one is located on an island area, and one is in an inland area. These models used the moving average of daily infiltration depth, historical groundwater level, and water demand from irrigated paddy-field districts as variables, taking into account the characteristics of the sites. For the site on an island area, the sea water surface level was additionally used as one of the variables. The model parameters were estimated by integrating the models with a global search method, the annealing-simplex method. The comparisons between the observed values and the forecasts in calibration and validation show that the forecasts are in close agreement with the observations. The sensitivity analyses of the models revealed that the variable for water demand affects the groundwater levels, depending on irrigation practices, and that the variable for sea water surface level is one of the factors affecting groundwater discharges. In comparing the predictive capabilities of the models with those of the other gray models, it was proved that the models have appropriate variables for forecasting groundwater levels with 1-10 days of lead time. Moreover, the accuracies of the models are higher than those of the base models. Finally, these results demonstrate that the models are slightly superior to other models and can reasonably forecast groundwater levels and the effects of groundwater pumping on groundwater states in real situations. © 2015 American Society of Civil Engineers. Source

Kang M.,Future Resources Institute | Park S.,Seoul National University
Agricultural Water Management | Year: 2014

A water flows network modeling system was constructed to quantify water flows in the Balan Watershed, South Korea, which has two serial irrigation reservoirs. A modified version of the Synthetic Streamflow and Reservoir Regulation (SSARR) model was used to simulate the water flows, taking into account irrigation return flows and reservoir operations. The model parameters were calibrated using a heuristic search method, Shuffled Complex Evolution method developed at the University of Arizona (SCE-UA). The simulated streamflows and reservoir water levels were in good agreement with the observed. The irrigation return flows from paddy fields considerably affected the flow regimes of the streams. Specifically, the return flow rates of the irrigation water ranged from 28.0% to 35.0%. In addition, the water supply capacities of the irrigation reservoirs were evaluated using the modeling system, and joint operation rules were assessed. The results showed that these could have negative influences on the water supply of existing irrigation districts, and the potential effects of these rules on water management should be investigated. The modeling system is useful for identifying the states of water flows in multiple irrigation reservoir systems and for providing information about reservoir operations to water managers and stakeholders. © 2014 Elsevier B.V. Source

Kang M.G.,Future Resources Institute | Jeong H.S.,Iowa State University | Lee J.H.,Joongbu University | Kang B.S.,Dankook University
Water Policy | Year: 2013

This paper presents a prototype framework for sustainable flood management at the national level which features stakeholder participation, and is modified and applied to a case study. Through literature reviews and an interview survey of South Korea (the case study country), the causes of recent flood damage are found to be heavy rainfall due to climate change, urbanization, insufficient channel capacities and the application of inadequate measures. The interview survey also shows that, to reduce flood damage, along with consistent implementation of systematic long-term plans, minimizing injudicious artificial development is critical and necessary. Using the framework developed for South Korea on the basis of the findings and the prototype framework, national flood management is assessed and discussed. In particular, an implementation process based on flood risk management and integrated strategies is proposed to practically achieve the objectives of management practices with the cooperation of governmental organizations and stakeholders under circumstances of high uncertainty. Consequently, it is concluded that the effective conduct of sustainable flood management at the national level in South Korea requires a recognition of the context of flood management, cooperation and information sharing about flooding, and social learning and change, all of which can be achieved through the active participation of stakeholders. © IWA Publishing 2013. Source

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