• Journal of Wetlands Research
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• v.26 no.2
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• pp.147-159
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• 2024

Lack of streamflow observations makes model calibration difficult and limits model performance improvement. Satellite-based remote sensing products offer a new alternative as they can be actively utilized to obtain hydrological data. Recently, several studies have shown that artificial intelligence-based solutions are more appropriate than traditional conceptual and physical models. In this study, a data-driven approach combining various recurrent neural networks and decision tree-based algorithms is proposed, and the utilization of satellite remote sensing information for AI training is investigated. The satellite imagery used in this study is from MODIS and SMAP. The proposed approach is validated using publicly available data from 25 watersheds. Inspired by the traditional regionalization approach, a strategy is adopted to learn one data-driven model by integrating data from all basins, and the potential of the proposed approach is evaluated by using a leave-one-out cross-validation regionalization setting to predict streamflow from different basins with one model. The GRU + Light GBM model was found to be a suitable model combination for target basins and showed good streamflow prediction performance in ungauged basins (The average model efficiency coefficient for predicting daily streamflow in 25 ungauged basins is 0.7187) except for the period when streamflow is very small. The influence of satellite remote sensing information was found to be up to 10%, with the additional application of satellite information having a greater impact on streamflow prediction during low or dry seasons than during wet or normal seasons.

• Economic and Environmental Geology
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• v.49 no.6
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• pp.433-444
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• 2016

The U-Pb ages of detrital zircons from the Baengnyeong Group were determined by LA-MC-ICPMS, yielding condensed age population in the range from 1100 Ma to 1800 Ma corresponding to the Mesoproterozoic to late Paleoproterozoic. However, detrital zircons of ca.1800-2000 Ma or ca. 2500 Ma ages, which appear frequently in the lower Paleozoic Joseon Supergroup and the upper Paleozoic Pyeongan Supergroup are lacking in the Baengnyeong Group. Such characteristics are identical to those of the Neoproterozoic Sangwon System of North Korea, suggesting that the Baengnyeong Group might be the southwestern extension of the Sangwon System. The zircon age distribution patterns from the Impi Formation in the Gunsan area closely resemble those of the Baengnyeong Group, implying possible correlation of the Impi Formation to the Sangwon System. Therefore, the Mesoproterozoic detrital zircons reported from the Hwangangni Formation of the Okcheon Metamorphic Belt and the Myobong, Sambangsan and Sesong Formations of the Taebaeksan Basin might be derived from the provenances within the Korean peninsula.

• Journal of Korea Water Resources Association
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• v.53 no.4
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• pp.285-291
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• 2020

The Noah 3.3 Land Surface Model (LSM) was used to estimate the global soil moisture in this study and these soil moisture datasets were assessed against satellite-based and reanalysis soil moisture products. The Noah 3.3 LSM simulated soil moistures in four soil layers and root-zone soil moistures defined as a depth-weighted average in the first three soil layers (i.e., up to 1.0 m deep). The Noah LSM soil moisture products were then compared with a satellite-based soil moisture dataset (European Space Agency Climate Change Initiatives (ESA CCI) SM v04.4) and reanalysis soil moisture datasets (ERA-interim). In addition, the five major basins (Yangtze, Mekong, Mississippi, Murray-Darling, Amazon) were selected for the assesment with the Gravity Recovery and Climate Experiment (GRACE)-based Total Water Storage Anomaly (TWSA) and TWS Change (TWSC). The results revealed that high anomaly correlations were found in most of the Asia-Pacific regions including East Asia, South Asia, Australia, and Noth and South America. While the anomaly correlations in the Murray-Darling basin were somewhat low, relatively higher anomaly correlations in the other basins were found. It is concluded that this study can be useful for the development of soil moisture based drought indices and subsequently can be helpful to reduce damages from drought by timely providing an efficacious strategy.

• Journal of Ecology and Environment
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• v.48 no.3
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• pp.233-246
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• 2024

Background: In this research work, epilithic communities of diatoms in macrophytes are listed and described to evaluate the ecological conditions of the surface waters of the Chipoco River, whose basin has been exploited for agricultural and mining purposes, degrading natural ecosystems. The diatoms studied are found in calcareous tufa deposits developed in swampy environments where little of their benthic microbiota has been studied, despite the regional relevance of these calcareous formations within the manganese mining district. To describe the diatoms and evaluate the ecological condition of the surface waters, the Chipoco River was divided into three sectors (North, Center, and South) collecting a total of 15 samples along 10 km. For the taxonomic identification of diatoms, scanning electron microscopy techniques, consultations with specialists and specialized literature were used. To evaluate the ecological conditions of the Chipoco River, the linear correlation coefficient was used, where the relationships between diatom species and environmental variables were evaluated. Likewise, species diversity was determined by applying the Shannon-Wiener index and Simpson's dominance value (D) was calculated to detect diversity impoverishment processes. Results: Ten genera of diatoms were identified in bryophytes of the species Plagiomnium cuspidatum that grow on the banks of said river. The linear correlation coefficient indicated that physicochemical characteristics such as total dissolved solids, temperature, and calcium, and hydrochemical characteristics of the water intervene in the distribution and abundance of four diatoms Rhoicosphenia abreviate, Epithemia turgida, Calloneis bacillum and Achanthidium minutissimum in the different sectors studied. The Shannon-Wiener diversity indices and Simpson's dominance show that there is greater diversity and marked dominance of diatoms in the northern sector compared to the central and southern sectors. Conclusions: Agricultural and mining activities and the poor sanitary infrastructure of human settlements have caused the Chipoco River to have poor ecological quality.

• Economic and Environmental Geology
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• v.47 no.5
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• pp.533-540
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• 2014

The Wangdol-cho area, in the Hupo Bank, plays a very important role in main fishing grounds, leisure tourism and marine environmental researches of the East Sea. We analyzed the detailed bathymetry and classified the seabed characteristics of the Wangdol-cho area, based on seafloor backscattering images and sediment grain size. The Hupo Bank is developed in parallel with the eastern coastal line of Korean peninsula, and the shallowest area (Wangdol-cho) of the Hupo Bank is located along the eastern part of Hupo Port. The Wangdol-cho comprises three summits; north summit, middle summit, and south summit. The middle summit area among the three summits has the most shallow water depth with minimum about 6 m. The north summit shows about 8 m minimum depth and the south summit about 9 m. The bathymetry data around three summits represent undulating seabeds with many scattered underwater reefs and shallow water depth. The area between the underwater reefs, the flat seafloor in the northeastern part of the survey site, and the western steep slope area have relatively coarse sediments such as sandy gravel and gravelly sand. The bathymetry in the western side of the Wangdol-cho shows steep slope seabed, extending to the Hupo Basin. Fine sediments including mud and silty sand occur in the Hupo Basin area of the survey site. The submarine detailed topography and the analysis of the seafloor characteristics of the survey area are expected to contribute to management for marine environmental researches and sustainable use of ecosystems in the Wangdol-cho.

• Journal of Korea Water Resources Association
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• v.41 no.1
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• pp.1-15
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• 2008

The purpose of this study is to propose a procedure that will be able to find the most efficient sets of weight coefficients for the Geum-River basin in Korea. The result obtained from multi-objective optimization model is inherently sensitive to the weight coefficient on each objective. In multi-objective reservoir operation problems, the coefficient setting may be more complicated because of the natural variation of inflow. Therefore, for multi-objective reservoir operation problems, it may be important for modelers to provide reservoir operators with appropriate sets of weight coefficients considering the inflow variation. This study presents a procedure to find an appropriate set of weight coefficients under the situation that has inflow variation. The proposed procedure uses GA-CoMOM to provide a set of weight coefficient sets. A DEA-window analysis and a cross efficiency analysis are then performed in order to evaluate and rank the sets of weight coefficients for various inflow scenarios. This proposed procedure might be able to find the most efficient sets of weight coefficients for the Geum-River basin in Korea.

• Journal of Korea Water Resources Association
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• v.45 no.8
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• pp.839-851
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• 2012

When we evaluate the water supply capacity of a river basin, it is a common practice to gradually increase the water demand and check if the water demands are met. This practice is not only used in the simulation approach, but also in the optimization approach. However, this trial and error approach is a tedious task. Hence, we propose a two-phase method. In the first phase, by assuming that the decision maker has complete information on inflow data, we use a goal programming model that can generate the maximum water supply capacity at one time. In the second phase, we simulate the real-time operation for the critical period by utilizing the water supply capacity given by the goal programming model under the condition that there is no foresight of inflow. We applied the two-phase method to the Geum-River basin, where multi-purpose weirs were newly constructed. By comparing the results of the goal programming model with those of the real-time simulation model we could comprehend and estimate the effect of perfect inflow data on the water supply capacity.

• Journal of Korea Water Resources Association
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• v.44 no.7
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• pp.565-576
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• 2011

Within a basin, there are potentially multiple locations that can be used as a washland, given their relatively small size when compared with other hydraulic facilities such a dam. However, it is unreasonable to install washlands in all these potential locations due to economic and environmental considerations. In this study, a new methodology for determination of installation priority of washlands is presented. How to integrate the decision variables in this decision making problem has been a key issue in previous studies because a washland can provide many benefits such as flood reduction, agricultural benefit and recreational benefit. In particular, a methodology is needed to integrate all decision variables realistically, properly and reasonably, in situations where there is not sufficient data for direct integration of all these decision variables such as construction cost or benefits a washland can provide. This new methodology aims to suggest how to integrate methodologies used in previous studies. The suggested methodology uses four different rankings which are determined based on a flood reduction effect, a relative significance index, an economic analysis, and a space planning suitability index. These rankings are integrated to determine a final installation priority ranking of washlands by a multi-dimensional scaling method. The new methodology has been applied to the Anseong river basin, to show its applicability, and the application result compared with those of previous studies.

• Journal of Korea Water Resources Association
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• v.49 no.5
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• pp.361-372
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• 2016

Reliable long-term dam inflow prediction is necessary for efficient multi-purpose dam operation in changing climate. Since 2000s the teleconnection between global climate indices (e.g., ENSO) and local hydroclimate regimes have been widely recognized throughout the world. To date many hydrologists focus on predicting future hydrologic conditions using lag teleconnection between streamflow and climate indices. This study investigated the utility of teleconneciton for predicting dam inflow with 1-month lead time at Andong dam basin. To this end 40 global climate indices from NOAA were employed to identify potential predictors of dam inflow, areal averaged precipitation, temperature of Andong dam basin. This study compared three different approaches; 1) dam inflow prediction using SWAT model based on teleconneciton-based precipitation and temperature forecast (SWAT-Forecasted), 2) dam inflow prediction using teleconneciton between dam inflow and climate indices (CIR-Forecasted), and 3) dam inflow prediction based on the rank of current observation in the historical dam inflow (Rank-Observed). Our results demonstrated that CIR-Forecasted showed better predictability than the other approaches, except in December. This is because uncertainties attributed to temporal downscaling from monthly to daily for precipitation and temperature forecasts and hydrologic modeling using SWAT can be ignored from dam inflow forecast through CIR-Forecasted approach. This study indicates that 1-month lead dam inflow forecast based on teleconneciton could provide useful information on Andong dam operation.

• Journal of Korea Water Resources Association
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• v.49 no.1
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• pp.1-9
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• 2016

A correlation analysis between raw water turbidity at two wide-area water treatment plants and hydrological data was conducted for efficient water supply, design and management of water treatment plant. Both correlation analysis and principal component analysis were conducted using hydrological time series data such as inflow discharge, outflow discharge, and rainfall at dam basin of intake station of wide-area water treatment plants. And, forecasting of change in turbidity was conducted using regression equation for turbidity prediction. The raw water turbidity of two water treatment plants was strongly related to time series of discharge. The raw water turbidity of Chungju water treatment plant is strongly related to outflow discharge at Chungju dam (0.708). Whereas, the raw water turbidity of Wabu water treatment plant is strongly related to inflow discharge at Paldang dam (0.805). Similar trends between turbidity forecasting result using regression equation and calculation result using estimation equation on Korea water supply facilities standard were obtained. The result of this study can provide basic data for construction and management of water treatment plant.