• Magazine of the Korean Society of Agricultural Engineers
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• v.45 no.4
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• pp.66-77
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• 2003

Monitoring data from agricultural reservoirs throughout the country were analyzed to classify agricultural reservoirs according to physical characteristics and COD concentrations, and evaluate the relationships bet-ween water quality items. The physical and chemical data of total 498 reservoirs were analyzed from 1990 to 2001. Average COD, TP, TN, Chl-a, SS concentrations for the reservoirs and pollutant loadings from their watersheds were used for the analysis. It was possible that reservoirs were classified to 4 types using the relationships between the ratios of effective storage per water surface (ST/WS ratio) and COD concentrations. It is recommended that the improvement measures of polluted reservoirs should be performed as following order : integrated consolidation type (complex mechanism type) $\rightarrow$ watershed consolidation type $\rightarrow$ integrated consolidation type (external mechanism type) $\rightarrow$ in-lake consolidation type $\rightarrow$ conservation type and the depth (ST/WS ratio) of reservoir maintained over 5~6 m for water quality improvement. The decision coefficients ($r^2$) between Chl-a and other items (COD, T-P, SS, T-N) were 0.6915, 0.6732, 0.5327, 0.3352, respectively. Therefore, reservoir managers could evaluate the trophic state of reservoirs by COD concentrations.

• Magazine of the Korean Society of Agricultural Engineers
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• v.43 no.4
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• pp.37-49
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• 2001

This study was performed in order to produce the basic data for developing prediction techniques of desalinization to be applicable to reclaimed tidal lands at the beginning stage. the desalinization experiments were carried out by two water management practices, namely, the leaching method by subsurface drainage and the rinsing method by surface drainage. The 5 soil samples used in this study were collected in 4 tidal land reclamation projects. Regression equations were obtained in order to investigate the changes of electrical conductivity during the desalinization of reclaimed tidal lands and to estimate water requirements for desalinization. The results obtained from this study were summarized as follows: 1. According to USDA Salinity Laboratory classification system of salt affected soils the reclaimed tidal land soils used in this study were saline-sodic soils with the high electrical conductivity and the high exchangeable sodium percentage. 2. With the increase of the water requirements for desalinization the electrical conductivity was decreased with high degree of correlationships and the desalinization effects were remakable in both the leaching method and the rinsing method. 3. In case of the leaching method the electrical conductivity had been reduced below the classification value of salt affected soils when the depth o water leached per unit depth of soil (Dwl/Ds) was 0.3 and the desalinization effects showed a tendency to be much the same in each treatment.

• Journal of Korea Water Resources Association
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• v.51 no.12
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• pp.1261-1271
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• 2018

This study evaluates the applicability of the classification rule of hydrological soil group proposed by Lee et al. (2018) with its application to three river basins (Jungmuncheon, Cheonmicheon, and Hancheon) in Jeju Island. The CN values are estimated as results of this application to these three basins, which is then compared with those estimated by applying the conventional three methods. Additionally, previous studies related with the classification of soil groups of Jesu Island, such as the infiltration and rainfall-runoff analysis, are reviewed to evaluate how the resulting hydrological soil groups vary depending on the adopted classification method.. Summarizing the results is as follows. (1) Comparison result of the hydrological soil groups of Jeju Island with respect to the classification method shows that the soil group B is dominant in the application of Lee et al. (2018). However, it is hydrological soil groups C and D in the application of Hu and Jung (1987), hydrological soil groups A and C in the application of Jung et al. (1995), and hydrological soil group D in the application of RDA (2007). (2) In all the applications of Lee et al. (2018) to three selected river basins in Jeju Island, the CN valuse are found to be smaller than those by other conventional three methods.. Lastly, (3) The evaluation results of previous studies related with the classification of hydrological soil groups analysis in Jeju Island shows that the CN value in the Jeju Island may be smaller than those estimated by conventional three methods, also the initial loss higher than 0.2S.

• Journal of Korea Water Resources Association
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• v.36 no.6
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• pp.985-997
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• 2003

The objective of this study is to propose Runoff Curve Numbers(CNs) for land cover and treatment classification of satellite image. For this purpose, land cover classifications by using satellite image in addition to the exiting SCS's land cover and treatment classifications studies and land cover classifications suggested by Ministry of Environment are selected to provide CNs depending on the classifications. CNs estimation method is statistical approach that is suggested by Hjelmfelt(1991). Result of this study may contribute to use efficiently for the estimation of CNs in using satellite image.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.10 no.7
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• pp.1668-1672
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• 2009

In this study, the method by Robertson which has been most commonly used for classifying soils, using piezocone test results, was compared with that by Schneider which was most recently proposed. Both methods were applied to the soils in Gyeonggi province and the classifying results were investigated. It has been found that the difference between the results according to the methods was not so large and Schneider's method showed slightly better results for clay region and vice versa. Such factors as large field database, normalized tip resistance, pore water pressure, and drain condition were found to need further research for more reliable soil classification.

• Communications for Statistical Applications and Methods
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• v.31 no.3
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• pp.309-322
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• 2024

Identifying algae in water is important for managing algal blooms which have great impact on drinking water supply systems. There have been various microscopic approaches developed for algae classification. Many of them are based on the morphological features of algae. However, there have seldom been mathematical frameworks for comparing the shape of algae, represented as a planar continuous curve obtained from an image. In this work, we describe a recent framework for computing shape distance between two different algae based on the elastic metric and a novel functional representation called the square root velocity function (SRVF). We further introduce statistical procedures for multiple shapes of algae including computing the sample mean, the sample covariance, and performing the principal component analysis (PCA). Based on the shape distance, we classify six algal species in watersheds experiencing algal blooms, including three cyanobacteria (Microcystis, Oscillatoria, and Anabaena), two diatoms (Fragilaria and Synedra), and one green algae (Pediastrum). We provide and compare the classification performance of various distance-based and model-based methods. We additionally compare elastic shape distance to non-elastic distance using the nearest neighbor classifiers.

• Journal of Environmental Impact Assessment
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• v.27 no.6
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• pp.704-716
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• 2018

The aim of this study is to examine the characteristics analysis of the discharge and water quality based on TPLMS (Total Pollution Load Management System) in the Jinwi River unit basin, and to propose a management plan by selecting the point that needs improvement of water quality in order to achieve the target water quality. We evaluated the discharge and water quality characteristics, statistical analysis, daily delivery load and daily delivery density, grade classification, for 14 total pollution load site's from 2014 to 2016 year in Jinwi river unit basin. The average discharge of Jinwi river unit basin is $22.411m^3/s$ and discharge of Hwangguji River is 32.8% and the water quality characteristics along the tributary river were clarified spatially. As the result, it was analyzed that Seongeun River is an indirect indicator of organic pollutants, Gwanri River is a seasonal factor, Osan River and Hwangguji River both affect water quality. Estimation of delivered pollutant loads at the HG-3 site was 6,470.4 BOD kg/day, 6,846.7 TN kg/day and delivered pollutant loads density increased to $220.9BOD\;kg/day/km^2$, $22.4TP\;kg/day/km^2$ at the HG-4 site. This result demonstrates that the total pollution load site needed to improve water quality of the Jinwi River unit basin was HG-3 site.

• Environmental and Resource Economics Review
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• v.17 no.4
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• pp.875-901
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• 2008

This article estimates the economic values of changes in water quality of the Paldang Watershed by using the Choice Experiment (CE). The conditional logit model estimation results show that a small improvement in water quality from the 'status quo' level to the level of 'very good' increases average household's monthly utility by 3,157 Won, whereas a water quality degradation down to the 'normal' level gives rise to an increase in the monthly average utility by 9,649 Won. The corresponding social gain and loss of water quality changes to the Metropolitan Area were thus estimated about 285 billion Won and 872 billion Won, respectively. This article seems meaningful in that it resorts to the new water ecosystem classification criteria and indices that are respondent-friendly. They help a CE study like this to overcome one of its critical weakness that the number and contents of attributes of a CE study can quickly add to the information overload problem, especially where the environmental good under investigation is hard for ordinary respondents to understand.

• Journal of Environmental Science International
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• v.25 no.6
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• pp.767-787
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• 2016

In this study, we analyzed on-site monitoring data for 15 tributaries in Geumho watersheds for 3 years (2011-2013) in order to sort out priorities on water quality characteristics and improvement. As a result of estimating contribution to contamination of the tributary rivers, Dalseocheon showed the highest load densities, despite the smallest watershed area, with 22.7% $BOD_5$, 30.7% $COD_{Mn}$, 31.3% TOC and 47.6% TP. After conducting PCA (principal component analysis) and FA (factor analysis) to analyze water quality characteristics of the tributary rivers, the first factor was classified as $COD_{Mn}$, TOC, EC, TP and $BOD_5$, the second factor as pH, Chl-a and DO, the third factor as water temperature and TN, and the fourth factor as SS and surface flow. In addition, arithmetical sum of each factor's scores based on grading criteria revealed that Dalseocheon and Namcheon were classified into Group A for their highest scores - 96 and 93, respectively -, and selected as rivers that require water environmental management measures the most. Also, water environmental contamination inspection showed that Palgeocheon had the most number of aquatic factors to be controlled: $BOD_5$, $COD_{Mn}$, SS, TOC, T-P, Chl-a, etc.

• Journal of Environmental Impact Assessment
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• v.7 no.2
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• pp.103-112
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• 1998

Nature-friendly river project has became common practice in Japan. In order to make it available for the conservation and rehabilitation of desirable water environment, water criteria for water environmental assessment must be established. Especially, the criteria estimating the effects on ecosystem in and around river should be constructed. In this paper, classification method for water quality has been developed using biological indices and applied to observed data in Honmyo River, Nagasaki, Japan. Modified PI method (BI') has been suggested and those of three most abundant species resulted effective estimate for an overall water quality with comparatively simple procedure. Extensive database management code was prepared for the comprehensive ecological monitoring of river basin, which includes various biota. That system enables easy access of all the ecological data for a dissemination of a sound and sustainable water environment. The result of this study could improve knowledge base, serve making consensus for citizens, and help river management plans. In Japan, citizen's realization and action are the most critical factor for nature-friendly river restoration project.