• Journal of Wetlands Research
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• v.20 no.4
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• pp.398-409
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• 2018

Organic farming practices including loach based ecosystem-farming have been demonstrated to be effective in conjunction with rice farming to increase yield and quality. This new form of farming combines agriculture and fishery and is quickly developing into a new industry. The current study investigated the effect of rice-fish mixed farming system on the vegetation-diversity function. Vegetation within the four study sites was surveyed and analyzed based on plant taxonomy. The vegetation survey demonstrated that 127 taxa of 38 families, 100 genera, 107 species, and 20 varieties occurred within the study sites. A total of 15 plant species taxa occurred in the rice-fish mixed paddy fields with a fish habitat and did not occur in the conventional paddy field lacking fish habitat. This difference is thought to arise from differences in moisture requirements for vegetation. Life form analysis demonstrated differences in hemicryptophytes, therophytes, and hydrophytes according to fish habitat. The naturalized plants identified were also determined to be species widely distributed throughout Korea. Frequency analysis demonstrated that the rice-fish mixed paddy fields with a fish habitat had a high ratio of both obligate and facultative wetland plants relative to the conventional paddy field. Based on the study results, it is likely that vegetation-diversity will increase with environment diversity. However, no statistical significance was observed according to paddy types. Future research should aim to identify additional environmental factors, including the existence of fish habitat, habitat area, depth of fish habitat, hydrological parameters, water quality, and paddy soil environment, to enhance vegetation-diversity and biocultural diversity.

• Journal of Wetlands Research
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• v.16 no.1
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• pp.19-32
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• 2014

The purpose of this paper is to obtain reliable rainfall data for runoff simulation and other hydrological analysis by the calibration of gauge rainfall. The calibrated gauge rainfall could be close to the actual value with rainfall on the ground. In order to analyze the wind effect of ground rain gauge, we selected the rain gauge sites with and without a windshield and standard rain gauge data from Chupungryeong weather station installed by standard of WMO. Simple linear regression model and artificial neural networks were used for the calibration of rainfalls, and we verified the reliability of the calibrated rainfalls through the runoff analysis using $Vflo^{TM}$. Rainfall calibrated by linear regression is higher amount of rainfall in 5%~18% than actual rainfall, and the wind remarkably affects the rainfall amount in the range of wind speed of 1.6~3.3m/s. It is hard to apply the linear regression model over 5.5m/s wind speed, because there is an insufficient wind speed data over 5.5m/s and there are also some outliers. On the other hand, rainfall calibrated by neural networks is estimated lower rainfall amount in 10~20% than actual rainfall. The results of the statistical evaluations are that neural networks model is more suitable for relatively big standard deviation and average rainfall. However, the linear regression model shows more suitable for extreme values. For getting more reliable rainfall data, we may need to select the suitable model for rainfall calibration. We expect the reliable hydrologic analysis could be performed by applying the calibration method suggested in this research.

• Journal of Wetlands Research
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• v.13 no.3
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• pp.547-565
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• 2011

Different types of schemes have been used in stage prediction involving conceptual and physical models. Nevertheless, none of these schemes can be considered as a single superior model. To overcome disadvantages of existing physics based rainfall-runoff models for stage predicting because of the complexity of the hydrological process, recently the data-derived models has been widely adopted for predicting flood stage. The objective of this study is to evaluate model performance for stage prediction of the Neuro-Fuzzy and regression analysis stage prediction models in these data-derived methods. The proposed models are applied to the Wangsukcheon in Han river watershed. To evaluate the performance of the proposed models, fours statistical indices were used, namely; Root mean square error(RMSE), Nash Sutcliffe efficiency coefficient(NSEC), mean absolute error(MAE), adjusted coefficient of determination($R^{*2}$). The results show that the Neuro-Fuzzy stage prediction model can carry out the river flood stage prediction more accurately than the regression analysis stage prediction model. This study can greatly contribute to the construction of a high accuracy flood information system that secure lead time in medium and small streams.

• Journal of Wetlands Research
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• v.15 no.4
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• pp.585-593
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• 2013

This study aims to investigate inundation characteristics such as inundated area, inundation depth according to variation in return period of design rainfall and to draw a comparison between the inundation characteristics by adapting design storm using dual-drainage model. Lidar data is used to construct terrain data with $1m{\times}1m$ resolution in Cheongju. The designed storm by return periods(10year, 30year, 50year and 200year) are acquired from Intensity Duration Frequency curve, which are distributed in 5 minutes interval using Huff's method. As a results, the inundation volume is linearly increased, but inundated area is gradually increased in accordance with swell of return period for design storm. On the other hands, as a result of calculating discharge capacity for each points, deficit of discharge capacity is not observed using designed storm of 10 year return period at every points. If the return period is increased up more than 10 years, both the deficit of discharge capacity for each PT and entire study area are enlarged drastically.

• Journal of Wetlands Research
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• v.11 no.3
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• pp.161-169
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• 2009

Rainfall-runoff procedures of urban area are more complicated than agricultural procedures. Extension and development of town leads to shift of the basin characteristics and it makes more difficult to use runoff models. In this study, the changes of hydrologic circumstances and the shape of hydrograph due to the urbanization in Cho-kyung river basin has been assessed which is the representative urban stream in Jeonju city. The urbanization can be classified as four typical year. The natural basin period(1924) that is before the urban development, the period of construction of Chonbuk National University campus (1963), the period of construction of residential area(1986), and urbanization process has been finally completed in 1995. The rainfall-runoff analysis has been carried out by Storm Water Management Model(SWMM) under condition of the basin characteristics and impervious area of each period. It was found that hydrologic characteristics such as river length, roughness coefficient, and coefficient of surface storage has been decreased. According to the land use change, the pervious area was decreased from 97.7% to 42%, while the impervious area was increased from 0.6% to 34%. The time of concentration was shorten from 90 minutes to 37 minutes. Along with decreasing the time of concentration, the peak discharge was increased from $4.37m^3/s$ to $111.13m^3/s$, and the runoff rate was also increased from 0.8% to 68%.

• Journal of Wetlands Research
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• v.18 no.2
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• pp.194-200
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• 2016

The impervious surface rate increased by urbanization causes various problems on the environment such as water cycle distortion, heat island effect, and non-point pollutant discharges. The Low Impact Development (LID) techniques are significantly considered as an important tool for stormwater management in urban areas and development projects. The main mechanisms of LID technologies are hydrological and environmental pollution reduction among soils, media, microorganisms, and plants. Especially, the media provides important functions on permeability and retention rate of stormwater runoff in LID facilities. Therefore, this research was performed to assess the pollutant removal efficiency for different types of media such as zeolite, wood chip, bottom ash, and bio-ceramic. All media show high pollutant removal efficiency of more than 60% for particulate materials and heavy metals. Double layered media is more effective in reducing heavy metals by providing diverse sizes of micro-pores and macro-pores compared to the single layered media. The results recommend the use of different sizes of media application is more cost-effective in LID than a single size of media. Furthermore, soluble proportion of total heavy metal in the stormwater is an important component in proper media selection and arrangement.

• Journal of Wetlands Research
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• v.18 no.2
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• pp.183-193
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• 2016

In this study, design and performance of infiltration trench using woodchip as media for treating stormwater from highway were examined through field monitoring. Average reduction efficiency for TSS, COD, BOD, TN, and TP was 88%, 94%, 85%, 80%, and 75% respectively, which is similar to values reported by other studies and design manuals even though direct comparison is not possible due to different monitoring and design conditions. Mean field infiltration rate estimated by measuring the change of water depth inside the observation well was about 40mm/hr, and the time taken for complete infiltration was about 0.83days, which corresponds well with design criteria recommended by MOE guidelines in Korea. In addition, according to analysis of infiltration rate and reduction efficiency, effective rainfall depth applied for determining water quality volume(WQv), 5mm was found to be properly established as design criteria. Woodchip must be considered and included as an alternative media together with crushed rock and gravel into the design guidelines because it has more advantages in terms of weight, porosity, cost, and easiness of management than other media materials.

• Journal of Wetlands Research
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• v.14 no.4
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• pp.519-535
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• 2012

In order to establish a rainfall-runoff model, calibration of hydrological parameters for the model is very important. Especially, Curve Number(CN), estimated by NRCS method, is a main factor to apply unit hydrograph theory to calculation of peak discharge. For using NRCS method, it is needed selecting AMC because CN is strongly connected with that. In this study, we focus our concern on finding a applicable standard for selecting AMC for CN. For this, three dams which are Boryeong, Habchon, Namgang are selected as target basins to use observed data including rainfall and dam inflow. As a result of this research, it is found that CN must be included as a calibrated parameter to calculate effective rainfall for the rainfall-runoff model. Also, it is preferred to use PWRMSE of HEC-HMS program as a objective function for optimizing hydrological parameters. From the analyzing result of variation of AMC for peak discharge, it is recommended to apply AMC-III to estimation of CN for calculating effective rainfall of design hydrograph.

• Journal of Wetlands Research
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• v.13 no.2
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• pp.329-341
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• 2011

This study was conducted with the national river, Munsancheon, which is located in Paju-si, Gyeonggi-do. The sediment discharge of Munsancheon was directly measured to analyze the sediment characteristics, and the results were used in the numerical model to predict the long-term river bed variation. The flow-total sediment discharge relation was derived using the measured total sediment discharge, and the results were compared with the total sediment discharge that was calculated using the existing prediction formula to derive a proper sediment discharge prediction method. In the actual measurements, the total annual sediment discharge was 5,478 ton/year, and the specific sediment discharge was 29.23 ton/$km^2$/year. The Ackers & White formula resulted in the values very close to the actual measurements. With the actual sediment discharge, geographical and hydrologic data as the input variables, HEC-6 and GSTARS models were comparatively analyzed. The test results showed that the HEC-6 model is suitable for the reliable prediction of the long-term river bed variation. Accordingly, the model was used for the long-term river bed variation prediction in this study. In the case of Munsancheon, deposition was continued in the downstream area and erosion occurred in the upstream area on the whole. It was expected that the stream would be stabilized in the river bed condition of 20 years later. The river bed variation was within 1 m, which was at the significance level. In the downstream area that is influenced by tide, however, the accumulation was continuously increasing within the section 2,000-7,000 m from the outlet. It seems that this should be considered in establishing the river management plans.

• Journal of Wetlands Research
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• v.16 no.1
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• pp.1-10
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• 2014

The research grasps water quality contamination source by investigating the data that are superordinate laws and the related plans implemented for establishing water quality improvement measures of upper stream for Chung-Ju Dam, present conditions of the hydraulic and hydrology, the present conditions and plans of environment basic facilities, and present conditions of main contamination source's occurrence load and discharge load, etc. The research used the QUAL2E simulation which is being widely applied to simulation of river water quality because the QUAL2E has high credibility among water quality simulations known throughout the country. On basis of this research, regulations and politic alternatives are required in order to water quality improvement upper stream for the Chung-ju dam, especially establishing processing facilities in the region where loading amount is concentrated should be considered with the additional research regarding cost-efficient facility of pollution source.