• Journal of Korea Water Resources Association
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• v.43 no.6
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• pp.533-541
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• 2010

It is basic for a flood prediction to calculate direct runoff from rainfall in a basin by the rainfall-runoff model. The direct runoff is calculated from rainfall excess or effective rainfall based on a rainfall-runoff model. The total rainfall minus rainfall loss equals rainfall excess with time. This loss can be treated equal to an infiltration loss under the assumption that the infiltration is a major one among the losses in the rainfall-runoff model. Practically obtaining the infiltration loss $\Phi$ index method, W index method or modified ones of these have been used. In this study it is assumed the loss of rainfall in a basin be a well-known Horton infiltration mechanism. And in case that the parameter set is given in the Horton infiltration model a procedure and assumption for calculating hourly infiltration loss and rainfall excess are offered and the results of its application are compared with those of $\Phi$ index method. By this study it is well shown the value of Horton infiltration function is exponentially decay with time as the Horton infiltration mechanism.

• Korean Journal of Remote Sensing
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• v.31 no.4
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• pp.337-346
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• 2015

Water body extraction based on backscatter information is an essential process to analyze floodaffected areas from Synthetic Aperture Radar (SAR) image. Water body in SAR image tends to have low backscatter values due to homogeneous surface of water, while non-water body has higher backscatter values than water body. Non-water body, however, may also have low backscatter values in high resolution SAR image such as Kompsat-5 image, depending on surface characteristic of the ground. The objective of this paper is to present a method to increase backscatter contrast between water body and non-water body and also to remove efficiently misclassified pixels beyond true water body area. We create an entropy image using a Gray Level Co-occurrence Matrix (GLCM) and classify the entropy image into water body and non-water body pixels by thresholding of the entropy image. In order to reduce the effect of threshold value, we also propose Water Body Texture Index (WBTI), which measures simultaneously the occurrence of repeated water body pixel pair and the uniformity of water body in the binary entropy image. The proposed method produced high overall accuracy of 99.00% and Kappa coefficient of 90.38% in water body extraction using Kompsat-5 image. The accuracy analysis indicates that the proposed WBTI method is less affected by the choice of threshold value and successfully maintains high overall accuracy and Kappa coefficient in wide threshold range.

• Journal of Wetlands Research
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• v.13 no.3
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• pp.411-426
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• 2011

The construction of composite indicators should be normalized and weighted to render them comparable and evaluable variables in the field, which undergoes absence of a distinct methodology and where the application of universally popular method is common. Constructing of indices does not compare and analyze applying various normalizing and weighting, but constructer generally use chosen method and develops indicators and indices in most research. In this study, indices are applied various normalization and weighting methods, thereby analyzing how much impact the index and identifying individual characteristics derive a more reasonable way to help other research in the future. 5 different methods of normalization and 4 different types of weights were compared and analyzed. There are different results depending applied normalized methods and Z-score method best reflects the characteristics of the variables. According to weighting methods, the calculated results show little difference, but the ranking results of indices did not changed significantly. It might be better to provide constructors with a set of normalization and weighting methods to reflect their characteristics in order to build flood indices through the result of this study.

• Journal of Korea Water Resources Association
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• v.52 no.1
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• pp.83-96
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• 2019

In order to properly manage the river water use, it is necessary to collect reliable data of river water use. However, It is not easy to get credible river water use data in Korea because there are some difficultites in reporting and measuring river water use data. Thus, Han River Flood Control Office has installed and operated measuring facility using V-ADCP on the EOUBO intake open channel in the Gosan-Bongdong station section of the Mankyung river, where the use of agricultural water is large. In this study, the applicability of the V-ADCP velocity profile method was evaluated for real-time river water use. For this reason, the parameter sensitivity of Chiu's 2D velocity distribution equation was analyzed and the optimal parameters based on actual discharge data were calculated. In addition, the characteristics of the velocity profile method were analyzed by comparative evaluation of the rating curve method and the index velocity method.

• Journal of Korea Water Resources Association
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• v.47 no.5
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• pp.491-500
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• 2014

To estimate the severity of streamflow drought, this study introduced the concept of streamflow drought index based on threshold level method and Seomjingang Dam inflow was applied. Threshold levels used in this study are fixed, monthly and daily threshold, The $1^{st}{\sim}3^{rd}$ analysis results of annual drought, the severe hydrological droughts were occurred in 1984, 1988 and 1995 and the drought lasted for a long time. Annual compared to extreme values of total water deficit and duration, the drought occurred in 1984, 1988, 1995 and 2001 was serious level. In the results of study, because a fixed threshold level is not reflect seasonal variability, at least the threshold under seasonal level was required. Threshold levels determined by the monthly and daily were appropriate. The proposed methodology in this study can be used to forecast low-flow and determine reservoirs capacity.

• Journal of Korea Water Resources Association
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• v.39 no.2 s.163
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• pp.161-178
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• 2006

Heathcote (1998) identified a systematic, seven-step approach to general watershed planning and management. It consists of 1) understanding watershed components and processes, 2) identifying and ranking problems to be solved, 3) setting clear and specific goals, 4) developing a list of management options, 5) eliminating infeasible options 6) testing the effectiveness of remaining feasible options, and 7) developing the final options. In this study the first five steps of that process were applied to the Anyangcheon watershed in Korea, which experiences streamflow depletion, frequent flood damages, and poor water quality typical of highly urbanized watersheds. This study employed four indices: Potential Flood Damage(PFD), Potential Streamflow Depletion(PSD), Potential Water Quality Deterioration(PWQD) and Watershed Evaluation Index(WEI) to identify and quantify problems within the watershed. WEI is the integration index of the others. Composite programming which is a method of multi-criteria decision making is applied for the calculation of PSD, PWQD and WEI (Step 2). The primary goal of the study is to secure instreamflow in the Anyangcheon during dry seasons. The second management goals of flood damage mitigation and water quality enhancement are also set (Step 3). Management options include not only structural measures that can alter the existing conditions, but also nonstructural measures that rely on changes in human behavior or management practices (Step 4). Certain management options which are not technically, economically, and environmentally feasible, are eliminated (Step S). Therefore, this study addresses a Pre-feasibility study, which established a master plan using Steps 1 through 5.

• Magazine of the Korean Society of Agricultural Engineers
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• v.26 no.3
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• pp.35-45
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• 1984

Generally speaking, agriculture exist in a climatic environment of uncertainty. Namely, normal rainfall value, as given by the mean values, does not exist. Thought on exists, itl does not affect like extreme Precipitation value on the part of agriculture and of others. Therefore, it is important that we measure the duration and severity index of drought caused by extreme precipitation deficit. In this purpose, this study was dealt with the calculation of drought duration and severity indexs by the method of monthly weighting coefficient. There is no quantitive definition of drought that is universally acceptable. Most of the criteria was used to identify drought have been arbitrary because a drought is a 'non-event' as opposed to a distinct event such as a flood. Therefore, confusion arises when an attempt is made to define the drought phenomenon, the calculation of duration, drought index is based on the following four fundamental question, and this study was dealt with the answers of these four questions as they related to this analytical method, as follows. First, the primary interest in this study is to be the lack of precipitation as it relates to agricultural effective rainfall. Second, the time interval was used to be month in this analysis. Third, Drought event, distinguished analytically from other event, is noted by monthly weighting coefficient method based on monthly rainfall data. Fin-ally, the seven regions used in this study have continually affected by drought on account of their rainfall deficit. The result from this method was very similar to the previous papers studied by many workers. Therefore, I think that this method is very available in Korea to identify the duration of drought, the deficit of precipitation and severity index of drought, But according to the climate of Korea exist the Asia Monsoon zone. The monthly weighting coefficient is modify a little, Because get out of 0.1-0.4 occasionally.

• Journal of Korean Society of Rural Planning
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• v.20 no.2
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• pp.1-10
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• 2014

Smartphones change the picture of data and information sharing and make it possible to share various real-time flooding data and information. The vulnerability indicators of farmland inundation is needed to calculate the risk of farmland flood based on changeable hydro-meteorological data over time with morphologic characteristics of flood-damaged areas. To find related variables show the vulnerability of farmland inundation using the binary-logit model and correlation analysis and to provide vulnerability indicators were estimated by fuzzy set method. The outputs of vulnerability indicators were compared with the results of Monte Carlo simulation (MCS) for verification. From the result vulnerability indicators are applicable to mobile_based information system of farmland inundation.

• Proceedings of the Korea Water Resources Association Conference
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• 2022.05a
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• pp.149-149
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• 2022

Accurate quantitative evaluation of baseflow contribution to streamflow is imperative to address seasonal drought vulnerability, flood occurrence and groundwater management concerns for efficient and sustainable water resources management in watersheds. Several baseflow separation algorithms using recursive filters, graphical method and tracer or chemical balance have been developed but resulting baseflow outputs always show wide variations, thereby making it hard to determine best separation technique. Therefore, the current global shift towards implementation of artificial intelligence (AI) in water resources is employed to compare the performance of deep learning models with conventional hydrograph separation techniques to quantify baseflow contribution to streamflow of Piney River watershed, Tennessee from 2001-2021. Streamflow values are obtained from the USGS station 03602500 and modeled to generate values of Baseflow Index (BI) using Web-based Hydrograph Analysis (WHAT) model. Annual and seasonal baseflow outputs from the traditional separation techniques are compared with results of Long Short Term Memory (LSTM) and simple Gated Recurrent Unit (GRU) models. The GRU model gave optimal BFI values during the four seasons with average NSE = 0.98, KGE = 0.97, r = 0.89 and future baseflow volumes are predicted. AI offers easier and more accurate approach to groundwater management and surface runoff modeling to create effective water policy frameworks for disaster management.

• Journal of Climate Change Research
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• v.3 no.1
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• pp.25-37
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• 2012

This research proposes the direction for the assessment of local government infrastructure vulnerabilities relating to climate change driven flood and analyzes the assessment result. In this research, the local government infrastructures are evaluated by three indices such as exposure, infrastructure sensitivity, adaptive capacity and each index is calculated by selected alternative variable. Climate change scenario(A1B) developed on National Institute of Environmental Research is used to calculate present and future(2020, 2050, 2100s) exposure. As the result of infrastructure vulnerability assessment on present, the infrastructures in Seoul, Northern Gyeonggi-do, Gangwon-do, coastal area of Gyeongsangnam-do are vulnerable to flooding. For future, although the spatial pattern of flooding vulnerable infrastructure are similar, the flooding vulnerabilities of infrastructure in Gyeonggido and Ganwon-do would be increased as close to 2100s. It is expected that this research can be utilized as the preliminary analysis for climate change adaptation in local government infrastructure because this research propose the method for the assessment of local government infrastructure vulnerability relating to climate change driven flood and the result such as a trend of infrastructure vulnerability to flooding and the level of contribution of each index and alternative variable.