Leakage in water distribution system causes social and economic losses by direct water loss into the ground, and additional energy demand for water supply. This research suggests a leak detection model of using adaptive Kalman filtering on real-time data of pipe flow. The proposed model takes into account hourly and daily variations of water demand. In addition, the model`s prediction accuracy is improved by automatically calibrating the covariance of noise through innovation sequence. The adaptive Kalman filtering shows more accurate result than the existing Kalman method for virtual sine flow data. Then, the model is applied to data from two real district metered area in JE city. It is expected that the proposed model can be an effective tool for operating water supply system through detecting burst leakage and abnormal water usage.

This study aims to develop a multiple criteria decision making (MCDM) approach for flood vulnerability assessment which considers uncertainty. The flood vulnerability assessment procedure consists of three steps: (1) use the Delphi process to determine the criteria and their corresponding weights-the adopted criteria represent the social, economic, and environmental circumstances related to floods, (2) construct a fuzzy data matrix for the flood vulnerability criteria using fuzzification and standardization, and (3) set priorities based on the number of assessed vulnerabilities. This study uses a modified fuzzy TOPSIS method based on -level sets which considers various uncertainties related to weight derivation and crisp data aggregation. Further, Spearman`s rank correlation analysis is used to compare the rankings obtained using the proposed method with those obtained using fuzzy TOPSIS with fuzzy data, TOPSIS, and WSM methods with crisp data. The fuzzy TOPSIS method based on -cut level sets is found to have a higher correlation rate than the other methods, and thus, it can reduce the difference of the rankings which uses crisp and fuzzy data. Thus, the proposed flood vulnerability assessment method can effectively support flood management policies.

This study attempts to estimate the benefits of environmentally-enhancing water ensuing from Sangkwan multi-purpose reservoir. To this end, we apply a survey technique, the contingent valuation (CV) method to elicit the public willingness to pay (WTP). Two CV surveys of randomly selected households were administrated to on-site and off-site areas. As it happens, a number of respondents reported zero WTPs for the environmentally- enhancing water. To deal with the zero WTPs, this study employs a spike model. The results show that average household`s WTP for the environmentally-enhancing water ensuing from Sangkwan multi-purpose reservoir is estimated to be 1,393.7 won for on-site area and 2,237.7 won for off-site area per year. The benefits of environmentally-enhancing water ensuing from Sangkwan multi-purpose reservoir amount to about 38.3 billion won per year. Our findings are expected to contribute to determining an appropriate level of investment and making management policies with regard to the benefits of environmentally-enhancing water.

There is imminent need to find a way to measure the recreational benefits of water so that appropriate actions can be taken to make a multi-purpose reservoir. Therefore, this study attempts to apply a choice experiment to quantifying the recreational benefits of a multi-purpose reservoir, using a specific case study of Sangkwan multi-purpose reservoir. We consider the trade-offs between price and attributes of recreational attributes for selecting a preferred alternative and derive the marginal willingness to pay (MWTP) estimate for each attribute. The results show that the MWTP for providing additional 10,000 ton of water is estimated to be 3 won per household per year. The MWTP for improving 1 level of water quality is computed to be 645.5 won per household per year. Moreover, the MWTP for providing recreation facilities is calculated to be 1,518.6 won per household per year. This study allows us to provide policy-makers with useful quantitative information that can reduce uncertainty in the decision-making process related to a multi-purpose reservoir construction projects.

The objective of this study was to evaluate spatio-temporal water shortage distribution in the Sapgyo catchment considering both permitted and non-permitted water rights obtained from the total water right survey conducted in 2010. The results showed that the agricultural water accounted for 98% of the total water uses with 83% being the non-permitted agricultural water uses. During the 11-year (2001~2011) simulation period, water shortage was shown only in the upper Gokgyo stream sub-catchment with the highest water stress from April to May in 2009, particularly because of the large demand for rice cultivation associated with low precipitation. As water shortage was not expected to happen when the permitted water rights were not considered, it was concluded that a proper management of non-permitted water rights would be urgent.

The purpose of this research is to develop an Integrated Water Resources Evaluation Index (IWREI) which can used to assess the performance of water resources projects in a regional perspective focusing on three major sectors including water use, flood, and river environment in water resources policies. The IWREI is estimated by integrating the Water Use Vulnerability Index (WUVI), the Flood Vulnerability Index (FVI), and the River Environment Vulnerability Index (REVI) which represent the vulnerability in each sector. These indices consist of total 26 indicators selected from the pressure indicators representing the causes of damages in water use, flood, and river environment, the state indicators and the response indicators. The estimated index describes the vulnerability and effectiveness of policies with five levels: Low, Medium Low, Medium, Medium High, and High. The results of evaluating total 115 hydrological units in Korea using the WUVI, FVI, REVI, and IWREI indicate that the project effectiveness in water resources policies is clearly verified by the improved index results compared to the past (early 1990s). Regional vulnerability and evaluation indices developed in this research could be used to establish goals of water resources policy and to select priority regions for project implementation.

This study aims to develop a multivariate daily rainfall simulation model considering spatial coherence across watershed. The existing Hidden Markov Model (HMM) has been mainly applied to single site case so that the spatial coherences are not properly addressed. In this regard, HMM coupled with Chow-Liu Tree (CLT) that is designed to consider inter-dependences across rainfall networks was proposed. The proposed approach is applied to Han-River watershed where long-term and reliable hydrologic data is available, and a rigorous validation is finally conducted to verify the model`s capability. It was found that the proposed model showed better performance in terms of reproducing daily rainfall statistics as well as seasonal rainfall statistics. Also, correlation matrix across stations for observation and simulation was compared and examined. It was confirmed that the spatial coherence was well reproduced via CLT-HMM model.