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This study presents a statistical approach for assessing meteorological hazards based on trends and abrupt changes in precipitation characteristics. Daily rainfall data from 64 stations in South Korea (SK) and 27 stations in North Korea (NK) were used to identify temporal patterns in the rainfall characteristics of both regions using seven rainfall indices, such as the total annual rainfall and annual number of wet days. This study suggests the use of three steps in identifying meteorological hazards based on two statistical analyses. In step 1, we conducted a trend analysis of a 10-year moving average of the rainfall index using the Mann-Kendall (MK) trend test. Most stations (65.6 %) in SK exhibit clear increasing trends in five indices, whereas far fewer have data indicating any trends in five of the indices in NK (25.9 %). In step 2, abrupt changes in all rainfall indices were identified using a Bayesian Change Point (BCP) approach. The results contradict those from the MK trend analysis. The proportion of stations in NK where trends were identified is much higher than that in SK. In step 3, the results from the two previous steps were integrated to identify the meteorological hazards based on the identified trend and change point. The BCP approach can be used to identify meteorological hazards that MK cannot, as the former approach focuses on the change point during the entire period. As a result, meteorological stability at the sites of weather stations can be identified, and then the meteorological hazards across the entire Korean peninsula can be spatially interpolated. Although SK and NK are located on the same peninsula, distinct differences in the trends were observed.

This study assessed the water use vulnerability to include the uncertainty of the weighting values of evaluation criteria and the annual variations of performance values using fuzzy TOPSIS coupled with the Shannon entropy method. This procedure was applied to 12 major basins covering about 88% territory of South Korea. Hydrological components were simulated using Soil and Water Assessment Tool (SWAT) of which parameters were optimally calibrated using SWAT-CUP model. The 15 indicators including hydrological and anthropogenic factors were selected, based on three aspects of climate exposure, sensitivity and adaptive capacity. Their weighting values were objectively quantified using the Entropy method. All performance values of 12 basins obtained from statistic Korea and SWAT simulation were normalized with the consideration of the annual variations from 1991 to 2014 using triangular fuzzy numbers (TFNs). Then, Fuzzy Technique for Order of Preference by Similarity to Ideal Solution (TOPSIS) technique was used to quantify the water use vulnerability and rank 12 basins as follows: A12 (Hyeongsan River) &gt, A6 (Seomjin River) &gt, A5 (Youngsan River) &gt, A8 (Mangyung River) &gt, A2 (Ansung River) &gt, A9 (Dongjin River) &gt, A10 (Nakdong River) &gt, A3 (Geum River) &gt, A4 (Sapgyo River) &gt, A11 (Taehwa River) &gt, A7 (Tamjin River) &gt, A1 (Han River). This framework can be used to determine the spatial priority for sustainable water resources plan and applied to derive the climate change vulnerability on sustainable water resources.

This study provides a systematic three-step approach to prioritizing feasible locations for permeable pavement, taking into account environmental, economic, and social aspects. Step 1 is the identification of potential locations on the basis of spatial and economic feasibility, and on the receptiveness of the local government and residents. Step 2 involves the use of Visual MODFLOW software to simulate groundwater levels with and without permeable pavement. Step 3 is the prioritization of all feasible locations using three multi-criteria decision making methods: the weighted sum method, composite programming and TOPSIS. Weighting values were derived from iterative feedback surveys completed by 22 regional experts. This framework was applied to the Mokgamcheon watershed, central Korea, which suffers from instream flow deficit during the dry season. The results show that by considering anthropogenic factors and hydrological effectiveness, this approach effectively prioritizes feasible alternatives that can be implemented into comprehensive hydrological cycle rehabilitation plans.

This study proposes an improved group decision making (GDM) framework that combines VIKOR method with fuzzified data to quantify the spatial flood vulnerability including multi-criteria evaluation indicators. In general, GDM method is an effective tool for formulating a compromise solution that involves various decision makers since various stakeholders may have different perspectives on their flood risk/vulnerability management responses. The GDM approach is designed to achieve consensus building that reflects the viewpoints of each participant. The fuzzy VIKOR method was developed to solve multi-criteria decision making (MCDM) problems with conflicting and noncommensurable criteria. This comprising method can be used to obtain a nearly ideal solution according to all established criteria. Triangular fuzzy numbers are used to consider the uncertainty of weights and the crisp data of proxy variables. This approach can effectively propose some compromising decisions by combining the GDM method and fuzzy VIKOR method. The spatial flood vulnerability of the south Han River using the GDM approach combined with the fuzzy VIKOR method was compared with the results from general MCDM methods, such as the fuzzy TOPSIS and classical GDM methods, such as those developed by Borda, Condorcet, and Copeland. The evaluated priorities were significantly dependent on the employed decision-making method. The proposed fuzzy GDM approach can reduce the uncertainty in the data confidence and weight derivation techniques. Thus, the combination of the GDM approach with the fuzzy VIKOR method can provide robust prioritization because it actively reflects the opinions of various groups and considers uncertainty in the input data.

This study proposes a robust prioritization framework for climate change adaptation strategies under uncertain climate change scenarios, using the VIseKriterijumska Optimizacija I Kompromisno Resenje (VIKOR) method, a multi-criteria decision-making approach, together with the Shannon entropy-based weights. The VIKOR method allows us to find a compromise solution between two decision strategies of maximizing group utility and minimizing individual regret, and the Shannon entropy is used to determine objective weights among multiple climate change scenarios. The proposed methodology was applied to the problem of selecting locations of subwatersheds for reusing treated wastewater (TWW) in a Korean urban watershed. Selected based on the sustainability concept, hydro-environmental and socioeconomic indicators were used to evaluate the sustainability of TWW reuse under multiple climate change scenarios, using the hydrologic simulation model results and statistical data. Finally, sustainability scores under multiple scenarios were aggregated using the VIKOR together with the Shannon entropy-based weights for the robust prioritization of adaptation strategies. According to the different levels of regret aversion or affinity, our results for water quality showed different sets of adaptation strategies as the best options, suggesting that our framework would help stakeholders seeking the robust options considering both the utility and regret.

Impacts of flood management alternatives are mostly assessed by inundation depth. Other inundation parameters such as velocity and duration are rarely taken into consideration. In this paper, a multi-criteria decision making (MCDM) based framework is used to analyze the effects of inundation velocity and duration on evaluation of flood management alternatives. The framework incorporates a two-dimensional (2D) flood model, Flood2D-GPU and a spatial MCDM (SMCDM) method, Spatial Compromise Programming (SCP). Flood2D-GPU is employed to simulate floods and SCP is applied to rank a set of flood management alternatives. Assessment of flood management options is conducted with multiple different weight set scenarios. First, alternatives are ranked without consideration of inundation velocity and duration. Then, the importance of these parameters increases and the alternatives are ordered in each weight set and a GIS map showing the best alternative in each grid cell is generated in each case. Best alternative maps (BAMs) are compared to investigate the impacts of inundation velocity and duration on selection of best strategy using F fit measure and κ analysis. The framework applicability is illustrated on the Swannanoa River watershed located in the state of North Carolina, US. Case study results indicate up to 49.7 % change of BAM by taking into account inundation velocity and duration. The presented approach addresses the change in selection of flood management strategies resulted by considering other inundation parameters rather than inundation depth. This can potentially reduce the uncertainties associated with the decisions made without consideration of inundation velocity and duration.

This study proposed a robust prioritization framework to identify the priorities of treated wastewater (TWW) use locations with consideration of various uncertainties inherent in the climate change scenarios and the decision-making process. First, a fuzzy concept was applied because future forecast precipitation and their hydrological impact analysis results displayed significant variances when considering various climate change scenarios and long periods (e.g., 2010–2099). Second, various multi-criteria decision making (MCDM) techniques including weighted sum method (WSM), Technique for Order of Preference by Similarity to Ideal Solution (TOPSIS) and fuzzy TOPSIS were introduced to robust prioritization because different MCDM methods use different decision philosophies. Third, decision making method under complete uncertainty (DMCU) including maximin, maximax, minimax regret, Hurwicz, and equal likelihood were used to find robust final rankings. This framework is then applied to a Korean urban watershed. As a result, different rankings were obviously appeared between fuzzy TOPSIS and non-fuzzy MCDMs (e.g., WSM and TOPSIS) because the inter-annual variability in effectiveness was considered only with fuzzy TOPSIS. Then, robust prioritizations were derived based on 18 rankings from nine decadal periods of RCP4.5 and RCP8.5. For more robust rankings, five DMCU approaches using the rankings from fuzzy TOPSIS were derived. This framework combining fuzzy TOPSIS with DMCU approaches can be rendered less controversial among stakeholders under complete uncertainty of changing environments.

An integrated framework is presented for sustainability-based flood hazard mapping of the Swannanoa River watershed in the state of North Carolina, U.S. The framework uses a hydrologic model for rainfall–runoff transformation, a two-dimensional unsteady hydraulic model flood simulation and a GIS-based multi-criteria decision-making technique for flood hazard mapping. Economic, social, and environmental flood hazards are taken into account. The importance of each hazard is quantified through a survey to the experts. Utilizing the proposed framework, sustainability-based flood hazard mapping is performed for the 100-year design event. As a result, the overall flood hazard is provided in each geographic location. The sensitivity of the overall hazard with respect to the weights of the three hazard components were also investigated. While the conventional flood management approach is to assess the environmental impacts of mitigation measures after a set of feasible options are selected, the presented framework incorporates the environmental impacts into the analysis concurrently with the economic and social influences. Thereby, it provides a more sustainable perspective of flood management and can greatly help the decision makers to make better-informed decisions by clearly understanding the impacts of flooding on economy, society and environment. Published version

When hydrological simulation models are calibrated, the optimized parameter set based on a single event often does not show good accuracy for other events, even using the same performance measure. Therefore, this study improved the robust parameter set (ROPS) selection method for hydrological simulation models to consider multiple rainfall events by combining the Minimax Regret Approach (MRA) with Pareto optimums. A multi-event objective function, which is the linear combination of three weighting values and three Nash-Sutcliffe coefficients, was used and individually solved using a genetic algorithm. All available 63 multi-objective functions with weighting values based on three events were determined and then, the Pareto optimum was derived. These optimized parameter sets were considered as the ROPS candidates for the final selection. This study used two approaches. First, Nash-Sutcliffe efficiencies (NSEs) for the additional three rainfall events were used to identify the ROPS. Second, four performance indices, the NSE, the Peak Flow Error (PFE), the Root Mean Square Error (RMSE) and the Percent Bias (PBIAS), were used for the other three events. From the results, it can be concluded that the optimized parameter set from the best weighted multi-objective function using multiple events can simulate most rainfall events well with relatively high precision for both the NSE only and the four performance indices. Furthermore, it can be extended to combine multiple events from multiple sites.

This study developed a multi-criteria decision analysis (MCDA) framework to prioritize sites and types of low impact development (LID) practices. This framework was systemized as a web-based system coupled with the Storm Water Management Model (SWMM). Using TOPSIS method, which is a type of MCDA method, multiple types and sites of designated LID practices are prioritized. This system is named the Water Management Prioritization Module (WMPM). WMPM can simultaneously determine the priority of multiple LID types and sites. In this study, an infiltration trench and permeable pavement were considered for multiple sub-catchments in South Korea to demonstrate the WMPM procedures. The TOPSIS method was manually incorporated to select the vulnerable target sub-catchments and to prioritize the LID planning scenarios for multiple types and sites considering social, hydrologic and physical-geometric factors. In this application, the Delphi method and entropy theory were used to determine the subjective and objective weights, respectively.

Developers are increasingly looking for the best management practices to reduce the risk of floods in rapidly growing urban areas. Low impact development (LID) is regarded as one of the most suitable solutions for urban stormwater management and thus the U.S. EPA’s (Environmental Protection Agency) SWMM5.1 (Storm Water Management Model) added the hydrological simulation function for LID structures in 2009. However, SWMM5.1 cannot consider the optimal or best physical specifications of LID design and planning fitted to a study area, nor can it instantly derive the best combination for multiple LID designs and plans. Therefore, in this study, a web-based decision support system (DSS) for the EPA’s SWMM 5.1, referred to as the Water Management Analysis Module (WMAM) is used to decide the most effective specifications of design and planning parameters for LID structure. This study was carried out over an urban catchment of University Technology Malaysia campus located in Johor, Malaysia. The hydrologic cycles with and without LID were simulated using EPA SWMM5.1. The sensitivity analysis and multiple scenario analysis were performed using WMAM. As a result, the effective specification of LID design parameters indicates that peak flow is reduced to 20.95% and 17.5% for two sub-catchments, S1 (highest by area) and S6 (lowest by area) by installing an LID structure. Thus, this study provides a tool for the best solution for what values for physical parameters will be the best for a specified LID type and what capacities can achieve the particular objectives using WMAM.

본 연구에서는 연 최저 유입량과 연 최대 부족량 자료를 이용하여 수문학적 가뭄을 평가하였고, 수자원 시설의 계획 및 관리에 이용할 수 있도록 물 부족량-지속기간-빈도 곡선을 제안하였다. 연 최저 유입량 분석결과, 대부분의 지속기간에서 1989년, 1996년 수문학적 가뭄의 재현기간이 가장 길었다. 연 최대 부족량 분석결과, 비교적 짧은 지속기간인 60일, 90일 부족량의 재현기간은 1982년에서 약 35년으로 가장 길게 나타났으며, 길게 지속되었던 수문학적 가뭄은 1995년으로 재현기간은 약 20년이었다. 가뭄은 크기와 함께 지속기간도 주요한 변수이지만 연 최저 유입량을 이용한 방법은 지속기간을 구분하지 못한다는 단점이 확인되었다. 【This study evaluated hydrological drought the using the annual minimum flow and the annual maximum deficit method and proposed the new concept of water deficit-duration-frequency curves similar to rainfall intensity-duration-frequency curves. The analysis results of the annual minimum flow, the return periods of hydrological drought in the most duration of 1989 and 1996yr were the longest. The analysis results of the annual maximum deficit, the return periods of 60-days and 90-day deficit which are relatively short duration were the longest in 1995yr, about 35-year, Hydrological drought lasted longer was in 1995, the return period was about 20-year. Though duration as well as magnitude is a key variable in drought analysis, it was found that the method using the annual minimum flow duration not distinguish duration.】

The goal of this study is to derive water resource vulnerability characteristics for South Korea according to individual district populations in a changing climate. The definition of water resource vulnerability in this study consists of potential flood damage and potential water scarcity. To quantify these vulnerabilities, key factors, or indicators affecting vulnerability, are integrated with a technique for order of preference by similarity to ideal solution (TOPSIS), which is a multi-criteria decision-making approach to determine the optimal alternative by considering both the best and worst solutions. The weight for each indicator is determined based on both the Delphi technique and Shannon’s entropy, which are employed to reduce the uncertainty in the process of determining the weights. The Delphi technique reflects expert opinions, and Shannon’s entropy reflects the uncertainty of the performance data. Under A1B climate change scenarios, medium-sized districts (200,000–300,000 inhabitants) are the most vulnerable regarding potential flood damage; the largest districts (exceeding 500,000 inhabitants) are found to be the most vulnerable with respect to potential water scarcity. This result indicates that the local governments of cities or districts with more than 200,000 inhabitants should implement better preventative measures for water resources. In addition, the Delphi and entropy methods show the same rankings for flood vulnerability; however, these approaches produce slightly different rankings regarding water scarcity vulnerability. Therefore, it is suggested that rankings from not only subjective but also objective weights should be considered in making a final decision to implement specific adaptive measures to climate change.

This study aims to improve the general flood vulnerability approach using fuzzy TOPSIS based on @a-cut level sets which can reduce the uncertainty inherent in even fuzzy multi-criteria decision making process. Since fuzzy TOPSIS leads to a crisp closeness for each alternative, it is frequently argued that fuzzy weights and fuzzy ratings should be in fuzzy relative closeness. Therefore, this study used a modified @a-cut level set based fuzzy TOPSIS to develop a spatial flood vulnerability approach for Han River in Korea, considering various uncertainties in weights derivation and crisp data aggregation. Two results from fuzzy TOPSIS and modified fuzzy TOPSIS were compared. Some regions which showed no or small ranking changes have their centro-symmetric distributions, while other regions whose rankings varied dynamically, have biased (anti-symmetric) distributions. It can be concluded that @a-cut level set based fuzzy TOPSIS produce more robust prioritization since more uncertainties can be considered. This method can be applied to robust spatial vulnerability or decision making in water resources management.

This study developed a multi-criteria approach to spatially assess the robust water resource vulnerability in sub-basins and applied it to the Han River basin. The Intergovernmental Panel on Climate Change (IPCC) suggested three factors of vulnerability; namely, exposure, sensitivity and adaptive capacity were used in this study with respect to water quantity and quality. In this study, 16 water quantity indicators and 13 water quality indicators were selected to identify the vulnerability using the Technique for Order of Preference by Similarity to Ideal Solution (TOPSIS) method. Environmental and socioeconomic data were obtained from the national statistics database, and hydrological data were simulated using the calibrated Soil and Water Assessment Tool (SWAT) model. Expert surveys and Shannon entropy method were used to determine subjective and objective weights for all indicators, individually. As a result, water quantity-vulnerable sub-basins were associated with high water use and water leakage ratios. Water quality-vulnerable sub-basins were associated with relatively high values of maximum consecutive dry days and heatwave days. The water quantity indices of both weighting methods showed relatively similar spatial distributions, while the distribution of water quality indices was distinct. These results suggest that considering different weighting methods is important for assessing the robust water resource vulnerability of sub-basins.

Recent climate change has resulted in the reduction of several surface water bodies (SWBs) all around the globe. These SWBs, such as streams, rivers, lakes, wetlands, reservoirs, and creeks have a positive impact on the cooling of the surrounding climate and, therefore, reduction in SWBs can contribute to the rise of land surface temperature (LST). This study presents the impact of SWBs on the LST across Bangladesh to quantify their roles in the rapid temperature rise of Bangladesh. The moderate resolution imaging spectroradiometer (MODIS) LST and water mask data of Bangladesh for the period 2000&ndash, 2015 are used for this purpose. Influences of topography and geography on LST were first removed, and then regression analysis was conducted to quantify the impact of SWBs on the LST. The non-parametric Mann&ndash, Kendall (MK) test was used to assess the changes in LST and SWBs. The results revealed that SWBs were reduced from 11,379 km2 in 2000 to 9657 km2 in 2015. The trend analysis showed that changes in SWBs have reduced significantly at a 90% level of confidence, which contributed to the acceleration of LST rise in the country due to global warming. The spatial analysis during the specific years showed that an increase in LST can be seen with the reduction of SWBs. Furthermore, the reduction of 100 m2 of SWBs can reduce the LST of the surrounding regions from &minus, 1.2 to &minus, 2.2 &deg, C.

This study assessed the vulnerability of the water supply to climate change and variability in the South Korean provinces for the present and future with a fuzzy VIKOR approach. The key indicators of vulnerability were profiled with the Delphi surveys based on the IPCC-based vulnerability concept, in which vulnerability is defined as a function of sensitivity, adaptive capacity and climate exposure. The fuzzy VIKOR was used to aggregate the key indicators into a vulnerability score because it can provide a compromise solution considering overall satisfaction and regret of the selection of wrong provinces. Markedly different rankings between the fuzzy VIKOR and a conventional weighted sum for overall satisfactions suggest the importance of regret component of the selection of wrong provinces and inclusion of the uncertainty of information in the vulnerability assessment and consequent decision making for adaptation. Furthermore, diverse vulnerability rankings with the six different future scenarios suggest the need for robust decision making given such uncertainty.

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.

Climate change is expected to worsen the depletion of streamflow in urban watershed. In this study, we therefore considered the treated wastewater (TWW) use as an adaptation strategy and devised a framework to identify prioritized areas for TWW use. An integrated framework that includes hydrological factors as well as social and environmental components were employed to determine the criteria for decision making. Fuzzy theory was employed to consider the uncertainties in the climate change scenarios and the weights of the performance value. All alternatives were evaluated using the fuzzy TOPSIS method. In addition, statistical method and decision making methods under complete uncertainty were used for robust decision making. As a result, ranking the alternatives using the fuzzy TOPSIS method and robust approach such as maximin, maximax, Hurwicz and equal likelihood criterion mitigated the level of uncertainty and ambiguity in each alternative. The finding of this study can be helpful in prioritizing water resource management projects considering various climate change scenarios.

The goal of this study is to evaluate and rank the effectiveness of the Korean governments’ Four Major River Restoration Projects. A hydraulic simulation model and geographic information system tools are used to analyze the flood mitigation effects provided by these projects. In addition, the rankings of four major rivers are derived using two sensitivity analyses to weight values and performance measures for Multi-Attribute Decision Making (MADM) technique. As a result, the flood risk presented by the Nakdong River can be most effectively decreased when considering these weights, and levee freeboards are the most critical criterion in the effectiveness ranking. The Youngsan River’s flow capacity criterion is also critical for this problem. This study will be helpful in the robust prioritization of various water resources plans.

Determination of the frequency and the magnitude of the extreme rainfall events are very important for water resources management and the designs of the hydraulic structures because the extreme rainfall events and the resulting floods usually cause a lot of damage to life and properties of human society. Recently an increase in the occurrence of extreme events due to global warming has been observed all over the world. Therefore, it is required that the conventional rainfall frequency analysis methods may be reconsidered in two ways. Firstly, the conventional probability distributions used in the frequency analysis should be evaluated again whether the probability distribution can represent the effect of the extreme value or not. Also, the uncertainty in the rainfall frequency analysis should be quantified for the flexible water resources management. Therefore, the comparative study with the Gumbel distribution and the GEV(Generalized Extreme Value) distribution are performed to evaluate the efficiency of the GEV distribution in this article. Also, the Bayesian MCMC(Markov Chain Monte Carlo) scheme and the MLE with a quadratic approximation for parameter estimation are compared to show the advantage of the Bayesian MCMC in the aspect of uncertainty analysis. Especially, the informative prior distributions using the additional information are elicited in the process of the Bayesian MCMC.

This study presents the feasibility of fuzzy multi-criteria decision making (MCDM) techniques for the robust prioritization of projects. It is applied to water resources planning problem. Results from weighted sum method (WSM), analytic hierarchy process (AHP), revised analytic hierarchy process (R-AHP), and TOPSIS are compared with those from Fuzzy WSM, Fuzzy, AHP, Fuzzy R-AHP, and Fuzzy TOPSIS. For the calculation, all weights on criteria and the normalized data were obtained from the same investigation. As a result, the rankings from four MCDM techniques are slightly different while those from fuzzy MCDM show the comparatively consistent ranking. Therefore, it is desirable to use fuzzy MCDM technique when MCDM is used for the prioritization problem, since fuzzy MCDM can include the uncertain variability of input data and weighting values on criteria.

This study aims to develop a new procedure that combines multi-criteria spatial vulnerability analysis with the traditional linear probabilistic risk approach. This approach is named integrated fuzzy flood vulnerability assessment because it combines the watershed-based vulnerability framework with stream-based risk analysis. The Delphi technique and pressure-state-impact-response framework are introduced to objectively select evaluation criteria, and the fuzzy TOPSIS technique is proposed to address the uncertainty of weights to all criteria and crisp input data of all spatial units. ArcGIS is used to represent the spatial results to all criteria. This framework is applied to the south Han River basin in South Korea. As a result, the flood vulnerability ranking was derived and vulnerability characteristics of all spatial units were compared. This framework can be used to conduct a prefeasibility study for flood mitigation projects when various stakeholders should be included.

This study developed a new framework that prioritized the best sites for treated wastewater (TWW) instream use using fuzzy Technique for Order of Preference by Similarity to Ideal Solution (fuzzy TOPSIS), a fuzzy-based multi-criteria decision-making (MCDM) technique. We identified key criteria for TWW use based on the Driver-Pressure-State-Impact-Response (DPSIR) framework that considered technical, social, economic and environmental aspects. We also introduced triangular fuzzy numbers and conducted individual interviews to consider the uncertainty of weighting values and input data. This procedure was applied at ten sites in a South Korean urban watershed, where hydrologic modeling exercises were performed. Our simulation results for water quantity (i.e., drought flow, low flow and the days to satisfy instream flow) and water quality (i.e., BOD concentration and the days to satisfy target water quality) showed significant inter-annual variability that could be better represented with fuzzy numbers. Furthermore, the use of fuzzy TOPSIS gave different rankings of the best sites for TWW use compared to those obtained from a weighting sum method, a traditional MCDM technique. Such varied rankings with different MCDM techniques indicate the need for fuzzy-based techniques, considering various uncertainties and thus being less controversial.

This study develops a framework to quantify the flood risk vulnerability in South Korea by considering climate change impacts. On the basis of the concept of exposure-sensitivity-adaptive capacity, 21 proxy variables are selected and screened, and their weights are determined for their objectivity by using the Delphi technique. The data from 16 provinces of South Korea and the weighting values of all proxy variables are fuzzified to consider uncertainty. In addition, the National Center for Atmosphere Research Community Climate System Model 3 (CCSM3) in conjunction with the Intergovernmental Panel on Climate Change (IPCC) Special Report on Emission Scenario (SRES) A1B, A2, B1, A1T, A1FI, and B2 are used for future climate data (2020s, 2050s, and 2080s). Therefore, 19 flood risk vulnerabilities of South Korea, including present conditions, are quantitatively evaluated and compared. Three Multi-Criteria Decision Making (MCDM) techniques - Weighted Sum Method (WSM), Technique for Order Preference by Similarity to Ideal Situation (TOPSIS), and fuzzy TOPSIS - are used to quantify all spatial vulnerabilities. As a result, some fuzzy TOPSIS rankings are quite different to those of WSM and TOPSIS, and the ranking patterns of the 19 climate change scenarios are also derived in a dissimilar way. In addition, if the variances of the provinces' rankings are considered, some provinces showing low values can plan their climate change adaptation strategies by taking into consideration their relatively certain rankings. In the end, the vulnerability assessment for climate change should consider not only various MCDM techniques but also the uncertainty of weighting values and proxy variable data.

유역 환경에 대한 복잡성의 증가는 단일 의사결정자들이 의사결정문제의 모든 부분을 고려하는 것을 점점 더 불가능하게 만들기 때문에 불확실성은 더욱 증가하게 된다. 따라서 본 연구는 그룹의사결정기법을 사용하여 우리나라 공간적인 홍수 취약성을 정량화하는 접근법을 제시하였다. 개인의 선호도를 분석하기위해 Fuzzy TOPSIS를 사용하였고 개인선호도의 통합을 위해 Borda count, Condorcet 그리고 Copeland 방법을 사용하였다. 마지막으로 도출된 결과를 Fuzzy TOPSIS 및 TOPSIS의 결과와 비교하였고 스피어만 순위상관계수와 켄달의 순위상관계수, Emond와 Mason이 제시한 순위상관분석을 이용하여 순위의 일치성을 검토하였다. 그 결과 일부 지역의 취약성 순위가 큰 폭으로 역전되는 현상을 보였다. 그룹의사결정 개념을 반영하여 지역별 취약성을 산정할 경우 우선순위의 변동이 클 수 있으므로 홍수 취약성 산정시 본 연구에서 제시된 모델을 고려할 필요가 있다. 【Increasing complexity of the basin environments makes it difficult for single decision maker to consider all relevant aspects of problem, and thus the uncertainty of decision making grows. This study attempts to develop an approach to quantify the spatial flood vulnerability of South Korea. Fuzzy TOPSIS is used to calculate individual preference by each group and then three GDM techniques (Borda count method, Condorcet method, and Copeland method) are used to integrate the individual preference. Finally, rankings from Fuzzy TOPSIS, TOPSIS, and GDM are compared with Spearman rank correlation, Kendall rank correlation, and Emond & Mason rank correlation. As a result, the rankings of some areas are dramatically changed by the use of GDM techniques. Because GDM technique in regional vulnerability assessment may cause a significant change in priorities, the model presented in this study should be considered for objective flood vulnerability assessment.】

The goal of this study is to develop a new framework that prioritizes the best sites for treated wastewater (TWW) use considering climate change impacts. Fuzzy TOPSIS which is a kind of multi-criteria decision making techniques was introduced to reflect the uncertainty of input data and criteria weighting values. Representative concentration pathway 8.5 scenario was included into the hydrologic simulations for the climate change impact to hydrologic regimes using hydrological simulation program-Fortran (HSPF). Furthermore, all year scenarios were considered to determine the rankings, respectively. It can take into consideration the uncertainty of time periods which always exists in all climate change scenarios. This study can be a baseline to start to combine the fuzzy multi-criteria decision making techniques with robust prioritization for climate change adaptation strategies.

In spite of the recent global effort in mitigating greenhouse gases, the temperature of the earth continues to increase because we are already committed past emissions. Therefore, adapting to the changing climate is an immediate challenge that requires choosing a successful strategy. This chapter reviews classical decision-making methods and discusses their limitations when applied to climate change adaptation planning. Three novel decision-making methods, robust decision making (RDM), real option analysis (ROA), and dynamic adaptive policy pathways (DAPP), are discussed, and their applications are then introduced in water resources planning under different climate change scenarios. Such methods should be either “robust” or “adaptive” for decision makers to capture the nonstationary and uncertain characteristics of climate change. As its name indicates, the RDM method focuses on the “robust” perspective and chooses an alternative that performs satisfactorily over a wide range of scenarios. In contrast, both the ROA and DAPP methods focus on the “adaptive” perspective and have a decision tree framework where risk is spread over time. ROA allows decision makers to delay or abandon the chosen alternative rather than just implementing it without modification, while DAPP introduces the tipping point concept that offers a systematic way of when to switch between alternatives. However, these advanced decision-making methods are resource intensive; thus, a continuous administrative effort and institutional as well as technical supports are required for their success in the climate change era.

Sustainable watershed management (SWM) can be achieved through recognition and reflection upon the values of citizens. Collaborative governance consisting of citizens is crucial for successful SWM. Collaborative governance definitely requires an active participatory decision-making process that reflects citizens' preferences. Citizen preference also tends to substantially change with life pattern and life quality. These shifts can be caused by slight variations in both social priorities and personal preferences for SWM. Therefore, collaborative water governance must be frequently renewed in response to citizens' values through the participatory framework. The An'yang Stream in South Korea is generally regarded as a representative urban stream restoration case that has been successfully led by collaborative governance. By conducting individual surveys with citizens on-site, this study addresses how citizens' preferences of the stream's management have changed between 2005 and 2015. In addition, this study used three quantitative hydrologic vulnerability indices: potential flood damage (PFD), potential streamflow depletion (PSD), and potential water quality deterioration (PWQD). They can spatially quantify citizen preference using the Analytic Hierarchy Process (AHP), which can systematically derive citizens' subjective relative-weighted preferences. In the end, this study identified critical differences in priorities in regard to vulnerable areas between in 2005 and in 2015.

This study develops an integrated approach to assess climate change and urbanization impacts on adaptation strategies in watersheds. We considered the two adaptation strategies for two small watersheds in Korea: the redevelopment of an existing reservoir and the reuse of highly treated wastewater treatment plant (WWTP) effluent. Climate change scenarios were obtained by statistically downscaling the predicted precipitation and temperature with a global climate model (A1B and A2), and urbanization scenarios were derived by estimating the impervious area ratios with an impervious cover model. With the climate change and urbanization scenarios, we used the Hydrological Simulation Program-Fortran model to derive the flow and biochemical oxygen demand (BOD) concentration (conc.) duration curves, and calculate the numbers of days satisfying environmental requirement for instreamflow and the target BOD conc. Climate change reduced the effectiveness of the adaptation strategies with respect to low flow and BOD conc., whereas urbanization generally increased their effectiveness. Climate change had a greater impact on the effectiveness of the adaptation strategies for BOD conc. than for low flow, whereas urbanization had a greater impact on low flow. Comparing impacts of two strategies, a larger decrease in the effectiveness was observed for the WWTP effluent reuse strategy in response to climate change and urbanization. However, the consistent trends cannot be found with ease if climate change and urbanization happens jointly.

This study will be a new attempt to quantify flood vulnerability taking into account uncertainty. Information obtained from the real world has lots of uncertainties. Therefore, this study developed an approach to quantify spatial flood vulnerability of Korea using Fuzzy TOPSIS approach. Also, Fuzzy TOPSIS were compared with TOPSIS and weighted sum method. As a result, rankings of some areas were changed dramatically due to the uncertainty. Spearman rank correlation analysis indicated that the rankings of TOPSIS and weighted sum method were almost similar, but quite different from ranking of Fuzzy TOPSIS. In other words, because applying Fuzzy concept in regional vulnerability assessment may cause a significant change in priorities, the model presented in this study may be a method of vulnerability assessment.

Although a rainwater harvesting system (RWHS) is an effective water supply alternative, its efficiency is often heavily influenced by the temporal distributions of precipitation and water demand. Furthermore, because recent precipitation patterns have changed due to climate change and will likely continue to do so, RWHS designs must take future precipitation forecasts into account. This study aimed to develop a methodology for establishing the probabilistic relationships between the storage capacity and deficit rate of an RWHS when considering climate change. A four-story building at a university was selected as a case study. The A2 scenario of the CGCM3 (Canadian Global Coupled Model 3) was considered and downscaled to the study area using the SDSM (Statistical DownScaling model), and the fitted probabilistic distributions were selected and modeled according to the results of goodness-of-fit tests. As a result, a set of curves describing the relationships between storage capacity and deficit rate was derived. From these curves, we determined that the studied RWHS's storage capacity could be reduced due to increased annual mean precipitation when the impact of climate change is considered. However, climate change consideration may not be important to determine the storage capacity of RWHS when the places showing enough rainfall all year around are planned. This result can be helpful for RWHS engineers and decision makers.

This study suggests the results of temporal and spatial variations for rainfall data in the Korean Peninsula. We got the index of the rainfall amount, frequency and extreme indices from 65 weather stations. The results could be easily understood by drawing the graph, and the Mann-Kendall trend analysis was also used to determine the tendency (up & downward/no trend) of rainfall and temperature where the trend could not be clear. Moreover, by using the FARD, frequency probability rainfalls could be calculated for 100 and 200 years and then compared each other value through the moment method, maximum likelihood method and probability weighted moments. The Average Rainfall Index (ARI) which is meant comprehensive rainfalls risk for the flood could be obtained from calculating an arithmetic mean of the RI for Amount (RIA), RI for Extreme (RIE), and RI for Frequency (RIF) and as well as the characteristics of rainfalls have been mainly classified into Amount, Extremes, and Frequency. As a result, these each Average Rainfall Indices could be increased respectively into 22.3%, 26.2%, and 5.1% for a recent decade. Since this study showed the recent climate change trend in detail, it will be useful data for the research of climate change adaptation.

This study aims to present the sensitivity analysis approach for multi-criteria decision making (MCDM) method to reduce the uncertainty of weighting and performance values. This study focuses on two major problems of the uncertainty for MCDM method. The first major problem is how to determine the most critical criterion and the second is how to determine the most critical measure of performance. This study used the application of weighted sum method for water resources planning. The criticality degrees and the sensitivity coefficients of criterion and alternative are used. This results of sensitivity analysis can be applied to the general water resources planning in real.

This study developed a new framework to quantify spatial vulnerability for sustainable water resources management. Four hydrologic vulnerability indices--potential flood damage (PFDC), potential drought damage (PDDC), potential water quality deterioration (PWQDC), and watershed evaluation index (WEIC)--were modified to quantify flood damage, drought damage, water quality deterioration, and overall watershed risk considering the impact of climate change, respectively. The concept of sustainability in the Driver-Pressure-State-Impact-Response (DPSIR) framework was applied in selecting all appropriate indicators (criteria) of climate change impacts. In the examination of climate change, future meteorological data was obtained using CGCM3 (Canadian Global Coupled Model) and SDSM (Statistical Downscaling Model), and future stream run-off and water quality were simulated using HSPF (Hydrological Simulation Program - Fortran). The four modified indices were then calculated using TOPSIS, a multi-attribute method of decision analysis. As a result, the ranking obtained can be changed in consideration of climate change impacts. This study represents a new attempt to quantify hydrologic vulnerability in a manner that takes into account both climate change impacts and the concept of sustainability.

This paper presents advancements to the approach for Total Maximum Daily Load (TMDL) development in Korea. The current Korean TMDL process does not directly consider uncertainty and it does not include an objective approach to allocate pollutant load reductions. This paper develops a methodology to address uncertainty by incorporating a margin of safety (MOS) based on three approaches: judgment, standard error of loading characteristics, and uncertainty and variability of loading characteristics. In addition, three pollutant load reduction allocation approaches are compared to assess their impact: equal load, equal percent, and equity standard reductions. These two proposed additions to the TMDL process in Korea are demonstrated for a BOD TMDL development in the Anyangcheon Watershed. The results confirm the importance of incorporating uncertainty into the TMDL process and clearly illustrate the significant differences in TMDL and load allocation produced when using different approaches to estimate the MOS. Further, the comparison of the three load allocation strategies highlights the potential limitations of equal load and equal percent reduction approaches. The use of technical expert and decision maker ranking of factors create an equitable and sustainable load allocation among the sub-watersheds. It can be concluded that incorporating uncertainty and providing an objective load allocation strategy are essential elements needed for future TMDL development in Korea.

This study analyzed the recent changed temporal and spatial variations of precipitation and daily average temperature in the South Korea. 65 weather stations were grouped, based on their latitudes and longitudes and the recent variable temporal and spatial variations of each latitude and longitude were derived, quantitatively. In addition, the Mann-Kendall trend analysis was used to determine the tendency (upward/downward/no trend) of rainfall and temperature. From these analyses, it was shown that the precipitation of zone 1 () has increased by 7% and the rate of increase showed 5%~18% as the latitude went up. During summer, the rate of precipitation increase has increased as the latitude went up. Due to the rapid increase of summer, the rate of precipitation increase has increased as the longitude went up. On the whole, average temperature has been increased as the latitude went up. The Mann-Kendall trend analysis derived that the temperature of South Korea has increased except zone 2 ()and summer period and the precipitation on latitude and longitude has increased during summer. Since this study showed the recent climate change trend in detail, it will be a preliminary data for the research of climate change adaptation.

This study analyzed the characteristics of 65 weather stations of Korea using rainfall and average daily temperature data and compared differences between before 2000 and after 2001. By seasons, all weather stations were divided into 9 groups depending on their rainfalls and temperatures. Also, the Mann-Kendall trend analysis was used to determine the tendency(upward/downward/no trend) of rainfall and temperature. From these analyses, recent temperature increases appear during spring, fall and winter period and rainfall increase have occurred during summer. Rainfall upward trend appeared in the region of central interior part and four more stations showed the same trend after 2001. For temperature, most coastal area showed the strong upward trend, but 11 weather stations of interior region showed the upward trend during the summer.

The objective of this paper is to introduce a continuous simulation-based screening procedure for ranking urban watershed management alternatives using multi-attribute decision making (MADM). The procedure integrates continuous urban runoff simulation results from the United States Environmental Protection Agency’s Storm Water Management Model (SWMM) with the use of an alternative evaluation index (AEI) and MADM techniques, following the driver-pressure-state-impact-response (DPSIR) approach. The analytic hierarchy process estimates the weights of the criteria, and SWMM results are used to quantify the effects of the management alternatives on water quantity and quality metrics. In addition, the tendency of AEI to reflect resident preferences toward management objectives is incorporated to include stakeholder participation in the decision-making process. This systematic decision support process is demonstrated for a Korean urban watershed. According to the AEI, seven alternatives were divided into three groups: poor (0∼0.3), acceptable (0.3∼0.6), and good (0.6∼1). The use of multiple MADM techniques provided a consistency check. The demonstration illustrates the ability of the continuous simulation-based MADM approach to provide decision makers with a ranking of suitable urban watershed management alternatives which incorporate stakeholder feedback.

The purpose of this study is to consider the interaction between surface water and groundwater in basin scale by developing TANK_GS model. The soil moisture structure of tank model with 3 tanks is improved to simulate the appropriate stream-aquifer interactions. Maximum likelihood method is applied to calibrate parameters with variance functions to deal with heteroscedasticity of residuals. The parameters of improved TANK_GS model and variance function are simultaneously estimated by Simulated Annealing method, a global optimization technique. The results of TANK-GE are compared to those of the SWMM-GE model which had been developed to consider the stream-aquifer interactions. The new TANK_GS model and SWMM-GE model are applied to Gapcheon basin, which belongs to Geum River basin. TANK_GS model showed better model performance compared to the original TANK model and characterized the relationship of stream-aquifer interactions as satisfactorily as the SWMM-GE model. The sustainable groundwater yield can be estimated for the regional water resources planning using the TANK_GS model

An index has been developed for the assessment of geographical distribution of susceptibility to hydrological hazards using easily available climate data. Catastrophe fuzzy theory and data clustering methods were used to avoid subjectivity in the estimation of the index of multiple climate indicators. The proposed index was used for the estimation of geographical distribution of hydrological hazard susceptibility index (HHSI) in Peninsular Malaysia using gauge-based, gridded rainfall and temperature data for the period 1948&ndash, 2010. The results showed that the northeast regions of Peninsular Malaysia are more susceptible to hydrological hazard, which matches very well with the general conception of the hydrological hazard susceptible zones. Assessment of susceptibility for sliding different 30-year periods between 1950 and 2010 revealed that HHSI has increased in the south and decreased in the northeast of the peninsula. The decrease in temporal and spatial variability of rainfall in the northeast and the increase in other parts can become the causes of spatial changes in hazard susceptibility. The changes of HHSI in recent years compared to the base period revealed the increase of hazard susceptibility in the south in the range of 8.81% to 21.01%, while a significant decrease (&gt, &minus, 31.84%) was observed in the northeast.

We assessed the relative hydrological impacts of climate change and urbanization using an integrated approach that links the statistical downscaling model (SDSM), the Hydrological Simulation Program—Fortran (HSPF) and the impervious cover model (ICM). A case study of the Anyangcheon watersh

This study developed an integrated approach to climate change and urbanization impact assessment by linking models of SDSM (statistical downscaling model), HSPF (hydrological simulation program?Fortran) and ICM (impervious cover model). A case study of the Anyangcheon watershed illustrated how the proposed framework can be used to analyze the impacts of climate change and urbanization in terms of flood control, water security and water quality. The evaluation criteria were the variations of flow and pollutant concentration duration curves. In this study, nine scenarios including three climate (present condition, A1B and A2) and three urbanization scenarios were analyzed using HSPF model. As a result, climate change is a large influence on the flowrate and the urbanization affects the pollutant concentration. Therefore, the impacts of both climate change and urbanization must be included into the watershed management and water resources planning for sustainable development.

This study develops a social-economic-engineering combined framework for decision making in water resources planning. This framework consists of four parts which are to spatially identify the grades on hydrological vulnerability (potential streamflow depletion and potential water quality deterioration), to evaluate the monetary values of improvements on hydrological vulnerability grades using the choice experiment method, to derive an alternative evaluation index (AEI) to quantify the effectiveness of all alternatives, and to combine the derived willingness-to-pays (WTPs) with the AEI and do the cost-benefit analysis of feasible alternatives. This framework includes the stakeholder participation in order to quantify the preferences with regard to management objectives (water quantity and quality) and WTPs of alternatives. Finally, the economic values of each alternative can be estimated by this study which combines the WTPs for improvements on hydrologic vulnerability grades with the AEI. The proposed procedure is applied in the Anyangcheon watershed which has been highly urbanized for past thirty years. As a result, WTPs are $0.24~$10.08/month-household for water quantity and $0.80~$8.60/month-household for water quality and residents of the five regions among six have higher WTPs for water quality improvement. Finally, since three of ten alternatives have BC>0, they can be proposed to the decision makers. This systematic screening procedure will provide decision makers with the flexibility to obtain stakeholders' consensus for water resources planning.

This paper employs a new estimation method for estimating stage–discharge rating curve parameters. In typical practical applications, the original non-linear rating curve is transformed into a simple linear regression model by log-transforming the measurement without examining the effect of heteroscedasticity of residuals. Therefore, the model with pseudo-likelihood estimation is developed in this study to deal with heteroscedasticity of residuals in the original non-linear model. The parameters of rating curves and variance functions of errors are simultaneously estimated by the pseudo-likelihood estimation (P-LE) method. Also simulated annealing, a sort of global optimization techniques, is adapted to minimize the log likelihood of the weighted residuals. At first, the developed P-LE model was applied to a hypothetical site where stage–discharge data were generated by incorporating various errors for statistical test. Also, the limit of stages for segmentation is estimated in the process of P-LE using the Heaviside function. For the validation of effects of the developed P-LE model, the results of the conventional log-transformed linear regression (LT-LR) model and the P-LE model are estimated and compared. After statistical simulation, the developed P-LE model is then applied to the real data sets from six gauge stations in the Geum River basin. It can be suggested that this new estimation method is applied to real river sites to successfully determine the weights taking into account error distributions from observed discharge data.

The objective of this study is to develop an alternative evaluation index (AEI) in order to determine the priorities of a range of alternatives using both the hydrological simulation program in FORTRAN (HSPF) and multicriteria decision making (MCDM) techniques. In order to formulate the HSPF model, sensitivity analyses of water quantity (peak discharge and total volume) and quality (BOD peak concentrations and total loads) are conducted and a number of critical parameters were selected. To achieve a more precise simulation, the study watershed is divided into four regions for calibration and verification according to landuse, location, slope, and climate data. All evaluation criteria were selected using the Driver–Pressure–State–Impact–Response (DPSIR) model, a sustainability evaluation concept. The Analytic Hierarchy Process is used to estimate the weights of the criteria and the effects of water quantity and quality were quantified by HSPF simulation. In addition, AEIs that reflected residents' preferences for management objectives are proposed in order to induce the stakeholder to participate in the decision making process.