Water2016, 8(2), 54; doi:10.3390/w8020054 (registering DOI) - published 6 February 2016 Show/Hide Abstract
Abstract: Global warming in recent years has resulted in climate change. To cope with future climate change and natural environment changes, much of our planning and thinking needs to be adjusted. To this end, safety and rapidness of evacuation have become primary research goals. In this study, geographic information and fuzzy expert systems are applied to debris flow evacuation sites in Ershui Township, Changhua County, for evaluating their hazard ratings. After a geographic information system is used to overlay the environmental sensitivity, FLO-2D is applied to simulate debris flow situations, and the results are utilized to establish a fuzzy expert system that successfully evaluates the hazard ratings of such sites in hillside areas. For future applications, another evaluation reference based on original evacuation sites and routes or evacuation mechanisms and disaster prevention models is proposed as a source of essential assistance to relevant sectors.
Water2016, 8(2), 55; doi:10.3390/w8020055 (registering DOI) - published 6 February 2016 Show/Hide Abstract
Abstract: The implementation of stormwater Best Management Practices (BMPs) could help re-establish the natural hydrological cycle of watersheds after urbanization, with each BMP presenting a different performance across a range of criteria (flood prevention, pollutant removal, etc.). Additionally, conflicting views from the relevant stakeholders may arise, resulting in a complex selection process. This paper proposes a methodology for BMP selection based on the application of multi-criteria decision aid (MCDA) methods, integrating multiple stakeholder priorities and BMP combinations. First, in the problem definition, the MCDA methods, relevant criteria and design guidelines are selected. Next, information from the preliminary analysis of the watershed is used to obtain a list of relevant BMPs. The third step comprises the watershed modeling and analysis of the BMP alternatives to obtain performance values across purely objective criteria. Afterwards, a stakeholder analysis based on survey applications is carried out to obtain social performance values and criteria priorities. Then, the MCDA methods are applied to obtain the final BMP rankings. The last step considers the sensitivity analysis and rank comparisons in order to draw the final conclusions and recommendations. Future improvements to the methodology could explore inclusion of multiple objective analysis, and alternative means for obtaining social performance values.
Water2016, 8(2), 56; doi:10.3390/w8020056 (registering DOI) - published 6 February 2016 Show/Hide Abstract
Abstract: The selection of stormwater Best Management Practices (BMPs) for mitigating the effects of urbanization on the hydrological cycle could be a complex process due to conflicting stakeholder views, and varying levels of performance of BMPs across a range of criteria (runoff reduction, erosion control, etc.). Part 1 of this article proposed a methodology based on the application of multi-criteria decision aid (MCDA) methods, which was tested here on a residential stormwater network in the Montreal area. The case study considered green roofs, rain gardens, rain barrels and pervious pavement over a range of economic, social, and water quality and quantity criteria by applying 4 MCDA methods under three different stakeholder views. The results indicated Elimination et Choix Traduisant la Réalité (ELECTRE) III to be the most appropriate method for the methodology, presenting flexibility concerning threshold values, criteria weights, and showing shared top choices across stakeholders (rain gardens, and rain gardens in combination with pervious pavement). The methodology shows potential for more formal applications and research opportunities. Future work may lie in the inclusion of multiple objective optimization, better stakeholder engagement, estimation of economic benefits, water quality modeling, long-term hydrological simulations, and estimating real BMP pollutant removal rates.
Water2016, 8(2), 57; doi:10.3390/w8020057 (registering DOI) - published 6 February 2016 Show/Hide Abstract
Abstract: Residents of south Louisiana face a range of increasing, climate-related flood exposure risks that could be reduced through local floodplain management and hazard mitigation planning. A major incentive for community planning to reduce exposure to flood risks is offered by the Community Rating System (CRS) of the National Flood Insurance Program (NFIP). The NFIP encourages local collective action by offering reduced flood insurance premiums for individual policy holders of communities where suggested risk-reducing measures have been implemented. This preliminary analysis examines the extent to which parishes (counties) in southern Louisiana have implemented the suggested policy actions and identifies key factors that account for variation in the implementation of the measures. More measures implemented results in higher CRS scores. Potential influences on scores include socioeconomic attributes of residents, government capacity, average elevation and past flood events. The results of multiple regression analysis indicate that higher CRS scores are associated most closely with higher median housing values. Furthermore, higher scores are found in parishes with more local municipalities that participate in the CRS program. The number of floods in the last five years and the revenue base of the parish does not appear to influence CRS scores. The results shed light on the conditions under which local adaptive planning to mitigate increasing flood risks is more likely to be implemented and offer insights for program administrators, researchers and community stakeholders.
Water2016, 8(2), 53; doi:10.3390/w8020053 (registering DOI) - published 5 February 2016 Show/Hide Abstract
Abstract: Sediment in river is usually transported during extreme events related to intense rainfall and high river flows. The conventional means of collecting data in such events are risky and costly compared to water discharge measurements. Hence, the lack of sediment data has prompted the use of sediment rating curves (SRC). The aim of this study is to explore the abilities of artificial neural networks (ANNs) in advancing the precision of stream flow-suspended discharge relationships during storm events in the Shiwen River, located in southern Taiwan. The ANNs used were multilayer perceptrons (MLP), the coactive neurofuzzy inference system model (CANFISM), time lagged recurrent networks (TLRN), fully recurrent neural networks (FRNN) and the radial basis function (RBF). A comparison is made between SRC and the ANNs. Hourly based water and sediment discharge during 8 storms were manually collected and used as inputs for the SRC and the ANNs. Results have shown that the ANN models were superior in reproducing hourly sediment discharge compared to SRC. The findings further suggest that MLP can provide the most accurate estimates of sediment discharge, (R2 of 0.903) compared to CANFISM, TLRN, FRNN and RBF. SRC had the lowest R2 (0.765), and resulted in underestimations of peak sediment discharge (−47%).
Water2016, 8(2), 51; doi:10.3390/w8020051 (registering DOI) - published 5 February 2016 Show/Hide Abstract
Abstract: The main objective of this study was to evaluate the performance and treatment efficiency of the Horizontal Sub-Surface Flow Constructed Wetland treatment system (HSF-CW) in an arid climate. Seventeen sub-surface, horizontal-flow HSF-CW units have been operated for approximately three years to improve the quality of partially-treated municipal wastewater. The studied design parameters included two sizes of volcanic tuff media (i.e., fine or coarse), two different bed dimensions (i.e., long and short), and three plantation types (i.e., reed, kenaf, or no vegetation as a control). The effluent Biological Oxygen Demand (BOD5), Chemical Oxygen Demand (COD), Total Suspended Solid (TSS), and phosphorus from all of the treatments were significantly lower as compared to the influent and demonstrated a removal efficiency of 55%, 51%, 67%, and 55%, respectively. There were significant increases in Electrical Conductivity (EC), sulfate, and calcium in the effluent of most HSF-CWs due to evaporative concentration and mineral dissolution from the media. The study suggests that unplanted beds with either fine or coarse media are the most suitable combinations among all of the studied designs based on their treatment efficiency and less water loss in arid conditions.