Water2016, 8(5), 179; doi:10.3390/w8050179 (registering DOI) - published 29 April 2016 Show/Hide Abstract
Abstract: The core idea behind sectorization of Water Supply Networks (WSNs) is to establish areas partially isolated from the rest of the network to improve operational control. Besides the benefits associated with sectorization, some drawbacks must be taken into consideration by water operators: the economic investment associated with both boundary valves and flowmeters and the reduction of both pressure and system resilience. The target of sectorization is to properly balance these negative and positive aspects. Sectorization methodologies addressing the economic aspects mainly consider costs of valves and flowmeters and of energy, and the benefits in terms of water saving linked to pressure reduction. However, sectorization entails other benefits, such as the reduction of domestic consumption, the reduction of burst frequency and the enhanced capacity to detect and intervene over future leakage events. We implement a development proposed by the International Water Association (IWA) to estimate the aforementioned benefits. Such a development is integrated in a novel sectorization methodology based on a social network community detection algorithm, combined with a genetic algorithm optimization method and Monte Carlo simulation. The methodology is implemented over a fraction of the WSN of Managua city, capital of Nicaragua, generating a net benefit of 25,572 $/year.
Water2016, 8(5), 182; doi:10.3390/w8050182 (registering DOI) - published 29 April 2016 Show/Hide Abstract
Abstract: This paper presents a modified Shuffled Frog Leaping Algorithm (SFLA) applied to the design of water distribution networks. Generally, one of the major disadvantages of the traditional SFLA is the high number of parameters that need to be calibrated for proper operation of the algorithm. A method for calibrating these parameters is presented and applied to the design of three benchmark medium-sized networks widely known in the literature (Hanoi, New York Tunnel, and GoYang). For each of the problems, over 35,000 simulations were conducted. Then, a statistical analysis was performed, and the relative importance of each of the parameters was analyzed to achieve the best possible configuration of the modified SFLA. The main conclusion from this study is that not all of the original SFL algorithm parameters are important. Thus, the fraction of frogs in the memeplex q can be eliminated, while the other parameters (number of evolutionary steps Ns, number of memeplexes m, and number of frogs n) may be set to constant values that run optimally for all medium-sized networks. Furthermore, the modified acceleration parameter C becomes the key parameter in the calibration process, vastly improving the results provided by the original SFLA.
Water2016, 8(5), 183; doi:10.3390/w8050183 (registering DOI) - published 29 April 2016 Show/Hide Abstract
Abstract: Many potato processors require on-farm washing of potatoes, creating large quantities of wastewater that requires treatment, starting in the fall until the end of the potato storage period in mid-summer. We studied the treatment of wastewater from a potato farm in Ontario, Canada, using a system of pretreatment (sedimentation, aeration) followed by a surface-flow wetland with a dense growth of cattails (Typha sp.). The raw wastewater had high average concentrations of 5-day biochemical oxygen demand (BOD5; 1113 mg·L−1), total suspended solids (TSS; 4338 mg·L−1), total nitrogen (TN; 311 mg·L−1) and total phosphorus (TP; 42.5 mg·L−1). Due to high influent loads, the pretreatment was enlarged during annual sediment cleaning at the end of Year 1 (Y1), which increased the hydraulic retention time and delayed the seasonal onset of wetland loading from winter in Y1 to spring in Year 2 (Y2). Total concentration reduction for the treatment system (pretreatment + wetland) in Y2 was 96% BOD5, 99% TSS, 86% TN and 90% TP; and in Y1 was 79% BOD5, 97% TSS, 62% TN and 54% TP. Overall, the best treatment in both the pretreatment and the wetland was seen in spring months. The enlarged pretreatment system enabled seasonal loading of the wetland during the spring and summer, which facilitated improved treatment performance.
Water2016, 8(5), 180; doi:10.3390/w8050180 (registering DOI) - published 29 April 2016 Show/Hide Abstract
Abstract: The mode of vertical recharge to aquifers is important to the application of appropriate recharge estimation methods. This study identifies the origin, geochemical evolution and mode of vertical leakage to the Gambier Basin confined aquifer, south east of South Australia. The recharge zone spans areas of the Glencoe-Nangwarry-Nagwarry (GNN). The Hundreds of Glencoe and Nangwarry are in South Australia, and the Parish of Nagwarry adjoins Nangwarry in western Victoria. The plot of stable isotopes of water molecules, δ2H versus δ18O, indicates that local rainfall with minor surface evaporation is the source of recharge. The results of hydrochemical analysis indicate that the sources of ions in the recharge zone groundwater are derived from carbonate and silicate weathering with cation exchange. The majority of water types (66% of samples) within the South Australian part of the recharge zone show Ca-Na-HCO3-Cl due to carbonate dissolution processes, and about 83% of samples within the Victorian part of the recharge zone show Na-Ca-HCO3-Cl water types, indicating cation exchange or mixing with other waters. The influence of faults on vertical leakage was studied at eight sites located in the Nangwarry and Nagwarry area using electrical conductivity logging, measuring the concentration of radiocarbon activity, δ18O, 222Rn and terrigenic 4He in the vertical profiles. Results show that regardless of land use in the study area, the interconnection of the unconfined Tertiary limestone aquifer with the Tertiary confined sand aquifer occurs, via both diffuse and preferential flows. Thus, the application of conventional vertical leakage estimation methods using Darcy’s equation or the application of tracer techniques may be inappropriate unless the duality of the flow system is considered.
Water2016, 8(5), 177; doi:10.3390/w8050177 (registering DOI) - published 28 April 2016 Show/Hide Abstract
Abstract: The impact of climate change on the hydro-climatology of the Indian subcontinent is investigated by comparing statistics of current and projected future fluxes resulting from three RCP scenarios (RCP2.6, RCP4.5, and RCP8.5). Climate projections from the CORDEX-South Asia framework have been bias-corrected using the Distribution-Based Scaling (DBS) method and used to force the HYPE hydrological model to generate projections of evapotranspiration, runoff, soil moisture deficit, snow depth, and applied irrigation water to soil. We also assess the changes in the annual cycles in three major rivers located in different hydro-climatic regions. Results show that conclusions can be influenced by uncertainty in the RCP scenarios. Future scenarios project a gradual increase in temperature (up to 7 °C on average), whilst changes (both increase and decrease) in the long-term average precipitation and evapotranspiration are more severe at the end of the century. The potential change (increase and decrease) in runoff could reach 100% depending on the region and time horizon. Analysis of annual cycles for three selected regions showed that changes in discharge and evapotranspiration due to climate change vary between seasons, whereas the magnitude of change is dependent on the region’s hydro-climatic gradient. Irrigation needs and the snow depth in the Himalayas are also affected.
Water2016, 8(5), 175; doi:10.3390/w8050175 (registering DOI) - published 28 April 2016 Show/Hide Abstract
Abstract: The meaningful participation of stakeholders in decision-making is now widely recognized as a crucial element of effective water resource management, particularly with regards to adapting to climate and environmental change. Social learning is increasingly being cited as an important component of engagement if meaningful participation is to be achieved. The exact definition of social learning is still a matter under debate, but is taken to be a process in which individuals experience a change in understanding that is brought about by social interaction. Social learning has been identified as particularly important in transboundary contexts, where it is necessary to reframe problems from a local to a basin-wide perspective. In this study, social learning is explored in the context of transboundary water resource management in the St. Lawrence River Basin. The overarching goal of this paper is to explore the potential role of serious games to improve social learning in the St. Lawrence River. To achieve this end, a two-pronged approach is followed: (1) Assessing whether social learning is currently occurring and identifying what the barriers to social learning are through interviews with the region’s water resource managers; (2) Undertaking a literature review to understand the mechanisms through which serious games enhance social learning to understand which barriers serious games can break down. Interview questions were designed to explore the relevance of social learning in the St. Lawrence River basin context, and to identify the practices currently employed that impact on social learning. While examples of social learning that is occurring have been identified, preliminary results suggest that these examples are exceptions rather than the rule, and that on the whole, social learning is not occurring to its full potential. The literature review of serious games offers an assessment of such collaborative mechanisms in terms of design principles, modes of play, and their potential impact on social learning for transboundary watershed management. Serious game simulations provide new opportunities for multidirectional collaborative processes by bringing diverse stakeholders to the table, providing more equal access to a virtual negotiation or learning space to develop and share knowledge, integrating different knowledge domains, and providing opportunities to test and analyze the outcomes of novel management solutions. This paper concludes with a discussion of how serious games can address specific barriers and weaknesses to social learning in the transboundary watershed context of the St. Lawrence River Basin.