Water Supply Systems

Several empirical and analytical approaches such as cost benefit analysis, life cycle analysis, community cost incorporating life cycle and environmental cost, and various multi-criteria assessment methods can be employed to provide an integrated assessment of hybrid water supply systems performance [22,31]. Of the various approaches, multi-criteria decision analysis (MCDA) is a technique that explicitly considers the multiple criteria in a decision making environment that aims to improve the transparency, auditability and analytical rigor of these decisions [43]. This approach has been widely utilized for urban water system analysis in several studies [24,44–47]. MCDA evaluates and ranks the finite number of decision options based on the weights of a finite set of criteria [45]. There are several MCDA methods used for water resources management problems. The most commonly applied methods includes fuzzy set analysis, Compromise Programming (CP), Analytic Hierarchy Process (AHP), Elimination et Choice Translating Reality (ELECTRE) and Preference Ranking and Organization Method for Enrichment Evaluation (PROMETHEE) [44]. These methods differ from each other in the methodology they use, the quality and quantity of the extra information they need, the sensitivity tools they offer, their ease of application, the mathematical properties they verify and availability of software [48]. The PROMETHEE method based on a pair-wise comparison [49,50] of options is proposed for this study because of its transparent computational procedure and the comparatively low time and effort needed by the Decision Maker to reach a conclusion [51]. The D-Sight Software [52,53] based on PROMETHEE will used in this study to rank alternative scenarios.

The use of computational modelling is a critical element in the processes, practices, management and operation of urban water supply systems. However, uncertainty exists throughout all aspects of managing and modelling urban water supply systems, from the collection and handling of data, the interpretation of the physical system into a computational simulation, accuracy of future predictions, value of input variables, operation of the model, etc. This uncertainty propagates through the model to the model output: the yield. Following, this uncertainty in the estimation of yield will be instilled onto any management policies derived from the yield estimate. Although the exact realisation of yield is impossible to obtain (due to the variability that occurs from climate events and lack of knowledge of the optimal position of the system polices, rules and thresholds), certainty in its estimation can be improved by identifying highly influential input variables, and investigating and refining their knowledge. This will improve the confidence in the yield estimate and any management procedures and processes that consider it, leading to optimised system policy development and enforcement, augmentation studies, water sharing strategies and other decision-making practices, as well as an optimal target demand.

In the last decades, climate change is affecting several aspects of human and natural systems worldwide. Concerning water resources, the main impacts are related to the combined effect of temperature increase and changes in availability and distribution of precipitation, which affects both quantity and quality. The Mediterranean is potentially very sensitive to climate change. In Calabria (Southern Italy) the projected reduction suggests a particular care in matching water resource availability and needs. In this paper, the province of Crotone in Calabria was analyzed as a study case. This area is characterized by a sufficient availability of resources as a whole when compared with the needs of the users, but with an unbalanced distribution through its networks. This condition requires the identification of a resource allocation optimization solution. Using a least-cost optimization model, water resource optimization solutions were identified and compared starting from a review of the existing water supply systems, taking into account both current water availability and possible future availability due to climate change.

The ability of water supply systems to operate satisfactorily for potential future demands and future hydrologic conditions is a critical objective for water management. Rather than base evaluations of water supply systems on cost and benefits alone, Hashimoto et al. developed a framework to assess system performance using risk-related performance criteria to understand how infrastructure may perform in an uncertain future [ Has82 ] . Reliability, resilience, and vulnerability are based on moderate common failures, such as light droughts that do not allow reservoir systems to meet contracted water services. Resilience (or engineering resilience for clarity [Thr09]) is defined as the time required for a system to recover from failure, once failure has occurred, and mathematical formulations were developed to calculate engineering resilience for a system [ Has82; SS11 ] . Another definition for engineering resilience was provided as the time taken for a system to return to a state of pre-disturbance [ Pim84 ] . Engineering resilience has been applied broadly and extended to evaluate many water supply systems [ SS11; Rom17; Meh15; Joã18; OVSS18; MA13; Tom18 ] . Dynamics in the engineering resilience of water supply systems were tested based on changes due to a non-stationary climate and population growth [ Joã18; Zha18 ] .

Hybrid water supply systems are typically installed in order to achieve more than one objective [15]. Multi-criteria decision analysis (MCDA) helps decision makers to incorporate preference data on multiple, sometimes conflicting priorities into evaluation and thereby select the best solution from a set of alternatives by assessing performance against a range of criteria [3,14,16]. MCDA provides the means to develop future strategies and a systems science methodology to make judgements about trade-offs, ranking servicing options in the presence of objectives and constraints which are sometimes noncommensurable and conflicting [17]. Thus, MCDA has been widely applied in water resources planning [18]. Only some MCDA methods are able to incorporate aleatory and epistemic uncertainty into assessments [19]. This paper evaluates several hybrid water supply scenarios through multi-criteria decision analysis using the Preference Ranking Organization METHod for Enrichment Evaluations (PROMETHEE) outranking method. It uses water and contaminant balance results from [15] as input for the MCDA analysis.

Abstract. Water supply systems (WSSs) are vital infrastructures for the well-being of people today. To achieve good customer satisfaction the water supply service must always be able to meet people’s needs, in terms of both quantity and quality. But unpredictable extreme conditions can cause severe damage to WSSs and lead to poorer levels of service or even to their failure. Operators dealing with a system’s day-to-day op- eration know that events like burst water mains can compromise the functioning of all or part of a system. To increase a system’s reliability, therefore, designs should take into account operating conditions other than nor- mal ones. Recent approaches based on robust optimization can be used to solve optimization problems which involve uncertainty and can find designs which are able to cope with a range of operating conditions. This paper presents a robust optimization model for the optimal design of water supply systems operating under di ff erent circumstances. The model presented here uses a hydraulic simulator linked to an optimizer based on a simulated annealing heuristic. The results show that robustness can be included in several ways for varying levels reliability and that it leads to more reliable designs for only small cost increases.

The nation's metropolitan or provincial water supply facilities are generally equipped with safe water supply facilities (Wheon-hwa et al., 2013; Korea Environment Corporation, 2014; Hyun-je et al., 2016). However, the village water supply system, which uses underground or valley water as its source as its main water supply facility in rural areas, is a blind spot for water contamination and facility management, requiring improvement through accurate diagnosis of the water quality and operation management of the facilities (Sang-min, 2009). The improvement of safety concerning the quality of water and facilities of the village water supply is seen as an urgent diagnosis and improvement task considering that the contamination of various chemicals used in agriculture, including air pollution, and drinking water sources caused by agricultural materials and livestock waste water, is one of the factors threatening a healthy living environment and safe life (Ministry of Health, Labor and Welfare, 2009a; Percival et al., 2004; USEPA, 2003; WHO, 2008). Most of the drinking water used in rural areas of Korea was shallow wells or government wells before 1970s (Ministry of Environment, 2016; Ministry of Environment, 2018). The well was installed inside the house, and was supplied with unsanitary drinking water to old facilities that are likely to be contaminated by adjacent toilets, livestock slaughter facilities, and sewage. In order to improve the reality of drinking water of villages in rural area, the government established a small water supply systems in the rural areas, which was 20 houses or higher, from 1970 to 1987, and used it as a major source of water to supply safe drinking water. Since then, the small water supply system has been supplying hygienic drinking water to farming and fishing villages, improving the residential and residential environment and enhancing residents' health and cultural life. Currently, the construction and management services of local water supply facilities are wholly delegated to the head of local governments (Sung-ryul, 2011; Jeong-hak and Kwang- hyun, 2007; Ministry of Agriculture, Food and Rural Affairs, 2018; Hamouda et al., 2018; Park and Gyeong-mi, 2012).

Genomes (chromosomes) are made from units called genes, i.e. decision variables arranged in a linear succession where every gene controls the inheritance of one or several characteristics (Fig.2). In the case of water- supply systems, the decision variables can be the diameters of the pipes, the range of which can vary in accordance with supplier-fixed diameters. The genomes can be represented in a number of ways. The simplest approach uses binary encoding where each chromosome consists of a string of binary digits (sequences of ones and zeros). It is important to know which gene carries information about a certain decision variable. For example, the first gene in Fig. 2 controls the inheritance of the value for a tank’s elevation.

Abstract: In the domestic water supply industry, the reduction of pumping costs is a continuing objective. With the efficient scheduling of pumping operations, it is considered that 10% of the annual expenditure on energy and related costs may be saved. A typical cost function will include all of the expenditure caused by the pumping process and also consider the electrical cost of pumping taking into account the various electrical tariffs, as well as peak demand and pump switching costs. Using only fixed speed pumps, it is possible to use an efficient dynamic programming based method, provided that the storage reservoir levels are known. Other techniques that are showing fruitful results in optimisation are genetic programming and simulated annealing. This paper compares these methods and discusses which is more appropriate in this type of pump scheduling problem.

The general opinion of reviews by Yakowitz (1982) and Yeh (1985) on systems analysis applications of water resources systems is that dynamic programming (DP) can be successfully used [r]

Over the centuries, Qanats have served as the main sup- plier of fresh water in arid regions of Iran. They provided the opportunity for people to live in extremely dry zones (even in deserts), and thus helped harmonize the popu- lation distribution across the country. Also, farming in saline and alkaline lands became possible using the water supplied through Qanats. In countries with active Qanat systems, socio-economic changes along with some tech- nical drawbacks associated with Qanats (i.e. long con- struction time, lower rate of water withdrawal, etc.) have significantly increased the use of motor-equipped deep water wells since 1950s. In this sense, comparing a Qanat system with a typical deep well, through their service life, may reveal and highlight the benefits of employing this ancient water supply system in arid areas (Beaumont 1971; Haeri 2003; Alizadeh 2008; Boustani 2008; Farzad- mehr and Nazari Samani 2009; WH 2015):

Abstract: This paper presents a monitoring-based investigation of rainwater collection systems using economic performance indicators in a group of households with nonconventional end-uses for rainwater that are not traditionally associated with rainwater supply. The monitored data for five household rainwater tank systems were analysed in two stages. For the first stage, the data was empirically analysed to develop a method to predict effective roof catchment areas. For the second stage, the effective roof catchment areas, together with roof area connection percentages, were analysed against different types of water demands in individual households. The individual systems were investigated for yield capacities, costs and water security using a modified Roof Runoff Harvesting Systems average annual yield model based on daily water balance procedures. The Life Cycle Costing analysis of the systems using the model was based on the Capital Recovery Method by taking into consideration the capital costs as well as ongoing costs for maintenance, replacement and operation of the systems. The analysis established the optimal sizing requirements for the studied rainwater tanks and their corresponding roof area connectivity.

In the Northwest Province of Cameroon Plan is mainly implementing gravity water systems. The sustainability of such systems has been assessed, by comparing a sustainable performance with the actual performance of two implemented systems. This assessment is based on the definition of a sustainable rural water supply system, which is made operational in a framework of indicators. An advantage of gravity water systems is that it is relatively easy and cheap to maintain. This might also give an explanation why the systems in both case studies are still functional most of the time, in spite of the poor financial management. However this ‘managing of the situation’ is not in accordance with the definition of sustainability. Comparing the definition of sustainability with the results of the case studies shows that the facilities are functional and being used for about 95%, that it has institutionalised management and that it can technically be operated and maintained at local level. Both systems lack however the recovery of costs at local level and – especially Bamali – lacks the delivery of appropriate benefits to all users. Most striking is that the lack of planning doesn’t give the facilities the capacity to continue to function over a prolonged time of life. This leads to the conclusion that though some elements of sustainability are there, both systems cannot be called sustainable. Results show also that the project implemented with the traditional approach is more sustainable than the one implemented with the CMP-approach.

service for more North Carolinians at lower costs.. A regional approach to water supply also has potential disadvantages. One possible disadvantage of regionalization is the loss of reve[r]

Professor Ben Dziegelewski and Mr. Tom Bik of Southern Illinois University conduct research on the economic and technical performance of water systems and the factors that seem to correlate with success in system management. Their paper reflects the results of a recent study that developed performance benchmarks for small public water systems in the Midwest. Information from a survey allows them to profile the infrastructure, finances, and management of small systems. We learn that 40% of the systems surveyed had no water treatment and another 10% reported chlorination only. Ground water was the major source of drinking water. Eighty percent of systems have some sort of supplemental water storage to maintain pressure and meet peak demands. Most systems (59%) reported an increase in the population served. Yet, 17% of systems reported total revenues that were less than total costs, and more than 35% of systems with less than 500 customers had no reserve fund. Additionally, 51% of these systems had not increased their water rates during the past five years. Dziegielewski and Bik recommend the development of case studies to demonstrate successful techniques for achieving sustainability including successful engagement of consumers, restructuring, and regionalization alternatives.

Abstract - This paper presents the necessitate and value, and also conception of water supply systems which flows in flexibly and can deliver water with flexibility in occurrence rate, and duration beneath the control of the farmer at the specific relevance using a partial rate stipulate or other schedule."Obstruction"-Total capacity and reserve time is essential to pledge water delivery at the specific frequency and desired rate as well as it introduces the needed expressions. It emphasizes the conversion of the economical steady deliver canal flows flexibly on-farm convention throughout the usage of service area reservoirs located between the secondary and tertiary systems. Partially closed pipelines and level-top canals as automatic distribution systems which tries the farmers the requirement for daytime as well as at night . Probably on-farm deliveries it used to permit optimization of on-farm water management. This enhanced management which be the ultimate source of augmented food production after improving land, and water resources, crops and reached to their maximum level. This is preferable for farmer’s and will save their lots of time and increased their work level without any uncertainty.

Since such simple application of a certain percentage of hot water usage or hot water usage ratio in summer compared to winter without taking into account scale of hot water usage round the year or usage pattern by season would cause some economical difference compared to the actual usage of hot water, it would be necessary to conduct researches which would present thermal load sharing ratios for economical optimal-sized solar-powered hot water supply systems tak- ing into account the hot water usage by actual building type. In this context, this study would present a method of esti- mating optimal thermal load sharing ratios for solar- powered hot water supply systems by considering economi- cal scale and efficiency of facilities when applying solar- powered hot water supply systems based on the analysis of usage pattern of hot water facilities by building type through case study of hot water us-

Abstract: - Over the last few decades water stress has been increasing both due to an increase in water demand and reduced water supply. Water leakage reduction in public water systems is a crucial part of water demand management. Leakage is usually the largest component of distribution loss yet it is not subject to regulation other than management decision by utilities. Leakage in public water supply systems results in loss of purified drinking water but also means wasting the energy and material resources used in abstraction, transportation and treatment. It results in secondary economic loss as well, in the form of, damage to the pipe network, public health concerns as it increases the risk of bacterial contamination of water resources in cities for human consumption, and can increase pollution loads into the environment. Leaks in pipe networks can result for several situations. A water operator must have an understanding of the causes of leaks so that they can be both repaired and prevented in the future.

Sustainable use of water resources requires a modern approach for complex water systems management based on system’s modeling, as unsung operation alternatives may only be devised and tested through a model. The now available IT computing tools enable setting the traditional modelling methodologies for planning and operation of such systems in a new framework. The present work deals with the development of decision support models for optimizing the operation of complex water supply systems with multiple uses and focuses on the validation of the optimization model of the regional water supply systems managed by an Italian water utility. The software used is Aquator, a state-of-the-art commercial tool for generic water resources system simulation and operational optimization. The paper shows and comments the results of the validation of the model and uses them to draw some general principles for the validation of such kind of models: in fact, operational optimization models are conceived for the enhancement of systems management and performance. Consequently, while on the one side model output is expected to reflect the actual state of the system, on the other it can point out significant management enhancements.

Another constraint mentioned by 38% of the respondents was the decrease in water output in summer. The low water output was mostly experienced between August and October, a period with the highest temperatures and evaporation rates. Another concern raised by 11% of the respondents was the siting of the sand abstraction points surrounded by infertile soils for their crops and vegetables. This complaint arises because sand abstraction well points are cited at locations with the greatest water yield potential and not near good soils for establishment of irrigation gardens. A substantial 16% of the respondents found the hand pumps fitted to the sand abstraction system to be breaking down frequently. This augment the limitation cited by 22% of the respondents that of sand abstraction systems maintenance work being labour intensive and time consuming. Through water management committees, the villagers organize themselves to maintain the water supply systems and fix broken pumps. These villagers feel that this process sometimes take much of their valuable time which could alternatively been have used in their gardens or other productive uses. According to Nyoni (2009), if SASs are not properly designed, sand abstraction equipment can be vulnerable to flooding and clogging. Such a system will always keep villagers busy with the maintenance woks. It’s possible that poor design may have attributed to the SASs breaking down frequently leading to the maintenance work being labour intensive and time consuming. Finally 2 % of the respondents found the water pumps to be inaccessible. These respondents were handicapped people who were not able to use the pump to draw water. It is a regrettable oversight that such basic technologies fail to take into account the needs of the disabled members of the community regarding a basic need for life such as water.