An optimization model for water quantity and quality integrated management of an urban lake in a water deficient city

This paper presents an optimization model for water quantity and quality integrated management of an urban lake in a water deficient city. A representative water quantity and quality safeguard system served urban lake, including multi-source water supply facilities, recirculating water purification facilities and surplus water discharge facilities, is widely used in Chinese water deficient cities. Because it is complicated, any mismanagement will result in water quality deterioration, water waste and high operation cost. The presented model attempts to achieve the objectives of controlling water pollution, reducing economic cost and improving water utilization efficiency through an optimized operating water safeguard system. The model is applied to Qingjing Lake in Tianjin, China. Results show that the model plays a more positive role for water quantity and quality integrated management.     

Multi-objective optimization of water distribution networks

Two multi-objective approaches to the consideration of pipe breakage data in water distribution network designs are formulated. Both models are based on the constraint method for multi-objective analysis. One model analyses the relationship between initial capital cost and subsequent repair and maintenance costs. Pipe breakage data is used to restrict the repair costs permitted in the system. The other model examines the relationships between initial pipe costs and the reliability of the pipes within the distribution network. In this second model, both the worst case and average system performance are examined in relation to the cost making model a three-objective approach. The pipe breakage data is used to restrict the expected number of failures allowed in any link. The actual number of expected breaks occurring in each link is then used to develop Poisson-based probabilities of node isolation. Application of the two approaches shows that the information obtained from such multi-objective approaches gives improved understanding into the nature of the issues behind initial cost and repair cost and initial cost and system reliability.     

Regional water quality management for the Karun–Dez River basin, Iran

To achieve water quality goals in a river basin, a water quality management model (WQMM) has been developed through the geographic information system (GIS) approach and a mathematical water quality model. The developed model has been applied to the Karun and Dez Rivers, where water quality has decreased due to heavy pollutant loads from Khuzestan province cities and surrounding areas. Pollution sources, land use, geographic features and measured water quality data of the river basin were incorporated into the Arc‐View GIS database. With the database, the management model calculated management type and management cost for each management project in the river basin. Until now, river management policy for polluted rivers in Iran first penalizes pollution sources and then constructs treatment plants for the pollution sources whose wastewater is released untreated and for which the wastewater quality goal of the Iranian Department of Environment is not met. Different management projects with a time programme were proposed and they were compared with the results of the river quality without any management approach. It became clear that the results based on the management approach were much better than those for the unmanaged condition from the viewpoint of the achievement of water quality goals and cost optimization.     

Eco-EAR: A method for the economic analysis of urban water systems providing services

In the context of new challenges and emerging needs for transparency regarding users, urban water management is obliged to forge links between different technical fields. This implies managing interfaces between multiple stakeholders on the one hand, and ensuring the adaptability and sustainability of technical infrastructures on the other hand. In a period dominated by public spending cuts, the optimisation and efficiency of the system's infrastructures and the organisation of the stakeholders involved has become important for guaranteeing the continuity of the services provided. From the economic viewpoint, this challenge is related to tracking and reducing costs. Moreover, it also concerns the need to communicate arguments related to service costs to both users and stakeholders. Consequently, the “Eco-EAR” method was developed by adapting Functional Analysis (FA), Activity Based Costing (ABC) and Whole Life Costing (WLC) approaches in view to describing how the direct costs of the sewerage service provided by wastewater utilities are structured. The cost structure is analysed according to the activities and physical flows comprising the primary and secondary functions of an urban water management system. Three goals are targeted: i) to explain the costs of the system to the local authority (owners) and users; ii) to identify the activities that have the greatest impact on costs in order to plan cost reduction actions; and iii) to assess the apportionment of costs per activity and per physical flow, in order to better understand the system by combining both its economic and technical dimensions. The performance indicators proposed by the “Eco-EAR” method could also be used for benchmarking. The method is implemented in a real case study: the sub-system territory around the city of Mulhouse (northeast France) under the responsibility of a water management authority.     

Economies of scale and scope in Australian urban water utilities

This paper estimates economies of scale and scope for 55 major Australian urban utilities over the period 2005/06 to 2008/09. The models used specify operating and capital costs as a function of chemical and microbiological compliance, water losses, water quality and service, water main breaks, total connected properties, and urban water supplied. The input variables used to help determine water utility costs include the density of properties served and the sourcing of water from bulk suppliers, groundwater, recycling and surface water. In terms of economies of scale, the evidence suggests strong economies of scale at relatively low levels of output (50–75% of current mean output). In terms of product-specific economies of scale (increasing the scale of a specific output in isolation), there is substantially stronger evidence that the operating costs of urban water utilities would benefit from increasing scale with regard to chemical compliance, water quality and service complaints, and the number of connected properties. In contrast, capital costs would benefit from scale increases with regard to the management of water losses and water main breaks. For economies of scope, it is clear that there are substantial cost benefits from the joint production of treated quality water delivered across a network with minimal water losses and main breaks. The main cost advantage at all levels of output is decreasing water losses, and this would benefit both operating and capital costs.     

Risk‐based water resources planning in practice: a blueprint for the water industry in England

Resilient water supplies in England need to be secured in the face of challenges of population growth, climate change and environmental sustainability. We propose a blueprint for water resources planning that uses system simulation modelling to estimate the frequency, duration and severity of water shortages at present and in the context of future plans and scenarios. We use multiobjective optimisation tools to explore trade‐offs between these risk metrics and cost of alternative plans, and we use sensitivity analysis to identify plans that robustly achieve targets for tolerable risk, alongside other performance objectives. The results of a case study in the Thames basin demonstrate that the proposed methodology is feasible given commonly available data sets and models. The proposed method provides evidence with which to develop water resource management plans that demonstrably balance the risks of water shortages, costs to water users and environmental constraints in an uncertain future.     

Assessing the financial and environmental performance of underground automated vacuum waste collection systems

The development of underground infrastructures for the efficient management and collection of urban waste streams offers great advantages and solutions in tackling problems relating to these activities. Nevertheless, in order for such alternatives to gain acceptance and be further utilized, besides their advantages in effectiveness and in environmental friendliness, they must prove their efficiency in terms of financial performance. The paper analyses modern techniques available as the underground automated vacuum waste collection system (AVAC) and presents the financial and environmental assessment of a proposed system in replacement of an existing conventional waste collection scheme in Athens. The comparative financial assessment is undertaken using the equivalent annual cost methodology (EAC) where the capital expenditures and annual operational and maintenance costs for both alternatives are calculated. The findings show that these two systems have roughly the same cost performance using the equivalent annual cost analysis. Yet, they have noticeably differentiations in the operational and capital costs with the AVAC system having almost 40% lower operational cost requirements. Finally the environmental comparison of the alternatives focusing on the city’ air quality is further highlighting the superiority of the AVAC scheme. Thus, the selection of such a fixed underground infrastructure over a conventional one can be pursued as it offers equivalent financial performance and yet enhanced operational and environmental characteristics.     

Understanding data requirements for trihalomethane formation modelling in water supply systems

Tighter regulatory standards for trihalomethanes in drinking water have been introduced in many countries in response to improved epidemiological evidence. This has led to the need to model better the THM concentrations in water distribution systems in order to manage efficiently economic, chemical and microbiological factors. THM modelling is a challenging process given the complex chemistry and dependence on river catchment, water treatment works and distribution system characteristics. It is demonstrated that a good understanding of the system from raw water to tap is needed if cost effective models of appropriate fidelity are to be produced. For appropriate systems models can incorporate, through empirical relationships, raw water quality variations based on river flow predictions, aspects of unit process management decision making variables as well as distribution system characteristics. In many systems model fidelity and hence efficient management is constrained by a lack of knowledge of system response.     

Exploration of domestic water demand attitudes using qualitative and quantitative social research methods

The sustainable evolution of the urban water system requires the recognition of uncertainty embedded in both climate and human behaviour. A challenge that water managers and policy makers need to tackle, is to understand the way the society’s water demand behaviour is affected. The inaccuracy between attitudes and behaviours and the cognitive association of water use to living standards, hinders the projection of society’s response to management’s measures. Thus, it is necessary to identify leverage points, where water demand management policies should aim their efforts. This work presents two parts of a social research held in Athens: quantitative questionnaire gathering information regarding the domestic water demand attitudes and behaviours; and a series of qualitative interviews aimed at exploring in-depth, the domestic water use attitudes, and behaviours. This work presents the design and results of both methods and the combination of the quantitative results with insights from the qualitative work.     

Application of system dynamics for developing financially self-sustaining management policies for water and wastewater systems

Recently enacted regulations in Canada and elsewhere require water utilities to be financially self-sustaining over the long-term. This implies full cost recovery for providing water and wastewater services to users. This study proposes a new approach to help water utilities plan to meet the requirements of the new regulations. A causal loop diagram is developed for a financially self-sustaining water utility which frames water and wastewater network management as a complex system with multiple interconnections and feedback loops. The novel System Dynamics approach is used to develop a demonstration model for water and wastewater network management. This is the first known application of System Dynamics to water and wastewater network management. The network simulated is that of a typical Canadian water utility that has under invested in maintenance. Model results show that with no proactive rehabilitation strategy the utility will need to substantially increase its user fees to achieve financial sustainability. This increase is further exacerbated when price elasticity of water demand is considered. When the utility pursues proactive rehabilitation, financial sustainability is achieved with lower user fees. Having demonstrated the significance of feedback loops for financial management of water and wastewater networks, the paper makes the case for a more complete utility model that considers the complexity of the system by incorporating all feedback loops.     

Reliability based optimal design of water distribution networks considering life cycle components

Water distribution systems play an important role in supplying water to consumers in a timely and efficient manner. The importance and complexity of such systems lead to extensive research in the area of optimal design of water distribution networks. Traditionally, only system costs are considered in design with few models incorporating environmental impacts. This paper presents a model for designing sustainable water distribution networks by minimising life cycle costs and life cycle CO₂ emissions, while ensuring hydraulic reliability for the life time of the system. The model integrates a multi-objective genetic algorithm with water network simulation software, EPANET. A traditional benchmark water distribution network is used to demonstrate the model. Eight scenarios have been developed to test and validate the model for a variety of objectives with different constraints. Trade-offs between life cycle costs and life cycle emissions, along with hydraulic reliability of the system are illustrated.     

区域供冷系统枝状冷水输送管网的优化设计

在各并联管路压力损失相等的条件下建立了优化设计模型,其目标函数为系统的年度费用,由冷水泵的年运行费用、冷水泵的折旧费用、管道的折旧和维修费用及输水管道冷量损失费用组成。通过实例计算,得到以下结论:区域供冷系统冷水管路的设计不能按传统的等比摩阻或等流速设计思想进行;采用优化模型比等流速设计年度总费用约减少17%,具有明显的经济效益;若采用等流速设计,各节点的压降偏差较大,会增加运行调节的困难,容易产生水力失稳,既不利于系统的稳定运行,又增大了运行费用。     

THE ROLE OF PRICING ON INTEGRATED WATER MANAGEMENT AT THE INDUSTRIAL PARK LEVEL: A CASE OF TEDA

Increasing water shortage and water pollution issues have attracted people to seek an integrated water management approach. This paper presents an integrated water management model at the industrial park level by employing a case of TEDA. Such a model is an overall management model for optimizing water resources within an industrial park, seeking potential water reuse among industries, incorporating the size and cost of reclaimed wastewater delivery systems. The main focus of this paper is to test how pricing strategy can influence water reuse scenarios by doing a cost sensitivity analysis. The results Indicate that when being set at the correct level, increased water charges could help reduce freshwater use and wastewater discharge, while covering administrative costs, financing environmental improvements (e.g. cleaner production), or subsidizing the operation of the wastewater treatment plant and the maintenance of freshwater infrastructure, therefore, providing water reuse incentives for water users within an industrial park.     

Economic implications of water efficiency measures I: assessment methodology and cost-effectiveness of micro-components

Economic efficiency has recently become one of the primary objectives of water management decisions. In particular, as vulnerability of freshwater systems has become evident and there is a trend for water supply managers to look towards water demand management, identifying the cost of such measures is becoming increasingly important. In England and Wales, Part G of the Building Regulations requires that water consumption of a new dwelling should not be more than 125 litres/capita.day. However, while compliance with this is determined by the water use characteristics of the installed micro-components (WCs, showers, basin taps, kitchen taps, baths, dishwashers and washing machines), the cost to consumers resulting from installing water efficient micro-components is not clear. This paper evaluates the potential economic implications of water saving micro-components, assessed from the consumers’ perspective. A methodology has been developed and implemented to assess the cost-effectiveness of several types of water efficient micro-components. A range of cost assessment methods was applied, and critically reviewed comparing their outcomes. It was found that conventional cost assessment methods are unsuitable for identifying the least cost options to consumers. Of the applied methods, the modified annualised assessment method appears to be a relatively better option.     

An Assessment of Water Demand Management Options from a Systems Approach

A systems approach is used to model the urban water and wastewater system. Scenarios are developed for the implementation of a range of water demand management measures, including (a) leakage reduction, (b) the increasing use of water metering, (c) the replacement of standard WCs by low-flow WCs, and (d) the introduction of greywater recycling systems. These measures are assessed according to the water saving, cost per unit of water saved, and other indicators of the relative contribution to the sustainability of the system. Preliminary assessments of selected environmental costs and benefits are also included.     

项目施工阶段成本管理浅析

通过分析当前项目施工阶段成本管理过程中存在的问题,针对如何提高项目的经济效益,提出项目施工阶段成本管理的措施,运用科学、合理和实用的方法,降低成本支出,实现成本动态管理,通过成本管理提高施工企业的经济效益。     

An integrated approach to the layout and design of water distribution networks

A model for the least cost layout and design of looped water distribution networks has been developed. The model consists of two linked linear programming formulations. One linear program determines the least cost layout of a looped distribution network given an initial pressure distribution. The other model determines the least cost component design given an initial flow pattern or pipe layout. The linkage between the two linear programs is provided by the use of output from one linear program as input to the other. Since the constraints in the layout model may provide looping without ensuring true redundancy in the system, a layout review is necessary after solutions of the layout model. If true redundancy is not present a set of ‘optional’ constraints can be applied and the layout model solved again. The procedure is demonstrated by application to a sample network.     

Embodied energy comparison of surface water and groundwater supply options

The embodied energy associated with water provision comprises an important part of water management, and is important when considering sustainability. In this study, an input-output based hybrid analysis integrated with structural path analysis was used to develop an embodied energy model. The model was applied to a groundwater supply system (Kalamazoo, Michigan) and a surface water supply system (Tampa, Florida). The two systems evaluated have comparable total energy embodiments based on unit water production. However, the onsite energy use of the groundwater supply system is approximately 27% greater than the surface water supply system. This was primarily due to more extensive pumping requirements. On the other hand, the groundwater system uses approximately 31% less indirect energy than the surface water system, mainly because of fewer chemicals used for treatment. The results from this and other studies were also compiled to provide a relative comparison of embodied energy for major water supply options.     

Effective efficiency in water resources management using efficiency elasticity index

Effective efficiency (EE) is a water use performance indicator of a system, integrating net evapotranspiration, volumes of water in and out of the system (including reused water) and their qualities. In order to analyse the nature of management and its options in promoting efficiencies, an efficiency elasticity index (EEI) is developed using EE. The maximum value of EEI for a given net evapotranspiration sets a threshold value for EE under which the management of the system should be improved. This makes it possible to evaluate how good the management of a system is and allows the decision makers to analyse efficiency targets using a graphical approach (assuming that interventions have the same costs). Hypothetical examples and real irrigation cases from United States and Egypt show the practical utility of EE and the methodology developed through the use of EEI. It is also shown that classical efficiency should be used with caution.     

The costs of adaptation to climate change for water infrastructure in OECD countries

There is concern that climate change may greatly increase the costs of providing water infrastructure in rich countries, but the estimates available cannot be compared across countries. This paper develops and applies a top-down approach to estimate the costs of adapting to climate change on a consistent basis for different climate scenarios. The analysis separates (a) the costs of maintaining service standards for a baseline projection of demand, and (b) the costs of changes in water use and infrastructure as a consequence of changes in climate patterns. The engineering estimates focus on the direct capital and operating costs of adaptation without relying upon economic incentives to affect patterns of water use. On this assumption, the costs of adaptation are 1–2% of baseline costs for all OECD countries with the main element being the extra cost of water resources to meet higher level of municipal water demand. There are large differences in the cost of adaptation across countries and regions. Adopting an economic approach under which water levies are used to cap total water abstractions leads to a large reduction in the burden of adaptation and generates savings of $6–12 billion per year under different climate scenarios.