Assessing productivity changes in water companies: a comparison of the Luenberger and Luenberger-Hicks-Moorsteen productivity indicators

ABSTRACT

Interest in evaluating productivity changes in water companies has increased in recent years. In this paper, for the first time, we employ the Luenberger-Hicks-Moorsteen Productivity Indicator (LHMPI) to evaluate productivity changes in a sample of Chilean water companies from 2010 to 2016. Productivity change estimations obtained by both the Luenberger Productivity Indicator (LPI) and the LHMPI are compared. Moreover, both indicators were computed assuming constant and variable returns to scale technologies. The LHMPI estimates illustrate that productivity in Chilean water companies has slightly improved over the period studied due to the positive trend of outputs, whereas the inputs negatively contributed to productivity changes. Results from the empirical analysis enabled us to verify that the LHMPI and LPI (and their drivers) are statistically different. This conclusion illustrates that water regulators need to pay attention to the indicators used when assessing productivity changes in water companies.     

A composite indicator for water meter replacement in an urban distribution network

In water supply management, volumetric water meter are typically used to measure users' consumption. With water meters, utilities can collect useful data for billing, assess the water balance of the system, and identify failures in the network, water theft and anomalous user behaviour. Despite their importance, these instruments are characterised by intrinsic errors that cause so-called apparent losses. The complexity of the physical phenomena associated with metering errors in aging water meters does not allow meter replacement to be guided by single parameters, such as the meter age or the total volume passed through the meter. This paper presents a meter replacement strategy based on a composite ‘Replacement Indicator’ (RI) that aims to reduce apparent losses. The performance of a meter during its operating life was analysed by means of this indicator, which signals when the meter needs to be replaced. To test the reliability and robustness of the proposed indicator, a Monte Carlo uncertainty analysis was performed. The methodology was applied to a real case study: a district metered area (DMA) in the Palermo city water distribution network (Italy). The analysis showed that ranking based on the composite indicator is better than common ranking procedures based on typical variables (e.g., the meter error curve or the meter age): the proposed indicator can better select the meters to be replaced and favourably affect the associated costs.     

Review of multi-criteria decision aid for integrated sustainability assessment of urban water systems

Integrated sustainability assessment is part of a new paradigm for urban water decision making. Multi-criteria decision aid (MCDA) is an integrative framework used in urban water sustainability assessment, which has a particular focus on utilising stakeholder participation. Here MCDA is reviewed in the context of urban water management used in a decision making framework. Three other commonly used integrated approaches in urban water management (cost-benefit analysis, triple bottom line and integrated assessment) are compared with MCDA. Generic types of shortcomings associated with MCDA are discussed to provide an understanding of MCDA's limitation in urban water management decision making; including 1) preferential independency, 2) double counting and under-counting, and 3) transparency of MCDA methods and results.     

Metabolism-modelling approaches to long-term sustainability assessment of urban water services

There is a discernible need for a holistic, long-term and sustainability approach in decision-making in water and wastewater utilities around the world. Metabolism-based modelling, which can quantify various flows within an urban water system (UWS), has shown its effective usability for a more comprehensive understanding of the impacts of intervention strategies and can be used by any water utility for future planning of UWS. This study presents the main principles of a holistic Sustainability Assessment Framework which can be simulated by using two analytical, conceptual, mass-balance-based models to quantify relevant key performance indicators (KPIs) associated with the metabolic flows of the urban water cycle. These two models are WaterMet² (WM2) and dynamic metabolism model (DMM), developed recently under the aegis of the EU TRUST (Transitions to the Urban Water Services of Tomorrow) project. There are clear differences between the two models which make them useful in different contexts and circumstantial situations. DMM is a mass-balance consistent model which quantifies and presents annually-aggregated performance values for system wide energy consumption, emissions, environmental impacts and costs for the entire UWS though it is also possible to derive corresponding indicators for individual sub-systems (e.g. water distribution and wastewater transport). WM2 is the opposite of this, it is a distributed metabolism model which simulates water related and other resource flows throughout the UWS components with a higher resolution both spatially (e.g. multiple water resources and service reservoirs) and temporally (e.g. daily and monthly), and thereby is useful in contexts where utilities would like to focus on further details of the UWS metabolism with the aim to understand and solve specific problems. Overall, these two complementary metabolism-based approaches enable any water utility to quantitatively explore and understand the influences of different external drivers and intervention strategies on future performance profiles linked to any physical, environmental and economic criteria.     

A multi-criteria analysis for bridge sustainability assessment: a case study of Penang Second Bridge,Malaysia

Bridges are a critical part of our nation's economic prosperity and local community well-being. One of the latest trends in bridge engineering is sustainable design, which is designing so that resources are available for many generations to come. Sustainable design considers the ecological, economic and socio-cultural environments and works to balance all three. There are some sustainable infrastructure rating systems (RSs) available, such as Envision that can be applied to bridges. However, no system has been developed that would specifically apply to bridge sustainability assessment. The objectives of this study are first, to investigate bridge sustainability issues from three main aspects: environmental, economical and social; and second, to apply multi-criteria analysis to assess the sustainability of the Penang Second Bridge in Malaysia. A hierarchy structure of the sustainable bridge attributes was developed for each RS, and an analytical hierarchy process method was then applied for the appraisal of the sustainability of a bridge pertaining to the relative attributes. The research involved a committee of Malaysian bridge professionals to support the rational decision-making. The results reveal that the case study has achieved most of the criteria of the sustainability assessments.     

Action for sustainability: preparing an African plan for sustainable building and construction

Sustainable development, and by extension sustainable building, is an evolving concept that relies for its implementation on the development of regional and local approaches and solutions. There is, in particular, a split between the definitions, approaches and priorities in developed and developing countries. Subsequently, a process for creating an international agenda for sustainable building is needed to recognize these regional and local differences. Part of this process is the development of regional action plans for sustainable building and construction at a number of regional sustainable building conferences. The key elements of an action plan for Africa, based on a discussion session at the SB04 Africa Conference, are considered and placed within the African context and the larger international issues. The key issue is the establishment of a solid knowledge foundation for Africa that will equip the public, professionals, development agencies and governments with accurate and relevant knowledge generated within the framework of the continent's social needs, its cultures and its biophysical environment to guide their decisions and actions towards establishing a sustainable built environment.     

Use of salinity mixing models to estimate the contribution of creek water fecal indicator bacteria to an estuarine environment: Newport Bay, California

The contribution of freshwater discharge to fecal indicator bacteria (FIB) impairment of an estuarine environment can be approximated from simple, two end-member mixing models using salinity as a tracer. We conducted a yearlong time series investigation of Newport Bay, a regionally important estuarine embayment in southern California, assessing the concentrations of FIB, specifically Escherichia coli and enterococci bacteria, and salinity. In total, eight within-bay stations and one offshore control site were sampled nearly once per week and the three tributaries draining into Newport Bay were sampled approximately daily. Using salinity as a conservative tracer for water mass mixing and determining the end-member values of FIB in both the creek sites and the offshore site, we created a linear, two end-member mixing model of FIB within Newport Bay. Deviations from the mixing model suggest either an additional source of FIB to the bay (e.g. bird feces, storm drain discharge) or regrowth and/or die-off of FIB within the bay. Our results indicate that salinity mixing models can be useful in predicting changes in FIB concentrations in the estuarine environments and can help narrow the search for sources of FIB to the bay and enhance our understanding of the fate of FIB within the bay.     

Developing an integrated water management strategy to overcome conflicts between urban growth, water infrastructure and environmental quality: a case study from Ashford, Kent

Ashford, in East Kent, is a government‐designated growth area. Between 2001 and 2031, the town is set to grow by 31 000 homes and 28 000 jobs, almost doubling in size. This raises numerous concerns about the ability of the local water infrastructure and Kentish Stour catchment to accept this pressure in the short and long term. The Ashford integrated water management study (AIWMS) set out to address all the issues around water quality, water resources, biodiversity and flood risk to allow Ashford's growth to occur without unacceptable environmental damage. The study reviewed current problems with the water environment, established the key constraints to growth that might arise from the proposed development and identified water management strategies to accommodate Ashford's expansion. The paper reviews the integration methodology that was developed and discusses the lessons learned from the experience.     

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.     

Using water consumption smart metering for water loss assessment in a DMA: a case study

ABSTRACT

In this study we analyse the benefits that may be gained from using a smart metering system to assess water losses at a district level with reference to a real case. Consumptions of all the users of this district metered area (DMA) were monitored at an hourly time step by means of electromagnetic meters. Assuming that information on water consumption was available for only a portion of users, we then estimated the water consumption of the entire DMA and calculated the error committed in this estimation as the number of available users varied. Finally, as the simultaneous hourly pattern of inflow into the DMA was also available, we used the water balance method to assess water losses. The results obtained show that monitoring even only 60% of users makes it possible to achieve an error of less than 2% in the estimation of daily consumption across the entire DMA.     

Ensuring sustainable development for the German water sector: setting the stage for the risk-based sustainability management system (RSS)

Abstract

The service provision of drinking water and the disposal of waste water are severely challenged by changing framework conditions. Although service providers necessitate systematic information regarding sustainability risks, no available management tool accounts for them comprehensively. In the context of the project NaCoSi ‘Ensuring Sustainability for Urban Water Systems’, a risk-based sustainability management system (RSS) was developed. This paper aims to introduce RSS and to discuss its contribution towards companies’ viability and transformation in the water sector. The paper describes the comprehensive self-screening approach of RSS, which is based on a causal-chain concept and comprises steps of risk analysis, monitoring and mitigation. Results of the testing phase suggest the validity of risk analysis and its effectiveness in deriving measures. Thus, RSS can help to improve the ability of service providers by analysing challenges and communicating them.     

Variability of fecal indicator bacteria in flowing and ponded waters in southern California: implications for bacterial TMDL development and implementation

Recreational water quality is assessed by using water quality objectives for fecal indicator bacteria (FIB) including total coliform, fecal coliform (or E. coli), and/or Enterococcus. It is required under the Clean Water Act that a TMDL be developed for a bacteria-impaired water body. The development and implementation of bacterial TMDLs has proven challenging and often difficult due to unknown source(s) of FIB. This study found that FIB levels varied significantly in flowing water, ponded water, and associated sediment. FIB levels in isolated ponded water in waterways were significantly higher than in flowing water. Sediment under ponded water contained a great amount of FIB. Furthermore, FIB concentrations in ponded water tended to increase with increasing water temperature and to decrease with increasing water salinity. The result provides the field evidence of survival/growth of FIB in water and sediment under ambient conditions in southern California. A holistic approach including natural sources (e.g., a reference system) should be considered for practical and applicable purposes while developing and implementing bacterial TMDLs for pathogen-impaired waterbodies.     

水输送系数:水系统的重要评价指标

将水输送系数控制在合理的范围可以节省电能,避免水系统大流量、小温差运行。给出了供暖水系统和空调水系统合理的水输送系数计算公式和提高水输送系数的措施。     

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.     

A theoretical study of an innovative ejector enhanced vapor compression heat pump cycle for water heating application

This study presents a novel vapor compression heat pump cycle in which an ejector associated with a subcooler is applied to enhance the heating performance for air-source heat pump water heater application. The heating coefficient of performance (COP_h) and heating capacity of the novel cycle using the non-azeotropic mixture refrigerant R417A are theoretically investigated, for the ranges of evaporating temperature (−15 to 10 °C) and condensing temperature (55-60 °C). The theoretical results show that the COP_h and volumetric heating capacity of the novel cycle are better than that of the conventional heat pump cycle. It is found that for the operating conditions considered, the maximum COP_h and volumetric heating capacity can be improved by up to 1.62-6.92% and 15.20-37.32% over the conventional heat pump cycle, respectively. The performance characteristics of the novel cycle show its promise in air-source heat pump water heater applications.     

A decision support tool for sustainable planning of urban water systems: Presenting the Dynamic Urban Water Simulation Model

Population growth, urbanisation and climate change represent significant pressures on urban water resources, requiring water managers to consider a wider array of management options that account for economic, social and environmental factors. The Dynamic Urban Water Simulation Model (DUWSiM) developed in this study links urban water balance concepts with the land use dynamics model MOLAND and the climate model LARS-WG, providing a platform for long term planning of urban water supply and water demand by analysing the effects of urbanisation scenarios and climatic changes on the urban water cycle. Based on potential urbanisation scenarios and their effects on a city's water cycle, DUWSiM provides the functionality for assessing the feasibility of centralised and decentralised water supply and water demand management options based on forecasted water demand, stormwater and wastewater generation, whole life cost and energy and potential for water recycling. DUWSiM has been tested using data from Dublin, the capital of Ireland, and it has been shown that the model is able to satisfactorily predict water demand and stormwater runoff.     

Probabilistic environmental risk assessment of urban wet-weather discharges: an approach developed for Switzerland

Technical solutions aimed at limiting the impacts of urban wet-weather discharges are historically based on an end-of-pipe approach. The characteristics of wet-weather discharges, e.g. intermittent pollution loads, high variations in pollutant concentrations, effects in the receiving waters, etc., are generally not considered. This study presents a new probabilistic approach that links the characteristics of wet-weather discharges to their potential impacts in receiving waters. This new approach involves coupling a model for predicting fluctuating concentrations in rivers along with sediment changes to water quality criteria. The new approach produces a risk profile for receiving waters and includes assessment of uncertainty in input data as well as the uncertainty inherent in local receiving system processes. This new approach is expected to offer a better management of wet-weather discharges, resulting in lower environmental impacts.     

Solar disinfection (SODIS): simulation of solar radiation for global assessment and application for point-of-use water treatment in Haiti

Haiti and other developing countries do not have sufficient meteorological data to evaluate if they meet the solar disinfection (SODIS) threshold of 3-5 h of solar radiation above 500 W/m2, which is required for adequate microbial inactivation in drinking water. We have developed a mathematical model based on satellite-derived daily total energies to simulate monthly mean, minimum, and maximum 5-h averaged peak solar radiation intensities. This model can be used to assess if SODIS technology would be applicable anywhere in the world. Field measurements were made in Haiti during January 2001 to evaluate the model and test SODIS efficacy as a point-of-use treatment option. Using the total energy from a measured solar radiation intensity profile, the model recreated the intensity profile with 99% agreement. NASA satellite data were then used to simulate the mean, minimum, and maximum 5-h averaged peak intensities for Haiti in January, which were within 98.5%, 62.5%, and 86.0% agreement with the measured values, respectively. Most of the discrepancy was attributed to the heterogeneous nature of Haiti's terrain and the spatial resolution of the NASA data. Additional model simulations suggest that SODIS should be effective year-round in Haiti. Actual SODIS efficacy in January was tested by the inactivation of total coliform, E. coli, and H2S-producing bacteria. Exposure period proved critical. One-day exposure achieved complete bacterial inactivation 52% of the time, while a 2-day exposure period achieved complete microbial inactivation 100% of the time. A practical way of providing people with cold water every morning that has undergone a 2-day exposure would be to rotate three groups of bottles every morning, so two groups are out in the sun and one is being used for consumption.     

The quest for safe drinking water: an example from Guinea-Bissau (West Africa)

While humans require water for life, one-sixth of our species lives without access to safe water. In Africa, the situation is particularly acute because of global warming, the progression of the Sahara desert, civil unrest and poor governance, population growth, migration and poverty. In rural areas, the lack of adequate safe water and sanitary infrastructures leaves millions with doubtful water quality, increasing the harshness of daily life. In this paper, a pilot study was conducted during the wet season on Bolama Island (Guinea-Bissau, West Africa), a UNESCO Man and the Biosphere Reserve. Twenty-eight shallow wells, supplying water to most of the population, were sampled for microbiological, physical and chemical water quality characteristics. A ten-parameter water quality index (WQI) adapted to tropical conditions was applied to compare the different wells. About 79% of the wells showed moderate to heavy fecal contamination. From the surveyed parameters, it was found that chemical contamination was less important, although all samples were acidic, with the pH averaging 5.12+/-0.08. The WQI was 43+/-4% (0%-worst; 100%-best quality), showing that the water from the majority of wells was polluted but should be suitable for domestic use after appropriate treatment. At the onset of the wet season, diarrhea represented 11.5% of all medical cases, 92.5% of which were children aged <15. This paper suggests inexpensive steps to reduce the fecal contamination and control the pH in order to increase the potability of the well water and, concomitantly, to raise the living standards of the population in one of the poorest countries of the world.