Staged cost optimization of urban storm drainage systems based on hydraulic performance in a changing environment

International audienceUrban flooding causes large economic losses, property damage and loss of lives. The impact of environmental changes mainly, the urbanization and the climatic change leads to increased runoff and increased peak flows which the drainage system must be able to cope with to overcome possible damage and inconveniences caused by the induced flooding. Allowing for detention storage to compliment the capacity of the drainage system network is one of the approaches to reduce urban floods. The traditional practice was to design systems against stationary environmental forcings ? including design rainfall, landuse, etc. Due to the rapid change in climate-environment, this approach is no longer economically viable and safe, and explicit consideration of changes that gradually take place during the life-time of the drainage system is warranted. In this paper, a staged cost optimization tool based on the hydraulic performance of the drainage system is presented. A one dimensional hydraulic model is used for hydraulic evaluation of the network together with a genetic algorithm based optimization tool to determine optimal intervention timings and amounts throughout the lifespan of the drainage network. The model was applied in a case study area in the city of Porto Alegre, Brazil. It was concluded that considerable financial savings and/or additional level of flood-safety can be achieved by approaching the design problem as a staged plan rather than one-off scheme

Development of GIS based contamination risk assessment in water distribution systems

The study aims at developing a GIS based contamination Risk Assessment procedure in water distribution systems. Water distribution network analysis model EPANET 2.0 was integrated with ArcGIS 8.3 for the water quality analysis retrieving data from the GIS database. Water supply system of Zone VIII of Guntur, India was selected for the case study. The results of water quality simulation were displayed in the GIS interface and the areas affected were mapped with the spatial analyst tool of GIS. Data on number of household connections and standpipes affected by a particular event of contamination was also retrieved from the GIS database. The events resulting in high risk were identified from the GIS maps. This information helps in the decision making process of prioritizing the maintenance activities particularly, in case of limited fund availability. Since the resource availability for maintenance activities are limited in developing countries, prioritizing the activities using GIS helps to achieve maximum risk reduction

Intermittent urban water supply under water starving situations

Rapid population growth in urban areas exerts negative pressure on existing water supply systems, whilst developing additional water sources is unrealistic option for many water companies in developing countries facing limited financial resources. As an alternative, intermittent water supply has been implemented there in attempt to distribute available water to as many people as possible, despite considerable negative impacts such approach is carrying. This paper summarises the main issues associated with intermittent supply, focusing to the importance of categorising the emerging problems. Required measures to improve the water supply situation of certain urban area should therefore differ according to the category of the problems. Moreover, these measures should also be realistic in meeting the consumers’ needs. New design guidelines, which could enhance equitable distribution and convenience for consumers, are suggested as a tool for design optimisation of urban water distribution systems with intermittent supply

Performance-based optimization of land and water resources within irrigation schemes I: Method

Optimum land and water allocation to different crops grown in different regions of an irrigation scheme is a complex process, especially when these irrigation schemes are characterized by different soils and environment and by a large network of canals. At the same time if the water supply in the irrigation schemes is limited, there is a need to allocate water both efficiently and equitably. This paper describes the approach to include both productivity (efficiency) and equity in the allocation process and to develop the allocation plans for optimum productivity and/or maximum equity for such irrigation schemes. The approach presented in this paper considers the different dimensions of equity such as water distribution over the season, water distribution during each irrigation, benefits generated. It also includes distribution and conveyance losses while allocating water equitably to different allocation units. This paper explains the approach with the help of Area and Water Allocation Model (AWAM) which uses the simulation-optimization technique for optimum allocation of land and water resources to different crops grown in different allocation units of the irrigation scheme

Performance based land and water allocation within irrigation schemes: 2: Application

The Area and Water Allocation Model (AWAM) which uses simulationoptimization technique for optimum allocation of land and water resources to different crops cultivated in different allocation units of the irrigation scheme was modified to include both productivity and equity in the process of developing the allocation plans for optimum productivity and/or maximum equity. This paper illustrates the potential of this approach with the help of a case study on Nazare medium irrigation scheme in India. The allocation plans were developed for optimization of different performance parameters (productivity and equity) for different management strategies based on irrigation amount and irrigation interval and cropping distribution strategies of free and fixed cropping. The results indicated that the two performance objectives productivity and equity conflict with each other and in this case, equitable water distribution may be preferred over free water distribution at the cost of a small loss in productivity. Though these results relate to one case study, they show the value of the approach of incorporating productivity and equity in the allocation process with the help of the simulation-optimization model described in the companion paper. 1 Director, (E-mail: [email protected]; Fax: +44 (0) 1509 211079. 2 Associate Professor, Mahatma Phule Agricultural University, Rahuri, India-413722 and Academic Visitor (E-mail: [email protected]/[email protected]) 3 Senior Lecturer (E-mail: [email protected]) Water Engineering and Development Centre (WEDC), Department of Civil and Building Engineering, Loughborough University, Loughborough, Leicestershire, LE11 3T

Water loss management: a case study of Ho Chi Minh City, Vietnam

Ho Chi Minh City in Vietnam has very high non-revenue water (NRW) of 91 million m3/year (about 40% of total production) while there is shortage in water supply in the city. Analysis of the causes and components of such high water losses is necessary to develop programmes for its reduction. This paper reviews the existing water supply and losses in the distribution systems, their components based on the field data and analyses it by calculating different water loss indicators. It was found that NRW is composed of 83% real losses and 17% apparent losses. Invisible leaks in the service pipes (due to ageing) is the major cause of water losses. There are no proper water auditing, distribution system maps or databases to quantify the water losses components accurately. The study showed that there is high potential for water saving in Ho Chi Minh city by implementing several short-term and long-term measures

A GIS based spatial decision support system for modelling contaminant intrusion into water distribution systems

The paper presents a GIS based spatial decision support system for modelling contaminant intrusion into water distribution system. Three models have been developed to simulate the process and risk of contamination. A seepage model predicts the contaminant zone of pollution sources and the change of concentration during migration through soil. A pipe condition assessment model ranks the condition of water pipe in terms of the potential of contaminant ingress. An ingress model combines the geometry algorithm with contaminant zone to obtain the potential pollution areas of water distribution pipe. The three models were integrated with ArcView GIS for supporting decision making for risk mitigation. Zone VIII of water supply system in Guntur, India was selected for the case study. The contaminant ingress potential and potential pollution area of water pipes were displayed as thematic maps in GIS. The areas resulting in high risk were identified from the GIS maps. The availability of resources for maintenance activities are limited in developing countries. Thus GIS based spatial decision support system helps to achieve maximum risk reduction

Assessing impacts of climate change on Lake Victoria Basin, Africa

The Nile River is mainly sourced by the Lake Victoria basin catchment. Potable water is vital in this region. Greenhouse gases induced climate change is believed to affect the water resources system leading to alteration in planning and management. Previous studies had been carried out in focus on the pollution, fisheries, wetland of the Lake Victoria basin, while limited research in view of the effects of climate change on hydrological regime. In view of the importance of water in that region, assessing the potential climate change impacts is necessary. Factors such as downscaling of climate scenarios obtain from general circulation models and climate scenarios should be taken into consideration

Reliability assessment of the Nonsan distribution network by the method of Ozger

The importance of water distribution network reliability is continuously growing nowadays in South Korea in order to improve the level of service to the consumers. The distribution network in the city of Nonsan occasionally experiences insufficient pressures and water quality problems. The reliability assessment of this network was performed according to the method of Ozger. The computer programme developed with EPANET Toolkit functions in Visual C++ language based on this method, conducts the Pressure-Dependent Network Analysis (PDNA). For more realistic assessment, the model network was analysed under the assumption of single pipe failure and with extended-period simulations for various ‘what-if’ scenarios. Prognosis of the reliability was established by using the life distribution models, which can describe an increase of pipe failure rates. According to the results, the reliability of the system is presently considered as satisfactory but the deterioration of the situation can be expected within a period of 10-15 years

Improving risk assessment and management in urban water supplies

The current approach to management of microbial risks in distribution systems places a high reliance on the results of testing indicator bacteria. There is evidence of the fundamental weaknesses of sole reliance on such approaches as the number of samples taken represent a minute proportion of the water supplied and studies have demonstrated that this approach results in limited protection of consumer health (Payment, 1991)