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The steady increase of urban population and the possible effects of climate change that may adversely affect the amount of water available in current water supply systems, makes the study of stormwater and rainwater harvesting and wastewater recycling a high priority. The basic proposition is that any system of water supply that can reduce the amount of water drawn from main reservoirs will be of benefit to the whole supply region especially in terms of drought security. This paper describes a versatile modelling framework which can simulate a wide variety of combinations of centralised and decentralised Integrated Urban Water Management schemes from the allotment to the whole suburb scale. The framework combines two modelling approaches. The first, called urbanCycle, simulates water supply and demand, stormwater and wastewater using allotments as the basic building block. Although urbanCycle can simulate processes in great detail, it assumes that the network forms a directed acyclic graph. This simplifies the connectivity logic but precludes investigation of systems with decentralised storage, feedbacks and multiple supply paths. To overcome this, a second model, called urbanNet, based on network linear programming, is embedded in the urbanCycle framework to enable the modelling of recycling and harvesting options, as well as on-the-fly supply and demand decision making, based on objectives rather than pre-set operating rules. [ABSTRACT FROM AUTHOR]

With the widespread realisation of the significance of climate change, urban communities are increasingly seeking to ensure resilience to future uncertainties in urban water supplies, yet change seems slow with many cities facing ongoing investment in the conventional approach. This is because transforming cities to more sustainable urban water cities, or to Water Sensitive Cities, requires a major overhaul of the hydro-social contract that underpins conventional approaches. This paper provides an overview of the emerging research and practice focused on system resilience and principles of sustainable urban water management Three key pillars that need to underpin the development and practice of a Water Sensitive City are proposed: (i) access to a diversity of water sources underpinned by a diversity of centralised and decentralised infrastructure; (ii) provision of ecosystem services for the built and natural environment; and (iii) socio-political capital for sustainability and water sensitive behaviours. While there is not one example in the world of a Water Sensitive City, there are cities that lead on distinct and varying attributes of the water sensitive approach and examples from Australia and Singapore are presented. [ABSTRACT FROM AUTHOR]

Waternet supplies clean and safe drinking water to the homes of almost one million Amsterdam citizens, and also collects and treats the resulting wastewater, ensuring its safe discharge back into the water system. Climate change poses a growing challenge. Firstly Waternet is affected by the consequences of climate change, such as longer periods of drought and heavier bursts of rainfall. Secondly, the company also plays a role in causing climate change, as emissions from the Amsterdam water chain contribute to global warming. This paper aims to focus attention on mitigation as an inseparable part of adaptation-programmes. The Climate Footprint methodology is applied to the integrated Amsterdam water chain: from the point of withdrawing water from the surface/groundwater water system for drinking water production, to the point of returning the purified wastewater to the surface water/groundwater system. In-between, the water is pre-treated with chemicals, transported, purified by dune-filtration, again treated for drinking water quality, distributed over the area of Amsterdam, used in households and industries, collected from there by sewers and pumps, transported to purification plants and finally again treated with chemicals and purified to end with acceptable surface water quality. The whole process generates CO2-emissions in three different ways: • Sewage treatment transforms the remains of human food consumption into CO2. These emissions do not originate from fossil fuels, but from food. They remain in a short carbon cycle and do not contribute to global warming. In fact, the sludge remaining from the purification plant is an important energy source. • Transport and purification processes require energy; this results in direct emissions e.g. in the case of fuel or natural gas use, and indirect emissions in the case of electricity. • The use of chemicals and materials for construction, transport systems, and all other facilities and services to keep the system running does require suppliers of these goods and services to consume energy and thus causes indirect emission. An inventory of these three different types of emissions is made for the (about) 1990 situation, the 2004 situation, and prognosticated for the 2007 situation. The 2004 situation reveals a 0.16 ton CO2 equivalent emission per person. Compared to the worldwide 4 ton emission per person, this would mean a 4% contribution from the urban water system. With all the improvements scheduled, a 50% elimination of greenhouse gas emissions looks attainable for the 2007 situation. Further possibilities for emission reductions may be found by talking to suppliers about the indirect emissions. [ABSTRACT FROM AUTHOR]

Climate change raises many concerns for urban water management because of the effects on all aspects of the hydrological cycle. Urban water infrastructure has traditionally been designed using historical observations and assuming stationary climatic conditions. The capability of this infrastructure, whether for storm-water drainage, or water supply, may be over- or under-designed for future climatic conditions. In particular, changes in the frequency and intensity of extreme rainfall events will have the most acute effect on storm-water drainage systems. Therefore, it is necessary to take future climatic conditions into consideration in engineering designs in order to enhance water infrastructure investment planning practices in a long time horizon. This paper provides the initial results of a study that is examining ways to enhance urban infrastructure investment planning practices against changes in hydrologic regimes for s changing climate. Design storms and intensity - duration -frequency curves that are used in the engineering design of storm-water drainage systems are developed under future climatic conditions by empirically adjusting the general circulation model output, and using the Gumbel distribution and the Chicago method. Simulations are then performed on an existing storm-water drainage system from NE Calgary to investigate the resiliency of the system under climate change. [ABSTRACT FROM AUTHOR]

This paper describes a probability-based method for assessing the potential impact of climate change on urban water supply systems. Specifically, the assessment method uses probability distributions to place a confidence level on the plausible values of response variables. The Benalla water supply system has been used to demonstrate applicability of the proposed assessment method. For the application, the impact of the 2030 climate change scenarios on streamflows and system yield has been examined. The preliminary results have demonstrated that the proposed assessment method can provide valuable insights into the impact of climate change on water supply systems, allowing it to be incorporated into planning decisions. [ABSTRACT FROM AUTHOR]