EAR methodology: an approach to Sustainable Urban Water Management
International audience ; In the last few decades, urban drainage systems have become much more than a simple removal of storm-water and sewage out of the city. Urban water management must adapt to the city and its evolutions; the driving forces are numerous with a diverse range of origins: social evolution (increasing expectations regarding levels of service), societal evolution (increasing complexity of regulations and institutions, which make urban water management more complex), environmental evolution (climate change and its consequences, etc.), technologic evolution (including new monitoring possibilities), economic evolution (global markets, share of costs between stakeholders). Importantly, urbanization has had significant impacts on urban water cycle (Chocat et al., 2007). Pressure exerted on cities and, in our context, on urban water system has lead to the need to consider more functions, thus making it necessary to modify (expand) the boundaries of the system. Urban water system must include drainage system, the catchment and the city itself, in order to establish a balance between each of the three sub-systems. This will enable functions such as ecosystem protection, water resource scarcity, adaptability, re-use of storm and waste waters to be promoted. Studies identifying these functions is well documented (Ashley et al., 2002 ; Ashley et al., 2007 ; Chocat et al., 2007 ; Fletcher et al., 2009 ; Novotny et Brown, 2007 ; Wong et al., 2008). This sustainable water management presents a worldwide challenge for the 21st century. In the scope of this challenge, it is necessary to replace traditional management approaches by a new concept, often referred to as sustainable urban water management (SUWM) (Brown et al., 2006; De Graaf, 2009; Hellström et al., 2000; Kaufmann, 2007; Larsen, 1997; Mitchell, 2009). One key aspect of this approach is the necessity that storm water and wastewater should become again considered as a resource (as they were a few centuries ago) and not as a nuisance or a risk (Chocat et al., 2007). This new paradigm introduces the necessity to evaluate new methodological approaches and new tools and technologies. In terms of methodological approaches, recent research has focused on three main directions: performance indicators (Matos et al., 2003), guidelines (Boogaard et al., 2008; Hall and Lobrina, 2009; Lems et al., 2006) and decision-support tools dedicated to a part or the whole system (Förster et al., 2003; Taylor et al., 2006; Le Gauffre et al., 2007 ; Moura, 2008; Saegrov, 2006). However, sustainable urban water management must also consider means of interactions and cooperation between all stakeholders and institutions, at the catchment-scale and at the city-scale. Methods must thus address both technical facilities (devices, treatment systems, etc) and the organisations (local authorities, private enterprise, community group, etc.) which play a role in urban water management. The objective of our project (Granger, 2009; Cherqui et al., 2009) is to develop and test a multi-disciplinary assessment management methodology, which gives (i) urban water manager the ability to measure the provided service by urban water system; and gives (ii) stakeholders the ability to choose a strategy that matches their expectation of the service provided. An implicit objective of this project is to initiate a cooperative relationship between service provider, local government and others stakeholders. This close collaboration has been initiated thanks to this project.