Damien Granger

Assessing urban potential flooding risk and identifying effective risk-reduction measures.

Flood protection is one of the traditional functions of any drainage system, and it remains a major issue in many cities because of economic and health impact. Heavy rain flooding has been well studied and existing simulation software can be used to predict and improve level of protection. However, simulating minor flooding remains highly complex, due to the numerous possible causes related to operational deficiencies or negligent behaviour. According to the literature, causes of blockages vary widely from one case to another: it is impossible to provide utility managers with effective recommendations on how to improve the level of protection. It is therefore vital to analyse each context in order to define an appropriate strategy. Here we propose a method to represent and assess the flooding risk, using GIS and data gathered during operation and maintenance. Our method also identifies potential management responses. The approach proposed aims to provide decision makers with clear and comprehensible information. Our method has been successfully applied to the Urban Community of Bordeaux (France) on 4895 interventions related to flooding recorded during the 2009-2011 period. Results have shown the relative importance of different issues, such as human behaviour (grease, etc.) or operational deficiencies (roots, etc.), and lead to identify corrective and proactive. This study also confirms that blockages are not always directly due to the network itself and its deterioration. Many causes depend on environmental and operating conditions on the network and often require collaboration between municipal departments in charge of roads, green spaces, etc.

Transitioning to sustainable urban water management systems: how to define expected service functions?

Sustainable water management is a worldwide challenge for the twenty-first century. It involves replacing traditional management approaches with a new concept, often referred to as sustainable urban water management (SUWM). This paradigm shift means that SUWM systems must include new services, some of which have already emerged. However, no publications have presented the expected SUWM system in terms of the full range of services it would need to include, and no publications have proposed a method for identifying the services the system must provide. This paper proposes a method for identifying these services and presents a generic petal diagram to represent the service functions of the SUWM system. Moreover, this paper presents a new method for defining these services in a specific territory. This method is based on the confrontation between a general representation and the objectives of the stakeholders in a given system in a given territory. The method is illustrated with a full-scale case study on the Doua eco-campus (Lyon University). This method is intended to aid practitioners to manage its system and to transition to SUWM. It is designed to improve the transparency of decision formulation and to involve stakeholders in the process.

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 systems 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.