Mediterranean Case Study Environmental Flows and Integrated Water Resource Management: the Vomano River case study Stefano MARAN Environment Business Unit, CESI, Italy maran@cesi.it SUMMARY Recent developments of legislation in Italy tend to consider environmental flows in the context of Integrated Water Resource Management (IWRM). Here, IWRM has been defined “a process that promotes the coordinated development and management of water, land and related resources in order to maximise the resultant economic and social welfare in an equitable manner, without compromising the sustainability of vital ecosystems”1. It is considered a basic principle in sustainable development and in the search for ways to reconcile multiple and competing water uses with environmental protection. One important tool for implementing this approach in the water allocation process is multi-criteria analysis2, wherein an environmental flow assessment provides a way to quantify the environment criteria. The concept of a Minimum Instream Flow was originally introduced in Italy in the late 1970’s for a very the specific purpose, i.e. protecting the aquatic fauna downstream river diversion. Since then several different applications and interpretations have evolved that extend the original meaning. In some recent regulations, it is considered to be an instrument to achieve water quality targets – together with other measures, in the framework of the Regional Water Management and Protection Plan. Environmental flows are now prescribed in the national legislation in Italy in general terms, as framework laws. The individual River Basin Authorities are required to set up specific rules for rivers under their responsibility. Current norms consider environmental flows only in the form of a minimum instream flows to be present downstream of water diversions. Eventually these rules are to be acknowledged by Regional Authorities in their Water Protection Plans, in which other specifications can possibly be made (e.g. different MIF requirements to address specific issues). This case study describes a pilot scheme to integrate environmental flow assessments with IWRM tools in the Vomano River in central Italy. Rivers flows in this basin are highly regulated, mainly for hydropower generation. It shows how environmental objectives were incorporated in multi-criteria analysis to develop an integrated water resource management plan and flow regulation policies. Typically the main challenge in such circumstances is to define an environmental score that can be computed for different scenarios – one that is inaccessible to experimentation and measure. The approach described overcomes this problem by using existing Minimum Instream Flow methodologies to define an environmental score, and combine this with Bayesian Belief Network techniques. It was thus possible to involve stakeholders explicitly in flow tradeoffs using multi-criteria formulations, and recommend an environmental flow regime that reflected both scientific analyses using the best available information and stakeholder perspectives.