Environmental flows: assessment and implementation in IRES

Intermittent rivers and Ephemeral Streams (IRES) are river water bodies characterised by temporary flow. Intermittent streams may dry up for some period of time within the year, while ephemeral streams flow only for a small period, usually after rainfall events. Such systems are widespread throughout the world. Intermittence of IRES is characterised by high variability, both in space and time, and can be caused by different reasons, naturally or artificially i.e. dry conditions, freezing of streams, small catchments, water abstraction etc. The purpose of this handbook is to help water managers to understand the natural processes prevailing in IRES and the importance of this type of streams for biodiversity, but also for local communities. Since it is widely accepted that this type of system has been up to recently neglected, the transfer of knowledge from scientists to water managers for better understanding IRES and the provision of tools for managing them in the best possible way, is considered crucial for their preservation. Furthermore, water authorities need to revise their River Basin Management Plans (RBMPs) in six-year cycles according to the Water Framework Directive (WFD), in which methods to assess ecological status for temporary rivers and suitable measures to protect and/or enhance them will be required.