Environmental flows from dams: the water framework directive

Abstract

The EU water framework directive (WFD) provides a template for sustainable water management across Europe. The WFD requires the development of procedures to ensure appropriate mitigation of anthropogenic impacts on river ecosystems resulting from water abstraction and impoundments. It is widely acknowledged that alterations to flow regime impact on riverine ecosystems. As a result, hydromorphology, which includes the hydrological regime, is embedded within the WFD as a supporting element to achieve good ecological status (GES). Environmental flow releases from impoundments such as reservoir dams will need to be implemented to mitigate impacts from their construction and operation. This paper outlines the process involved in the analysis of available scientific information and the development of guidance criteria for the setting of environmental flow release regimes for UK rivers. The paper describes two methods-developed by round-table expert knowledge and discussions and supported by available data-for implementation of the WFD for rivers subject to impoundments. The first is a method for preliminary assessment of a water body to determine if it is likely to fail to achieve GES because of changes to the flow regime (indexed by simple flow regime statistics) in systems where appropriate biological assessment methods are limited or currently unavailable. The second is a method for defining an environmental flow regime release based on the requirements of riverine ecological communities and indicator organisms for basic elements (building blocks) of the natural flow regime.

Natural streamflow simulation for two largest river basins in Poland: a baseline for identification of flow alterations

“…Due to the EU Water Framework Directive and its environmental flow policy (Acreman et al, 2009) this situation is gradually changing, and more importance is given to flow requirements of valuable ecosystems such as riparian wetlands (Piniewski et al, 2014). It is anticipated that designing environmental flows from dams will sooner or later become an important topic in Poland.…”

Evaluating hydrometric networks for prediction in ungauged basins: a new methodology and its application to England and Wales

“…Some sites which are heavily impacted by artificial influences, whilst of limited regionalisation value, are needed to understand the ecological impacts of changes in flow regime (e.g. Acreman et al, 2009). Clearly, the attributes assembled by the methodology are also highly relevant to these other aims, so provided it is not used in isolation, the method facilitates consideration of other drivers of network evolution.…”

Research Priorities to Improve Future Environmental Water Outcomes

“…Environmental flows usually aim to consider all aspects of the flow regime, not just quantity One feature of critical importance to river functions is inundation of floodplain areas and wetland ecosystems (Yarnell et al, 2015). Environmental water management needs to maintain these critical ecosystem processes through the integration of high flow events with flood management for protection of infrastructure and floodplain uses (Acreman et al, 2009;Arthington, 2012). Drought management also presents significant challenges, including protection of refuge habitats for aquatic biota at landscape scale, and options to provide environmental flows in critical river reaches (Bond et al, 2008).…”