Over-exploitation of some water resources and changes in the hydromorphology of water systems have also damaged aquatic ecosystems. Setting and enforcing minimum ecological water flow rates in rivers and restoration of morphology of river channels and banks and flow regimes to a more natural state are increasingly a part of environmental planning in some OECD countries, stimulated in the European Union by the European Water Framework Directive (Box 5.9). It is expected that these effects will be aggravated by climate change and increased water temperatures (Mooij et al.,