Research shows that changes in water quality and water quantity may affect sustain-ability of aquatic and terrestrial ecosystems. For centuries, natural conditions in rivers have been affected and human activity has reduced the capacity of water resources to support ecosystems and biodiversity (Covich et al., 1997; Poff et al., 2002). Ecosystems, however, have an important role in the hydrological cycle, as they have natural cleaning capacity and reduce the concentration of many (organic) pollutants in water. Ecosystems also help to reduce extremes in runoff through their capacity to store water and play an important role in supplying food, fibre, wood and medicine, and of course support the existence of many species (Gilbert and Janssen, 1998). Since the Dublin Statement (1992) on water and sustainable development, the importance of water for the environment and the environment for water is increasingly taken into account. To date, however, the role of ecosystem security in water management and in the development of adaptive strategies has been minor, and should deserve greater attention (Kabat and van Schaik, 2003).

Apart from pressures as populations increase and land use changes, climate change (CC) will affect the capacity of water resources to support ecosystems. Important factors are changes in precipitation, temperature, runoff and ecological processes (Band et al., 1996; Lettenmaier et al., 1999; IPCC, 2001). Climate change has the potential to increase the impact of other pressures that are currently affecting the environment and it is irreversible. Studies on water and ecosystems have not addressed this issue adequately, since the focus is either at the species scale or at the higher - global - ecosystem scale. Studies at the intermediate - basin - scale are lacking and integral impact or adaptation studies to look both at CC impacts to the environment and other water uses (food, industry, etc.) are scarce. Only a few studies have a more integrated approach across different scales. White et al. (1999), for example, show how vegetation responds to CC at different scales.

© CAB International 2004. Climate Change in Contrasting River Basins

The ADAPT study has focused on the integrity of ecosystems under climate change and assessed different adaptation options to achieve sustainability. In this project, ecosystems are treated as one of the users of water in a catchment, apart from agriculture, industry and domestic use (Aerts et al., 2003). Consequently, ADAPT pays attention to different adaptation measures ranging from socio-economic to engineering measures, as recommended by working group II in the IPCC Third Assessment Report (TAR) (Klein and MacIver, 1999). As agriculture, industry and domestic use often compete with environmental users, ADAPT addresses the trade-off between the different water users in the basin and the tension that is raised by this trade-off (e.g. Doll etal.,2003).

This chapter focuses on environmental aspects of adaptation to climate change and describes how to develop and evaluate environmental adaptations to climate change for river systems. First, the possible effects of climate change on the environment, through changes in water quantity and quality are addressed. The possible environmental effects related to water and climate change are briefly described on a global and regional scale. Then the AMR framework (see Chapter 1) is used to specifically develop and evaluate adaptations with respect to environmental security. The method will be illustrated using two case studies. One case study is located in Central Asia (the Syr Darya Basin, Chapter 5) and one case study is situated in Western Europe (Rhine Basin, Chapter 7).

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