It has been predicted that access to water will create conflict between countries. In Africa, central Asia, west Asia and the Americas, some countries are already arguing fiercely over access to rivers and inland seas, and confrontations could arise as water shortages grow (Gleick, 2000). Countries currently or potentially involved in international disputes over access to river water and aquifers include:
- Turkey, Syria and Iraq (the Tigris and Euphrates rivers);
- Israel, Jordan, Syria and Palestine (the Jordan River and the aquifers of the Golan Heights);
- India and Pakistan (the Punjab rivers);
- India and Bangladesh (the Ganges and Brahmaputra rivers);
- China, Indochina and Thailand (the Mekong River);
- Tajikistan, Kyrghyzstan and Uzbekistan (the Oxus and Jaxartes rivers);
- Ethiopia, Sudan and East African riparian countries, including Kenya, Tanzania, Rwanda, Burundi, Uganda and Egypt (the Nile River) (Gleick, 2000; Villers, 1999).
Freshwater ecosystem alterations have been carried out through much of modern history, with the intensity of modifications increasing in the early to mid-1900s. Common waterway modifications, such as the construction of dams and irrigation channels, inter-basin connections and water transfers, can impact on the hydrology of freshwater systems, disconnect rivers from floodplains and wetlands, and decrease water velocity in riverine systems. This, in turn, can affect the seasonal flow and sediment transport of rivers downstream, impacting on fish migrations and changing the composition of riparian ecosystems. Exotic species often thrive at the expense of indigenous ones, leading to an unquantifiable loss in freshwater biodiversity and inland fishery resources (Revenga et al., 2000).