Space technology put into service for global water resources ob...( The worlds rivers lakes reservoirs a...)

The worlds rivers, lakes, reservoirs and groundwater as well as snow fields and glaciers are the main sources of freshwater to support terrestrial life and human livelihoods.

Continuous observations are crucial to manage these water resources for the benefit of mankind and the environment and also to provide crucial forecasting services to prevent water-related disasters such as floods and droughts. These tasks are routinely undertaken by the National Hydrological Services of countries. However, hydrological information is insufficient especially in developing countries and many areas of the world are currently not monitored for their water resources. Therefore, critical hydrological information that is necessary to manage the worlds water resources and prevent water-related disasters is inadequate especially in the developing world.

In this situation, remote-sensing techniques have demonstrated an extremely active innovation capacity in the field of continental waters during the last 20 years. They can now be used to locate water bodies and delineate river networks, to quantify and/or estimate water related variables such as precipitations, soil wetness, water levels, water storage, to monitor water balance of large river basins on time scales ranging from weeks to years, to quantify spatial parameters relevant for hydrological models and to provide real-time information for flood forecasting.

Among the most promising space missions are satellite altimetry missions, such as ESA's ERS and Envisat and NASA-CNES Topex-Poseidon, that provide surface water levels (lakes, reservoirs, rivers, wetlands and floodplains) and space gravity missions, like ESA's GOCE and NASA's GRACE, that provide estimates of the variations of terrestrial water storage (in soils, lakes, reservoirs and groundwater) in space and time. Used in conjunction with conventional observations and hydrological modelling, these observations from space also have the pot
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