The database Hydroweb offers River Height and Lake Height products derived from spatial altimetry. These time series provide the height of rivers and the height of lakes and reservoirs around the world continuously and over long periods of time. The river products are provided at the point where a satellite repeatedly passes over a river, thus defining ‘virtual stations’.
Hydroweb distinguishes between “operational stations”, whose results are available 1 to 2 days after satellite observation, and “research stations”, whose series cover areas observed by previous missions or targets for which specific processing is applied. They cannot be produced with the same regularity and are therefore only updated from time to time. The products are regularly validated by comparison with in situ data. The accuracy of lake products is 13 cm on average, but reaches accuracies of 3-4 cm for the largest lakes. The accuracy of river products ranges from 10 to 25 cm, depending on the catchment area and various factors (such as river gradient) that affect their accuracy.
Better coverage of Asia and high latitudes
Thanks to the efforts of Cnes, its partners and the Copernicus programme, the number of targets monitored by Hydroweb continues to grow worldwide. New operational time series of water level over rivers are now available.
Global coverage has been particularly improved in Asia and at high latitudes, making the most of the efforts made by space agencies to update digital terrain models on board Copernicus programme altimeters, enabling better acquisition of the altimeter signal. The number of operational products on rivers has thus risen to more than 22,800 stations (compared with around 11,300 up to now), using data from the Sentinel-3A, Sentinel-3B and Sentinel-6A altimeters.