River and Lake Project

Satellite radar altimeters have been used for many years to map the surface of the earth's oceans. More recently, the technique has been used to measure and monitor heights of inland water. However, the numbers of sites successfully monitored has been limited to those where the echo from the surface resembles that from the open ocean. This has limited the primary application of this technique to large lakes and the very widest rivers.

However, there is an urgent and growing requirement for accurate and timely inland water information, as this critical resource is currently measured by an ad-hoc network of in-situ gauges. Each, the number of unguaged catchments continues to rise, as the equipment falls out of use and is not replaced.

At the EAPRS lab, a processing system has been designed and implemented which successfully retrieves river and lake heights from thousands of crossings worldwide. The primary key to the success of this approach is to analyse and 'retrack' the echoes from the surface, analysing each echo to firstly identify which part of the complex signal is from an underlying water surface, and then calculating the range from the satellite to that point. This then permits the height of the waterbody above some reference surface, usually mean sea level, to be determined. This approach has been very successful, and the system is now run by the EAPRS lab on behalf of ESA (see ESA River & Lake) retrieving inland water heights within 2-3 days of the satellite overpass globally for both EnviSat and Jason2 targets, and disseminating these data to the water resource management and scientific communities worldwide.

Examples of a few combined timeseries from current and past missions (ERS2, Topex, EnviSat and Jason-1) can be seen here. Results from this work were recently showcased at the WMO workshop

To see the River and Lake - Near Real Time products section, click here. Or alternatively take a look at the Next Generation of the River and Lake project.