Radar Altimetry Aids Managing Gauge Networks

The hydrological observation network in the Amazon basin is made of conventional rainfall and water level stations presently maintained by the Agência Nacional de Águas (ANA), the National Agency for Waters. The water level network has long been plagued by difficulties associated with spatial coverage, timely delivery and data errors. Satellite observations are important means for providing hydrologic data with acceptable spatial and temporal resolution, and radar altimeters embarked onboard successive satellites since the early 1970s collect measurements of water level over rivers in a well-defined geodetic reference frame and can be used to address some of these problems. Nowadays, satellite altimetry can be used to collect the time variations of the water levels over many rivers throughout the word, as long as the reach are several hundred meters wide. This ability is particularly interesting in ungauge basins but it can also be used as an independent source of information to cross-check existing gauge series. In the present study, we focus on examples from the Amazon basin where radar altimetry has been used to provide an independent dataset that can be used to support the management of hydrological observation networks by including new data together with conventional field data,