On the use of radar altimetry and its integration with other satellite sensors for river discharge estimation and forecasting
Event: 2016 Ocean Surface Topography Science Team Meeting
Session: OSTST Opening Plenary Session
Presentation type: Type Keynote/invited
River discharge represents a key variable for quantifying the water cycle, along with water storage on a local and a global scale. Its estimation is not direct and, traditionally, it consists of in-situ measurements of water flow velocity, channel cross section depth at different measuring points and the water level, all linked through mathematical formulas or calibrated relationships, referred as rating curves. As a uniform distributed and continuous information is extremely difficult to be gathered, especially in developing countries, Earth Observation data are recently used for filling in the gaps within the existing streamflow-gauging networks. Radar altimetry represents an interesting alternative to record the in situ water level measurements in the continental environment. The high accuracy of altimetry data provided by the latest space missions and the convincing results obtained in the recent applications suggest that these data may be employed for hydraulic/hydrological applications as well. If used in synergy with the modeling or with other satellite sensors, the potential benefits of the altimetry measurements can grow significantly, becoming a very useful tool for estimation and prediction of river discharge. The availability of new sources of data motivates the development of new procedures for river discharge estimation based on remote sensing technologies. In this context, we have investigated the possibility to explore the use of multiple satellite data through different approaches aimed to the river discharge estimation and the flood forecasting with particular attention to the ungauged river sites. Such methods are based on the coupled use of altimetry satellite data and the MODerate resolution Imaging Spectroradiometer (MODIS) in order to fully exploit the characteristics and the strengths of the two sensors. Applications in some rivers in Europe showed that MODIS and radar altimetry could be successfully used for estimating river discharge variation in rivers with different characteristics. Moreover, the potential of remote sensing for river discharge forecasting is also investigated through the use of MODIS and radar altimetry in Niger-Benue River system, in Nigeria, where severe floods have damaged properties and caused loss of lives in recent years. These results are very promising for an application of the Sentinel-3 mission data for which optical and high-resolution SAR altimetry data are collocated.