Leveraging inland radar altimetry over rivers with low cost GNSS reflectometry

The monitoring of surface water levels in lakes and rivers is essential for adequate water resource management and timely responding to extreme events. Monitoring an entity as large as the Nile river comes with significant challenges. The cross-boundary nature of the Nile, complicates its management due to different jurisdictions and interests, furthermore there are logistical challenges related to accessibility and site safety.

Radar altimetry has the potential to offer remotely sensed water heights, but still requires expert knowledge and site-specific trial and error. Generating in-situ records of water level heights is therefore invaluable activity both for monitoring and validation purposes.

Low-cost Global Navigations Satellite Systems (GNSS) interferometric reflectometry promises a low-cost solution for monitoring water heights, and devices can be locally constructed using off the shelf components which are now widely available. Furthermore, the development of internet of things (IoT) networks in Africa is moving forward and creates opportunities for remotely controlled measurement stations.

Here, we present our activities on designing and deploying low-cost GNSS-R receivers on the shores of Lake Victoria. We show several designs based on raspberry Pi’s and a low-power version based on the Actinius Icarus platform (zephyr based). We further explore possibilities to apply on-board processing of GNSS signal to noise ratio series, which will pave the way for using low bandwidth networks.