Rationale and aim

Globally, floods affect 250 million people and cause 40 billion USD in losses on an annual basis (OECD, 2016). Meanwhile water availability is being severely stressed by the continual growth in demand for water. It is a reality that freshwater management requires quantitative observations of how much water is flowing through and is being stored within river catchments and yet, in many cases, our water monitoring capabilities fall short of requirements. This makes being able to accurately quantify water resource availability and monitor major flood events anywhere in the world with earth observation data a truly transformative step for hydrology.

Previous efforts to determine river discharge from Earth Observation (EO) data have largely been based on the determination of water surface height and extent alone, and lacked the critical parameter of flow speed. Two recent advances have provided a potential step-change in our ability to observe freshwater flows from space.

The first is the availability of satellite networks such as the SkySat constellation operated by Planet that combine very high-resolution video imagery with frequent revisit times. The second is the development of proven non-contact methods for digital video-based 'surface velocimetry' methods for streamflow determination. Surface velocimetry techniques work on the principle that by tracking the movement of visible features on the water's surface through the frame of digital video files, one can detect and quantify the movement of flowing water.

Leveraging on these advances, FluViSat successfully determined the speed of movement of water on the Earth's surface from high resolution satellite EO video imagery in Phase 1 of the project. In the second Phase the method will be expanded to include high framerate still imagery from Planet Labs SkySat constellation. 

FluViSat project objectives

Phase 1 of the FluViSat project had three interlinked objectives:

  1. To simultaneously collect satellite video, low altitude drone video, and surface Acoustic Doppler Current Profile (ADCP) data for high flow events, in rivers and tidal locations in the UK, Australia and Norway.
  2. To derive and compare surface velocities and river discharges from data collected using each of the monitoring platforms.
  3. To explore the potential of satellite-based surface velocimetry methods in hydrometry and their implications for EO data providers.

In Phase 2 the project will:

  1. Validate the performance of still frame veolicmetry
  2. Demonstrate the potential of satellite-based observations when extreme hydrometeorological events occur
  3. Improve pre-processing of satellite-derived video and still frame imagery to expand the range of locations and conditions in which the methods can be used and increase the accuracy of velocimetry results. 

By extending the project, ESA is enabling the FluViSat project to explore the usability of the FluViSat method to a product that is available across other platforms. Furthermore, the project will be developing an initial framework for applying the method to disaster preparedness.