EarthConsole® Stories: monitoring sand dams’ impact on water availability with satellite image time-series analysis

EarthConsole^® Stories are experiences about how we helped universities, research centres or service developers to leverage Earth Observation data to extract valuable insights for their research, educational or pre-commercial projects.

Climate change driven by human activity is significantly altering the water cycle at global, regional, and local levels, with these effects expected to intensify in the coming years (Pörtner et al. 2022). In semi-arid regions, prolonged dry periods and high evaporation are already reducing the availability of usable water in river systems, with direct negative consequences for ecosystems and the livelihoods of local communities (Kalele et al. 2021).

Currently, around 1.5 billion people live in semi-arid areas and this number is expected to increase due to shifts in climate zones. To ensure their food security and counteract the impending water shortage, measures are necessary on different spatial and temporal scales. A comparatively simple and cost-effective method is the construction of dams along the flow cross-section of seasonal rivers. These act as natural barriers and within a few years fill up with sediment, in which the water collects and is protected from evaporation and too rapid runoff.

Led by Dr. Andreas Braun from the University of Tübingen, this research project aims to assess the impact of sand dams on water availability in selected African regions. Using time series analysis of satellite images, the study seeks to quantitatively and qualitatively evaluate how sand dams influence their surrounding environments.

To conduct this research, the research team needed advanced Earth Observation (EO) tools capable of analyzing long-term surface changes around sand dams. These dams gradually alter ground levels, leading to positive environmental effects such as for example increased soil moisture, enhanced vegetation growth, and reduced land degradation.

However, conventional EO approaches often struggle to capture changes in seasonal river systems, requiring the use of indirect indicators like vegetation cover and land-use modifications. To overcome this limitation, the team sought a solution that could track changes through closely spaced time series observations.

EarthConsole^® was selected for its access to the P-SBAS (Parallel Small BAseline Subset) on-demand service for Sentinel-1, provided by IREA-CNR. This service implements an advanced InSAR technique enabling the generation of Earth surface deformation time-series and, more generally, interferometric products through an intuitive graphical user interface (GUI). The GUI allows the user to select SAR data for specific areas and time periods, set processing parameters, and download processing results autonomously.

Reflecting on his experience, Dr. Braun shared:

EarthConsole^®’s P-SBAS for Sentinel-1 on demand service has been selected to enrich our research. In addition to Sentinel-2, US Landsat Missions and hyperspectral data such as EnMap, we wanted to explore the potential of Sentinel-1 SAR data to provide new insights into deformations caused by water extraction but also increased storage volume near the identified sand dams.

Dr. Andreas Braun, Academic Researcher, University of Tübingen – Germany

 

This research has the potential to transform the use of sand dams as a climate adaptation strategy. It is based on the hypothesis that sand dams have a positive effect on their environment, but that this effect varies depending on the climate zone and landscape. By incorporating satellite-based monitoring, the project aims to showcase how sand dams can effectively mitigate water shortages, helping local communities build resilience against climate change.

This project has been supported via the ESA Network of Resources initiative.