Detecting Land Degradation Using Geospatial Data
To sustainably manage and protect forests (SDG 15), you need accessible data and tools to identify damaging trends.
The Place: Apamprama Forest Reserve, Ghana
Figure 1. Apamprama Forest Reserve highlighted on a basemap of satellite imagery data, accessed through the Digital Earth Africa Open Data Cube.
The Apamprama Forest Reserve in central Ghana is a forested area housing a portion of the Ofin river, interspersed with volumes of semi-deciduous trees and medicinal herbs. The reserve also contains rich gold deposits.
The reserve represents an important Ghanaian ecosystem and a source of great biodiversity.
Ghana's Environmental Protection Agency (EPA) and Ghana Statistics Service (GSS) wanted to use electro-optical satellite data to better understand the health of the reserve's ecosystem and identify factors that were adversely affecting the environment.
"Protect, restore and promote sustainable use of terrestrial ecosystems, sustainably manage forests, combat desertification, and halt and reverse land degradation and halt biodiversity loss"
The Process: Accessing Data
Digital Earth Africa (DE Africa) provides free access to open source satellite imagery data and tools for data analysis via the DE Africa Open Data Cube.
Users of any background and skill-level can access browser based imagery and data over any part of Africa and analyse it for bespoke results, tailored to their interests.
The Issue: Land Degradation
Figure 2. Apamprama Forest Reserve between 2017 and 2021.
Simple RGB electro-optical imagery, accessed through the DE Africa Open Data Cube, demonstrated the extensive land degradation that occurred in Apamprama Forest Reserve between 2017 and 2021.
The land degradation and subsequent biodiversity loss is likely a result of gold mining in the protected reserve.
Without easy access to satellite data through the DE Africa Open Data Cube, the overall scale of land degradation and biodiversity loss issues in Apamprama Forest Reserve, would have remained unknown to the EPA and GSS.
Figure 3. Satellite imagery of Apamprama Forest Reserve in 2017 and 2021.
Figure 4. Aerial photograph of Apamprama Forest Reserve correlated with satellite imagery.
The Analysis: Understanding Vegetation Loss Data
After identifying land degradation as the primary issue facing Apamprama Forest Reserve, additional data analysis was needed to better understand the year-by-year environmental changes and to formulate a plan to halt the degradation.
Figure 5. Vegetation Change and Detection data analysis displaying vegetation loss in Apamprama Forest Reserve.
Using the DE Africa Vegetation Change and Detection tools within the Open Data Cube sandbox environment, users are able to measure the presence of vegetation from Landsat imagery and apply a hypothesis test to identify areas of significant change (along with the direction of the change).
The Vegetation Change and Detection data analysis tools give greater insight into the dramatic sprawl of land degradation in the reserve, highlighting the rapid increase in potential mining activity between 2017 and 2020.
It provides a foundation to track the locational scope of land degradation in the reserve and give institutions improved capacity to combat damaging environmental trends.
Figure 6. Using vegetation change detection data to identify possible mining sites and degraded areas.
The Result: Identified sources and scale of environmental issues
Using DE Africa's data access and analysis tools, the EPA and GSS were able to identify adverse trends affecting the Apamprama Forest Reserve.
By identifying the probable cause and geographic parameters of land degradation within the reserve, a foundation for planning the halting and reversal of degradation was established. DE Africa's free and accessible data tools provide necessary value-add for local, regional and federal stakeholders, responsible for policy and decision-making.
