Terrain and soil mapping for disaster risk management in the British Virgin Islands

The British Virgin Islands (BVI) are prone to earthquakes, tsunamis, hurricanes, storm surges, flooding and landslides, as well as droughts and extreme heat events. The BVI government has identified soil maps as a priority for environmental management, i.e. construction, waste disposal, water resources, degraded land, biodiversity monitoring and conservation - as well as for modelling impacts from climate change.

Archipelagos are relatively expensive to map, given the time needed to visit and survey many individual islands, as well as associated logistical challenges and travel costs. Remote sensing and GIS can greatly reduce those survey costs, providing standardised approaches to mapping each island.

Elevation data from aerial laser scanning (LiDAR) has been used to map the BVI terrain. Using Multi-Criteria Decision Analysis and GIS, the DEM-derived geomorphometric data have been integrated with geological map data, satellite imagery highlighting areas of post-hurricane erosion, and meteorological data, to produce a map showing the geodiversity of the BVI. That map has then been used to select sample sites for the soil survey. The main BVI rock types have been classified into wet or dry subtypes and then further subdivided by geomorphological position: valley floor, hillside, and ridge/plateau.

The BVI Soil GIS and associated geospatial datasets will be used to assess potential hazards from different types of land use, supporting risk assessment (i.e., geohazard, vulnerability and exposure) for planning reviews of new developments, as well as identifying fertile soils for cultivation, highlighting soils that need careful management because of slope instability, erosion or degradation.