PROJECT DESCRIPTION

Samoa is a group of volcanic islands in the Pacific Ring of Fire and as such is prone to tropical cyclone, tsunami, and earthquakes.

Accelerating climatic and environmental changes are worsening weather-related disaster events, making flood hazard modelling, and mapping an urgent need for developing Pacific Island states.

With in house GIS specialist skills, GWP were appointed to produce coastal and river flood hazard maps for the country.

CHALLENGE

Remote and developing countries may lack geospatial datasets from which to model hazards and identify trends.

National-scale Lidar data was available to this project,

though not previously deployed nor quality assessed. A challenge of this project was the absence of essential hydrometric data.

SOLUTION

GIS-based preliminary geomorphological (e.g. slope) and hydrological (e.g. flow routing) analyses were undertaken, using a hydrologically corrected LiDAR and Digital Elevation Models (DEM), to enable primary flood flow routes, catchment boundaries, and catchment characteristics to be determined.

• An ArcGIS’s Collector App was developed and deployed to assist with field activities (validating GIS-based flood hazard products and producing a drainage infrastructure database), significantly reducing time inputs.
• ArcGIS Online platform capabilities were used to deliver interactive flood hazard products and improve stakeholder communication regarding risks.

Altogether, GWP produced a seamless national scale GIS flood hazard dataset, covering an area of 3,350km2