Input layer sources

Ecosystems

A 0.01-degree resolution raster of real area was generated for each of the four considered ecosystems using an equation that approximate Earth ellipsoid.

In the case of forest coverage, the initial WRI classification was grouped in three classes: woodland, open forest and closed forest. The final forest ecosystem percentage is based on the spatial sum of these three classes area.

The areas with a deforested status (“Potential forest lands that are currently non forest were assumed to be deforested”) were not included in these new classes.

Hazard exposure

For each natural hazard, a 0.01-degree resolution raster was generated, illustrating hazard annual frequency weighted with portion of pixel potentially affected. Landslide hazard is separated in two categories: landslides triggered by earthquakes or rainfall. In our case, the final frequency raster is the sum of both hazard annual frequencies. The underlying hypothesis is that a pixel affected by an earthquake triggered landslide event could still be affected by a rainfall-triggered landslide event during the same year and somewhere else in the pixel.

In the case of cyclones, annual frequency raster is calculated using the Saffir-Simpson largest buffer of each event.

Physical exposure was calculated for each natural hazard multiplying the hazard frequency raster with the population raster. The flood hazard model has various return period layers, the final physical exposure is the sum of each single physical exposure.

Population

This work has been conducted jointly by UNEP and UNEP GRID-Geneva with funds from the European Union.