Horn of Africa: annual probability of flooding

This map illustrates the likelihood that a given region will sustain any flood within any given year.

On average, the Shabeelle floods once a year and the Juba and Tana flood once every two years. Worst effects of flooding include human deaths (typically 10s to 100s), displacements (typically 1k to >100k), destroyed homes, submerged agriculture, and waterborne diseases (e.g. malaria, diarrhea, and Rift Valley fever).

Data from the Dartmouth Flood Observatory is the basis for calculating flood probability. A grid cell is considered to have flooded anytime a river intersecting that cell has flooded.