Disaster risk profile: Zanzibar

This disaster risk profile for Zanzibar seeks to provide a basis for the future implementation of disaster risk financing through the improved understanding of disaster risks. The risk modelling undertaken focused on three perils: tropical cyclones, floods and earthquakes. In addition, as part of the earthquake risk assessment, tsunami risk zones were also identified. The hazard and exposure data, as well as the results of the risk analysis, has been collated and stored on open data geospatial platforms in Zanzibar and made available to a wide range of end-users.

This analysis suggests that on average, Zanzibar experiences nearly US$2.2 million in combined losses from earthquakes, floods, and tropical cyclones each year. However, a specific event such as severe flooding can produce significantly larger losses. For example. the results suggest that a 100-year return period flood event would produce direct losses of $13 million and require approximately $2.9 million in emergency costs.

Flooding is by far the most significant risk in the study, causing nearly 90 percent of the average loss per year from all three perils, although infrequent, strong earthquakes can cause losses comparable to those from the worst floods. In the analysis, the residential sector experiences over 85 percent of the combined losses. In terms of both absolute amount and amount relative to the value of local assets, the highest loss takes place in the Kusini·Pemba region. Of the country's two main islands, Zanzibar Island has slightly higher absolute flood losses than Pemba Island, but Pemba Island has higher losses relative to local assets. In addition to the direct losses, an annual average of nearly $500,000 is estimated for emergency costs.