October 10, 2023
A study conducted by the World Bank has revealed that human settlement in the world’s riskiest flood zones has increased by 122% since 1985, leading to greater vulnerability to water-related disasters driven by climate change. The study, published in the journal Nature on October 4, 2023, used satellite data to examine settlement extent and expansion instead of relying on population figures.
Rapid Growth in Flood-Prone Areas
The study found that settlement growth in the riskiest flood zones increased by 122%, while growth in the safest areas was 80%. Overall, built-up regions worldwide grew by 85% from 1985 to 2015. The growth in flood-prone areas was particularly pronounced in middle- and low-income countries, whereas richer countries, such as the United States and parts of Europe, saw more growth in safer regions than in flood-prone areas.
Drivers of Settlement Growth in Flood Zones
According to the study, the phenomenon is driven by several factors:
- People’s search for better lives and job opportunities often leads them to settle in areas they know are dangerous.
- As nations grow wealthier, there is a shift from rural to urban living, with cities often located near waterways that are prone to flooding.
- The expansion of cities can result in growth into previously avoided flood zones.
The study highlighted the following global trends:
- Most countries, especially in East Asia, witnessed more settlements in regular flood zones and ultra-high flood zones than in dry areas.
- Countries like Libya and Pakistan, which have recently experienced devastating flooding, had significant increases in settlement extent in high-risk flood zones.
- China and Vietnam saw their settlement extent more than triple in the past 30 years, outpacing the growth of dry land areas.
The Challenge Ahead
The study raises the question of whether it is more cost-effective to fortify flood-prone areas or relocate people to safer regions. It emphasizes that climate change and rapid urbanization are interconnected issues, with both exacerbating the vulnerability of populations in flood-prone areas. The authors suggest that smart planning and urban development can help prevent further settlement in high-risk areas.
Dar es Salaam, Tanzania: A Case Study
Dar es Salaam, Tanzania, serves as an example of this challenge. It has experienced significant population growth, transforming from a fishing village of about 83,000 people in 1950 to over seven million people today. The study underscores the need for thoughtful urban planning to address the risks associated with rapid urbanization and settlement in flood-prone zones.