世界发展银行-People-in-Harm_s-Way---Flood-Exposure-and-Poverty-in-189-Countries_28页_2mb

Summary of "People in Harm's Way: Flood Exposure and Poverty in 189 Countries"

Core Content

This working paper from the World Bank explores the relationship between flood exposure and poverty across 189 countries. It presents a global assessment of the number of people exposed to intense flooding, with a focus on how this exposure intersects with poverty levels. The study uses high-resolution flood hazard maps and poverty estimates from the World Bank's Global Monitoring Database to provide a comprehensive analysis.

Main Findings

• Global Flood Exposure: 1.47 billion people, or 19% of the world population, are directly exposed to substantial flood risks during 1-in-100 year flood events.
• Regional Distribution:
  • South and East Asia account for the majority of flood-exposed people (1.36 billion).
  • China and India are the largest contributors, with 329 million and 225 million people respectively.
• Poverty and Flood Risk:
  • 89% of flood-exposed people live in low- and middle-income countries.
  • 55% of the 132 million people living in extreme poverty (under $1.9 per day) also live in high flood risk areas.
  • Sub-Saharan Africa has the highest proportion of people in extreme poverty facing high flood risk (55%).
  • 587 million people live in high flood risk areas and earn less than $5.5 per day.

Key Insights

• Flood Risk and Poverty Correlation:
  • While high-income regions are more exposed to flood risks, poor people are disproportionately affected in some cases, such as in Ho Chi Minh City, where poor populations are more concentrated in flood-prone areas.
  • Informal settlements are often located in hazardous zones due to land scarcity and lack of access to safe housing.
• Urbanization and Climate Change:
  • Rapid urbanization in flood-prone areas increases exposure.
  • Land subsidence and climate change are expected to exacerbate flood risks in the future.
• Future Projections:
  • The 2020 flood exposure estimate of 1.47 billion people already exceeds earlier projections (e.g., 1.3 billion by 2050).
  • Sea level rise could affect 190 million to 630 million people by 2100, depending on emissions scenarios.

Methodology

• The study uses high-resolution flood hazard maps (from Fathom Ltd and GTSR) and population density data (from GHSL) to assess flood exposure.
• Flood risk categories are defined based on inundation depth:
  • Low risk: 0–0.15 meters
  • Moderate risk: 0.15–0.5 meters
  • High risk: 0.5–1.5 meters
  • Very high risk: Over 1.5 meters
• Poverty estimates are based on the World Bank's $1.9, $3.2, and $5.5 per day thresholds.
• The computational process involves:
  1. Merging flood hazard maps (coastal, pluvial, and fluvial) into a single combined flood map.
  2. Categorizing each pixel into flood risk levels.
  3. Converting the raster data into Boolean integer arrays for risk classification.
  4. Aggregating the results to the administrative unit level and calculating exposure headcounts.

Data Sources

• Flood Hazard Data: From Fathom Ltd (2016 and 2019 versions), including fluvial, pluvial, and coastal flooding.
• Population Data: From the Global Human Settlement Layer (GHSL), with a resolution of 3 arc seconds (~90 m).
• Poverty Estimates: From the World Bank's Global Monitoring Database, based on Living Standards Measurement Surveys (LSMS).
• Administrative Boundaries: Based on the World Bank's global administrative map, with subnational units where available.

Implications

• The findings highlight the intersection of poverty and flood risk, particularly in low-income and subnational regions.
• Climate change and land subsidence are expected to increase flood exposure in the coming decades.
• The study underscores the need for targeted disaster risk reduction and inclusive urban planning to protect vulnerable populations.
• It contributes to the 2020 Poverty and Shared Prosperity Report and supports global development policy discussions.

Conclusion

This paper provides a global and detailed analysis of flood exposure and its connection to poverty. It emphasizes the local and regional disparities in flood risk and poverty and calls for more accurate and comprehensive flood risk assessments that consider both the intensity and distribution of flooding. The study also highlights the importance of integrating poverty data into disaster risk management strategies to ensure equitable protection for all populations.