2015年-世界发展银行全球_Urban_Flooding_of_Greater_Dhaka_in_a_Changing_Climate___Building_Local_Resilience_to_Disaster_Risk_259页_18mb

Summary of "Urban Flooding of Greater Dhaka in a Changing Climate: Building Local Resilience to Disaster Risk"

Core Content

This report, authored by Susmita Dasgupta, Asif Zaman, Subhendu Roy, Mainul Huq, Sarwar Jahan, and Ainun Nishat, provides an in-depth analysis of urban flooding in Greater Dhaka, Bangladesh, in the context of climate change. It outlines the challenges posed by extreme weather events, the current state of the city's drainage systems, and the need for local resilience strategies to mitigate flood risks.

Main Views

• Urban Flooding as a Critical Issue: Dhaka, the capital and largest city of Bangladesh, is highly vulnerable to urban flooding due to its dense population, rapid urbanization, and inadequate drainage infrastructure.
• Climate Change Impact: Climate change is expected to increase the frequency and intensity of extreme rainfall events, exacerbating flood risks in the coming decades.
• Need for Climate-Smart Adaptation: The report emphasizes the importance of implementing climate-smart policies and investments to enhance the city's resilience to climate-related disasters.
• Integrated Approach Required: A comprehensive and integrated adaptation strategy is necessary to address the complex interplay of factors contributing to flood vulnerability in Dhaka.

Key Information

Study Overview

• The study focuses on the potential intensification of urban flooding in Greater Dhaka under changing climate conditions.
• It uses hydrological modeling, vulnerability assessment, and cost-benefit analysis to estimate flood damage and adaptation costs.
• The analysis covers multiple sub-areas within Greater Dhaka, including Old Dhaka, Central Dhaka, Kallyanpur, Goranchatbari, Eastern Dhaka, DND, and Narayanganj.

Methodology

• Hydrological Modeling: The study employs a conceptual framework for modeling, calibrated with historical data and future climate scenarios.
• Detailed Area Modeling: Seven drainage models were developed for the study area, each focusing on specific regions within Greater Dhaka.
• Vulnerability Assessment: A Flood Vulnerability Index (FVI) was developed to assess the vulnerability of different areas and populations.
• Damage Estimation: The report estimates both direct and indirect damages from flooding, including economic and social impacts.
• Adaptation Costs: It provides cost estimates for addressing current and future flood risks, including the costs of infrastructure improvements and maintenance.

Key Findings

• Flood Vulnerability: Vulnerable populations, particularly those in fringe areas, slums, and shanties, face higher risks from flooding.
• Climate Change Projections: The Intergovernmental Panel on Climate Change (IPCC) and World Meteorological Organization (WMO) suggest more erratic monsoon rainfall and increased climate extremes in the Ganges, Brahmaputra, and Meghna Basin.
• Adaptation Strategies: The report outlines complementary flood-mitigation measures, including improved solid waste management, maintenance of conveyance systems, and the use of temporary and permanent water pumps.
• Cost Estimates: The study provides detailed cost estimates for infrastructure adaptation, including the cost of meeting current and future adaptation deficits.

Recommendations

• Integrated Adaptation Strategy: The report recommends an integrated strategy that includes both structural and non-structural measures to build local resilience.
• Stakeholder Engagement: It stresses the importance of involving local communities, government agencies, and development partners in the planning and implementation of flood adaptation measures.
• Policy and Investment Focus: Climate-smart policies and investments are essential for reducing flood damage and improving the city's resilience to climate change.

Structure and Components

• Part 1: Methods

  • Chapter 2: Hydrological Modeling
  • Chapter 3: Detailed Area Modeling
  • Chapter 4: Vulnerability Assessment
  • Chapter 5: Estimating Flood Damage

• Part 2: Results

  • Chapter 6: Assessment of Dhaka's Modeled Zones
  • Chapter 7: Assessment of Dhaka City's Flood Resilience
  • Chapter 8: Complementary Flood-Mitigation Measures
  • Chapter 9: Toward an Integrated Adaptation Strategy

Appendices

• Appendix A: Individuals consulted for estimating adaptation costs.
• Appendix B: Basin and region modeling and rainfall analyses.
• Appendix C: Previous study findings on Dhaka rainfall.
• Appendix D: DAP-proposed water retention areas and water bodies.
• Appendix E: Status of 26 Khals under DWASA jurisdiction.

Supporting Materials

• Boxes: Clarify key concepts and provide additional context on flood vulnerability and climate change impacts.
• Figures: Include maps, flood simulations, and data visualizations to support the findings.
• Photos: Illustrate the current state of drainage systems and flood-affected areas.
• Tables: Present detailed data on population density, land levels, runoff coefficients, and cost estimates.

Conclusion

The report serves as a critical resource for policymakers and development partners in Bangladesh, offering a comprehensive understanding of flood risks in Greater Dhaka and the associated adaptation costs. It underscores the need for a multi-sectoral, integrated approach to building local resilience against the growing threat of urban flooding in a changing climate.