2010年-世界发展银行全球_Economic_of_Adaptation_to_Climate_Change___Bangladesh_Volume_2_Annexes_31页_2mb

Summary of the Economics of Adaptation to Climate Change in Bangladesh

Core Content

This document provides an analysis of the economics of adaptation to climate change in Bangladesh, focusing on the impacts of cyclones and the associated economic costs for preventing embankment overtopping by 2050. It includes data on historical cyclone events, modeling approaches for simulating flood risks, and cost estimates for adaptation measures.

Major Cyclones (1960-2009)

A list of major cyclones that have crossed the Bangladesh coast is provided, with details including:

• Year of occurrence
• Landfall date
• Landfall location
• Wind speed (km/hr)
• Storm surges (m)
• Human casualties
• Number of people affected
• Estimated economic loss

Some notable cyclones include:

• 1960: 10,000 human casualties, 200,000 people affected, $11.9 billion loss
• 1963: 11,520 casualties, 1,000,000 people affected, $46.5 billion loss
• 1991: 133,882 casualties, 15,438,849 people affected, $1,780 billion loss
• 2007: 2,388 casualties, 8,978,541 people affected, $2,300 billion loss
• 2009: 190 casualties, 3,935,341 people affected, $270 billion loss

These events highlight the significant impact of cyclones on the region, with increasing economic and human tolls over time.

Cyclone Simulation Model

The analysis employs a storm surge model combining a cyclone model and a hydrodynamic model. Key parameters used in the cyclone model include:

1. Radius of maximum winds
2. Maximum wind speed
3. Cyclone tracks, forward speed, and direction
4. Central pressure
5. Neutral pressure

The MIKE21 hydrodynamic modeling system is used to simulate inundation risks under climate change scenarios. The model domain extends from Chandpur to 16° latitude, with a grid size of 200m in the Meghna estuary and coastal regions of Bangladesh. Bathymetry data is sourced from various projects including C-Map, MES II, Mongla Port Study, and IPSWAM. A Digital Elevation Model (DEM) is also used for topographic data, with a grid size of 50m x 50m.

Polders Likely to Be Overtopped

The document lists polders that are likely to be overtopped in baseline and climate change scenarios. Key details include:

• Polder name
• Length (km)
• Existing height (m)
• Height to be raised (m)
• Overtopping depth (m) for both scenarios

Some polders like P40/1-2, P41-42, P45, and P46-47 show increased overtopping risk in the 2050 scenario, with P59/2 and P59/3B experiencing significant overtopping in both scenarios.

Estimated Costs to Prevent Overtopping

Cost estimates for preventing overtopping of polders by 2050 are provided, with costs categorized into:

• Earthwork (300 m to 1.0 km)
• Earthwork (1.0 km to 5.0 km)
• Turfing
• Plantation (Vetivera)
• Land acquisition
• Major protection work
• Toe protection

The total cost for interior polders in the baseline scenario is $317 million, while for sea-facing polders it is $2,144.9 million. Under the climate change scenario, the total cost for interior polders is $706.4 million, and for sea-facing polders it is $2,144.9 million.

The cost breakdown highlights the significant investment required for earthwork and major protection work, especially for large-scale polders like P56/57(E) and P72, which require substantial financial resources to mitigate the risk of overtopping.

Key Information

• Bangladesh is highly vulnerable to cyclones and storm surges, with significant human and economic losses reported.
• Climate change is expected to increase the risk of overtopping for many polders along the coast.
• Adaptation measures such as raising embankments, earthwork, turfing, and land acquisition are essential for risk mitigation.
• The MIKE21 model is used for hydrodynamic simulations to assess inundation risks and climate change impacts.
• The economic costs for adaptation are substantial, with earthwork and major protection work being the most expensive components.

Conclusion

The document underscores the economic and social vulnerability of Bangladesh to cyclones and climate change. It provides detailed data on historical events, modeling techniques, and cost estimates for adaptation measures, emphasizing the need for sustainable and cost-effective strategies to protect coastal infrastructure and reduce flood risks.