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Flood Risk Analysis of Ganges BasinThesis Student: Mufazzal Hossain Registration Number: 09205046
Flood Risk Analysis of Ganges Basin
Introduction Literature Review and Methodology
Data Analysis and Discussion
Conclusion and Recommendation
Introduction: Background Flood in the Past:
Lesser population in the floodplain
Lesser development in the floodplain
More benefits than risks Social Benefit Economical Benefit Environmental and
Agricultural Benefit
Flood in the Present: With time floodplain
population has increased. Amount of development has
increased in floodplain. Risks started to become more
visible than benefits. Some response and
prevention measures are: Structural Defenses Upstream Storages Land-use Controls
To calculate the discharge by flood frequency analysis, generate hydrographs by using the concept of synthetic unit hydrograph for 5, 10, 15, 25, 50 and 100 years return period.
Calculate the probability of occurrence at least once of such floods within 2063.
To identify the various risks such floods poses in the study area. To present the flood effect mitigation measures and emergency
response for planning purpose at the study area.
Introduction: Objectives
Introduction to Ganges Basin
Figure: Ganges, Brahmaputra & Meghna River Watershed (Rahaman, 2006)
Literature Review and Methodology
Flood Risk Analysis can be defines as the process of analyzing the risk due to flood in order to find out the probable impact level and then preventing irreversible changes and mass damages from happening or mitigate with the adverse impacts.
Flood Risk Analysis
Literature Review and Methodology
Determine the Causes of Flood
Risk Based Approach to
Flood Management
Reviewing the Strategy and
Policy Framework
Flood Risk Assessment and
Mapping
Planning and Development
Protecting Communities in
Floodplain
Defending Individual Properties by
Resistance and Resilience
Forecast and
Warning Systems
Flood Response and Recovery Insurance
Funding to Support Flood Risk
Analysis and Management
Protecting Communities at
Risk in the Longer Term
Literature Review and Methodology
Methodology
Data Analysis Methods
Rational Method
Flood Frequency Analysis
Snyder’s Synthetic Unit Hydrograph
Risk Analyzing Methods
Risk Identification Method
Risk Rating Method
Risk Level Determining Method
According to the Royal Academy of Engineering of United Kingdom, the Prevention and Emergency Response Measure can be implemented in the 5 following ways. Avoid Reduce Mitigate Transfer Do Nothing
Prevention and Emergency Response
Literature Review and Methodology
Data Analysis and Discussion
1 10 10018,000,000,000.0019,000,000,000.0020,000,000,000.0021,000,000,000.0022,000,000,000.0023,000,000,000.0024,000,000,000.0025,000,000,000.00
f(x) = 2233203565.957 ln(x) + 16669474605.17R² = 0.999826155803164
Gumbel’s Probabil-ity Paper
Return Period (T)Dis
char
ge, Q
(m
3/Fl
ood
perio
d)Return Period in
YearsDischarge (m3/Flood
Period)
5 20,240,964,312
10 21,835,839,289
15 22,735,654,274
25 23,365,681,657
50 27,824,046,011
100 29,210,340,372
Discharge Frequency Curve Calculated Discharge for Different Return Period
Data Analysis
0 100 200 300 4000
100000200000300000400000500000600000700000800000900000
1000000
Flood Hydrograph for the Return Period of 5 YearsFlood Hydrograph for the Return Period of 10 YearsFlood Hydrograph for the Return Period of 15 YearsFlood Hydrograph for the Return Period of 25 YearsFlood Hydrograph for the Return Period of 50 YearsFlood Hydrograph for the Return Period of 100 Years
Time (Hours)Dis
char
ge, Q
(m3 /s
)
Hydrograph for Each Return Period
Data Analysis and Discussion
Data Analysis
Flood Events Probability
5 Years Return Period Flood 1
10 Years Return Period Flood 0.99
15 Years Return Period Flood 0.96
25 Years Return Period Flood 0.87
50 Years Return Period Flood 0.64
100 Years Return Period Flood 0.39
Probability of Various Flood Events
Data Analysis and Discussion
Data Analysis
RiskLikelihood Consequences Risk
RatingCategory Level Description Category Level Description
Damage of Houses and Household Products A 6 Likely II 5 Major 30
Inundation of Road Networks and Their
Damage & DestructionA 6 Likely II 5 Major 30
Damage of Crops and Losses of Live Stocks A 6 Likely III 4 Serious 24
Erosion of Agricultural Land and Problems in Relocation of People
A 6 Likely I 6 Catastrophic 36
Spread of Diseases and Affect on Health A 6 Likely I 6 Catastrophic 36
Risk Rating Table
Data Analysis and Discussion
Risk Analysis: Risk Rating
Risks Risk Rating Risk Level Color CodeRemarks on Prevention and
Emergency Response Measures
Damage of Houses and Household
Products30 High Red
Requires emergency prevention measures,
mitigation and management measures, evacuation of people along with food
supply and treatment facility supplies.
Inundation of Road Networks and Their
Damage & Destruction
30 High Red
Damage of Crops and Losses of Live
Stocks24 High Red
Erosion of Agricultural Land and Problems in
Relocation of People36 High Red
Spread of Diseases and Affect on Health 36 High Red
Risk Analysis: Risk Leveling and Remarks
Risk Level of Identified Risk and Remarks
Data Analysis and Discussion
Current Mitigation Measures Structural Mitigation
Non-Structural Mitigation
Legislation, Policy and Planning
Training & Public Awareness
Institutional Arrangements
Warning Systems
Local Disaster Action Plans
Coordination Mechanism
Comprehensive Disaster Management Program
Suggested Mitigation Measures Environmental Management
Mangrove Preservation
Afforestation
Waste Management
Water Resource Management Drainage
Rain Water Harvesting
Infrastructural Measures Road Networks
Building & Houses
Agricultural Mitigation Measures Mitigation Related to Fisheries
Development of Storm Resistant Boats
Conflict Resolution Between Shrimp & Rice Farmers
Discussion on Prevention & Emergency Response Measures
Data Analysis and Discussion
By using the flood frequency analysis the flood discharge for 5, 10, 15, 25, 50 and 100
years return period has be calculated to be 20.24 × 109 m3/Flood period, 21.84 × 109
m3/Flood period, 22.74 × 109 m3/Flood period, 23.37 × 109 m3/Flood period, 27.82 ×
109 m3/Flood period and 29.21 × 109 m3/Flood period respectively and by using the
synthetic unit hydrograph the peak discharge during each event has been calculated to
be 639775.8 m3/s, 690186.5 m3/s, 718627.8 m3/s, 753880.7m3/s, 879461.6 m3/s and
923279.5 m3/s respectively. The probability of the floods with the various return
period stated above has found to be 1, 0.99, 0.96, 0.87, 0.64 and 0.39 respectively. The
hydrographs was shown in slide 15.
The probability of the floods with the various return period stated above has found to
be 1, 0.99, 0.96, 0.87, 0.64 and 0.39 respectively.
Conclusion & Recommendation
The identified risks which is posed by various flood events are Damage of Houses and
Household Products, Inundation of Road Networks and Their Damage/Destruction,
Damage of Crops and Losses of Livestock and Spread of Diseases and Effects on
Health.
Suggested mitigation measures are Environmental Management, Water Resource
Management, Infrastructural Measures, Agricultural Mitigation Measures and
Mitigation Measures Related to Fisheries.
Conclusion & Recommendation
In order to make an improvement of this study one can do the followings,
Obtain the unavailable data & information and overcome the disadvantage of not
having high technological software.
By completing the Flood Frequency Analysis by Log-Pearson Type III distribution
and Log Normal Distribution for comparison with Gumbel’s Extreme-Value
Distribution method results
Conclusion & Recommendation
Recommendation