FLOODS IN GHANA June 5, 2015 Walter Hays, Global Alliance Walter Hays, Global Alliance for Disaster Reduction, for Disaster Reduction, Vienna, Virginia, USA Vienna, Virginia, USA
FLOODS IN GHANAJune 5, 2015
Walter Hays, Global Alliance for Walter Hays, Global Alliance for Disaster Reduction, Vienna, Virginia, Disaster Reduction, Vienna, Virginia,
USA USA
EARLY REPORTS OF SOCIETAL IMPACTS OF THE FLOODS,
FIRE, AND EXLOSION
A PROLONGED SEASONAL RAIN STORMCLOSURE OF ROADS AND SERVICES
POWER OUTAGEFAULTY GENERATOR CAUSED FIRE AND EXPLOSION150 DEAD FROM FLOODING, FIRE, AND EXPLOSION
60 REQUIRED HOSPITAL TREATMENT
FLOODS ARE A PART OF GHANA’S NATURAL
WATER CYCLE
ACCRA: JUNE 29, 1959: 22 CM (7 ½ IN) PARALYZES CAPITAL
GHANA IS IN WEST AFRICA
GHANA (ACCRA IS THE CAPITAL)
ACCRA: THE CAPITAL
ACCRA: THE CAPITAL
The Red Cross of Ghanaprovided blankets, mats and drugs to residents in Accra
and the six other communities affected by the
2015 flooding, fire, and explosion.
Officials blamed the losses from the floods on people
building homes and businesses within the city’s waterways, blocking natural drainage
systems.
TOWARDS FLOOD RISK ASSESSMENT
AND RISK REDUCTION
Officials: 59, 68, 71, 2015, …We have to stop flood disasters from
happening again
PHYSICALPHYSICAL
EFFECTSEFFECTS
ELEMENTS OF RISKELEMENTS OF RISK
EXPOSUREEXPOSURE
VULNERABILITYVULNERABILITY LOCATIONLOCATION
RISKRISK
PHYSICAL EFFECTS OF FLOODS
INUNDATION, HIGH-VELOCITY FLOW, HIGH-VOLUME DISCHARGE, EROSION, AND
SCOUR
DAMAGE FROM DAMAGE FROM INUNCATIONINUNCATION
AN ASSESSMENT INTEGRATES PHYSICAL EFFECTS AN ASSESSMENT INTEGRATES PHYSICAL EFFECTS AND SOCIETAL IMPACTS TO DETERMINE RISKAND SOCIETAL IMPACTS TO DETERMINE RISK
EROSION, SCOUR, AND EROSION, SCOUR, AND LANDSLIDESLANDSLIDES
LOSS OF LOSS OF FUNCTIONFUNCTION ECONOMIC LOSSECONOMIC LOSS
RISKRISK
TYPICAL IMPACTS OF FLOODS
DAMAGE TO CONTENTS, LOSS OF FUNCTION OF BUILDINGS AND
INFRASTRUCTURE, RELEASE OF HAZARDOUS MATERIALS,
TRANSPORTATION OF DEBRIS, AUTOS, AND HOUSES, ENVIRONMENTAL DEAD ZONES,
AND DISEASE VECTORS
VULNERABILITY ASSESSMENT FOR
FLOODS
Vulnerability: A Vital Part of Risk AssessmentVulnerability: A Vital Part of Risk Assessment
FLOOD FLOOD HAZARDSHAZARDS
EVENTEVENT
VULNERABILITYVULNERABILITY
PEOPLESTRUCTURESPROPERTYENVIRONMENTINFRASTRUCTURE
EXPOSUREEXPOSURE
EXPECTED EXPECTED LOSSLOSS
WHAT INCREASES VULNERABILITY
MANKIND’S ACTIONS AND NATURAL EVENTS CAN CHANGE THE
VULNERABILITY OF ELEMENTS AT RISK TO FLOODS
An element’s vulnerability (fragility) is the result of a community’s actions or
nature’s actions that change some part of the regional water
cycle (e.g., precipitation, storage, runoff, transpiration,
evaporation).
MANKIND’S CONTRIBUTIONAn element’s vulnerability
(fragility) is the result of flaws that enter during the planning,
siting, design, and construction of a community’s buildings and
infrastructure.
ACTIONS THAT CAN CHANGE KEY PARTS OF THE WATER CYCLE
• Urban development or industrial development in areas that were formerly wetlands.
• Locating buildings and infrastructure in a river floodplain.
MANKIND’S ACTIONS THAT CHANGE SOME PART OF THE WATER CYCLE
• Actions that increase or decrease river gradients (deforestation, dams, etc).
• Actions that change the runoff pattern or rate (e.g., the city’s concrete footprint)
NATURE’S ACTIONS THAT CAN CHANGE THE NORMAL WATER CYCLE
• A flash flood.• Ice jams/ice dams on the river• Rapid melt of snow and ice• Extreme or prolonged
precipitation caused by stalled low-pressure systems.
LOSS OF FUNCTION OF STRUCTURES IN FLOODPLAIN
FLOODS
INUNDATION
INTERACTION WITH HAZARDOUS MATERIALS
STRUCTURE & CONTENTS: DAMAGE FROM WATER
WATER BORNE DISEASES (HEALTH PROBLEMS)
EROSION AND MUDFLOWS
CONTAMINATION OF GROUND WATER
CAUSES OF RISK
DISASTER LABORATORIES
A RISK ASSESSMENT
• A risk assessment involves the probabilistic integration of:
• The hazard (e.g., floods) and their potential disaster agents (inundation, erosion, etc) that are directly related to the location of the community and what happens in the regional water cycle.
RISK ASSESSMENT (Continued)
• The location of each element of the exposure in relation to the physical demands of the hazard (i.e., inundation, etc.)
RISK ASSESSMENT (Continued)
• The exposure (e.g., people, and elements of the community’s built environment), represents the potential loss when the natural hazard occurs.
RISK ASSESSMENT (Continued)
• The vulnerability (or fragility) of each element comprising the exposure when subjected to the potential disaster agents.
POLICY POLICY ADOPTIONADOPTION
RISK ASSESSMENT
• VULNERABILITYVULNERABILITY
• EXPOSUREEXPOSURE
• EVENTEVENT
POLICY ASSESSMENT
• COSTCOST
• BENEFITBENEFIT
•CONSEQUENCESCONSEQUENCES
FLOOD RISK ASSESSMENT LEADS TO FLOOD RISK ASSESSMENT LEADS TO DISASTER-RISK REDUCTIONDISASTER-RISK REDUCTION
FLOODSFLOODS EXPECTED EXPECTED LOSSLOSS
REQUIRED INFORMATION
• Physical characteristics of the regional drainage system.
• Physical characteristics of each river system and its floodplain.
• Physical characteristics of the regional water cycle.
REQUIRED INFORMATION
• Physical characteristics of catchment basins, reservoirs, and wetlands in the region.
• Physical characteristics of dikes, levees, and dams controlling water discharge and flooding in the region.
REQUIRED INFORMATION
• The hazardous materials located in the floodplain.
DISASTER-RISK REDUCTION POLICES FOR FLOODS
MITIGATION, PREVENTION, PREPAREDNESS, FORECASTS AND
WARNING, EVACUATION, EMERGENCY RESPONSE, RECOVERY AND
RECONSTRUCTION, AND EDUCATIONAL SURGES
MITIGATION
SANDBAGS, ETC
PREVENTION
DAMS, STORM BARRIERS, LEVEES, SPILLWAYS, CATCHMENT BASINS,
RESERVOIRS, WETLANDS, ETC
THREE GORGES DAM: 2309 M LONG, 190 M HIGH, 15 M THICK
FLOOD PREVENTION: LONDON, ENGLAND