FLOODS IN REPUBLIC OF GEORGIA

June 13-15, 2015

Walter Hays, Global Alliance for Walter Hays, Global Alliance for Disaster Reduction, Vienna, Virginia, Disaster Reduction, Vienna, Virginia,

USA USA 

REPUBLIC OF GEORGIA

The heavy rain that began shortly before midnight Sunday caused a

landslide that blocked what is normally a pleasant stream in Tbilisi,

a hilly city, but as the floodwaters grew in strength, a fierce torrent

broke through.

14 DEAD; 40 HOMES DESTROYED

PHYSICAL EFFECTS OF FLOODS

INUNDATION, HIGH-VELOCITY FLOW, HIGH-VOLUME DISCHARGE, EROSION, AND SCOUR

LOSS OF FUNCTION OF STRUCTURES IN FLOODPLAIN

FLOODS

INUNDATION

INTERACTION WITH HAZARDOUS MATERIALS

STRUCTURAL/CONTENTS DAMAGE FROM WATER

WATER BORNE DISEASES (HEALTH PROBLEMS)

EROSION AND MUDFLOWS

CONTAMINATION OF GROUND WATER

CAUSES OF RISK

FLOOD DISASTER LABORATORIES

FLOODING IN TBILISI

FLOODING IN TBILISI

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

SITING AND BUILDING ON UNSTABLE SLOPES

LANDSLIDES

SOIL AND ROCK SUCEPTIBLE TO FALLS

SOIL AND ROCK SUCEPTIBLE TO TOPPLES

SOIL AND ROCK SUCEPTIBLE TO LATERAL SPREADS

SOIL AND ROCK SUSCEPTIBLE TO FLOWS

PRECIPITATION THAT TRIGGERS SLOPE FAILURE SHAKINGGROUND SHAKING THAT

TRIGGERS SLOPE FAILURE

CAUSES OF DAMAGE

GLOBAL DISASTER LABORATORIES

ATYPICAL IMPACT: ANIMALS ESCAPE FROM TBILISI ZOO

TBILISI: TRANQUILIZED HIPPO

RECAPTURING THE HIPPO

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 CONTRIBUTION

An 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.

POLICY POLICY ADOPTIONADOPTION

RISK ASSESSMENT

• VULNERABILITYVULNERABILITY

• EXPOSUREEXPOSURE

• EVENTEVENT

POLICY ASSESSMENT

• COSTCOST

• BENEFITBENEFIT

•CONSEQUENCESCONSEQUENCES

FLOOD RISK ASSESSMENT LEADS TO FLOOD RISK ASSESSMENT LEADS TO FLOOD-DISASTER-RISK REDUCTIONFLOOD-DISASTER-RISK REDUCTION

FLOODSFLOODS EXPECTED EXPECTED LOSSLOSS

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.

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.

GEORGIA’SGEORGIA’S

COMUNITIESCOMUNITIESDATA BASES DATA BASES AND INFORMATIONAND INFORMATION

HAZARDS: GROUND SHAKING GROUND FAILURE SURFACE FAULTING TECTONIC DEFORMATION TSUNAMI RUN UP AFTERSHOCKS

•FLOOD HAZARDS MAPS•INVENTORY•VULNERABILITY•LOCATION

RISK ASSESSMENTRISK ASSESSMENT

RISK

ACCEPTABLE RISK

UNACCEPTABLE RISK

FLOOD DISASTER FLOOD DISASTER REDEUCTIONREDEUCTION

•PREPAREDNESS•PROTECTION/PREVENTION•EARLY WARNING•EMERGENCY RESPONSE•RECOVERY/RECONSTRUCT.

POLICY OPTIONSPOLICY OPTIONS

DISASTER-RISK REDUCTION POLICES FOR FLOODS

MITIGATION, PREVENTION, PREPAREDNESS, FORECASTS AND

WARNING, EVACUATION, EMERGENCY RESPONSE, RECOVERY AND

RECONSTRUCTION, AND EDUCATIONAL SURGES