LESSONS LEARNED FROM PAST NOTABLE DISASTERS

MEXICOPART 1: FLOODS

Walter Hays, Global Alliance for Disaster Reduction, Vienna,

Virginia, USA 

MEXICO

NATURAL HAZARDS THAT HAVE CAUSED NATURAL HAZARDS THAT HAVE CAUSED DISASTERS IN MEXICODISASTERS IN MEXICO

FLOODS

SEVERE WINDSTORMS

EARTHQUAKES

VOLCANIC ERUPTIONS

ENVIRONMENTAL CHANGE

GLOBAL CLIMATE CHANGE

HIGH BENEFIT/COST FROM BECOMING DISASTER RESILIENT

GOAL: PROTECT PEOPLE GOAL: PROTECT PEOPLE AND COMMUNITIESAND COMMUNITIES

Natural Phenomena that Cause Disasters

Planet Earth’s atmospheric-hydrospheric-lithospheric interactions create situations favorable for FLOODS

CAUSES OF NOTABLE FLOODS IN MEXICO

THE ANNUAL RAINEY SEASON RAINFALL FROM THE ANNUAL TROPICAL

STORMS AND HURRICANES BEFORE, DURING, AND AFTER THEY MAKE

LANDFALL ON THE GULF COAST OR THE PACIFIC COAST

THE SPECIFIC WEATHER SYSTEM DEFINES THE RISK PARAMETERS

HIGH POTENTIAL LOSS EXPOSURES IN A FLOOD

Entire communities;People, property, infra-structure, business enterprise, government centers, crops, wildlife, and natural resources.

FLOODS IN MEXICO’S STATES OF

TABASCO AND CHIAPAS

WORST FLOODING IN 50 YEARS1 MILLION PEOPLE ADVERSELY AFFECTED

ONE OF THE WORST NATURAL DISASTERS IN MEXICO’S HISTORY

NOVEMBER 1-2, 2007

FLOODS IN MEXICO: NOVEMBER 1-2, 2007

ANNUAL FLOODING IN TABASCO

• Mexico’s state of Tabasco has a history of annual floods during November.

• Many of Tabasco’s low-lying neighborhoods, such as Villahermosa, the state capital, have become accustomed to living with water in the first floor of their residence for six months of every year.

70 PERCENT OF TABASCO STATE UNDER WATER: NOV 2, 2007

80 PERCENT OF VILLAHERMOSA, TABASCO’S CAPITAL, FLOODED

70 PERCENT OF TABASCO STATE UNDER WATER: NOV 2, 2007

SOCIETAL IMPACTS IN TABASCO

• Nearly all services in Villahermosa were shut down.

• Thousands clung to roofs of houses or waited inside water-soaked houses or designated shelters, waiting to be rescued or to receive emergency assistance.

• Elevated parking structures were turned into temporary shelters because many houses were unsafe.

SOCIETAL IMPACTS IN TABASCO

• After a week of rain in October-November 2007, the Grijalva River rose 2 m (7 feet) above flood stage and overflowed, along with other regional waterways.

• Approximately 80 percent of Villahermosa and 70 percent of Tabasco were under water.

• 900,000 houses were flooded.• Potable water supplies were exhausted.

SOCIETAL IMPACTS IN THE STATE OF CHIAPAS

• Tabasco’s neighboring state of Chiapas, which is also flood-prone, experienced extensive flooding in November 2007.

• 100,000 people were adversely affected and faced the same problems as in Tabasco state.

A GLOOMY FORECAST• More rain was forecast for the heavily

drenched region.• With food and drinking water scarce,

and some 300,000 of the 1,000,000 still cut off from rescuers, the conditions for serious medical problems such as cholera and other water-borne diseases increased dramatically.

FLOODING ASSOCIATED WITH HURRICANE DEAN

AUGUST 21, 2007

IMPACTS IN MEXICO

• Hurricane Dean’s storm surge flooded Ciuidad del Carmen, a town of 120,000, with waist deep sea water.

• Heavy rainfall accompanying Dean caused rivers to rise rapidly throughout the region.

CHETUMAL: FLOODING AFTER “DEAN” ON AUGUST 21, 2007

BACALAR: FLOODING AFTER “DEAN” ON AUGUST 21, 2007

IMPACTS REACH SOUTH TEXAS

• The impacts in Mexico and South Texas were mainly flooding and landslides associated with and exacerbated by the runoff from the heavy rainfall accompanying the storm.

THE ALTERNATIVE TO A FLOOD DISASTER IS

FLOOD DISASTER RESILIENCE

MEXICO’SMEXICO’S

COMMUNITIESCOMMUNITIESDATA BASES DATA BASES AND INFORMATIONAND INFORMATION

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

•FLOOD HAZARDS•PEOPLE & BLDGS. •VULNERABILITY•LOCATION

FLOOD RISK FLOOD RISK

RISK

ACCEPTABLE RISK

UNACCEPTABLE RISK

GOAL: FLOOD DISASTER GOAL: FLOOD DISASTER RESILIENCERESILIENCE

• PREPAREDNESS•PROTECTION•EARLY WARNING•EMERGENCY RESPONSE•RECOVERY and RECONSTRUCTION

POLICY OPTIONSPOLICY OPTIONS

A FLOOD RISK ASSESSMENT HELPS

GUIDE POLICY ADOPTION AND IMPLEMENTATION

DAMAGE FROM DAMAGE FROM INUNDATIONINUNDATION

A FLOOD RISK ASSESSMENT INTEGRATES PHYSICAL A FLOOD RISK ASSESSMENT INTEGRATES PHYSICAL EFFECTS AND SOCIETAL IMPACTS TO DETERMINE EFFECTS AND SOCIETAL IMPACTS TO DETERMINE

RISKRISK

EROSION, SCOUR, AND EROSION, SCOUR, AND LANDSLIDESLANDSLIDES

LOSS OF LOSS OF FUNCTIONFUNCTION ECONOMIC LOSSECONOMIC LOSS

RISKRISK

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

FLOOD DISASTER RISKS

DAMAGE TO CONTENTS, LOSS OF FUNCTION OF BUILDINGS AND

INFRASTRUCTURE, RELEASE OF HAZARDOUS MATERIALS,

TRANSPORTATION OF DEBRIS, AUTOS, AND HOUSES, ENVIRONMENTAL DEAD ZONES,

AND WATER BORNE DISEASES

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.

UNDERSTANDING VULNERABILITY: THE

ULTIMATE DRIVER OF RISK

Vulnerability: The Driver of Risk Vulnerability: The Driver of Risk

FLOOD FLOOD HAZARDSHAZARDS

EVENTEVENT

VULNERABILITYVULNERABILITY

PEOPLESTRUCTURESPROPERTYENVIRONMENTINFRASTRUCTURE

EXPOSUREEXPOSURE

EXPECTED EXPECTED LOSSLOSS

An element’s vulnerability (fragility) is the result of a community’s actions or of

nature’s actions that change some part of the regional water

cycle (e.g., precipitation, storage, runoff, transpiration,

evaporation).

WHAT INCREASES VULNERABILITY

MANKIND’S ACTIONS AND NATURE ITSELF CAN CHANGE THE VULNERABILITY OF

ELEMENTS AT RISK TO A FLOOD, A PART OF THE REGIONAL WATER CYCLE

MANKIND’S CONTRIBUTIONAn element’s vulnerability

(fragility) is the result of flaws that enter during the planning,

location, siting, design, and construction of a community’s buildings and infrastructure.

MANKIND’S ACTIONS THAT CHANGE SOME PART 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 rate or pattern (e.g., the city’s concrete footprint)

NATURE’S ACTIONS THAT CHANGE THE 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 weather systems.

REQUIRED INFORMATION FOR A COMPREHENSIVE

VULNERABILITY ASSESSMENT

REQUIRED INFORMATION

• Physical characteristics of the regional water cycle and drainage system.

• Physical characteristics of each river system, its tributaries, and its floodplains.

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 potential in the region.

REQUIRED INFORMATION

• The hazardous materials and other elements located in the floodplain.

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 DISASTER

CASE HISTORIES

A DISASTER is --- --- the set of failures that overwhelm the capability of a community to respond without external help  when three continuums: 1)  people, 2) community (i.e., a set of habitats, livelihoods, and social constructs), and 3) complex events (e.g., floods, earthquakes,…) intersect at a point in space and time.

Disasters are caused by single- or multiple-event natural hazards that, (for various reasons), cause

extreme levels of mortality, morbidity, homelessness,

joblessness, economic losses, or environmental impacts.

THE REASONS ARE . . .

• When it does happen, the functions of the community’s buildings and infrastructure can be LOST for long periods.

THE REASONS ARE . . .

• The community is UN-PREPARED for what will likely happen, not to mention the low-probability of occurrence—high-probability of adverse consequences event.

THE REASONS ARE . . .

• The community is UN-PREPARED for what will likely happen, not to mention the low-probability of occurrence—high-probability of adverse consequences event.

THE REASONS ARE . . .

• The community LACKS THE CAPACITY TO RESPOND in a timely and effective manner to the full spectrum of expected and unexpected emergency situations.

THE REASONS ARE . . .

• The community is INEFFICIENT during recovery and reconstruction because it HAS NOT LEARNED from either the current experience or the cumulative prior experiences.

POLICY POLICY ADOPTIONADOPTION

RISK ASSESSMENT

• VULNERABILITYVULNERABILITY

• EXPOSUREEXPOSURE

• EVENTEVENT

POLICY ASSESSMENT

• COSTCOST

• BENEFITBENEFIT

•CONSEQUENCESCONSEQUENCES

MOVING TOWARDS FLOOD DISASTER MOVING TOWARDS FLOOD DISASTER RESILIENCERESILIENCE

FLOODSFLOODS EXPECTED EXPECTED LOSSLOSS

LESSONS LEARNED ABOUT DISASTER RESILIENCE

ALL FLOODS PREPAREDNESFOR THE EXPECTED AND UNEXPECTED IS ESSENTIAL FOR DISASTER RESILIENCE

LESSONS LEARNED ABOUT DISASTER RESILIENCE

ALL FLOODS EARLY

WARNING (THE ISS) AND EVACUATION ARE ESSENTIAL FOR DISASTER RESILIENCE

LESSONS LEARNED ABOUT DISASTER RESILIENCE

ALL FLOODS TIMELY EMERGENCY RESPONSE IS ESSENTIAL FOR DISASTER RESILIENCE

LESSONS LEARNED ABOUT DISASTER RESILIENCE

ALL FLOODS RECOVERY AND

RECONSTRUCTION USUALLY TAKES LONGER THAN THOUGHT.