Flood Hazards, Vulnerability and Risk ReductionChapter # 01

MUHAMMAD HANIF

IntroductionFlooding is one of the most frequent andwidespread of all weather-related hazards.Various types of floods occur in the most regions of the globe causing:

Loss of lives Damage and disruption to: Infrastructure Livelihood Businesses Services Public Health Critical resources

Introduction

Report of RCRC (Form 1993 to 2002) People effected per year 140 million on

average across the globe.As per report of (CRED) 2003-to-2004 significant

increased recorded in above average.

INTRODUCTION

A flood is usually caused by rain, heavy thunderstorms, and thawing of snow.

Its considered to be a temporary condition of two or more acres of dry land either:

• Overflowed with inland or tidal waters

• Rapid or runoff of surface waters• Mudflows

How does Flooding Start and end?

The shore or land by or surrounding a body of water erodes and this erosion causes waves currents that result in a flood.

Flood disasters have been increased because of the expansion of settlements.

Floods could be slow or fast but usually occur over a matter of days.

After the water eventually goes down or dries up. On coastal floods, low tides and high tides makes a change in heights.

Floods and flood hazard

Flood can take many forms and it is not easy to pin down a precise definition for the term however a flood refers to an excess accumulation of water across a land surface.

The leading cause of floods is heavy rainfall of long duration or of high intensity, creating high runoff in rivers.

Flood Disasters

An event that brings widespread losses anddisruption to a community is the disaster. Flood disaster and their mortality impacts are heavily skewed towards Asia, where there are high population concentrations in the floodplains of major rivers, such as the Ganges-Brahmaputra, Mekong and Yangttze basins, and in cyclone-prone JCOASTAL REGIONS, SUCH AS AROUND THE Bay of Bengal and the South China, Japan and the Philippines. Asia accounts for 98 percent of all people affected by flood disasters and 90 percent of all people affected by wind storms during the period 1990 to 2004

for more detail Text Book page No. 13

Recent Trends in flood frequency

Flooding and its impacts not only vary acrossspace, but also across the time. Year to year shot-term change in the incidence of floods caused by variability of climate. The second is longer term change associated with significant shifts in flood trends over multiple decades.The notion that the incidence of flooding may already be increasing as a result of alteration of greenhouse gas levels in the atmosphere, leading to climate change.

Future climate Change and floodingThese include:- Increases in heavy downpours - Rising temperature - Rising sea level- Rapidly retreating glaciers- Thawing permafrost- Lengthening growing seasons- Lengthening ice-free seasons etc

Key Findings

5. Crop and livestock production will be increasingly challenged- Many crops show positive responses to elevated carbon dioxide and low levels

of warming. But higher levels of warming often negatively affect growth and yields.

- Increased pests, water stress, diseases, and weather extremes will pose adaptation challenges for crop and livestock production.

6. Coastal areas are at increasing risk from sea level rise and storm surge • Increasing risk of erosion and flooding, especially along the Atlantic and Gulf Coasts, Pacific Islands, and parts of Alaska. • Energy and transportation infrastructure - very likely to be adversely affected.

Key Findings

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8. Climate change will interact with many social and environmental stresses• Climate change will combine with pollution, population growth, overuse of resources, urbanization, and other social, economic, and environmental stresses

Key FindingsNumber of Days Over

100ºF

Higher Emissions Scenario, 2080-2099

Coastal FloodsCoastal floods are caused by tides,

storms, tropical cyclones, or tsunamis.

They happen in the ocean and effects the general public and maritime interests along the coastline.

They are caused by heavy surf, tidal piling, and storm surges,

Other factors are tidal cycles, behaviors of the storm, river or stream runoff, no offshore reefs or other barriers, and high winds.

Venezuela in December of 1999.

River Floods

Riverine floods are caused by melting of snow and precipitation over large areas. They take place in rivers. Floods in large rivers take hours to days.

The ground conditions effects the runoff.

What can we conclude about future flood risk resulting from climate changeIncreasing the predictive evidence of heightened global risk of inland and coastal flooding is evering it is perhaps premature and misleading to attempt to produce a future flood risk map; but it is apparent that some areas, at least, are highly likely to experience more intense or frequent flood events over the next 100 years.

Social Dimension of flood risk

Contribution from literature on disaster management, the political ecology of hazards and climate change adaptation, for example, have highlighte the social construction of risk, root causes of vulnerability and the differential vulnerability and coping capacity of social groups.

What is Adaptation…

And why does it matter?

NOAA

NASA –GSFCUSGCRP 2009

Social Dimension of flood risk The definition concept of risk, hazard, vulnerability, coping capacity and adaptation. Risk = the probability of harmful consequences to a human population

resulting from flooding (a function of flood hazard and vulnerability) Vulnerability = a set of conditions and processes that determine the

likelihood of exposure and the resulting susceptibility of humans or human systems to the adverse effects of a flood hazard.

Coping capacity = the ability of people/systems to avoid exposure to flood hazard and to avoid, tolerate or recover from adverse effects (the converse of vulnerability)

Adaptation change in behavior, resources, infrastructure or the functioning of a system that reduces vulnerability.

What is Adaptation…

And why does it matter?

NOAA

NASA –GSFCUSGCRP 2009

Adaptation• Adaptation is not a choice – our choice is

whether to adapt proactively or respond to the consequences.

• We have always adapted to variability – but now the trends are moving outside of human experience and we need to be prepared.

• Adaptation requires a paradigm shift, focusing on managing risks. We know the trends, but not the magnitude.

• Vulnerability and social differentiation• Coping capacity and adaptation• Disaster Management Cycle

I. Emergency ResponseII. RecoveryIII. MitigationIV. Preparedness