Dealing with Natural Floods

National Authority for Civil Protection

Luis Sá

Concepts

1.By popular demand we know that a flood is an overflow of an expanse of water that submerges land.

2. EU Floods directive defines a flood as a “temporary covering by water of land not normally covered by water”

3. For Civil Protection there is a concern when that land, now covered by water, is normally used by activities

that are important for the society

4. But, not all floods are bad… some are quite good…

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Causes PT

• Fundamentally, in Portugal, floods are usually the result of high values of accumulated rainfall, which are

typically due to:

Depressions caused by convective interaction between the polar and tropical circulations,

reaching typically the South, and the regions of Lisbon, Alentejo and Algarve

Passage of weather fronts with high activity often reaching regions of the North and Center

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Increment

• The effects of these phenomena are enhanced by:

Misuse of land;

Excessive impermeabilization of large cities;

Poor performance of pseudo-separative collectors systems;

Territorial Disordering

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Flood Management

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Floods Management is a serious business…

• Affects thousands of people and cause millions of euros in damage each year.

• Many of these events are impossible to predict precisely

But the disaster response community has a variety of solutions it can employ to reduce their effects.

The disaster life cycle includes several phases:

Mitigation: involves directly preventing future emergencies and minimizing their negative effects.

Preparation: include plans or preparations made in advance of an emergency that help individuals and

communities get ready.

Response: includes any actions taken in the midst of or immediately following an emergency, including efforts to

save lives and to prevent further property damage

Recovery: actions to return the community to its pre-disaster state and make it less vulnerable to future risk.

Mitigation

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In matter of prevention the European Union published the Floods Directive (DIRECTIVE 2007/60/EC) that

requires Member States to engage their government agencies to draw up a Preliminary Flood Risk

Assessment

The information will be used to identify the areas at significant risk which will then be modelled to produce

flood hazard and risk maps

These risk maps will include detail on the flood extent, depth and level for three scenarios (high, medium and

low probability).

Step by Step

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1. In Portugal, the Decree-Law 115/2010 established a Working Group (WG/PT) for the implementation of the

Floods Directive, which has the following entities:

- Environmental Agency

- Agency of Territorial Development

- National Civil Protection

- Azores Government

- Madeira Government

2. In simple terms we are going to cross a flood map with the land use of that territory

Floods Directive – 3 Deadlines

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The Floods Directive has 3 major deadlines:

• 1º Preliminary Flood Risk Assessment

• by Dec 2011

PT was granted an excuse

• 2º Flood hazard and risk maps

• by Dec 2013

The EU Commission extended until JUN2014

• 3º Flood risk management plans

• by Dec 2015

Flood Intensity

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3. The modelling will be done with software programs like HEC – HMS and HEC – RAS

4. To achieve maps of flooded areas and maps of flood intensity

5. And to obtain the flood intensity (I) in each pixel f the map

Intensity = water depth x (velocity + 0.5)

20, 100 and 1000 years

Flood Intensity

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The working group decided to use land tools classification to define the potential consequences in a flood

event for a certain location.

We have Chosen

- Corine Land Cover (2006)

- Land Use Cartography 2007

Charting…

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So we have a flood intensity, that must be crossed with land use…

To Have a Risk Map

Charting…

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• A risk map is an essential tool because:

Locates and defines hazards that affect the territory;

Makes the appropriate framework for the natural dynamics;

Can be integrated into multiple sets of spatial data in geographic information systems

Response

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• In Portugal, the water management during flood time is performed in partnership between the National

Water Institute (INAG), the National Autority for Civil Protection and dam management owners.

• There are also permanent contacts with Spanish Authorities in order to ensure the management of

flows in common rivers.

TejoGuadiana

Douro

Hot Spots

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• In Portugal in terms of river floods the worst problems are located in:

River Douro, especially in Peso da Régua and Porto, tipically caused by the rainfall observed in

the right bank of the basin

River Tejo, especially in Lower Tejo, tipically caused by the discharged flow of Alcantara dam

(Spain), other portuguese dams and the rainfall observed in Ponsul and Sever tributary

basins

Early Warning - PT

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• The Portuguese Civil Protection uses a Surveillance and Alert System for the permanent analysis on

the water resources (called SVARH)

• This system is sustained by the Environmental Agency but it can be used, at any time, by the Civil

Protection due to a cooperation agreement.

• This system allows us to follow the evolution of hydrological situation in our main basins, a fact that

can be useful to make predictions using emergency plans that contain charts with estimated flow

arrival time and expected effects

Early Warning - EU

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Following the disastrous floods in the Elbe and Danube in August 2002, the Commission launched an activity

on the development of a European Flood Alert System (EFAS)

EFFAS does simulations of discharge with the same model providing comparable results EFAS provides for a integrated early warning system

Portugal and Spain don´t use much of EFAS because they are only 2 countries in the edge of Europe and share hydro information in a regular basis for many years

Recovery• In matter of recovery it´s important to say that Civil Protection houses the National Platform for Disaster Reduction in the United Nations Framework.

This Platform is a multi-sector space for:

– Promotion of risk reduction and limit negative impacts of disasters;

– Creating solid institutional and political framework for ours cities

– Building resilience strategies

• In another perspective, Portugal also as Financial mechanism, the ANPC emergency account, that can support expenditure to people affected by

disaster or calamity, relating to:

a) Reconstruction and repair of housing;

b) Units of economic exploitation;

c) Coverage of other pressing social needs.

The coverage takes place only when their damage is not covered by other public entities, or other private entities like insurance companies

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In short

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The Main Acting principles of ANPC are:

• In Prevention Is a Flood Directive active partner

Has Emergency Flood Planning (Tejo, Douro, Mondego,…)

Does Surveillance of hydro-meteorological situation and reservoir storage

In Response Does Operations co-ordination if necessary and in the scope of emergency

plans

Cooperates with the Meteorological Authority and Water Authority

Cooperates with Local Civil Protection and Local Agents

In Recovery With the ISDR national platform, recommends Guidelines for increment

resilience

Manages the Emergency account, mobilizing supporting means and resources

Thank you luis.sa@prociv.pt