Traditional Flood Management Practices and Future Challenges by realtuff29


									                    World Meteorological Organization
                    Working together in weather, climate and water


              Traditional Flood Management Practices
                         Future Challenges

                                             Jan T.L. Yap
                                      Capacity Building Specialist
                                     Water Resources Management
                      Training of Trainers on Integrated Flood Managament,
                             Jakarta, Indonesia, 23-28 February 2009

WMO; Climate and Water Department                                  

                                    Outline presentation

      • Understanding Flood
      • The Process
      • The Actors
      • Urban Hydrographs & Statistics of Extremes
      • Future Challenges

              Understanding Floods

         Understanding Floods

• Floods cannot be fully controlled, it should be accepted as a
  permanent fact of life;
• it is a perfectly natural phenomenon in terms of probability of
  occurrence and should be approached following a risk management
• Floods is not necessarily a problem as such and do not always lead
  to situations which require development of capital-intensive flood
  protection infrastructure;
• A Flood protection effort: attempt to mitigate flood damage.
• Disasters from flooding are the result of a random act of nature
  combined with poor risk management, uncontrolled development
  and mis-management of natural resources.

Erosion, solids and water quality

Illustration: União da Vitória

Normal Flow                  1983 Flood

The Process

           Flood Management Practices

   • Reducing Flooding;

   • Reducing susceptibility to flood damage;

   • Structural & non-structural measures;

   • Physical & institutional interventions;

   • Emergency actions: Before, during & after floods.

           Traditional Interventions

• Source control: runoff control, infiltration, afforestation;

• Storing runoff: reservoirs, detention basins;

• Increasing river capacity: deepening, widening;

• Separate river and population: embankment, flood proofing,
  land use control;

• Emergency: flood warning, fighting, evacuation;

• Recovery: counseling, compensation, insurance.

        Flood Control & Protection practices

• Reactive practices;

• Problem driven & Symptom Combatment;

• Project approach: solution seems self-evident without giving
  any thought to the impacts;

• Largely relied on Structural Measures;

• Ad-hoc & essentially mono-disciplinary;

• Thinking in engineering solutions, and not in options or

        Drainage canals increase floods

Impervious areas
and conduits
increase the
surface runoff flow

         Technical Constraints

• The most important cause is lack of systematic
  Maintenance for the river and drainage system;

• Absence of a consistent spatial plan has lead to
  considerably reduced retention capacity;

• Encroachment of the riverbanks adds to increased risk
  of flooding and flood damage;

• Due to extensive groundwater extraction, large areas
  have subsided making those areas more vulnerable to
  impeded drainage & tidal floods from the sea.

• Symptom Combatment vs. Real Problem Solving

        Institutional Constraints

• The basic challenge is
   – the limited, if any, coordination between the different
   – the absence of a proper metropolitan structure for
     Maintenance, and severely constrained Maintenance budgets.
• No coordination platform exists for proper planning,
  O&M of the entire flood control system, collaboration &
  coordination between regional & central governments;
• The organizations responsible for the flood control and
  drainage system in the Municipality lack sufficient
  skilled human resources;
• Beneficiaries and stakeholders do not participate in the
  process of planning, implementation and O&M of the
  drainage and flood system.

          Traditional interventions
          Fallen short!

    Structural measures generally disturbed eco-system balance;

    Rather than mitigating flood risk we largely succeeded in only
    shifting them:
       Impact on the river & users elsewhere,
       Tendency to shift the problem spatially & temporarily,
       Reactive response,
       Failure to learn from the past.

    Non-structural measures: weak coordination,
      poor communication strategies,
      limited or passive participation civil society.

                    The Actors

        The Engineers

• Hydrologists, hydraulic & civil engineers played an important,
  if not dominant, role in flood protection, control and
• Engineers were and are de facto the decision-makers in case of
• Their technological approach in solving flood problems was
  almost never contested.
• Flood “Problem Solving” are always made from hydraulic &
  civil engineering point of view;
• Many flood problems today can be derived from “engineering
  solutions” in the past and uncontrolled urban and regional

         The Stakeholders

• The population or the citizens are the most important

• They should be informed on the consequences of a flood.

• The population should be made aware that it is impossible to
  protect them against the risk of flood and to make them understand
  the meaning of risk, and that the risk of flood is real and it is
  always there to strike at anytime.

• They must be made aware of and prepared for this risk, the

• The same applies for the industry & other infrastructure managers.

         The Stakeholders

• Today Engineers are not the sole decision-makers anymore. They
  are a supporting group for the political decision makers;
• There is no “optimal” solution. Terms as ”acceptable” solution or
  “the best compromise” indicate that there are other stakeholders
  involved in the decision making process;
• Usually there are many equally bad solutions and the exercise is
  to select from these bad solutions or to find compromises;
• “Flood free” propaganda: Give a false sense of security!

           The Stakeholders

• Human: Difficult to understand probability and risk;

• Participate in the preparation of the management of
  emergencies and the crises.

• Computer technology, hydraulic and hydrology modeling to
  simulate various modes of flood scenarios to prepare and
  rehearse emergency situations, simulation, what if scenarios.

• Powerful tool to assist in the decision making process and to
  inform the citizens and the industry.

         The Flood Disaster Managers

• The National & Regional Coordination Board for Disaster and
  Refugee Management.
• These institutes are end-users of anything hydraulic, hydrology,
  and ICT can offer to cope with the disaster.
• Hydraulic and hydrology professionals can only offer systems
  of monitoring, forecast, and interpretation to assist the decision
  makers and to implement the decisions taken.
• These implies that the requirements for these support systems
  including the ICT means should be defined by the end-users.
• Hydraulic and ICT professionals only conceive and elaborate

       The Flood Disaster Managers

• Both risk reduction and disaster management are multi-
  disciplinary processes, engaging a wide range of stakeholders.
• Risk reduction is a developmental imperative for achieving
  sustainable growth, and a strategy that protects the lives and
  livelihoods of those most vulnerable.
• Disaster management is a multi-disciplinary field focused on
  minimising losses from the vast array of hazards.
• The challenge many countries faces is how best to advocate for
  improved disaster-management and risk-reduction policies and
  practices so that these become integral aspects of existing
  strategies to achieve sustained development and social equity.

                 Urban Hydrographs
                 Statistics of Extremes
                (Emile Gumbel – 1952)

        What is “Return Period”?

  N=     10       years

 T       1/T      X=1-1/T    X^N       Pr

  1           1         0   0.00000   1.0000
  2         0.5       0.5   0.00098   0.9990
  5         0.2       0.8   0.10737   0.8926
  10        0.1       0.9   0.34868   0.6513
  20       0.05      0.95   0.59874   0.4013
  25       0.04      0.96   0.66483   0.3352
  50       0.02      0.98   0.81707   0.1829
 100       0.01      0.99   0.90438   0.0956

10000    0.0001    0.9999   0.99900   0.0010

             Future Challenges

        Paradigm shift required

• From defensive to pro-active approaches;

• From Ad-hoc to Integrated Flood Management (IFM);

• Towards a culture of prevention by managing flood risk & living
  with floods;

• Balancing flood risk and achieving sustainable development

• Change in decision making processes to include risk
  management approaches.

           Multi-disciplinary nature

 • Recent floods in the world and in The Soutgh-Eastg Asian
   Region clearly indicated that it is more than engineering;
 • Political, institutional and social aspects, are decisive factors as
   well in the decision making process, especially when a flood
   disaster happens.
 • Flood disasters are now increasingly being seen as the outcome
   of cumulative risk processes rooted in patterns of behaviour like
   poor land-use practices, ill-conceived development projects,
   lack of rules and guidelines, absence or inconsistent law
   enforcement, etc.

          Coordination and Communication

• Citizens should be informed on the consequences of a
• There is no such thing as ”flood free”;
• The populations should be made aware that it is
  impossible to protect them against the risk of flood;
• Make them understand the meaning of risk, that the risk
  of flood is real and it is always there to strike at
• They must be made aware of and prepared for this risk,
  the unknown;
• The same applies for the industry and other
  infrastructure or asset managers.

         Urban development

The main vulnerabilities related to urban waters are:

• Change in the water availability: demand increase, pollution of
  the water source and decrease of the flow due to climate
  variability and change. The impacts are in amount of water and
  the pollution of the existing water flow due to the lack of
• Environment impacts: water quality deterioration (river and
  aquifers), gas emissions, environment fragmentation, etc.
• Increase of flood frequency and its effects on the health.
  Changing the flood conditions and impacts.

        Developing Countries Vulnerabilities

• Lack of sanitation and transferring floods to downstream has
  created a high urban vulnerability in developing countries;
• Asia, Central America & Asia where the population is moving
  from rural to urban are the more vulnerable;
• High population concentration in a small area without IUWM is
• The source of the problem is uncontrolled urban development
  without taking its impacts on Urban Waters into consideration.


 • Flood: A natural permanent fact of life, cannot be
   controlled and eradicated;

 • Not necessarily a capital-intensive problem;

 • Phenomenon in terms of probability of occurrence;

 • A risk management approach & flood damage

 • Disasters from flooding are the result of random act
   of nature combined with poor management,
   uncontrolled development and mis-management of
   natural resources.


• IFM is a development policy concept that is flexible and robust
  enough to fully integrate a climate change adaptation perspective
  (« autonomous » adaptation option)
• Flood management can be become a source of « maladaptation »
  Applying IFM principles in adaptation process reduces the risk of
• Key research areas remain
   – non-stationarity in hydrological time series and implications on flood
   – projections of precipitation and streamflow in different CC scenarios
• Increased use of climate information in water resources
  management on seasonal to interannual time scales as a major
  opportunity of the next decade

Thank you


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