Towards Sustainable Flood Management in and around Metro Manila

Development of Master Plan

Inception Report WorkshopMarch 17, 2011

The Setting

• Rainfall events and flooding are not isolated events, but are annual hazard occurrences.

• Manila is a vulnerable area with flood prone areas. It is in a floodplain/tidal basin – the city is a drainage basin, making flood management difficult, but not impossible (many large cities are in floodplains).

• These are facts of life, but there are measures that can be implemented to reduce the impact of high rainfall events under changing circumstances (population growth, climate change, etc.). Government has a continuous responsibility with regard to the safety and protection of its people.

Ondoy (Ketsana)

• Need for new Master Plan triggered by Ondoy• Ondoy was a very high-rainfall event with an estimated 180

years return period (448 mm in 12 hrs) resulting for example in peak flow of 5,800 m3/sec in the Marikina River that by far exceeding the system design parameters. Also Laguna Lake went up by 1.2 meters overnight and it took months to return to average level.

• Even under the best of circumstances, drainage and river system could not have coped with the sudden volume of water.

Ondoy - A wake-up Call

The impact of Ondoy was so damaging and lasting that it has renewed the focus on a number of issues:• Deforestation in the upper catchment of the Marikina River, resulting

in erosion, with sediments accumulating in the lower reaches of the river system;

• Solid waste deposits clogging the drainage systems; • Failure to maintain carrying capacity for lack of regular river cleaning;• Reduced absorptive capacity of soil due to rapid urbanization that

results in increased flash flood events; • Under-designed and insufficient flood management infrastructure

resulting in an insufficient level of protection of a large urban area that is a main engine of economic growth for the country;

• Lack of maintenance of existing flood management infrastructure, including clogged drains and outlets;

• Flawed land use and urban planning, resulting in both legal and illegal settlements in high flood hazard areas;

• Lack of adequate preparedness, early warning communication, and evacuation of typhoon-affected communities;

• Groundwater extraction causes land subsidence; • Climate change and sea level rises may exacerbate the

problem of flood management and drainage control; and• Fragmented institutional flood management arrangements.

• Ondoy was an extreme event, but no time for complacency and thinking that the population is safe for now.

• An event like Ondoy or worse could happen again this year.• Government should determine to what safety level it should

protect the area and its people and in addition work out the situation of ‘living with floods’.

• Thus a key policy decision to be made has to be what safety level of protection does the government intend to give to its population.

• This relates both to river flows and Laguna Lake level. • The answer to this question will determine the needed level of

physical development for proper flood management, as well as a determination of the optimum institutional structure.

Scope of Services

Prepare a comprehensive flood management master plan for the entire Metro Manila Basin Area that determines a set of priority structural and non-structural measures that will provide sustainable flood management up to a certain safety level.

Ongoing and Planned Activities

• Services not to be implemented in isolation. A lot has and is happening already.

• GoPh (especially DPWH), assisted especially by JICA have done many investments.

• Now working on Pasig-Marikina River system. • Planning flood simulation and preparation of hazard maps

along sections of the Pasig-Marikina Rivers.• A joint JICA-WB-ADB study on ‘Climate Risks and Adaptation

in Asian Coastal Mega-Cities’ was recently completed. The study includes the case of Manila, prepared by JICA.

• AusAID is implementing a program of disaster risk reduction, mainly with PAGASA. One of the components relates to hazard risk and vulnerability mapping. The tasks are:– collection of data and information on floods and risk exposure

(e.g. information on characteristics, frequency, and potential extent of flood hazards, data on people and structures exposed to flood hazards), preparation of a digital elevation model (DEM) using Light Detection and Ranging (LIDAR) technology;

– development of flood hazard maps for sections of Metro Manila through hydrological and hydraulic modeling, coupled with digital terrain data and GIS.

The Proposed Main Tasks

• A. Detailed Review of Current Situation and Arrangements of Flood Management in and around Metro Manila.

• B. Constraints and Barriers to Improvements of Practices.• C. Development of an Integrated Flood Management Master

Plan.

A. Review of Current Situation and Arrangements of Flood Management in Metro Manila

• Gather information on and understanding the existing flood management conditions in Metro Manila, looking at the physical context, the population and economy, and the government institutions and other agencies involved with flood management.

• To describe policies and legislation; physical content of floods; major recent flood events; current design parameters; existing infrastructure; main vulnerable areas and how this affects people; early warning systems in place; institutional structure; current O&M arrangements and funding.

B. Constraints and Barriers

• Based on (A) the review and assessment of the current situation with flood management in and around Metro Manila, determine the constraints and barriers to implementation of needed flood management practices. – Policy, laws and regulations;– Institutional factors;– Funding, and funding mechanisms;– Structure of planning approaches;– Social factors;– Knowledge and information;– Awareness and preparedness;– Technology and equipment;– Land use planning.

C. Development of an Integrated Flood Management Master Plan

• Develop an overall macro-framework for comprehensive integrated flood management plan that will guide government and agencies involved with flood management during the next decades towards sustainable flood management in and around Metro Manila. Based on global good practices that are applicable to Metro Manila.

• The plan will include the optimization and prioritization of four main key elements:– the institutional foundation; – managing flood hazards through structural and non-structural

measures; – managing exposure to flood hazards; – managing vulnerability to the residual flood risks.

C.1. Institutional Foundation

– Propose an optimum institutional structure; maybe lead agency with effective partnerships.

– Clarify roles and responsibilities.– Legislative improvements.– Training and awareness programs to raise exposure of staff

about flood management.

C.2. Managing flood hazards through structural and non-structural measures

– Propose and agree with relevant government agencies on the preferred flood return periods for flood infrastructure.

– Make detailed proposals for required flood management infrastructure ranging from small interventions like local storage to large-scale infrastructure, and for existing infrastructure that needs upgrading or reconstruction. Each proposal should describe the technical requirements, the capital and operation and maintenance cost estimates, and the economic viability. They should also be reviewed against the World Bank safeguard policies, including environmental and social aspects, land acquisition, and resettlement.

– Proposals should take into account the most likely future scenario of climate change that may lead to increased typhoon activity, sea level rise.

– Prepare a mathematical model of the existing flood management system in and around Metro Manila, including Laguna Lake, to test the existing system for floods of varying magnitude and to test new infrastructure developments.

– Make proposals to reduce the sediment loads in the major flood management infrastructure, especially the rivers that carry flood waters to the sea.

• Prepare a detailed costed proposal of prioritization of the construction or rehabilitation/modernization of infrastructure (examples are upstream cascade of dams to retain flood water; River straightening; Additional dikes; Additional pumping stations; Outlet from Laguna Lake to Manila Bay (e.g. Paranaque floodway) to maintain the lake at a pre-determined level; Upper catchment rehabilitation and management) between 2010 and 2030 that would guarantee Metro Manila, Laguna Lake, and other areas’ safety against floods up to the agreed return period.

• The prioritization program needs to be technically feasible and economically, environmentally, and socially viable.

• A detailed program of implementation of the infrastructure needs to be prepared.

C.3. Managing exposure to flood hazards

– Describe the features of how flood hazard mapping for Metro Manila by application of hydrological and hydraulic modeling, coupled with digitally available terrain data and GIS, will be used to manage exposure to flood hazards. Important also is to describe how flood hazards will change over time as more infrastructure and non-structural measures are developed.

– Develop proposals to restrict further development in flood risk areas to types of development that are most compatible with the flood risk (i.e. regulate human activity).

– Develop proposals and programs to enforce compliance with the flood hazard mapping, which is typically a task for municipalities and local government.

C.4. Managing vulnerability to the residual flood risks

– Develop proposals for community engagement in flood risk management.

– Develop proposals for the establishment of a Flood Management Information Support Center (FMISC) where modern advances and state of the art tools are used (real-time satellite data, hydrological and mathematical models, etc.) in order to carry out adequate and timely flood forecasting.

– Develop proposals for adequate flood warning and emergency response systems. This is to be achieved through structural (e.g. communication systems and early warning systems) and non-structural measures (e.g. preparedness exercises).

Communications

• Regular communication of key messages is of critical importance during the services.

• Dissemination of the status and results of the services at regular intervals is needed.

• Dissemination will include workshops with stakeholders to agree on the proposed action plan.

• A clear communication plan will have to be developed at the start of the services.

Steering Committee and Technical Working Group

• Overall aim is to avoid that the study is conducted in isolation, to ensure effective participation and contribution from all stakeholders, and to screen the recommendations and proposals.

• High-level Steering Committee at policy-makers level with representation of all major agencies and organizations that are involved in flood management, as well as private sector and key NGOs. Mandate is to oversee the preparation of the master plan, ensure consistency with the strategic programs and priorities of the Administration, and facilitate coordination and convergence with various government agencies, private sector, municipalities, and the population at large.

• Technical Steering Committee, comprising senior staff of agencies involved in flood management as well as the main donors, to provide overall technical and administrative support and guide the consultants in their work.

EXPECTATION

To have a quality master plan that is approved by NEDA Advisory Board and ultimately by government to become the blueprint for future developments for flood management in and around Metro Manila. It should get the necessary buy-in from government, politicians, donors, and the population at large.