Docstoc

Flood Forecasting

Document Sample
Flood Forecasting Powered By Docstoc
					         Introducing Community Based Warning System in the Philippines

                                Jessie C. Felizardo1
     1
      Flood Control and Sabo Engineering Center, Department of Public Works and
                               Highways, Philippines,
                              email: jesscf@yahool.com

Background
Philippine Environmental Setting Vulnerability to Disaster
The geology, topography, climate and geographical location of the Philippines
make it one of the most disastrous countries in the world. It consists of 7,100 islands
with a total land area of approximately 300,000 km2. The climate of the country is
influenced by the numerous mountains, valleys, and the surrounding seas. It is bounded
by the South China Sea on the west and the Pacific Ocean on the east. It is often visited
by an average of 20 typhoons annually, with mean precipitation of approximately of
2,100 mm intensified by the southwest and northeast monsoons. The terrains are mostly
mountains with narrow to extensive coastal lowlands stretching to 34,600 km. There are
421 principal rivers with catchment area of at least 40 km2. 22 out of 200 volcanoes along
the volcanic belt are considered active.
High vulnerability of human settlements to floods, flashfloods and landslides in major
rivers exists as communities occupy river deltas, alluvial fans and river valley floors
bounded by steep mountain slopes.
The Philippines is in dire economic crisis for so many decades. Economic growth for
2005 grew only 5.1% below the target of 5.3% to 6.3% while the population growth rate
is at 2.36%. These figures fell short to make significant inroad into high poverty and
unemployment.
Livelihood and job opportunities in the country sides are heavily affected by economic
and political situations giving rise to unresolved insurgencies involving different
renegade groups for almost a half century. For refuge and safety, rural affected dwellers
venture to cities and other urban communities which congest the Metropolis overtime.
Costly property and immediate necessity for shelters have placed them in risky areas such
as river banks, underneath the bridge, garbage dumpsites, and etc.
Introduction
Government Strategy
The government current thrust inclines towards building and maintenance of roads,
bridges, light rail transits among others, leaving meager budget for disaster
countermeasures. Infrastructure investments are distributed to 47.4 % for roads, 11.2 %
for flood control, 0.2% for engineering and others, and 41.1% for various infrastructures.
Out of these investments, 42% are foreign assisted. Foreign assisted flood control
projects are package based for a certain river basin, leaving the high risk areas
unattended. In light of disaster mitigation, holistic approach is remote possibility due to
huge money involved; hence, prioritization of approaches is necessary.
Previous studies for flood mitigation were focused on the major river basins prioritizing
those with high economic importance and most prone to floods and cities and areas with
history of heavy damages and loss of lives. Reactive strategies prevailed with this set up.
However, in recent years, extreme weather conditions have brought heavy toll to some
eastern seaboard provinces: Camiguin Island Disaster 2001, Quezon-Aurora Tragedy
2004, Leyte Tragedy 2003 and 2006, etc. These areas are characterized by steep river
with short reaches from the alluvial fan to the mouth. The events prompted the leaders to
draw out plans to integrate different approaches.
Early Initiatives
Early warning systems in Luzon northern part of the Philippines are telemetered type,
financed through foreign assistance. These are in the Pampanga, Agno, Bicol and
Cagayan River Basins (abbreviated as PABC) built in the 1980s, under the Philippine
Atmospheric, Geophysical and Astronomical Services Administration (PAGASA),
weather agency of the country. The system is associated with the dam operations.
Additional telemetered system, the Effective Flood Control Operation System (EFCOS)
for Metro-Manila river basins, was built and expanded in 1993 and 2001, respectively.
This is mainly for flood control structure operations supervised by Metro-Manila
Development Authority (MMDA). It is envisioned that forecasting and warning system
                                              will cover also the central and southern
                                              part of the country.
                                                As the telemetered systems are financed
                                                through loan or grant, the designs are by
                                                the foreign consultants using foreign
                                                technology adopted locally. The rapid
                                                technological evolution has outpaced the
                                                system within few years of operation.
                                                Major components wear out while the
                                                parts break down or are stolen in the
                                                field. Sustainable operation can not be
                                                ensured unless these parts are available.
                                                Procurement of the same specification
                                                would entail higher price since
                                                production     stopped      and    special
                                                fabrication from abroad is required. There
        Source : PAGASA
                                                will be operation gaps until such time
                                                budget becomes available and the needed
parts are shipped in. Otherwise, the only alternative is to overhaul the system with new
technology or abandon it.
Purpose
Present Government Thrust
Ideally, vulnerable groups or those at risk are relocated to safer places requiring big
budgets to acquire lands, provide shelters along with the provisions for livelihood,
hospitals, schools, markets, and etc., to meet their daily subsistence. Alternative feasible
approaches in lieu of long term relocation are preferred applying scientific knowledge
with ready available indigenous low technology.
Due to the spate of disasters in the recent years, different strategies were formulated by
different agencies of the government. Action plans include 1) mapping the natural
hazards, 2) conducting information-education campaign, and 3) establishing community-
based early warning system.
In the year 2004 to 2005, due to budget difficulties and moratorium in foreign borrowing,
the recent approach geared to non-structural disaster mitigation measures.
Methodology
                                       Community based early warning system is
                                       prioritized over structural measures in some
                                       cases due to financial consideration. One
                                       example is the JICA assisted project in the
                                       Province of Camiguin, under the Department of
                                       Public Works and Highways, even though
                                       feasibility study for structural measures was
                                       completed a year ahead. Another case is
                                       countermeasures for Quezon, which was
                                       devastated by flashfloods and landslides in
                                       November 2004. The Philippine Institute of
                                       Volcanology and Seismology (PHIVOLCS) in
                                       coordination with PAGASA, and the Mines
                                       and Geosciences Bureau (MGB-DENR)
                                       established a project for the strengthening the
                                       Disaster Preparedness Capacities to Geologic
                                       and      Meteorological    Hazards     of   the
                                       municipalities of Real, Infanta and General
                                       Nakar, Quezon (REINA Project). One of the
components was the early warning system.
Parallel activities of PAGASA aside from the above, initiatives are on-going or
completed with the cooperation of the local government units. These projects are shown
on the shaded portions on the map:
1. Allied Rivers of Agno –those areas not covered by the telemetered system.
2. The Province of Bulacan, sub-basin of Pampanga River System.
3. Dumangas, Iloilo
4. Part of Peñaranda River Basin, Nueva Ecija, Region III
Another milestone of similar endeavor with duration of four years is the Collective
Strengthening of Community Awareness on Natural Disasters (CSCAND) under UNDP
funding. Phivolcs engages in volcano, ground rupture, liquefaction, ground shaking, and
tsunami hazards; PAGASA in flood and storm surge hazards; and MGB in flood and
landslide hazards. Short-term and immediate priority area, covered under the project
                                  Hazards Mapping and Assessment for Effective
                                  Community-based Disaster Risk Management
                                  (READY) covers Surigao del Sur and Surigao del
                                  Norte for 2006 and the remaining 19 provinces in the
                                  identified Philippine Eastern Seaboard provinces
                                  within three years after. Please refer to the map.
                                  However, continuing activities are expected to cover
                                  the entire country after the completion of this project.
                                    The costs for the putting up of the system are
                                    relatively low ranging from US$1,700 to 50,000,
                                    depending on the density of the gauges (with the
                                    exception of Camiguin Island costing around
                                    US$155,000, JICA grant).
                                    Establishing a viable warning system for
                                    communities at risk requires components interacting
with each other. In the design of the system for each project common activities can be
noted forming a chain of components. The essential links consist of the following:
Interviews and Consultations
Interviews and consultation with the affected barangaysa determine the awareness and
preparedness level, knowledge on mitigation measures and warning systems, response
capacity, and the interest, support and participation and willingness in the undertaking.
Data Gathering and Analysis
Data through survey (social, institutional, assessment for rain gauge and water level sites,
warning and evacuation studies) are culled and collated from different sites and past
studies or documents.
Consultations and surveys help determine the felt needs of the community and set the
tone for the design of the system accordingly. Information on demographic distribution,
the cultural practices and belief, the institutional structures and responsibilities, the
technical-know-how and educational attainment are important parameters. On the
physical parameters, the following are considered river length, terrain, vegetation, built-
up areas, roads, ground elevations and others.
Hazard Mapping
Different hazards have different maps, which include the level of risk and vulnerability of
the locality. Maps are essential for land use planning, disaster preparedness, identification
and prescribing remedial measures to flood and other hazards. Preparation for the
formulation of the early warning and identification of safe places for evacuation for
community requires sensible maps.
Multi-hazard is currently formulated and harmonized by different agencies (Phivolcs,
PAGASA, MGB, NAMRIA) to avoid confusion for public use. However, in specific area
where warning system is underway, mapping may be preliminary and finalized later
according to the harmonization process.
Setup of Monitoring and Warning Systems
Monitoring and warning systems normally consist of rain and water level gauges, and
communication equipment. Alongside with the hardware is the procedures for monitoring
debris and flood monitoring. Monitoring manuals are essential as reference for training
and as guides not only for the present but also for future observers and other users.
Improvised locally manufactured instruments are used in the field, such as tipping bucket
or any direct rainfall measuring instrument with human intervention. Rainfall gauges are
placed in school yards, within municipal government premises, hospital compounds, and
other strategic public places. Water level gauges are normally staff gauges or marker on
the pier of bridges, on concrete or hard river embankment. Graduated flood markers are
also painted on the peculiar places in the communities as compliment to the system.
Philippines can not afford radar-derived rainfall estimates. Thus, the observers on site
monitor the hydro-meteorological element normally at the announcement approaching
tropical disturbance by PAGASA. Different indicators are set per location, such as stages
for alert, monitoring, preparatory, and evacuation depending on the rainfall intensities
and flood stages.




a
    Small administrative unit in the municipality
Status of rain and water stage at designated central monitoring stations is relayed for the
decision makers. Usually, the central stations are barangay or municipal halls, where
decision making, the standby patrol, warning instruments are based.
Communications are through two way hand held radio systems or cell phones. Warnings
are given through the church bells, small bells (or batingting) located in the barangay
centers, megaphones, sirens and public address systems. Relaying the message to the
affected constituents is by roaming on horseback, motorcycles or vehicles. In Camiguin
Island, bandilyo is used through word of mouth by the roaming staff of the barangays
relaying the message from place to place.
Formulation of warning and evacuation criteria
The critical rainfall and flood level triggers procedures for evacuation. Critical levels and
the lead time are determined by modeling and/or established through experience.
It is significant that warnings and advisories are acceptable, accurate and timely.
Otherwise, the credibility of the system will be at stake. The established parameters as
observed in the field may be one of the bases for the decision making. During evacuation
drills, some trends can be derived on the route and movement of the people, the concerns,
the basic needs, the means to usher people, the proximity, the features and the capacity of
the center. Gender, age and physical capability are also considered.
In rapids or in steep rivers, where flash floods usually occur, the lead time is very short. It
is imperative that the information be given promptly to the right group. Time motion
intensive activities and simulations can prepare the people in the actual calamity.
Redundant or series of exercises will help imbibed the necessary procedures.
Criteria are designed and fined tune to specific sites, which may vary from place to place.
Information, Education and Communication Campaign
Information, education and communication campaign empowers the constituency by
raising their awareness, familiarizing them with the introduced system layout and give
them direction. Series of trainings and regular drills are simulated on hazard monitoring,
warning and evacuation, system and procedures, disaster simulation drills, formulation of
disaster prevention plan to enhance the capability of the community. Workshops are held
in different barangays, public places and municipal halls. Leaflets for various groups and
stakeholders, bill boards on conspicuous places, manuals in vernacular tongue, are
produced. Complimentary activities require development of public awareness materials
(warning boards and signages, information boards, posters, and pamphlets)
Integration of disaster awareness to school curricula of is also practiced to help prepare
the children. Visit also to PAGASA and other national government agencies dealing with
disaster mitigations are also encouraged. The activities expose the children to the
activities and roles of different agencies and the science and technology relating to
climatic and natural calamities.
Establish Self-sufficiency of the Community During Calamity
Memorandum of Agreement is normally signed between the Local Government Units as
the receiving parties and the national agencies which initiated the project, stipulating the
operation and maintenance of the system. During the time of calamity, the local
government is expected to operate independently given the training, technology transfer,
drills and the equipment with intervention from the national government as the case arise.
Technical assistance is also provided by the national government in terms of training,
analysis, repair and modification of equipment and sometimes additional budget. In the
case of Agno Allied Rivers, data are transmitted to PAGASA flood forecasting branch
and analyzed and disseminated to municipalities.
Common Issues To Address For Effective System
Communication Noises
Some concerns of the people at risk may interfere with the immediate response with the
warning, e.g., whereabouts of the household members, their belongings and properties,
and others. Elucidating them the necessity to act in time will save their lives.
Another significant point to consider is the reduction of warning sounds during heavy
downpour. Church bells during normal weather condition can reach a kilometer radius,
however, during heavy downpour, the sound coverage, not only of the bells but also of
other warning devices could be lesser. When storms occur at night, those at risk may be
difficult to provoke. In this case patrol should ensure that all the residents are given
proper warning.
Mobility of Foot Patrol
The movement of the patrol carrying out warning to reach far flung areas is constraint
sometimes by the flood level and the condition of the terrain. To ensure that warning will
cover the area at risk and avoid the negligence of groups, the high risk areas should be
vacated once advisory of signal becomes available.
Attachment to the Place
Affinity to the place or cultural heritage can hinder the movement to safer place. In the
case of Barangays Magatas and Catmon, just adjacent to Guinsaugon, St. Bernard,
Southern Leyte, where the landslide buried the whole community last February, 2006, the
residents at the foot of the mountain refused to leave even though the cracks are evident
for impending landslides. The reason is that, aside from little awareness of the
mechanism of disaster, they can not find livelihood elsewhere.
Sustainability of the Warning System Under the Local Officials
The change of administration or terms of the local officials lasting for only three years,
may have reduced the effectiveness of the operation and maintenance due to lessened
familiarity of the succeeding officials. Commitment of the community despite the change
of guard should ensure the sustainability of the system. Contingency plan will be needed
to ensure continuity even when key staff members leave.
Support for New Local Innovation
Recently an automated monitoring system (AMS) which relays hydro-meteorological
information from the field was innovated by University of the Philippines’ National
Institute of Geological Sciences Geologist Dr. Carlo Primo David and computer
engineering students Ardin Lopez, Von Padlan, and Allan Malunes, Don Bosco
Technical College. Housed in a silver waterproof box as big as a suitcase, the AMS can
also monitor water and air temperature, river flow rates and water turbidity. The recorded
data are sent straight from the field to a cell phone as a text message. The Automated
Monitoring System costs at a cheap amount of US$385 (P20,000).
However, this system is not yet acquired by any government agency at the moment even
though demonstrated to them in several occasions.
Assessment of the Community Based Warning System
Evaluating the success of the community based warning system in terms of the safety of
the residents is too early to date because some are in the process of setting up while the
others have not experienced major floods. However, the level of awareness and alertness
of the people are raised, community participation and voluntarism are encouraged, and
the community rapport is developed.
Comparison with and without warning system
Last February 17, 2006, after a two week rainfall, landslide in Guinsaugon, St. Bernard,
Southern Leyte, buried around 1,400 casualties. There was no official warning from the
authorities; however, it was reported by the natives a month prior to the incident that
cracks along the slope were evident. The information was relayed to the barangay captain
but was ignored for unclear reason. Natives with sufficient money for transportation fled.
In less than a month, landslide occurred in Tubaon and Taragona, Davao Oriental.
PAGASA gave warning of possible incidences of flash floods and landslides due to
frequent rains. The mayor ordered the police and village leaders not to allow residents to
the town, after the Mines and Geosciences Bureau warned that the area is unstable
because of continuous heavy rains. Evacuations were carried out right after the warning
and as a result there was no casualty.
These exemplify the scientific intervention in analyzing the situation and relaying the
information to the affected communities by the local officials.
Conclusion
In light of the current socio-economic and environmental conditions in the country, self
sufficient and sustainable community based approaches to disaster mitigation should be
pursued with vigor. Low cost and indigenous technology based on scientific knowledge
in contextual environment is more appropriate than adopting high end technology which
necessitates costly acquisition, operation and maintenance. Replication of the successful
native early warning system established in some areas in the country can be fine tuned to
suit specific locations.
Information dissemination through formal and non-formal channels coupled with drills
should elucidate the what, where, when, how and why of disaster mitigation with the aim
to assimilate the concept and practice in their localities.
References
ADB’s outlook for the Philippines, Asian Development Outlook 2006, from
  http://www.adb.org/Documents/Books/ADO/2006/documents/phi.pdf. Retrieved
  April 10, 2006.
Department of Public Works and Highways, Basic Study for Non-Structural Disaster
   Prevention Measures for the Province of Camuiguin, Philippines, Final Report, 2004
Department of Public Works and Highways 2003, Study for the Preparation of Flood
   Control Manual for Department of Public Works and Highways Technical Standards
   and Guidelines, Final Report, Main Report Volume 1, Philippines.
Japan International Cooperation Agency and Department of Public Works and Highways,
    Water and Floods, A Look at Philippine Rivers and Flood Mitigation Efforts, March
    2004.
Philippine Atmospheric, Geophysical and Astronomical Services Administration,
    Community-Based Flood Mitigation Management Program (CBFMMP) for the
    Province of Bulacan, 2006.
Philippine Atmospheric, Geophysical and Astronomical Services Administration,
    Community-based Flood Forecasting and Warning System (CBFFWS) In the Allied
    Rivers of Agno, 2005.
Philippine Atmospheric, Geophysical and Astronomical Services Administration,
    Establishment of a Community-Based Flood Management Program (CBFMP), 2005.
Philippine Institute of Volcanology and Seismology, Strengthening the Disaster
    Preparedness Capacities of the Municipalities of Real, Infanta and Nakar, Quezon
    Province, Philippines to Geologic and Meteorological Hazards (REINA), Summary
    Report, 2006.

				
DOCUMENT INFO
Shared By:
Tags:
Stats:
views:304
posted:3/8/2011
language:English
pages:8