Title of the Good
Comprehensive Flood Mitigation for Cavite Lowland Area in the
practice/case study
Philippines
Which key area/questions the
HFA-2, Area 5 'Reducing Exposure and Underlying Risk Factors
example contributes to
Japan International Cooperation Agency
Abstract
To cope with the complex factors of vulnerability to floods in
Cavite Province in the Philippines, a comprehensive flood
mitigation plan was proposed, including a variety of structural and
non-structural project components.
Context
The study area is located in the eastern part of Cavite Province
and close to Metro Manila. The project is area is about 407 km2.
The lower reaches of the project area are especially vulnerable to
recurrent floods because of gentle slope gradient, braided
channels and low carrying capacity of river. The vulnerability is
further intensified by regular human encroachments onto the
active flood channel and
rapid increase
in the
built-up area. This has
reduced
the
carrying
capacity
and
the
peak
increased
channel
runoff. In year 2000, 2002
and 2006, the floods in
Imus and San Juan rivers
have caused damages to
houses,
and
infra-structure
even
human
casualties. Almost every
year,
thousands
of
residents are affected by
heavy inundations in the
lowland areas.
Project Area
The objective of the project is
to mitigate flood damages in
the lowland area; Prepare
flood mitigation master plan;
Execution of feasibility study
for
the
priority
components;
and
project
capacity
building of flood dealing organizations
How the problem was
The structural flood mitigation plan aims at mitigating damages
addressed?
caused by river overflow. The design scales for the proposed flood
mitigation measures were determined taking into consideration,
affordability of the project cost, the possible extent of land
acquisition, and other relevant factors.
The plan includes the identification of both short-term and
long-term projects. The short-term projects are defined as the
priority projects, and the target completion year is set at 2013.
Other components are classified as the long-term projects, and
their target completion year is set at 2020.
The following structural measures are proposed: (1) off-site flood
impeding basin, (2) partial river improvement, (3) on-site flood
regulation pond, and (4) Inland Drainage Improvement.
The non-structural project component could bring about the
early effect of flood mitigation with less implementation cost as
compared to the structural project component. The following
project components are proposed: (1) control of excessive land
development, (2) community-based flood mitigation, and (3)
management of river area.
The Department of Public Works and Highway (DPWH) and the
Provincial Government of Cavite acted as the counterpart
agencies for the Study. The Steering Committee was also setup to
guide the smooth implementation of the Study and to coordinate
the relevant government and non-government organizations
under the supervision of DPWH and the Provincial Government of
Cavite. The Technical Working Group was set up, to provide
technical support.
Information and education campaign on cleanup of waterways
was conducted in collaboration with the relevant government
agencies and NGOs to raise awareness on the necessity of clearing
the river and drainage channels, which is vital to keep the flow of
water within the channel.
Initially, a map exercise for the residents was carried out for the
preparation of the flood hazard map. Based on the indigenous
knowledge, the local community to understand the flood extents
and area at risk. They also know the routes for flood rescue and
evacuation from the flooded areas. However, a considerable
number of the residents hardly expressed their knowledge on the
maps and hardly recognized the locations indicated on the maps.
Three half-day workshops for the map exercise were organized,
where 107 community members and 29 government officials
participated. The provincial government in coordination with the
municipality has organized a half-day seminar to conduct
evacuation drills and understand the community members on the
contents of flood hazard map. Similarly, the Provincial
Government arranged one-day seminar to impart technical
expertise and skills to the government officials on development of
flood hazard map.
These activities are specially required for the establishment of
flood warning and evacuation system.
Climate change impact was simulated. The storm rainfall intensity
would increase by 11 to 20% in 2050. The present rainfall intensity
of 10-year return period is estimated at 295mm, while the
intensities of same return period in 2050 would increase to 327354mm, which are almost equivalent to the present rainfall
intensities of 20 and 50-year return period, respectively.
Results
A comprehensive flood mitigation plan was proposed, including a
variety of structural and non-structural project components.
Various organizations at national, local, community levels were
involved in the project.
Measuring success
NA
HFA 2
Have the result contributed to HFA2 progress in the country?
The Philippine Government is planning to implement some
components recommended in the project.
Did HFA1 play a role in enabling this initiative?
The Concept of HFA is useful to design flood management
projects on the ground.
Potential for replication
- Can this initiative be replicated? : Yes. It is useful to replicate
to other areas vulnerable to flood disasters.
- Explain how or why not? to follow the approach of
comprehensive flood management, which was established in
this project
Contact
Ishiwatari.mikio@jica.go.jp