This document discusses a flood control master plan for a study area that aims to prioritize projects based on quantity and cost indicators. It analyzes various flood control work items across different catchment basins, including declogging, dredging, box culverts, and interceptors. Based on the analysis of project length, volume, and unit costs, it recommends prioritizing declogging in the Buendia and NAIA basins and dredging in the Buendia basin first due to their higher cost-efficiency. Designing culverts with larger cross-sections is also identified as a more cost-effective long-term solution compared to interceptors.

1. PROFILING OF FLOOD CONTROL PROJECTS
BASED ON QUANTITY AND COST
INDICATORS FOR PRIORITIZATION AND
RISK IMPLEMENTATION
Leovin-Rane D. Sanchez
Civil Engineer / Water Resources and Hydraulics
STUDY AREA FLOOD CONTROL PLAN
The major watershed areas were divided into
smaller sub-catchments through big interceptors
(RCBC). It contains the majority of the 50-year
flood and diverted to a bigger body of water such
as the Pasig River and Manila Bay. The remaining
volume of 50-year flood from the downstream side
of the proposed interceptors is contained by the
existing drainage channels. Thus, the remaining 50-
year flood could be said equivalent to a 10-year
flood. Restoration of the existing drainage network
and installation of new flood control facilities as
part of the overall flood control mitigation project
were considered.
CONCEPT
100
1,000
10,000
100,000
1 10 100 1000 10000
UnitCost(Php)
Volume (m3)
Declogging
Buendia
NAIA
Trend
0
10,000
20,000
30,000
40,000
50,000
60,000
0 2000 4000 6000 8000 10000 12000 14000 16000 18000
UnitCost/Barrel/Length/Width(Php)
Length (m)
Dredging
Buendia
Maricaban
NAIA
Parañaque
85,000
87,500
90,000
92,500
95,000
97,500
100,000
0 500 1000 1500 2000 2500 3000 3500 4000 4500
UnitCost(Php)
Length (m)
Interceptor
Box Culvert
Trend
This work item in the
Parañaque basin has the
most number of works in
terms of length but it
turned out as one of the
most economical project
in the long run.
Overall, the dredging
works for Buendia is the
most economical. This
could be prioritized for
budgeting.
QUANTITY AND COST INDICATORS
PRIORITY PROJECTS PER CATCHMENT AREA
In the long run, the declogging
work becomes cost efficient as
the quantity of work increases.
As a solution to the undersized drainage network of the study area, a flood control master plan has been updated. Due to economic or budget constraint, the flood control projects can’t be implemented all at the same time. For
urgent or small budget allocation, the following are suggested to be prioritized: (1) Declogging of existing drainage mains in the Buendia and NAIA basin, (2) and Dredging of channels in the Buendia basin. Also, construction of
interceptors(RCBC) is evidently costly but designing of culverts with big cross-section, that is sufficient for a higher design flood, is more cost-effective in the long run.
CONCLUSION
The present drainage network of Metro Manila is
only designed for 10-year flood and being not
maintained, the capacity of the drainages have
continuously decreased. The Department of Public
Works and Highways (DPWH), has released a new
memorandum that requires drainage systems be
designed for 25-year flood with a free board of 50-
year flood due to frequent high intensity rainfalls.
Being highly urbanized, increasing the capacity of
the existing channels is almost impossible. The
challenge is to introduce new flood control
structures and facilities that will help the
undersized drainage network to manage the flood.
PROBLEM
Design and construction
of culverts with big cross-
section is more cost-
efficient over a period of
time.
BP1-3
BP1-2
BP1-1
BP1-4
BP1-5
BP2-2
BP2-6
BP2-6
BP2-2
BP2-1
BP2-5
BP2-6
BP2-3
BP3-1
BP3-1
BP3-1
BP3-1
BP3-1
MP1-2
MP1-3
MP1-1
MP2-1
MP3-1
MP3-2
NP1-1
NP1-2
NP1-3
NP1-4
NP2-4
NP2-7
NP2-6
NP2-3
NP2-2
NP2-1
NP3-3
NP3-1
NP3-2
PP1
PP1-1
PP1-5
PP1-4
PP1-4
PP1-2
PP1-3
PP2-1
PP3-1
BUENDIA BASIN
Work Item Code and Specification
BP1 Declogging
BP1-1 Vito Cruz
BP1-2 Buendia
BP1-3 Libertad
BP1-4 EDSA
BP1-5 Zobel-Orbit
BP2 Dredging
BP2-1 Calatagan Creek
BP2-2 Makati Diversion Channel
BP2-3 Estero de Pandacan
BP2-4 Estero de Provisor
BP2-5 Estero de Paco
BP2-6 Estero de Tripa de Gallina
BP3 Box Culvert BP3-1 PNR Interceptor
MARICABAN BASIN
Work Item Code and Specification
MP1 Dredging
MP1-1 Maricaban Creek I
MP1-2 Maricaban Creek II
MP1-3 Maricaban Creek III
MP2 Box Culvert MP2-1 Maricaban Interceptor
MP3 Retarding Pond
MP3-1 Villamor Airbase
MP3-2 Philippine Navy
NAIA BASIN
Work Item Code and Specification
NP1 Declogging
NP1-1 Rivera
NP1-2 Airport Road
NP1-3 Librada
NP1-4 Seaside
NP2 Dredging
NP2-1 Inland Channel
NP2-2 Libertad Channel
NP2-3 Redemptorist Channel
NP2-4 Seaside Channel
NP2-5 Parañaque Channel
NP2-6 Cut-cut Creek
NP2-7 Ibayo Creek
NP3 Pumping Station
Np3-1 Redemptorist
NP3-2 Seaside
NP3-3 Parañaque
PARAÑAQUE BASIN
Work Item Code and Specification
PP1 Dredging
PP1-1 Baliwag River
PP1-2 South Parañaque River
PP1-3 San Dionisio River
PP1-4 San Isidro River
PP1-5 Don Bosco River
PP2 Pumping Station PP2-1 NAIA Relief
PP3 Parapet Wall PP3-1 Dongalo River