DAGUPAN CITY — The Flood Mitigation Commission (FMC) has recommended the construction of dikes, flood gates and pumping stations as measures to mitigate and control flooding in the city.
In a 142-page report, the FMC also proposed the rehabilitation of the city’s creeks and estuaries and dredging of the city’s heavily-silted rivers.
Mayor Brian Lim formally received the report from FMC commissioners led by its chair, businessman Joseph Lo, on Wednesday, November 27, 2019.
Last July, Mayor Lim issued an executive order creating the FMC, which was mandated to conduct a comprehensive assessment of flooding in the city and formulate a master plan to resolve the city’s flooding problem.
In its assessment, the FMC found that aside from natural causes, such as heavy rains and rising sea levels, the perennial flooding in the city was also caused by improper disposal of garbage, conversion of fish ponds and other catch basins into residential and commercial subdivisions, and illegal structures erected by residents and some business establishments along the creeks.
The FMC also observed that the city’s rivers have become shallower because the river bed had a thick deposit of muck and unconsumed fish feeds from the pens along the river beds.
The FMC also listed engineering issues that had caused the flooding, such as the absence of a topographic map of the city that could have helped engineers determine the elevation of the city’s streets and flow of rain water.
Among the social issues identified included the growing number of illegal settlers on river banks, storm drains and canals, where they also dumped their waste, causing waterways to clog and rivers to be polluted.
The FMC also said that some local food stores do not have grease traps in their sewages, causing drainage systems to clog.
The FMC said that dikes must be built on both sides of the Pantal River from the Land Transportation Office in Barangay Poblacion Oeste up to the city’s boundary with Calasiao town to prevent soil erosion while dredging is in progress.
The FMC also said that gaps between river dikes must be built and the holes must be closed to prevent return flow of water through the sewers during heavy rainfall and high tide.
“The dikes will also serve as wall to separate sewage water from river water. Water flow shall be controlled by pumping stations and flood gates,” the FMC said.
To control water flow from the rivers to the city’s sewers, the FMC recommended the installation of summer and overflow gates. The summer gate shall only be open during summer while the overflow gate will be open during the typhoon months.
Noting that most of the city’s creeks are clogged, the FMC proposed their immediate rehabilitation, especially the Mariposa and Rizal-Galvan creeks.
To allow smooth flow of water in the creeks, the FMC said obstructions, including illegal structures, garbage and plastics must be removed.
The FMC also recommended the construction of higher creek walls to enable the creeks to accommodate more water during heavy rains.
The FMC proposed the construction of seven pumping stations in the different flood-prone areas of the city. It also recommended that sump pits with pumps be built in four areas along the Pantal River.
To increase the carrying capacity of the Pantal River, the FMC recommended a “large scale dredging” of the river from its mouth in Barangay Pugaro inward to the city, saying it is the only way to improve water flow toward the sea.
The FMC said that dredged sediments must have a clear dumping site and not on river banks to prevent them from eroding back to the river.