Grey, blue, and green technologies are seen to help manage Metro Manila flooding.
Flooding in Metro Manila has been a constant and increasing concern among residents and a difficult challenge for the government.
Experts say the perennial flooding is caused by geographical factors such as low-lying terrain, where large parts of the city are situated.
Also, several rivers, including the Pasig River, flow through the city and when these rivers overflow during heavy rains or typhoons, they can cause widespread flooding.
Aside from geographical factors, rapid urbanization has led to increased impervious surfaces like roads and buildings, which reduce the ground’s ability to absorb rainwater.
Inadequate drainage systems and solid waste management also exacerbate the flooding problem.
So how can the government address flooding?
Tech to manage flooding
Five years ago, Dr. Tobias Börger, an Environmental Economist then with the University of Stirling (UK) researching flood infrastructure in Vietnam, explained that three infrastructure technologies could help manage flooding: grey, blue, and green infrastructure.
Grey infrastructure simply means the expensive concrete dams, dikes, and sewage systems that governments like to build and hopefully properly maintain.
According to a 2017 press statement published on the website of the Asian Infrastructure Investment Bank (AIIB), the World Bank (WB) and the AIIB will provide funding to improve flood management in select drainage areas in Metro Manila.
“The project will cost $500 million, of which $207.6 million will come from WB as approved by its Board of Executive Directors on September 28, 2017. AIIB will provide another US$207.6 million separately approved by its Board of Directors on September 27, 2017. The Philippine government will provide the remaining $84.79 million.”
That’s how expensive grey infrastructure is. The amount is supposed to include funding support for the government’s resettlement of informal settlers along the metropolis’ waterways, locally referred to as esteros.
One project is the Metro Manila Flood Management Project, where 36 existing pumping stations will be modernized and 20 new ones will be constructed along critical waterways in the cities of Manila, Pasay, Taguig, Makati, Malabon, Mandaluyong, San Juan, Pasig, Valenzuela, Quezon City, and Caloocan.”
The DPWH and the Metro Manila Development Authority will reportedly implement the project in close coordination with local governments and key shelter agencies. The project is scheduled to be completed in 2024.
Blue and green infrastructure refers to the non-concrete, more nature-based solutions which include vegetative riverbanks, wetlands, and green areas. These plant-and-water systems will reduce flood risk and potential flood impact because more rainwater will be absorbed by the ground more easily, according to Dr. Börger.
Needless to say, blue and green infrastructure contributes to cleaner air and lower ambient temperature.
The citizens of Metro Manila should be more educated on these technologies and actively monitor the effective implementation of flood management projects.
After all, they are the ones paying for the government’s share of the project cost and will be paying for the repayments on the loans provided by the WB and AIIB.
Video by Dae Bunao.
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