Reduced vegetation cover as a result of urbanization is leading to frequent floods in Metro Manila and Rizal province.
“Based on our analysis, Metro Manila is prone to flooding also partly because the entire downstream area, namely Marikina, Cainta and San Mateo, is built-up and thereforeall rain falling in the downstream are converted into floodwaters,” said Department of Environment and Natural Resources (DENR) Undersecretary for Integrated Environmental Scienc Carlos Primo David.
“The largest opportunity in decreasing floods are the conversion of moderate vegetation areas into dense forests and rationalize built-up development. Rivers must also be restored and cleared of obstructions within their natural floodplains,” David added.
The DENR last week called on local government units in Metro Manila to work together with the agency for drastic measures to mitigate the recurring issues on flooding.
“Increased rain intensity and frequency due to climate change, depleted forest cover, land conversion, and modification of our waterways are among the reasons why Metro Manila and Rizal get easily inundated with floodwaters much too often,” said David
He said the government needs to work together to decrease flood heights downstream by increasing green spaces, transitioning to permeable pavements and implementation of offline flood storage and direct flood water injection.
David, who also heads the agency’s Geospatial Database Office (DENR-GDO) and Water Resource Management Office (WRMO), said the agency has already begun talks with the private sector for an intensive reforestation of the Marikina Watershed and rehabilitation of the old Wawa Dam, a gravity dam constructed in 1904 and decommissioned in 1968.
On reforestation, the DENR said it aims to plant three million trees in the Upper Marikina River Basin Protected Landscape within the next four years in partnership with the Department of Public Works and Highways (DPWH), non-government organizations, local government units, and the private sector.
The DENR official presented satellite images, showing how vegetation cover in the 69,817-hectare Marikina River Basin has decreased over the last 10 years. Between January 2014 and January 2024, the DENR-GDO found “notable negative changes in the vegetation cover in the river basin mainly due to urbanization.”
The Marikina River Basin covers parts of Metro Manila and the province of Rizal, including the 26,123.6-ha Upper Marikina River Basin Protected Landscape (UMRBPL).
Marikina River flows approximately 11kilometers, with a number of tributaries in the form of creeks and rivers draining to four towns and a city in Rizal province, and three cities in Metro Manila, and empties into the Pasig River.
“No quarrying was found in the protected area or the Upper Marikina River Basin Protected Landscape,” David said. “The areas where there is a stark decrease in vegetation cover coincided with urban development.”
“Meanwhile, the areas that gained forest cover include the reforestation areas east of Antipolo and parts of Rodriguez,” he added.
President Ferdinand Marcos Jr.cited the need to develop new ways to mitigate the effects of floods amid changes in weather patterns.
“We’re dealing with a large volume of water that overwhelmed our existing flood control systems, which are no longer sufficient,” he said, referring to the devastation in the province.
The President said new flood-control measures would include building impounding projects upstream to prevent water from reaching low-lying areas. DENR News
