DAVAO CITY (PIA) -- The loss of urban wetlands in Davao City is one of the contributing factors to flooding during heavy rains and other weather disturbances.

Lemuel Manalo, program coordinator of environmental group IDIS (Interfacing Development Interventions for Sustainability), said the rapid urbanization of Davao City has resulted in the loss of 95 percent of its urban wetlands since the 1940s.

In 1944, based on United States Army data, the city had 471 hectares of wetlands; in 2002, it dwindled to 84.55 hectares; and based on a 2021 study, urban wetlands in Davao City shrank to 24.46 hectares.

“Nag-boost ang economy sa Davao City during the 1970s, 80s, and 90s and nag-increase pud ang iyang population nidaghan ang iyang settlements,” Manalo cited the city’s growth as the cause of the wetland loss.

(The economy of Davao City boosted during the 1970s, 80s, and 90s, and its population also increased, leading to the growth of its settlements.)

A wetland is any land area that can hold surface water and also support flora and fauna. In urban spaces such as Davao City, it occurs in the form of swamps, marshlands, lakes, and ponds.

Manalo pointed out that the wetlands are very crucial for Davao City as they function to store surface water during monsoons and ensure water availability during dry seasons. Wetlands also control floods by absorbing excess water and protect nearby settlements from flooding.

In his study, which uses historical land use changes using old Spanish and American era maps of the city, it was determined that Davao City was settled in an area with a large network of riverine and estuarine wetlands connected by creeks and waterways.

Agdao Tidal Marsh

One large wetland is in Agdao, in the area around Jerome Street in R. Castillo Avenue, which in the 1940s was a tidal marsh. Today, it is a heavily populated area in the city, and the remnants of the tidal marsh are drainage canals that run along the community.

“Tidal marshes diri musulod ang tubig dagat, kung high-tide siya diri muadto sa mga areas, but since wala na sila karon kaning tidal marsh nahimo na siyang settlements and tubig muadto na sa drainage, ang tidal seawater didto na musulod sa mga drainage canals, which is insufficient na pundohan ug tubig,” Manalo said.

(Tidal marshes are where the sea water enters during high tide, but since there is no more tidal marsh, the tidal water now settles and goes into the drainage canals, which is insufficient to store water.)

“Nawala na ang wetland (the wetland disappeared)," Manalo said of the Laverna wetland.

“Before it was a wetland, it could really store a large volume of water, and if people do not live in wetlands, we do not have that much risks,” Manalo said.

Matina wetlands

“We have several wetlands in Matina, and they came from the previous floodplains of the Davao River,” Manalo said.

The Matina portion of the Matina River is a low-lying area before it reaches the Shrine Hills.

“Taas ang elevation sa Shrine Hills area, and its slope is rigid normally areas under this type of geological formations diri pud magtapok ang wetlands,” Manalo said.

(The elevation of the Shrine Hills area is high, and its slope is rigid, and normally, in areas under this type of geological formation, we can find wetlands.)

He added that the old course of the Davao River curved its way to the Matina area, noting that “maybe in the 18th or 19th century the river once passed through that area.”

He said there are wetlands that serve as a catchment area of Shrine Hills, particularly the wetland in Juna Subdivision inside Jaroda compound; one wetland near the Alexian Brothers; a wetland inside Davao Global Township; and a wetland inside Coca Village.

“These wetlands are perfect examples coming from a riverine influence.They are effectively functioning wetlands; we really need these wetlands,” Manalo said of the need to preserve them.

Policy advocacy

Manalo called on the government and owners of private property, like real estate projects where wetlands are located, to preserve these spaces which are crucial to mitigate flooding in the city.

“Ang pwede buhaton sa subdivisions is to leave them those wetlands; do not reclaim them, ayaw tambaki (do not fill it up) make them functional wetlands,” Manalo said.

He added that as part of their policy advocacy, they already submitted two wetland studies (historical study and ecological profiling) to the public and to different government agencies, particularly the City Government of Davao’s City Planning and Development Office.

“They (CPDO) already included our recommendations in the crafting of the newly approved Comprehensive Land Use Plan (CLUP) of Davao City,” Manalo said.

Davao City First District Councilor Temujin Ocampo, who sits as chairperson of the City Council Committee on Environment and Natural Resources, said that the newly approved CLUP will be able to preserve the remaining wetlands of Davao City.

He said the loss of the wetlands decades ago was due to spot zoning, where settlements and establishments just built on environmentally critical zones like wetlands.

“With CLUP, naka-identify na ang mga area, mga zones asa nato ibutang mga subdivision, asa nato ibutang mga commercial establishments,” Ocampo said. 

(With the CLUP, we identified the areas and zones where we can put the subdivisions and where to put the commercial establishments, and this will protect the wetlands because there will be strict implementation of the CLUP.) (RGA/PIA Davao)