Mitigating the Impact of Recurrent Flooding Through Building a Bamboo River Embankment

Barangay Mainit, Cateel, Davao Oriental

Bernardo Mondragon, Vicenta Abella, Anthony Fernandez, Rovic Satorre, Jupiter Gayanilo, Divina Sillvosa, Cornelia Pascual, & Erlinda Aljebe

Child Alert Mindanao developed a dike that could help mitigate recurrent flooding and soil erosion in Barangay Mainit, Cateel, Davao Oriental. Their innovation uses locally-sourced bamboo and the vetiver plant to build the bamboo river embankment.

The goal is to build out the rest of the dike to protect the not only entire stretch of Mainit river, but also the whole of Cateel. In three to five years, the innovators want Barangay Mainit to become a model barangay not only in terms of pioneering the bamboo dike, but also as a model barangay in producing seedlings of the vetiver plant for distribution nationwide.

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The innovation team and the community are asking for support from local government units and other partners to fund the rest of the dike. They also need help in scaling up their production of the vetiver plant to help provide livelihood for the community.

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If there is no dike, the swelling water from the river will seep into the community.

They now understand that nobody can help them better than themselves. They no longer wait for the government to act. They realize that the government can provide trainings, but if they don’t apply it, it means nothing.

OVERVIEW

Mainit river runs alongside Barangay Mainit in Cateel, Davao Oriental. During the rainy season and when storms come, the river swells and floods the community. The rushing water also loosens and erodes the soil on the banks. The bamboo river embankment was introduced mitigate that risk.

There have been other efforts to build dikes in the area, but this project is innovative because it makes use of raw and locally-sourced materials, like bamboo. The dike’s design and assembly have also been modified after a series of testing to ensure the dike’s rigidity.

Community involvement in planning, designing and actual construction of the dike was also part of the innovation.

BACKGROUND

As a coastal community, Cateel is no stranger to weather disturbances. In 2012, Typhoon Pablo wiped out most of the community. It again fell prey to Typhoon Agaton in 2014. The typhoons wrought a lot of damage to the area, particularly in Barangay Mainit, a low-lying community along Mainit river.
Darcesio delos Santos, an indigenous peoples leader and barangay tribal chieftain, recalls how Pablo blew away their houses like paper. Their crops were also destroyed by the storm.

Richard Morales, a farmer, has first-hand experience of the dangers of living near a river. In one occasion when the river swelled, “the water slowly ate away the soil underneath our house. The waters came into our home and washed our house away.”

Janice Vebar, an upland rice farmer, says Mainit river could swell high enough to reach the village and parts of Barangay Mainit Elementary School. “We fear for our children and for our homes,” she says.

CHALLENGE

Barangay Mainit is a small community often overlooked by local government units. The challenge is how to mitigate the risk of recurrent flooding and soil erosion from the local level. Vicenta Abella, Project Officer of Child Alert Mindanao says, a dike could help keep the rising waters away from barangay residents. “If there is no dike, the swelling water from the river will seep into the community,” she says. Morales agrees: “had the dike been there, the flood couldn’t have swept my home away.”

As flood waters rise, the soil around the community loosens and erodes. Previous efforts have already been made to mitigate these, but these did little to protect the community during the rainy season. The idea of a bamboo dike was thus born.

RESPONSE

Numerous consultations with the community have been conducted prior to the actual construction of the dike. Abella says they approached the new project from with a human-centered design in mind: “We always consider the recommendations from the community. They should know better because they’re the ones who experience the floods,” she adds.

The design and construction method of the embankment have been modified to reflect the community’s input, as well as the results of the tests they did on the dike’s resilience and stability.

Instead of sandbags, the bamboo river embankment now uses soil to fill the sacks sandwiched between the bamboo walls of the dike. The soil was also held together by the roots of the vetiver plant, a bunchgrass widely used abroad to help prevent soil erosion. Vetiver was also planted on the dike as a failsafe. Once the bamboo walls deteriorate in a few years time, the bunchgrass would have grown its full height of several feet. It could be tall enough to be a natural barrier that could reinforce the riverbank.

Innovators also agreed to use Bantakan bamboo to build the dike’s walls. This variant has been proven more durable than the common bamboo, especially when it’s soaked in water for extended periods.

Two hundred fifty meters of the bamboo river embankment have already been built. It was subjected to artificial testing in August 2018. Firefighters bombarded the dike with water from high-pressure hoses and it was able to withstand the force.

In January 2019, heavy flooding also put the dike to the test. The embankment was able to prevent water from flowing into the community. It also withstood the eroding forces of the the rushing waves.

One of the facilitators, Ongod, observes, “There’s a huge difference in the past. We’ve noticed that the dike prevented flooding and the further eroding of the soil.”

COMMUNITY INVOLVEMENT AND IMPACT

With this innovation in place, the people of Mainit now feels a little more secure. “I’m very happy that the dike was constructed. I’m more optimistic about building my house again,” says Morales.

The community-driven innovation also empowered the villagers. “They no longer hesitate to speak up and voice out their concerns. The community has also been empowered enough to be more prepared and resilient in the face of disaster,” declares Abella.

Members of the community themselves split into teams that will build the dike in phases. Mothers grouped together to weave the dike’s walls. They consider the work their contribution in protecting and keeping their families safe. Fathers came together to dig up holes where the dike’s posts will be. They wanted to be part of something that could help their entire community. A supervising and support team was also put together to mobilize the community and to coordinate their efforts with the local government.
“They now understand that nobody can help them better than themselves. They no longer wait for the government to act. They realize that the government can provide trainings, but if they don’t apply it, it means nothing,” states Abella.

Using vetiver on the bamboo dike also opened new livelihood opportunities for the people of Barangay Mainit. “If you have enough vetiver leaves, you can make handicrafts like bags, mats and hats,” says Abella. She says the community has now set sight on propagating the bunchgrass as a secondary source of income. Part of the proceeds they make from the vetiver trade goes to a disaster savings group fund.

To prevent other issues arising from the river, the innovation team also taught the community proper waste management. Residents no longer throw out their garbage in the waterway.

SUSTAINABILITY

In the near term, residents of Barangay Mainit want to exten the existing dike. “I hope the embankment will also be able to cover the back of the school where our kids study,” says Vebar.

The innovation team also hopes to turn Barangay Mainit into a model community in three to five years: model in terms of disaster resilience because of the bamboo dike embankment; and model in terms of having a self-sustaining livelihood through the planting and processing of vetiver plants into other products.

“The problem is just funding,” admits Abella. The team is planning to bring up the project to the LGUs concerned, and to other government agencies, such as the DENR, DPWH and the NDRRMC.