BANGUED, Abra —Known for a slogan, “Asenso Abrenio,” or “Arya Abra,” the province of Abra is on the road to leverage this year nature-based solutions for flood risk management for the Abra River Basin, the 6th largest basin in the Philippines.
It comes on the heels of a just finished and approved comprehensive Asian Development Bank (ADB) -led Infrastructure Preparation and Innovation Facility (IPIF), collaborated by its Flood Risk Management Project Sector helping the Philippine Government in flood risk management in six major river basins in the Philippines.
This ADB technical assistance loan supporting the Philippine government is intended for short, medium and long-term strategies prioritizing the Apayao-Abulog River Basin in Cordillera Administrative Region (CAR), Abra River Basin in CAR, Jaluar River Basin in Region VI, Agus River Basin in ARMM, Buayan-Malungon River Basin covering Region XI and XII and Tagum-Libuganon River Basin covering Region XI and XIII.
Last year, the Global Climate Risk Index ranked the Philippines fourth most vulnerable to extreme weather events like flash floods and tropical cyclones.
“Rapid population growth and urbanization of low-lying areas will further increase flood risk and endanger unprotected communities, many informal settlements in flood-prone areas are among the most vulnerable to natural hazards,” the ADB technical report said.
Homing on this threat, the Philippine government has set aside 5 per cent of its Gross Domestic Product (GDP) for projects on hard infrastructure. A large share of the 5 per cent will go for river projects that will impact natural resources management, ecosystems health and improving biodiversity, aside from the ADB technical loan.
For Abra, all systems go for the provincial government to implement what are termed Nature-Based Solutions (NBS) and Natural River Management (NRM) approaches for the Abra River Basin, in combination with hard-engineering solutions, the ADB report detailed.
Overarching aim behind the multiple approaches is about flood damage reduction – found out to be one of the biggest among the problems besetting the six river basins studied.
Expected impacts arising from the proposed nature-based solutions will be the implementation of “smart quarrying strategy,” in the Abra River Basin, designed to reduce overbank flooding and lateral bank erosion in the basin.
Such designed approach is expected to positively affect people’s livelihood in Abra and produce co-benefits, as compared to deforestation.
“Deforestation might decrease when the local community plays an active role in quarrying the riverbed. They would not need to do as much as slash-and burn vegetation to sustain their way of life,” the ADB technical report observed.
In short, it is choosing between two evils: quarrying or deforestation. Quarrying is by far the lesser evil.
On the whole, ADB has recommended to the Abra provincial government the concept of smart quarrying by reducing riverbank erosion and flooding while promoting livelihood opportunities.
But ADB fully detailed in its lengthy report that quarrying activities should a “fully monitored program” by the Abra provincial government, complete with restrictions, penalties or other standards the provincial government deem robust in implementing a smart quarrying program.
ADB recommended a long-term monitoring program on water levels must be embedded in the smart quarrying strategy that can easily shed light on amount of quarried sediment through specific gauge analysis and hydrological changes.
Other aspects that ADB recommended to be implemented include riverbed topography and water levels at gauge stations to be established by ADB, along with the annual calibration of their stage-discharge relationships.
Interventions proposed as nature-based solutions are aimed to give room for the Abra River Basin to accommodate natural river meandering, braiding and channel movement.
Smart quarrying practices can be utilized to facilitate desired morphological development of the Abra River Basin, by quarrying only at strategic areas. It must be done at targeted areas to divert the river channels away from vulnerable assets and communities, the ADB report explained.
Then, depositing sediment at other locations can help the river’s morphology or physiology improves in an adaptive manner.
In overall conduct of the study to uplift condition of the Abra River Basin, ADB carefully took into account the observations of the Abra River Basin Management Council (ARBMC) established by the Abra provincial government and the Department of Environment and Natural Resources (DENR-CAR) to oversee the river’s status.
One of the many observations listed by ARBMC was “unregulated quarrying/mining,” among environmental issues and problems confronting the basin.
Other observations by ARBMC include shortage of water supply, denuded watershed areas and garbage dumping along Abra River.
ARBMC observed that in unregulated quarrying/mining, the problem is aggravated because of poor implementation of mining laws, lack of political will, few income sources and high demand of construction materials like aggregates, building stones and sand.
As to shortage of water supply affecting Abra River, ARBMC listed poorly constructed irrigation systems and inappropriate planting periods.
Regarding denuded watershed areas that severely impact Abra River Basin, problems listed were illegal logging and kaingin system, inadequate financial resources for protection and conservation of watershed areas and, lack of sound watershed or forest protection conservation plan and inadequate forest cover.
As to garbage dumping that great affect sanitation of the Abra River Basin, it was blamed on absence or lack of garbage dump sites and non-segregation of garbage.
Abra River Basin extends over Region 1 and CAR, covering Ilocos Sur, Abra, Benguet and Mountain Province. ADB explained it flows from CAR through a gap in the mountain ridge to the coast of Ilocos Region.
The basin has a holding area of about 5, 125 km2.
Topography of the northern, eastern and southern portions of the basin is rugged and mountainous. Elevations rise to 1500 meters above sea level and 10 per cent of flat terrain makes up for the watershed.
Most of the basin is covered by vegetation in the form of 34 per cent shrubs, 29 per cent open forests and 14 per cent grass land. Agricultural lands found in valleys and plateaus straddle 10 per cent of the watershed surface.
Closed forest cover of the basin is merely 8 per cent. Latest data released by DENR-CAR to ADB showed forest cover in Abra province was 258,479 hectares.
Environmental challenges facing Abra and Abrenians are natural hazards that affect their basin. These are soil erosion. Floods, landslides, typhoons and drought. Overbank flooding affects an estimated 7,700 Abrenians and 5,570 hectares of agricultural land in the midstream section of the Abra River.
ADB noted the municipality of Bangued is the second largest settlement within the scope of the basin and it is a “hotspot” for flooding.
Bank erosion is a persistent problem due to Abra River’s significant lateral displacement and constantly evolving braided channels that cost annual damage estimated at 344 million pesos.
Agricultural land and vital bridges on the flat flood plain at the convergence of the Tineg and Abra rivers are vulnerable to wandering channels, scouring and bed incision, ADB technical people found out.
Quarrying in the Abra River is also a frequent problem as it artificially changes the geomorphology of the basin. As a result, flooding and erosion worsen.
Nonetheless, ADB recommended smart quarrying to facilitate the desired morphological development of the basin, especially lateral bank erosion.
Such proposed nature-based solutions are interventions designed to give room for the Abra River to accommodate natural river meandering, braiding and channel movement.
These interventions also allow the river to overflow onto the floodplains during peak flows and help to reduce vulnerability of assets to natural hazards by creating more room for the river, according to ADB technical people.
Allowing Abra River to naturally meander slows down the flow of the river and reduces the river’s carrying capacity and helps minimize soil erosion risks of settlements and assets directly downstream.
Nature-based solution proposed by ADB for Abra River Basin is completely in lock-step with ARBMC’s mission of “Undertaking sustainable development and management of Abra River Basin resources through Integrated River Basin Management (IRBM) approach.”