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River Rechanneling and Accretion Development

River Rechanneling and Dredging

In many high risk and flood frequent areas, flooding is managed through the implementation of flood control measures. Some examples of flood control measures are: (1) river rechanneling, the process of creating a new path for the river system; (2) dredging, the removal of accumulated sediments from the water bed; (3) river bank stabilization, the use of engineering measures to reinforce river banks; and (4) vegetation in open spaces and river banks [2][3].

Climate Adaptation Effectiveness

Each flood control measure contributes to decreasing flooding events, and minimizing damages and casualties. River rechanneling changes the path of the river to move away from communities that could be affected by flooding. Dredging is done to increase flow capacity, lessening the impacts to communities located alongside river systems. River bank stabilization prevents soil erosion and inundation on flood plains while vegetation increases flow resistance and decreases flow velocity. However, it is important to note that vegetation along riverbanks can promote sediment deposition which could increase flooding risk. Increased flow resistance also causes an increased flood height in the upper portion of the river basin which would cause flooding in the lower areas [1][2].

Climate Hazards

  • Rain-Induced Flooding


  • Hijo River, Tagum City, Tagum City, Davao del Norte, Region XI (Davao)

Adapatation Sectors

  • Disaster Risk Reduction
  • Ecosystem-Based Approaches
  • Water Management

CCET Instuments

  • Action Delivery

Target Group based on Vulnerability

Basic Sectors:
  • Artisanal Fisherfolk
  • Businesses
  • Children
  • Farmers and Landless Rural Workers
  • Formal Labor and Migrant Workers
  • Indigenous Peoples
  • Persons with Disabilities
  • Senior Citizens
  • Urban Poor
  • Women
  • Workers in the Informal Sector
  • Youth and Students


Economic / Financial Effectiveness

In comparison to the other flood control measures, planting vegetation has the lowest cost but is less effective compared to stabilizing river banks and dredging. These two methods are much more expensive due to structures to be implemented for river bank stabilization and the recurring financial costs for periodic dredging. A good solution would be a combination of an ecological and infrastructure approach to minimize the costs and optimize the effectivity of the solution [2]. For Tagum LGU, due to the high cost of flood control measures, the Reforestation, Conservation Environment Protection Fee was utilized. This channels the transaction fees between an individual, business or establishment with the city government to fund the project. Contributions can also come from private entities [3].

Technical Feasibility

Flood control measures in the Hijo River in Davao del Norte resulted in the lowering of flood water level from 10 to 4 meters since 2009. There was then no onset of a major flooding event [3].

Social Acceptability

Dredging and ecological approaches are widely accepted as a solution for minimizing flood risks. However, the hesitation for implementing such measures is the high initial and maintenance costs especially for infrastructure measures [2].

Environmental Impact
Mid (+)

An increase in vegetation in the area would reduce soil erosion and would lead to the increase of conservation areas while improving biodiversity. It could also become a secondary source of income acting as a tourism site and generating products to be marketed [2]. However, there are negative impacts from dredging that highly affects the biodiversity of a certain environment. The process liberates sediments and introduces more nutrients thereby, altering the natural state of the habitat [4].

Mitigation co-benefit

Ecological approaches implemented as flood control measures contribute to mitigation of climate change by limiting the modification of the Earth’s surface. The introduction of vegetation can contribute to carbon sequestration.


flooding, river rechanneling, de-silting/dredging, improve river flow, ecosystem-based adaptation to flooding, river rechanneling; river bank stabilization


[1] Anderson, B., 2005. Will replanting vegetation along river banks make floods worse? Cooperative Research Centre for Catchment Hydrology.
[2] Daigneault, A., Brown, P. and Gawith, D. (2016). Dredging versus hedging: Comparing hard infrastructure to ecosystem-based adaptation to flooding. Ecological Economics, 122, pp. 25-35.
[3] Martinez, C. (2012). HIjo River Rechanneling and Accretion Development along Hijyo River Tagum City. In: MDGF: Compendium of Good Practices on Climate Change Adaptation.
[4] Todd, V. L., Todd, I. B., Gardiner, J. C., Morrin, E. C., MacPherson, N. A., DiMarzio, N. A., & Thomsen, F. (2015). A review of impacts of marine dredging activities on marine mammals. ICES Journal of Marine Science, 72(2), 328-340.