Assessing Sediment Delivery from Catchment Areas to Coastal Ecosystems in the Pacific Islands: A Study in an Urban Context
- 1School of Engineering and Centre for Water Security and Environmental Sustainability, The University of Newcastle, Callaghan 2308, Australia (eliana.jorquera@uon.edu.au)
- 2School of Engineering, Deakin University, Waurn Ponds, Australia
- 3School of Environmental and Life Sciences, The University of Newcastle, Callaghan 2308, Australia
- 4Secretariat of the Pacific Regional Environment Programme, PO Box 240, Apia, Samoa
Coastal mangroves provide vital habitats for marine and coastal ecosystems while also stabilising coastlines, preventing erosion and mitigating the impact of storms. Sea-level rise poses a significant threat to these areas, causing submergence, vegetation changes, and hydrodynamic alterations. Sediment accretion can attenuate the effects of sea-level rise by promoting sedimentation. Mangroves trap sediments with their roots, which gradually create soil layers. The balance between soil accretion and sea-level rise will determine the mangrove's ability to adapt and survive. It is, therefore, crucial to determine the amount of water and sediments produced in the tributary catchment that reaches mangrove areas.
Moata'a is an urban village on the Upolu Island of Samoa, comprising around 300 to 500 households. It is home to a mangrove wetland that has been negatively impacted by human activities such as urban expansion, uncontrolled extraction of natural resources, pollution, and modification of input flows and tidal regime. Furthermore, Moata'a is susceptible to extreme weather conditions such as tropical cyclones, floods, and droughts, which may worsen as a result of climate change.
The amount of water and sediments that flow into the Moata'a mangrove area is influenced by the Vaisigano River. Moata'a is situated in the Vaisigano River's floodplain region, one of the primary rivers on Upolu Island. The Vaisigano River catchment is characterised by a hilly terrain covered with forests and a narrow coastline. During significant flooding events, water is transferred from the Vaisigano to the Moata'a catchment. Significant sediments can be discharged into the mangrove areas in these extreme circumstances.
This contribution presents a hydro-sedimentological assessment of the Moata’a’s mangrove catchment. The Soil & Water Assessment Tool (SWAT) was used to quantify the amount of water and sediment generated in the Moata’a’s catchment and the water and sediments produced by the Vaisigano catchment that are transferred to Moata’a’s mangroves during extreme events.
How to cite: Jorquera, E., Rodriguez, J. F., Saco, P. M., Quijano Baron, J. P., Breda, A., Sandi, S., Verdon-Kidd, D., and Nelson, F.: Assessing Sediment Delivery from Catchment Areas to Coastal Ecosystems in the Pacific Islands: A Study in an Urban Context, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-13758, https://doi.org/10.5194/egusphere-egu24-13758, 2024.
