Resource information
Suspended sediment transport into Laguna Lake (Philippines) due to soil erosion from agricultural activities in the Pagsanjan–Lumban catchment is of great concern because of its impacts on water quality. The Pagsanjan–Lumban catchment contributes about 18–20% of the total freshwater inflows to the lake but represents only 10% of the catchment area. In this study the suspended sediment transport model, SedNet, was used to assess the relative impacts of changes in land use within the catchment on the quantities of suspended sediment discharged to the lake. The SedNet model predicted the total suspended sediment supply from the Pagsanjan–Lumban catchment (280km²) to be 231.2kt/y of which almost 70% was predicted to come from Balanac River, 23% from Bombongan River and the remaining 7% from the catchment downstream of these two river systems. Overall, the suspended sediment supply was predicted to decrease by 8% for every 20% of intercropped coconut plantations converted to forest. A greater reduction in the total suspended sediment yield discharging to the lake was predicted when reforestation was targeted at the steep slopes (
