Water Resources Research Act Program

Details for Project ID 2020PR350B

Geomorphic evolution of the Río Grande De Añasco Lower Valley and its impact on water resources

Institute: Puerto Rico
Year Established: 2020 Start Date: 2020-03-01 End Date: 2021-02-28
Total Federal Funds: $23,000 Total Non-Federal Funds: $16,086

Principal Investigators: Walter Silva

Abstract: Erosion and sedimentation due to meander evolution in the Río Grande De Añasco Lower Valley impact water resources. The bank material is easily removed by the river velocities promoting meander migration and erosion. Agricultural zones are affected, and sediment deposition occurs downstream. The river morphodynamics changes rapidly creating oxbows. Contaminants move in sediment particles and discharge in the Mayaguez Bay, causing pollution in coastal areas and affecting coral reefs. The river has a long history of meander migration and changes in horizontal alignment.The water intake for the Miradero Water Treatment Plant is in an active meander migration zone. The treatment plant supplies water to more than 65,000 households from five municipalities. During hurricane María, the meander upstream of the water intake migrated to a position close to merging with the next downstream meander. If both meanders merged the river will not pass by the water treatment intake, leaving the water plant intake isolated from the river raw water supply.This proposal will quantify meander migration in the lower valley of Río Grande De Añasco by using the International River Interface Cooperative (iRIC) state-of-the-art movable boundary models. Personnel from the USGS Geomorphology and Sediment Transport Laboratory (GSTL) will oversee training, including one day of field data collection. Existing and new field data will be collected and used for model preparation. Several scenarios will be modeled to determine meander evolution and impacts on infrastructure (treatment plant intake) and agriculture in the floodplain. The project will strengthen collaboration with USGS Research Hydrologists and provide a case-study for future studies in the flood-prone alluvial valleys in Puerto Rico and the Caribbean.