Fajardo River Water Resources: Using Earth Observations to Evaluate Land Cover and Water Quality in the Fajardo River Watershed, Puerto Rico

The Fajardo River Watershed, located in Eastern Puerto Rico, drains into vulnerable coastal areas that contain critical marine ecosystems like coral reefs, seagrass beds, and mangrove forests. Assessments of land and water health in the region have been limited, and the impacts of land-based pollution on surrounding marine areas are unclear. DEVELOP partnered with two Puerto Rico-based, marine conservation groups—Sociedad Ambiente Marino (SAM) and the Environmental Mapping Consultants (EMC)—and collaborated with NASA’s Water2Coasts project to examine the viability of remote sensing to assess land cover land use change (LCLUC) and coastal water quality in the region. Using data from Landsat 7 Enhanced Thematic Mapper Plus (ETM+), Landsat 8 Operational Land Imager (OLI), Envisat Medium Resolution Imaging Spectrometer (MERIS), Suomi National Polar-Orbiting Partnership (NPP) Visible Infrared Imaging Radiometer Suite (VIIRS), and Plankton, Aerosol, Cloud, ocean Ecosystem (PACE) Ocean Color Instrument (OCI) satellites, our LCLUC analysis found increased vegetation cover and decreased crop and barren land cover over the past two decades. Our water quality analysis indicated moderate concentrations of chlorophyll-a and Kd490—two important water quality indicators—and observed higher concentrations during Puerto Rico’s rainy seasons. We were unable to evaluate the relationship between LCLUC and coastal water quality due to coarse data resolution and limits in data availability. However, by analyzing regional water quality trends, we were able to inform our partners’ decision-making processes in coral reef conservation and assist in the identification of at-risk coral reef sites and locations of potential water quality monitoring stations. We determined that Earth observations successfully reflected local observations and can be utilized by partners for more advanced assessments of ocean and land health in the area.