AN HISTORICAL EVALUATION OF DRAINAGE BASIN MORPHOLOGY AT RíO GRANDE DE MANATí, MANATí, PUERTO RICO (2000-2010)

A historical evaluation of the drainage basin morphology was done at The Río Grande de Manatí located in Manati municipality in the north-central coast of Puerto Rico Island from 2000 to 2010. The main objective of this study is identified possible changes in drainage basin morphology and land cover and its possible relation with river and suspended sediment discharge. Data was collected using the integration of remote sensing and Geographic Information System (GIS) techniques. Multispectral images and GIS data were used for the identification and characterization of possible changes in river drainage basin morphology and land cover in the study area. Interviews with local fishermen were done to identify possible man-made impact in the site. River discharge, suspended sediment, and precipitation data were collected from published data from US Geological Survey (USGS). Preliminary results showed high sediment discharge at Rio Grande de Manatí in the last years. Mayor part of fishermen indicated that can observe river sediment plumes in the nearshore area at least in monthly basis near the shoreline. High turbidity waters may relate with man-made activities associates with river modification, sand and gravel extraction in the lower western site of the drainage basin area and land cover changes. Fishermen identified man-made activities as one of the causes that produce high river suspended sediment in the nearshore area.