Caribbean Water Science Center Science Plan 1999

Watershed Issues

The principle watershed issue in Puerto Rico and the U.S. Virgin Islands is the effect of landcover changes on peak flow, baseflow, and water quality.   In addition, these land-cover changes affect the amount of potable water available at intakes that depend on run-of-the-river low flow and the amount of storage in reservoirs.

The USGS-funded Luquillo Water, Energy, and Biogeochemical Budgets (WEBB) program is an example of watershed-scale research.  The study is aimed at improving understanding of processes controlling terrestrial water, energy, and biogeochemical fluxes, their interactions, and their relations to climatic variables; and the ability to predict water, energy, and biogeochemical budgets over a range of spatial and temporal scales.  The work of Luquillo WEBB researchers focuses on water, energy, carbon, nutrient, dissolved-constituent, and sediment (suspended and bed load) budgets in four watersheds located in eastern Puerto Rico.  Two of the watersheds are in tropical rain forest in the Luquillo Experimental Forest (LEF), an 11,300 hectare forest preserve administered by the U.S. Forest Service.   Two additional watersheds are located in the agriculturally-developed and partially urbanized Río Grande de Loíza basin.  The WEBB approach serves as a model for watershed- to island-scale research that the USGS can conduct in Puerto Rico.

Information Needs and Deficiencies

1. The general sources of sediment and their transport mechanisms need to be defined.
2. GIS-based models and applications that can forecast the effect of land-cover changes on peak flow, baseflow, and water quality are needed.
3. There is a lack of understanding of long-term climatic changes on the hydrologic systems of the Caribbean.
4. A shortage of aggregate for construction has increased pressure on fluvial systems because of increased extraction permits. The short and long term effects of sand extraction from rivers are poorly understood.

Program Opportunities

1. Analyze sediment records to define watershed-scale sediment loads, develop sediment transport models for selected basins, and integrate the results for the entire island of Puerto Rico.  Using these models, conduct geomorphologic studies for selected river drainage basins to determine sources of fluvial sediment and residence time of sediment in active and semi-active storage compartments.
2. Develop GIS-based models and applications that can forecast the effect of land-cover change on peak flow, baseflow, and water quality.
3. Conduct paleoclimate research to reconstruct past hydrologic regimes in Puerto Rico and their impact on the development of present hydrologic conditions.
4. Initiate site specific studies of the downstream and upstream effects of rivers and extraction with attention to channel bed and bank erosion.

Next: Fate and Transport of Contaminants

• Caribbean Water Science Center Home Page
• Caribbean Water Science Center Science Plan Table of Contents