Sedimentation Surveys in Puerto Rico Active
Reservoirs provide most of the water supply for Puerto Rico. Most of them were constructed in the early and middle 20th century and sediment accumulation has significantly reduced their original storage capacity. The U.S. Geological Survey (USGS) has been conducting a series of bathymetric surveys using a global positioning system (GPS) and a geographic information system (GIS) technology on the principal reservoirs in Puerto Rico, and comparing the results with previous surveys to quantify storage capacity loss.
The humid tropical environment and mountainous terrane of Puerto Rico are conducive to high rates of sedimentation. Washed from the hillslopes and construction sites, sediments settle out in the calm waters of the reservoirs, reducing the storage capacity and eventually ending their useful life. Major floods associated with hurricanes and tropical disturbances cause extensive land erosion and sediment transport that rapidly deplete the storage capacity of reservoirs.
The USGS, in cooperation with the Government of Puerto Rico, has conducted sedimentation surveys since 1994 in 14 reservoirs used for domestic and industrial water supply, power generation, and irrigation. A GPS, a survey-grade echo sounder, and GIS, were used to plan, collect, and analyze hydrographic data to determine the existing storage capacity, the sedimentation rates, and the sediment yield of the reservoir drainage areas.
Bathymetric surveys were conducted by collecting data of geographic location and water depths simultaneously, and storing the data in a portable personal computer. The standard methodology consisted of navigating the reservoirs at pre-established cross sections spaced at 50 meters (or less as needed), starting at the reservoir dam and continuing upstream along the different branches of the reservoirs. The collected data were then edited to eliminate spurious positions and depths, and adjusted to represent water depths at spillway or normal pool elevations. A triangulated irregular network (TIN) of reservoir bottoms, contour maps, cross sections representing the reservoir bottom depths from shore to shore, and longitudinal sections along the thalweg of the different branches of the reservoirs were generated using GIS, to graphically show the location and amount of sediment deposition.
Sediment accumulation has substantially reduced the storage capacity of the principal water-supply reservoirs in Puerto Rico over time. Their storage losses range from 12 to 81 percent of the reservoirs’ original storage capacities. Some of the smaller reservoirs studied are near the end of their useful life. The individual sedimentation trends of the various reservoirs vary with land use, topography, development, and principally, rainfall magnitudes and frequencies within the basins.
The capacity loss rates per area and basin sediment yields, increase with rainfall magnitudes and frequencies, and with human impacts. Also, the drainage area extension and morphology influences sediment erosion processes and sediment transport rates within the basins.
Below are some publications associated with this project.
Sedimentation survey of Lago Cerrillos, Ponce, Puerto Rico, April-May 2008
Selected Hydrologic, Water-Quality, Biological, and Sedimentation Characteristics of Laguna Grande, Fajardo, Puerto Rico, March 2007-February 2009
Sedimentation History of Lago Dos Bocas, Puerto Rico, 1942-2005
Sedimentation Survey of Lago Icacos, Puerto Rico, March 2004
Sedimentation survey of Lago Loiza, Puerto Rico, January 2004
Sedimentation Survey of Lago Toa Vaca, Puerto Rico, June-July 2002
Sedimentation Survey of Lago El Guineo, Puerto Rico, October 2001
Sedimentation survey of Lago de Matrullas, Puerto Rico, December 2001
Sedimentation history of Lago Loiza, Puerto Rico, 1953-94
- Overview
Reservoirs provide most of the water supply for Puerto Rico. Most of them were constructed in the early and middle 20th century and sediment accumulation has significantly reduced their original storage capacity. The U.S. Geological Survey (USGS) has been conducting a series of bathymetric surveys using a global positioning system (GPS) and a geographic information system (GIS) technology on the principal reservoirs in Puerto Rico, and comparing the results with previous surveys to quantify storage capacity loss.
The humid tropical environment and mountainous terrane of Puerto Rico are conducive to high rates of sedimentation. Washed from the hillslopes and construction sites, sediments settle out in the calm waters of the reservoirs, reducing the storage capacity and eventually ending their useful life. Major floods associated with hurricanes and tropical disturbances cause extensive land erosion and sediment transport that rapidly deplete the storage capacity of reservoirs.
The USGS, in cooperation with the Government of Puerto Rico, has conducted sedimentation surveys since 1994 in 14 reservoirs used for domestic and industrial water supply, power generation, and irrigation. A GPS, a survey-grade echo sounder, and GIS, were used to plan, collect, and analyze hydrographic data to determine the existing storage capacity, the sedimentation rates, and the sediment yield of the reservoir drainage areas.
Bathymetric surveys were conducted by collecting data of geographic location and water depths simultaneously, and storing the data in a portable personal computer. The standard methodology consisted of navigating the reservoirs at pre-established cross sections spaced at 50 meters (or less as needed), starting at the reservoir dam and continuing upstream along the different branches of the reservoirs. The collected data were then edited to eliminate spurious positions and depths, and adjusted to represent water depths at spillway or normal pool elevations. A triangulated irregular network (TIN) of reservoir bottoms, contour maps, cross sections representing the reservoir bottom depths from shore to shore, and longitudinal sections along the thalweg of the different branches of the reservoirs were generated using GIS, to graphically show the location and amount of sediment deposition.
Sediment accumulation has substantially reduced the storage capacity of the principal water-supply reservoirs in Puerto Rico over time. Their storage losses range from 12 to 81 percent of the reservoirs’ original storage capacities. Some of the smaller reservoirs studied are near the end of their useful life. The individual sedimentation trends of the various reservoirs vary with land use, topography, development, and principally, rainfall magnitudes and frequencies within the basins.
The capacity loss rates per area and basin sediment yields, increase with rainfall magnitudes and frequencies, and with human impacts. Also, the drainage area extension and morphology influences sediment erosion processes and sediment transport rates within the basins.
- Publications
Below are some publications associated with this project.
Sedimentation survey of Lago Cerrillos, Ponce, Puerto Rico, April-May 2008
Lago Cerrillos dam, located in the municipality of Ponce in southern Puerto Rico, was constructed in 1991 as part of the multipurpose Rio Portugues and Bucana Project. This project provides flood protection, water supply, and recreation facilities for the municipio of Ponce. The reservoir had an original storage capacity of 38.03 million cubic meters at maximum conservation pool elevation of 174.6AuthorsLuis R. Soler-LópezSelected Hydrologic, Water-Quality, Biological, and Sedimentation Characteristics of Laguna Grande, Fajardo, Puerto Rico, March 2007-February 2009
Laguna Grande is a 50-hectare lagoon in the municipio of Fajardo, located in the northeasternmost part of Puerto Rico. Hydrologic, water-quality, and biological data were collected in the lagoon between March 2007 and February 2009 to establish baseline conditions and determine the health of Laguna Grande on the basis of preestablished standards. In addition, a core of bottom material was obtainedAuthorsLuis R. Soler-López, Carlos R. SantosSedimentation History of Lago Dos Bocas, Puerto Rico, 1942-2005
The Lago Dos Bocas Dam, located in the municipality of Utuado in north central Puerto Rico, was constructed in 1942 for hydroelectric power generation. The reservoir had an original storage capacity of 37.50 million cubic meters and a drainage area of 440 square kilometers. In 1948, the construction of the Lago Caonillas Dam on the Rio Caonillas branch of Lago Dos Bocas reduced the natural sedimenAuthorsLuis R. Soler-LópezSedimentation Survey of Lago Icacos, Puerto Rico, March 2004
The Lago Icacos, a small reservoir built in 1930 and owned by the Puerto Rico Electric Power Authority, is part of the Rio Blanco Hydroelectric Power System. The reservoir is located in Naguabo, within the Caribbean National Forest in eastern Puerto Rico. The original storage capacity of the reservoir was 19,119 cubic meters in 1930. The bathymetric survey conducted by the U.S. Geological Survey iAuthorsLuis R. Soler-LópezSedimentation survey of Lago Loiza, Puerto Rico, January 2004
No abstract available.AuthorsLuis R. Soler-López, Fernando Gómez-GómezSedimentation Survey of Lago Toa Vaca, Puerto Rico, June-July 2002
The Lago Toa Vaca dam is located in the municipality of Villalba in southern Puerto Rico, and is owned and operated by the Puerto Rico Aqueduct and Sewer Authority. Construction was completed in 1972 as the first phase of a multi-purpose project that contemplated four possible diversions from other basins to mitigate the rapid storage capacity loss of Lago Guayabal, located immediately downstreamAuthorsLuis R. Soler-LópezSedimentation Survey of Lago El Guineo, Puerto Rico, October 2001
Lago El Guineo has lost about 17.5 percent of its original storage capacity in 70 years because of sediment accumulation. The water volume has been reduced from 2.29 million cubic meters in 1931, to 2.03 million cubic meters in 1986, and to 1.89 million cubic meters in 2001. The average annual storage-capacity loss (equal to the sedimentation rate) of Lago El Guineo was 4,727 cubic meters for theAuthorsLuis R. Soler-LópezSedimentation survey of Lago de Matrullas, Puerto Rico, December 2001
Lago de Matrullas reservoir, constructed in 1934, is located at an altitude of approximately 730 meters above mean sea level in the municipality of Orocovis in central Puerto Rico, and has a drainage area of 11.45 square kilometers. The reservoir is part of the Puerto Rico Electric Power Authority Toro Negro Hydroelectric Project, which also includes the Lago El Guineo reservoir and a hydroelectriAuthorsLuis R. Soler-LópezSedimentation history of Lago Loiza, Puerto Rico, 1953-94
No abstract available.AuthorsR. M. Webb, L.R. Soler-Lopez