Geology topics
Research about Puerto Rico
Source-linked reports with geographic coverage including Puerto Rico.
Bouguer gravity maps, rock property data, and principal facts for gravity data compiled for the island of Puerto Rico and vicinity
No abstract available.
Using 222Rn to examine groundwater/surface discharge interaction in the Rio Grande de Manati, Puerto Rico
222 Rn was used in the karst drainage basin of the Rio Grande de Manati in Puerto Rico to study groundwater/surface flow relationships. Locations of groundwater influx along two sections of the Rio Grande de Manati were identified. The 222 Rn measurements were used together with stream discharge data in a mass balance equation to quantify the groundwater inputs. The investigation established that both of the sections of the Rio Manati surveyed not only gained groundwater, but lost surface flow. It was calculated that the river gained about 1.2m 3 s −1 and lost 0.5m 3 s −1 to the aquifer between Ciales and United States Geological Survey gauging station 5. Between United States Geological Survey gauging stations 6 and 7, groundwater influx and stream flow loss occurred simultaneously with groundwater inputs equalling surface discharge losses of 4m 3 s −1 . The study successfully demonstrated the innovative application of 222 Rn as a geochemical tracer in examining groundwater/surface flow relationships in a karst system.
Single-well injection and recovery of freshwater from an aquifer containing saline water at Arecibo, Puerto Rico
No abstract available.
Potentiometric surface of the alluvial aquifer and hydrologic conditions near Caguas, Puerto Rico, March 1988
No abstract available.
Water required, water used, and potential water sources for rice irrigation, north coast of Puerto Rico
A 3-yr investigation was conducted to determine the water required and used (both consumed and applied) for irrigation in the rice-growing areas of Vega Baja, Manati, and Arecibo along the north coast. In addition, the investigation evaluated the water resources of each area with regard to the full development of rice farming areas. Based on experiments conducted at selected test farms, water required ranged from 3.13 to 5.25 acre-ft/acre/crop. The amount of water required varies with the wet and dry seasons. Rainfall was capable of supplying from 31 to 70% of the water required for the measured crop cycles. Statistical analyses demonstrated that as much as 95% of rainfall is potentially usable for rice irrigation. The amount of water consumed differed from the quantity required at selected test farms. The difference between the amount of water consumed and that required was due to unaccounted losses or gains, seepage to and from the irrigation and drainage canals, and lateral leakage through levees. Due to poor water-management practices, the amount of water applied to the farms was considerably larger than the sum of the water requirement and the unaccounted losses or gains. Rivers within the rice growing areas constitute the major water supply for rice irrigation. Full development of these areas will require more water than the rivers can supply. Efficient use of rainfall can significantly reduce the water demand from streamflow. The resulting water demand, however, would still be in excess of the amount available from streamflow. Groundwater development in the area is limited because of seawater intrusion in the aquifers underlying the rice-growing areas. Capture of seepage to the aquifers using wells located near streams, artificial recharge, and development of the deep artesian system can provide additional water for rice irrigation.
Bottom sediment types of the northern insular shelf of Puerto Rico; Punta Penon to Punta Salinas
No abstract available.
Water resources of the Rio Grande de Añasco-lower valley, Puerto Rico
A large amount of water suitable for most uses is available in the lower Rio Grande de Anasco Valley, the major source of which is the Rio Grande de Anasco which contributes about 95% of the surface water inflow to the lower valley. River flow at El Espino exceeds 100 cu ft/sec about 85% of the time and 200 cu ft/sec 50% of the time. Average daily flow for the driest months of the year (February, March, and April), is almost always <100 cu ft/sec. In contrast, the average daily flow for the wettest, months of the year (September, October, and November), is > 120 cu ft/sec. During the study period, flows of the Rio Canas averaged about 5 cu ft/sec. The lower valley is underlain by igneous rocks that have been eroded to depths of 350 ft or more below sea level. The valley is filled with 250 ft or more of limestone and clay, that in turn is overlain by as much as 100 ft of alluvium. The amount of groundwater available is unknown. There are large volumes of water in the saturated mostly fine-grained alluvium of Zone II, but as a whole the alluvium does not yield water readily to wells. Sand and gravel deposits associated with former river channels yield an estimated 100 to 150 gal/min to wells. The principal source of groundwater is the limestone of Zone III, that reportedly yields as much as 500 gal/min to wells. The quality of surface water especially that of Rio Grande de Anasco was very good. Specific conductance seldom exceeds 250 microsiemens/cm, even at low flows. Both salinity and sodium are low, falling in the Cl-S1 irrigation water classification. Water quality in the lower 5,000 ft or so of the river was affected by saltwater encroachment from the sea. The water quality of the other streams and canals in the lower valley was variable depending on susceptibility of saltwater encroachment, contamination from man-made sources, and concentration of minerals by evapotranspiration. Specific conductance however seldom exceeded 500 microsiemens/cm and the water usually falls in the C1-S2 classification. The quality of groundwater in the alluvial aquifer was about the same as that of the water of the Rio Grande de Anasco except where encroached by saltwater or contaminated. The water from the limestone was more mineralized than that of the alluvium (about 600 to 700 microsiemens/cm), and was somewhat similar to that of the smaller streams and canals in the valley.
Geochemical evolution of waters within the north coast limestone aquifers of Puerto Rico: A conceptualization based on a flow path in the Barceloneta area
Water samples along a groundwater flow path in the Barceloneta area, Puerto Rico, were collected from wells screened in the Montebello Limestone Member of the Cibao Formation (artesian aquifer) and in the overlying Aguada and Aymamon Limestones (water table aquifer). The groundwater chemistry changes as water migrates from recharge areas to downgradient zones in the aquifers. Dissolved magnesium, dissolved sulfate, pH, and carbon-13 isotope generally increase down-gradient. Total inorganic carbon and calcium decrease within the freshwater parts of the aquifer. Mass transfer calculations show that the likely reaction model is carbon dioxide incorporation as water infiltrates through the soil zone, followed by calcite dissolution as water recharges the aquifer. As water moves downgradient within the artesian aquifer, carbon dioxide may degas as a result of calcite precipitation while gypsum and dolomite are dissolved. Within the water table aquifer, continuous recharge of waters rich in carbonic acid maintains the dissolution of the carbonate minerals. Near the coast the mixing of fresh groundwater with saltwater is the primary process affecting water chemistry within the water table aquifer.
Hydraulic analyses of water-surface profiles in the vicinity of the Coamo Dam and Highway 52 bridge, southern Puerto Rico: Flood analyses as related to the flood of October 7, 1985
The magnitude, frequency and extent of the flood of October 7, 1985 at the Rio Coamo in the vicinity of the Coamo Dam and Highway 52 bridge in southern Puerto Rico, were investigated. The observed flood profiles were used to calibrate a step-backwater model. The calibrated model was then used to investigate several alternative flow conditions in the vicinity of the bridge. The peak discharge of the flood at the Highway 52 bridge was 72,000 cu ft/sec. This peak discharge was determined from the peak computed at a reach in the vicinity of the Banos de Coamo, about 1.2 mi upstream from the bridge. The computed discharge at the Banos de Coamo of 66,000 cu ft/sec was adjusted to the dam and bridge location by multiplying it by the ratio of the drainage areas raised to the 0.83 power. The flood had a recurrence interval of about 100 yr, exceeding all previously known floods at the site. The flood overtopped the spillway and levee of the Coamo Dam just upstream of Highway 52. The flow over the spillway was 54,000 cu ft/sec. Flow over the levee was about 18,000 cu ft/sec. About 10,000 cu ft/sec of the flow over the levee returned to the main channel at the base of the embankment at the northeast approach to the bridge. The remaining 8,000 cu ft/sec flowed south through the underpass on Highway 153. The embankment and shoulder on the northern span of the bridge were eroded with the eventual collapse of the approach slab.
Potentiometric surface of the alluvial aquifer and hydrologic conditions in the central Aguirre Quadrangle, Puerto Rico, March 1986
No abstract available.
Potentiometric surface of the alluvial aquifer and hydrologic conditions in the Salinas quadrangle, Puerto Rico, March 1986
No abstract available.
Potentiometric surface of the alluvial aquifer and hydrologic conditions in the Guayama quadrangle, Puerto Rico, March 1986
No abstract available.
A history of annual streamflows from the 21 water-resource regions in the United States and Puerto Rico, 1951-83
Annual streamflows from the 21 water-resource regions in the United States and Puerto Rico were calculated for the period 1951-83. The total streamflow discharging to the oceans from the conterminous United States during this period averaged 1,270 billion gallons per day. The outflow from the Lower Mississippi Water-Resource Region (08), which drains 41 percent of the land area of the conterminous United States, contributes 34 percent of the total streamflow to the oceans, which is the most of any region. A 15-year moving average of the annual streamflow was also calculated for each region. The Mid-Atlantic (Region 02) shows a decreasing trend in streamflow since the mid-1970's whereas the Upper Mississippi (Region 07), the Missouri (Region 10), the Rio Grande (Region 13), the Upper Colorado (Region 14), the Lower Colorado (Region 15), the Great Basin (Region 16), and California (Region 18) all show an increasing trend in streamflows. Streamflow from the Upper and Lower Colorado (Regions 14 and 15) appear to be heavily affected by large storage reservoirs. Streamflow from the Upper Colorado (Region 14) shows a decreasing streamflow in 1963 and 1964, which may be due to filling of Lake Powell.
Evaluation of landslide hazards resulting from the 5-8 October 1985, storm in Puerto Rico
No abstract available.