Measurement of sediment oxygen demand rates in the Mangrove Lagoon, Vessup Bay, and Benner Bay in southeastern St. Thomas, U.S. Virgin Islands
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Geology topics
Publications and source records attributed to Orlando Ramos-Gines.
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Flood-peak discharges and frequencies are presented for 57 gaged sites in Puerto Rico for recurrence intervals ranging from 2 to 500 years. The log-Pearson Type III distribution, the methodology recommended by the United States Interagency Committee on Water Data, was used to determine the magnitude and frequency of floods at the gaged sites having 10 to 43 years of record. A technique is presented for estimating flood-peak discharges at recurrence intervals ranging from 2 to 500 years for unregulated streams in Puerto Rico with contributing drainage areas ranging from 0.83 to 208 square miles. Loglinear multiple regression analyses, using climatic and basin characteristics and peak-discharge data from the 57 gaged sites, were used to construct regression equations to transfer the magnitude and frequency information from gaged to ungaged sites. The equations have contributing drainage area, depth-to-rock, and mean annual rainfall as the basin and climatic characteristics in estimating flood peak discharges. Examples are given to show a step-by-step procedure in calculating a 100-year flood at a gaged site, an ungaged site, a site near a gaged location, and a site between two gaged sites.
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Water truly Is a resource that gets used and used for everything. The same Water can be utilized many times. This poster depicts 12 water uses which ere labeled in bold red letters, beginning with mining end ending with transportation. Withdrawals (water removed from the river or ground), distribution, and returns (water returned to the river or ground) are depicted by the blue arrows. The poster is folded Into 8 1/2" x 11" panels; front and back panels can easily be photocopied.
A water-resources investigation was conducted during 1989 in the Rio Lapa mountain basins in southern Puerto Rico, to define the hydrology, water quality, and to describe alternatives for additional water- resources supply. The total water budget for both surface- and ground-water resources in the study area was estimated to be 7,530 acre-feet per year for 1989. The water budget for the ground-water system, from which water needs are supplied in the study area, was estimated to be 2,760 acre-feet per year for 1989. Concentration of dissolved solids and fecal bacteria increased during the dry season as both streamflow and ground-water levels decreased. Water samples collected at two stream sites exceeded the recommended U.S. Environmental Protection Agency fecal bacteria concentration for natural water of 2,000 colonies per 100 milliliters during June to November 1989. Water samples obtained from a well in the Rio Lapa Valley exceeded the secondary drinking-water standard for dissolved solids of 500 milligrams per liter during four dry months. In addition, fecal bacteria concentrations at this water-supply well exceeded the primary fecal- bacteria drinking-water standard of 1 colony per 100 milliliter during June to October 1989. Existing water resources can probably be developed to meet additional demands of 110 acre-feet per year pro- jected for 1995. Storage of the surface-water runoff during the wet season and its gradual release to the study area could offset ground-water declines during the dry season. Ground-water withdrawals can be increased by the construction and use of low- capacity wells to reduce the amount of water lowing out of the study area.
Prior to 1930, the principal source of water for irrigation in the Santa Isabel-Juana Diaz area was surface water from outside the study area, which was delivered by a complex channel-pond system. Recharge from water applied to the fields, estimated to be 18.7 million of gallons per day, and discharge by ground-water flow to sea, estimated to be 17 million of gallons per day, were the major water- budget components prior to intensive development of the ground-water resources. Development of the ground-water resources after 1930 resulted in a substantial increase in irrigation, primarily furrow irrigation. The surface water supplied by the complex channel-pond system continued to be used and ground-water withdrawals increased sub- stantially. By 1966-68, ground-water recharge from irrigation water applied to the fields, estimated to be 37 million of gallons per day, and discharge by pumpage for irrigation, estimated to be 77 million of gallons per day, were the two major components of the ground-water budget. By 1987, drip irrigation had become the principal method of irrigation in the study area, and surface-water irrigation had, for the most part, been discontinued. The estimated aquifer recharge from irrigation water in 1987 was about 6.6 million of gallons per day, which occurred primarily in the remaining fields where furrow irrigation was still practiced. Although aquifer recharge had been reduced as a result of the conversion from furrow to drip irrigation, water levels in the aquifer were higher in 1987 than in 1968 because of the large reduction in ground-water withdrawals and subsequent recovery of ground-water levels.
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