66 resultados para Contact Area.
em Aquatic Commons
Resumo:
Phosphorus removal by wetlands and basins in Lake Tahoe may be improved through designing these systems to filter storm water through media having higher phosphorus removal capabilities than local parent material. Substrates rich in iron, aluminum and calcium oftentimes have enhanced phosphorus removal. These substrates can be naturally occurring, byproducts of industrial or water treatment processes, or engineered. Phosphorus removal fundamentally occurs through chemical adsorption and/or precipitation and much of the phosphorus can be irreversibly bound. In addition to these standard media, other engineered substrates are available to enhance P removal. One such substrate is locally available in Reno and uses lanthanum coated diatomaceous earth for arsenate removal. This material, which has a high positive surface charge, can also irreversibly remove phosphorus. Physical factors also affect P removal. Specifically, specific surface area and particle shape affect filtration capacity, contact area between water and the surface area, and likelihood of clogging and blinding. A number of substrates have been shown to effectively remove P in case studies. Based upon these studies, promising substrates include WTRs, blast furnace slag, steel furnace slag, OPC, calcite, marble Utelite and other LWAs, zeolite and shale. However, other nonperformance factors such as environmental considerations, application logistics, costs, and potential for cementification narrow the list of possible media for application at Tahoe. Industrial byproducts such as slags risk possible leaching of heavy metals and this potential cannot be easily predicted. Fly ash and other fine particle substrates would be more difficult to apply because they would need to be blended, making them less desirable and more costly to apply than larger diameter media. High transportation costs rule out non-local products. Finally, amorphous calcium products will eventually cementify reducing their effectiveness in filtration systems. Based upon these considerations, bauxite, LWAs and expanded shales/clays, iron-rich sands, activated alumina, marble and dolomite, and natural and lanthanum activated diatomaceous earth are the products most likely to be tested for application at Tahoe. These materials are typically iron, calcium or aluminum based; many have a high specific surface area; and all have low transportation costs. (PDF contains 21 pages)
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This study was done to determine the amount and kinds of water being produced from the lower Hillsboro Canal Area in Palm Beach and Broward counties. All of the potable ground water being produced from the Biscayne aquifer is developed from the canal through infiltration. Rainfall in the area is the ultimate source for all of the water. Careful control and management will allow the development of large quantities of water from the canal toward Lake Okeechobee, but a fresh water head must be maintained along the contact of fresh water with sea water to prevent salt water intrusion. (PDF contains 51 pages.)
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Otter trawls are very effective at capturing flatfish, but they can affect the seaf loor ecosystems where they are used. Alaska f latf ish trawlers have very long cables (called sweeps) between doors and net to herd fish into the path of the trawl. These sweeps, which ride on and can disturb the seaf loor, account for most of the area affected by these trawls and hence a large proportion of the potential for damage to seaf loor organisms. We examined modifications to otter trawls, such that disk clusters were installed at 9-m intervals to raise trawl sweeps small distances above the seafloor, greatly reducing the area of direct seafloor contact. A critical consideration was whether flatfish would still be herded effectively by these sweeps. We compared conventional and modified sweeps using a twin trawl system and analyzed the volume and composition of the resulting catches. We tested sweeps raised 5, 7.5, and 10 cm and observed no significant losses of flatfish catch until sweeps were raised 10 cm, and those losses were relatively small (5–10%). No size composition changes were detected in the flatfish catches. Alaska pollock (Theragra chalcogramma) were captured at higher rates with two versions of the modified sweeps. Sonar observations of the sweeps in operation and the seaf loor after passage confirmed that the area of direct seafloor contact was greatly reduced by the modified sweep
Resumo:
Upward leakage of saline water from an artesian aquifer below 1,500 feet has caused an increase in chloride concentration in the lower Hawthorn aquifer from less than 1,000 mg/1 (milligrams per liter) to values ranging from about 1,300 to 15,000 mg/1. Similarly the higher temperatures of the intruding water has caused an increase in water temperatures in the aquifer from 82"F to values ranging from 83 to 93"F. The intruding water moves upward either through the open bore hole of deep wells or test holes, or along a fault or fracture system, which has been identified in the area. From these points of entry into the lower Hawthorn aquifer, the saline water spreads laterally toward the south and southeast, but is generally confined to components of the fault system. The saline water moves upward from the lower Hawthorn aquifer into the upper Hawthorn aquifer through the open bore hole of wells, which connect the aquifers. This movement has resulted in an increase in chloride from less than 200 mg/1 in the unaffected parts of the upper Hawthorn aquifer to values commonly ranging from about 300 to more than 3,000 mg/1 in parts of the aquifer affected by upward leakage. The upper Hawthorn aquifer is the principal source of ground-water supply for public water-supply systems in western Lee County. Similar effects have been noted in the water-table aquifer, where chloride increased from less than 100 to concentrations ranging from about 500 to more than 5,000 mg/1. This was caused by the downward infiltration of water discharged at land surface from wells tapping the lower Hawthorn aquifer. The spread of saline water throughout most of the McGregor Isles area is continuing as of 1971. (40 page document)
Resumo:
The water problems confronting Hallandale are similar to those of other coastal cities of southeastern Florida which are undergoing rapid growth with tremendous increase in water demand. The highly permeable Biscayne aquifer underlying the Hallandale area is an excellent source of water; however, the permeable nature of the Biscayne aquifer would permit the intrusion of sea water, if fresh water levels were lowered excessively, as well as the infiltration of urban or industrial contaminants, from land surfaces and surface water bodies. This study is to provide the hydrologic data necessary for proper water resource development and planning in the Hallandale area. (40 page document)
Resumo:
The center of low pressure of a tropical disturbance which moved northward in the Gulf of Mexico, reached land between Panama City and Port St. Joe, Florida, on September 20, 1969. This system was nearly stationary for 48 hours producing heavy rainfall in the Quincy-Havana area, 70-80 miles northeast of the center. Rainfall associated with the tropical disturbance exceeded 20 inches over a part of Gadsden County, Florida, during September 20 through 23, 1969, and the maximum rainfall of record occurred at Quincy with 10.87 inches during a 6-hour period on September 21. The 48-hour maximum of 17.71 inches exceeded the 1 in 100-year probability of 16 inches for a 7-day period. The previous maximum rainfall of record at Quincy (more than 12 inches) was on September 14-15, 1924. The characteristics of this historical storm were similar in path and effect to the September 1969 tropical disturbance. Peak runoff from a 1.4-square mile area near Midway, Florida, was 1,540 cfs (cubic feet per second) per square mile. A peak discharge of 45,600 cfs on September 22 at the gaging station on the Little River near Quincy exceeded the previous peak of 25,400 cfs which occurred on December 4, 1964. The peak discharge of 89,400 cfs at Ochlockonee River near Bloxham exceeded the April 1948 peak of 50,200 cfs, which was the previous maximum of record, by 1.8 times. Many flood-measurement sites had peak discharges in excess of that of a 50-year flood. Nearly $200,000 was spent on emergency repairs to roads. An additional $520,000 in contractual work was required to replace four bridges that were destroyed. Agricultural losses were estimated at $1,000,000. (44 page document)
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(11 page pamphlet)
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The goal of this project was to gather information on wetland restoration projects in the Moro Bay, California, region. Data provided to the San Francisco Estuary Institute (SFEI) will be used to enhance a web-based, public access database, the Bay Area Wetland Project Tracker. Wetland Tracker provides information on the location, size, sponsors, habitats, contact persons, and status of included projects. Its website provides an interactive map of planned and completed wetland projects (http://www.wetlandtracker.org). (Document contains 4 pages)
Resumo:
The scope of the investigation involved the drilling of test holes and the detailed inventorying of existing wells in order to define the location, depth, potential yield, and chemical quality of the water contained in the shallow aquifer that might be used for the development of a central water-supply system. The field work and collection of data for the investigation covered the period 1961 through 1963. Much of the data collected for the report on the ground-water resources of Collier County (McCoy, 1962) is incorporated into this report. (Document has 36 pages.)
Resumo:
In recent years, difficulties encountered in obtaining ground-water supplies with acceptable chemical characteristics in the Myakka River basin area led to the implementation of a test drilling program. Under this program, well drilling and data collection were executed in such a manner that all water-producing zones of the local aquifers, together with the quality and quantity of the water available, were effectively identified. A step-drilling method was utilized which allowed the collection of formation cuttings, water samples, and water-level data, from isolated zones in the well as drilling proceeded. The step drilling procedure is described. The driller's logs, geophysical logs, and chemical quality of water tables are presented.(Document has 66 pages.)
Resumo:
The Econfina Creek basin area in northwestern Florida, which includes Bay County, southeastern Washiigton County, and parts of Calhoun, Gulf, and Jackson counties is shown in figure 1. The basin has an abundant supply of ground water and surface water of good quality. This determination is based on a three-year investigation of the water resources of the basin by the U. S. Geological Survey in cooperation with the Division of Geology, Florida Board of Conservation, during the period from October 1961 through June 1964. The purpose of this report is to assemble the basic data collected during this investigation for those persons interested in water development or management in this basin. (Document has 131 pages.)
Resumo:
The Sarasota-Manatee area is a water-short area and the study was undertaken in 1963 in order to determine the storage capability and discharge rates of the Myakka water shed. It was found that many of the streams of the water shed were virtually dry during part of every year. However, the basins of the Myakka lakes, through which the river flows offer some storage potential, that if properly developed would provide a continuance drift of about seven million gallons of water per day of good quality water that would be high in color and temperature upon occasion. With reasonable treatment some of this water could be used to meet the present needs of the rapidly expanding coastal areas. (PDF contains 40 pages.)
Resumo:
The purpose of the investigation is to make a detailed study of the geology and ground water in the Ruskin area, especially as related to the problem of salt-water encroachment. The major objectives of the program includes: (1) An inventory of wells to determine their number and distribution, their depths and diameters, and other pertinent information. (2) A study of artesian pressures. (3) Analyses of water from selected wells to determine the location and extent of any areas in which the artesian water is salty. (4) A study of the surface and subsurface geology as related to the occurrence and movement of ground water. (5) An estimate of the quantity of ground water withdrawn. (PDF contains 24 pages.)
Resumo:
Because the Stuart area is, at times, surrounded on three sides by saline water, the underlying fresh-water aquifer is vulnerable to salt-water encroachment. With progressively larger withdrawals of ground water for public and private supplies, the possibility of salt-water contamination of freshwater supplies is increased. (PDF contains 51 pages.)