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901.
The economic inputs and outputs for the Possum Point Biological Station in Belize during 1990–1992 are described to illustrate some aspects of an ecotourism operation. Eight hundred fifty-four people in 59 groups visited Possum Point during the study period to tour rain forests, estuaries, and coral reefs. The economic input to Possum Point from these groups increased from $74,552 in 1990 to $166,268 in 1992. Outputs were for license fees, capital improvements, goods and services, labor, fossil fuels, and development of a historic sugar mill site. An annual donation was also made to a scholarship fund for local Belizean students. The net cash balance of income and outputs changed from negative (−$6678) in 1990 to positive (+$4811) in 1992, suggesting development of the economic operation. Possum Point meets the economic criteria for ecotourism by feeding back some tourist monies for community and environmental support, particularly donations for the sugar mill site and the scholarship fund. Most of the outputs from Possum Point (about 80%) were retained in the local economy through employment and purchases, which have a positive influence on the local community. We conclude that ecotourism operations, such as Possum Point, offer important sustainable development opportunities for Belize.  相似文献   
902.
ABSTRACT: Two sampling strategies designed to test for compliance with water quality objectives are examined. For objectives based on long-term mean requirements, fixed frequency sampling at frequent intervals is most advantageous regardless of the underlying distribution of the data. For objectives that are based on maximum allowable concentrations, effective sampling strategies increase the likelihood of detecting noncompliance. If data are highly autocorrelated or sharply seasonal in distribution, an exceedance-driven sampling strategy is more effective and efficient for detecting violations than fixed frequency sampling. However, data generated by exceedance-driven sampling provide biased estimates of mean and standard deviation.  相似文献   
903.
Book reviews     
ANALYTICAL PLANNING: THE ORGANISATION OF SYSTEMS

Thomas L. Saaty and Kevin P. Kearns

Pergamon Press, 1985. Price: U.S. $40.00, U.K. £29.50.

THE GEOGRAPHER AT WORK

Peter Gould

Routledge and Kegan Paul, London 1985’ Price: £8.95.

UTOPIA ON TRIAL

Alice Colman

Hilary Shipman Ltd., 19 Framfield Road, Highbury, London. May 1985 (reprinted August, 1985). Price: £7.95.

SIR RAYMOND UNWIN: ARCHITECT, PLANNER AND VISIONARY

Frank Jackson

A. Zwemmer Ltd., London 1985. 187 pp. with maps and illustrations.

STRATEGIC PLANNING IN ACTION: THE IMPACT OF THE CLYDE VALLEY REGIONAL PLAN 1946–1982

R. Smith and U. Wannop (eds)

Gower, 1985, 272 pp. Price: £16.50.

LOCALITIES, CLASS AND GENDER

The Lancaster Regionalism Group (Linda Murgatroyd, Mike Savage, Dan Shapiro, John Urry, Sylvia Walby, Alan Warde, with Jane Mark‐Lawson)

Pion Ltd., 1985. Price: £12.00.  相似文献   

904.
905.
HEC1F is a computer program for making short- to medium-term forecasts of uncontrolled flood runoff. The program employs unit hydrographs and hydrologic routing to simulate runoff from a subdivided basin. Estimates of future rainfall can be accommodated. Runoff parameters for gaged headwater subbasins can be estimated (optimized) in real time. Blending of calculated with observed hydrographs can be performed. HEC1F is a component of an on-line software system that includes capability for data acquisition and processing, precipitation analysis, streamflow forecasting, reservoir system analysis, and graphical display of data and simulation results. The conceptual framework for HEC1F is described, and application of the program is illustrated.  相似文献   
906.
Loss of Louisiana's coastal wetlands has reached catastrophic proportions. The loss rate is approximately 150 km2/yr (100 acres/day) and is increasing exponentially. Total wetland loss since the turn of the century has been almost 0.5 million ha (1.1 million acres) and represents an area larger than Rhode Island. The physical cause of the problem lies in man's attempts to control the Mississippi River's flooding, while enhancing navigation and extracting minerals. Levee systems and control structures confine sediments that once nourished the wetlands to the river channel. As a consequence, the ultimate sediment deposition is in deep Gulf waters off the Louisiana coast. The lack of sediment input to the interdistributary wetlands results in an accretion deficit. Natural and human-induced subsidence exceeds accretion so that the wetlands sink below sea level and convert to water. The solution is to provide a thin veneer of sediment (approximately 0.6 cm/yr; an average of 1450 g m?2 yr?1) over the coastal marshes and swamps and thus prevent the submergence of vegetation. The sediment source is the Mississippi River system. Calculations show that 9.2% of the river's annual suspended sediment load would be required to sustain the deltaic plain wetlands. It should be distributed during the six high-water months (December–June) through as disaggregated a network as possible. The problem is one of distribution: how can the maximum acres of marsh be nourished with the least cost? At present, the river is managed through federal policy for the benefit of navigation and flood control. A new policy structure, recognizing the new role for the river-sediment distribution, is recommended.  相似文献   
907.
Para grass, irrigated with secondary domestic sewage effluent, showed excellent response for disposal of large amounts of water, effective nitrogen removal, and high production of excellent fodder. This grass is found throughout the tropics and parts of the subtropics. It endures flooding and forms dense, easily maintained stands. This is the first time its use has been reported for effluent irrigation. Water, nitrogen, and biomass budgets over a 17-month period were measured in eight percolate style lysimeters. Under irrigation rates as great as 98 mm/day, five days/week, evapo-transpiration averaged 4.6 mm/day. With nitrogen applications of 130 to 2,600 kg/ha/yr, ≥ 79 percent of applied nitrogen was harvested in the grass; 3 percent percolated; and ≤ 28 percent was denitrified. With the highest effluent irrigation rates, nitrate-nitrogen levels remained below the 10 mg/L maximum recommended for potable water. Crop productivity for full effluent treatments averaged 110 t/ha/yr, dry weight. Maximum calculated crude protein content was 13 percent. No nitrate-nitrogen level in the forage exceeded 0.1 percent.  相似文献   
908.
909.
Effects of distance lags between landfills and monitoring wells on contaminant detection capability were quantified in several groundwater velocity settings. Detection efficiency calculations were made with and without imposing a time limit on contaminant travel. In general, longer distance lags yieldedhigher detection efficiencies. However, detection efficienciesdecreased as monitoring wells approached a buffer zone boundaryimposing a maximum permissible contaminant transport distance.Imposing a time limit on contaminant travel substantially reduced detection efficiency in low velocity settings, especiallyat longer distance lags. Time limits were less significant in high velocity settings where contaminants more quickly reachedmonitoring wells. Detection efficiencies also decreased as velocity increased, but decreases were minor once the velocityreached a threshold value.  相似文献   
910.
Indoor NO2 concentrations were measured in the kitchen, the living room and bedroom of 612 houses in two different areas in the Netherlands. In a group of housewives living in these homes, personal exposure to NO2 was measured. NO2 concentrations indoors were dependent on the presence or absence of (un)vented gas appliances. Personal NO2 exposure was only different between the two areas in the group with the lowest indoor concentrations. In this study, it was determined that gas appliances inside the house are the most important factor with respect to NO2 exposure and that outside NO2 concentration played a secondary role, except in situations where gas appliances were absent.  相似文献   
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