THE EFFECT OF SOME BASIC STATISTICAL AND BIOLOGICAL PRINCIPLES ON WATER POLLUTION CONTROL1

ABSTRACT: The hypothesis of this paper is that the frequently used regulatory practice which employs point estimates in water pollution control objectives, in combination with monitoring at infrequent intervals, is an inadequate scientific procedure for the measurement and control of pollution. The first part of this paper outlines the relevant sampling theory which applies to the measurement of effluent from industrial plants and describes the possible errors in sampling practice which currently affect the interpretation and enforcement of environmental standards. In the second part of the paper, the authors describe briefly the environmental significance of biological damage functions. In the final part of the paper, the authors recommend that existing pollution control regulations be restructured to be more efficient and effective in the protection of both corporate and social interests. By adopting two different approaches to regulation depending upon the nature of the appropriate damage functions and critical fish species, it is possible to reduce significantly the waste of resources.     

THE SOUTHEAST FLORIDA EXPERIENCE IN RESOLVING DEVELOPMENT AND ENVIRONMENT CONFLICTS1

ABSTRACT: Land development projects that are presumed to have regional impact according to the Florida Land and Water Management Act of 1972 are forced to minimize adverse environmental impact through a detailed procedure called Application for Development Approval (ADA). In Southeast Florida, as part of this review process, the water-supply and flooding conflicts must be resolved with the regional water management agency, Central and South Florida Flood Control District (FCD). This paper discusses the efforts to resolve these two conflicts for a large proposed residential development in Broward County, Florida. The project, as envisioned by Leadership Housing, Inc., places 25,000 dwelling units on the 3,960-acre site. The project is located in a flood prone area of the Hillsboro Canal Basin and is at the northwest edge of the Biscayne Aquifer. Significant land modification is required to flood-proof the project. The water-supply conflict was resolved only when the FCD was assured that the ultimate water demand for the project was balanced by the natural recharge to the site. Significant water-resources studies were required to produce these conflict resolutions.     

RAINFALL POINT INTENSITIES IN AN AIR MASS THUNDERSTORM ENVIRONMENT: WALNUT GULCH,ARIZONA1

ABSTRACT: Point rainfall intensities for a given return period are often used to formulate design storms for rainfall/runoff models to simulate design floods. These design floods are in turn used to design bridges, culverts, and a variety of drainage and flood control structures. The projected rapid growth in the southwestern United States will require very substantial monetary investments in drainage infrastructure. Accurate estimates of point rainfall intensities are critical to ensure both safe designs while not wasting dollars in overdesign. Rainfall point intensities (accumulated rainfall depth over a specified duration) for 5‐, 15‐, 30‐, and 60‐minute durations for the 2‐, 5‐, 10‐, 25‐, 50‐, and 100‐year return periods were determined for southeast Arizona. Thirty‐five years of rainfall record (1961 to 1995) were used in this study. The records came from 20 stations that were grouped into five sets of four independent stations to extend the rainfall records. The stations are in the USDA‐ARS Walnut Gulch Experimental Watershed (WGEW), which is representative of large portions of the Southwest whose runoff generation is dominated by air‐mass thunderstorms. The 5‐, 15‐, 30‐, and 60‐minute maximum intensities per year followed log‐normal distributions. The mean point rainfall intensities of the five sets of gages are very close (between 0 and 11 percent) to the NOAA values of the 5‐, 15‐, 30‐, and 60‐minute durations for all return periods. Much larger differences between the mean point rainfall intensities for all durations were found when these results were compared to those of a previous study done with a shorter rainfall record (between 14 and 33 percent for the 25‐, 50‐, and 100‐year return‐periods). The difference between the largest and the smallest values of point rainfall intensities recorded by each group, for all durations, usually increases as the return period increases.     

ESTIMATING RESIDENTIAL FLOOD CONTROL BENEFITS USING IMPLICIT PRICE EQUATIONS1

ABSTRACT: An implicit price model relating residential lot value to price determining characteristics of land is developed to measure the benefits of a structural flood control project. Special attention is given to the selection of relevant price determining characteristics of residential lots. An implicit price equation is estimated for both the with and without project conditions. Flood damages are quantified through the use of a dummy variable indicating a flood plain location. The analysis shows that annual flood damages were reduced by $15,275.     

Vertical distribution of radionuclides in soil of a grassland site in Chernobyl exclusion zone

Five soil profiles from a site about 8 km SE of the Chernobyl NPP were investigated for the vertical distribution of radionuclides. The average (137)Cs-inventory at the site is about 2.6 MBq/m(2) (reference date 1 May 1986). Apart from (137)Cs, the following radionuclides have been identified (their activity ratios to (137)Cs in brackets): (134)Cs (0.537), (125)Sb (0.068), (60)Co (0.0022), (154)Eu (0.016), (155)Eu (0.020), (94g)Nb (9.5E-5), (239/240)Pu (0.0088), (238)Pu (0.040), (90)Sr (0.30) and (241)Am (0.011). Apparent vertical migration velocities are between 0.14 and 0.26 cm/a, apparent dispersion coefficients range from 0.02 to 0.13 cm(2)/a. The rankings of the velocities v for different radionuclides are (Sr, Cs, Sb, Co, Pu)< Am < Eu and Sr < (Cs, Nb), for D, the following rankings have been found: (Nb, Sr, Cs) < Am < Eu, Cs相似文献