SEDIMENT DEPOSITION ESTIMATION FROM CESIUM-137 MEASUREMENTS1

ABSTRACT The movement of fallout ¹³⁷Cs carried by soil particles was studied as an indicator of erosion and sedimentation in the Allerton watersheds and 4-H Memorial Lake located near Monticello, Illinois. Sediment deposition was greater in the waterway draining from watershed IB than in the waterway from watershed IA. At the average rate of 2.3 cm/yr of sediment deposition in the lake (from 1954 to 1979), there will be a loss of over 2 meters of water depth in the next century. However, there appears to be a decreasing rate of sediment deposition in the 4-H Memorial Lake as a result of improved conservation practices on the watersheds and the increased effectiveness of vegetated waterways and buffers for retaining sediment.     

Taxation of uranium mining in Canada and Australia

The objective of this paper is to compare the nature of the taxation schemes facing uranium mine operators in Australia's Northern Territory and in Canada's Province of Saskatchewan. The findings demonstrate that, although the Canadian system appropriates up to 85% of incremental sales revenue, it is extremely sensitive to industry profitability. Its Australian counterpart is, in contrast, a regressive scheme which, at the current selling price of yellowcake, captures a significantly larger proportion of available economic rent.     

SIMULATED RELATIONSHIPS BETWEEN SPECTRAL REFLECTANCE,THERMAL EMISSIONS,AND EVAPOTRANSPIRATION OF A SOYBEAN CANOPY1

ABSTRACT: A canopy reflectance model is incorporated into a routine for simulating water and energy flows in the soil-plant-atmosphere system. The reflectance model is structured tocalculate canopy albedo throughout each simulation period and to determine spectral reflectances at a specified time during the day. Spectral vegetation indices are then calculated from the reflectances and related to the evapotranspiration and thermal response of the canopy. The canopy reflectance model is also used to establish the photo-sytheticaily active radiation load at various depths in the canopy. Stomatal resistances are calculated using these radiation values and integrated to give the minimum canopy resistance. Actual canopy resistance is obtained by adjusting minimum canopy resistance for environmental stresses such as leaf water potential and leaf temperature. Using data for a soybean canopy, canopy evapotranspiration and temperatures are simulated for a range of leaf area index values and compared with the corresponding spectral vegetation indices. The resuits indicate that the normalized difference spectral index has an inverse linear relationship with canopy temperature, concurring with results obtained from satellite observations. The possibility of using a spectral vegetation index and thermal observations together to parameterize surface moisture availability for evapotranspiration is considered.     

The problem of acid rain: An overview

Summary The solution to the problem of acid rain is perhaps one of the main environmental and political issues facing the peoples of the industrialized nations, and their neighbours today. There is no doubt about the damage which acid rain has caused, but what remains unclear are the precise causes of acid rain and the most efficacious means of reducing its environmental, economic and political impacts. We have presented a balanced look at the differing points of view on the current state of knowledge in acid rain research with respect to atmospheric processes, environmental effects, measurement procedures, and the legal and political issues surrounding acid rain. This review indicates that the atmospheric processes creating and transporting acid rain are not well enough understood to enable its reduction with any guarantee of success. This conclusion is based on the confusing or conflicting evidence presented by recent scientific studies. It appears that more research must be undertaken to understand the problem of acid rain before final recommendations may be made for its solution.Mr Eney is a lecturer and Dr. Petzold is Professor of Climatology in the Department of Geography at the University of Maryland. They have recently completed research on the spatial distribution of acid rain over the Washington, D.C. metropolitan area of USA.     

STORM CHARACTERISTICS OF CONVECTIVE-SCALE PRECIPITATION1

A classification scheme for convective precipitation, having applications in both analysis and modeling of meteorological and hydrological events, is presented. The method is based upon observations of rainfall at the ground, radar scans of storm events, and visible and infrared satellite imagery of larger storm systems. Empirical and theoretical frequency distributions are derived for total storm rainfall, rainfall duration and time between storms for each of the convective categories. This stratification is directly applicable to the experimental design and evaluation of weather modification projects and may be useful for the development and interpretation of meteorological and hydrological models. When atmospheric conditions limit storm development to cells, rainfall was seldom observed. Small clusters also produce small amounts of rainfall but have a longer lifetime than cells and are likely candidates for cloud seeding attempts to encourage their growth to large clusters. Large and nested clusters usually produce large amounts of natural precipitation. A few large storms account for most of a season's rainfall.     

COAL ASH BASIN EFFECTS (PARTICULATES,METALS, ACIDIC pH) UPON AQUATIC BIOTA: AN EIGHT-YEAR EVALUATION1

ABSTRACT Coal ash effluent effects including particulates, acidic pH excursions, elemental concentrations and bioconcentration in selected organisms have been studied as changes in water quality and densities of benthic macroinvertebrate and mosquitofish (Gambusia affinis) populations in a swamp drainage system over an eight-year period. Three changes in the ash basin settling system were made between mid- 1973 and January 1982. Initial density of the aquatic biota was altered severely by heavy ash siltation, followed by acidic pH excursions and perhaps overall by elemental concentrations and bioaccumulation. Heavy ash siltation, followed by acidic Ph excursions (mean of 5.5, extreme of 3.5) after the addition of fly ash to the original settling basin system, had the most profound effect on biota. Dipterans (chironomids) and some odonates (Plathemis lydia and Libellula spp.) were resistant to heavy ash siltation, while mosquitofish, which showed no discernible responses to ash siltation, were absent at acidic pH, along with the few previously surviving invertebrate populations. Elemental concentrations of arsenic, cadmium, chromium, copper, selenium, and zinc did not appear to limit aquatic flora and fauna on a short-term, acute basis. Long, chronic elemental exposures may have been instrumental in retarding the recovery of all forms of aquatic life in the receiving system. Elemental concentrations (except for arsenic and selenium) in the receiving system were generally one to two orders of magnitude higher than the Water Quality Criteria set by the U.S. Environmental Protection Agency (1980) for protection of aquatic life for the minimum and 24-hour mean values. From collective elemental exposures in the receiving system, bioconcentration factors in macrophytes, invertebrates and fish were generally lower than those reported in the literature for laboratory, single elemental concentrations. By 1978, when the new settling basin systems were operating effectively, invertebrate populations were largely recovered, and mosquitofish populations recovered within one year afterward.     

A DYNAMIC SYSTEM MODEL FOR SIMULATING SEDIMENT DISCHARGE1

ABSTRACT: A dynamic sediment discharge model was developed and proposed for the simulation of watershed systems. It war developed from an expansion of splash and flow erosion relationships under steady state conditions. It was described as a general erosion model that can be reduced to forms comparable to many conceptual soil erosion and sediment yield models. The model incorporates eight parameters such as rainfall intensities, runoff rates, and previous sediment discharges. The model was tested with two small watersheds with simulation results which were very satisfactory compared to the data.     

Water Resources Research Prioritization and Management-Problems and Perspectives1

ABSTRACT: At a time when productive water resources research is essential to protecting the quality of and wisely using our limited water resources, pervasive trends toward consumerism, fiscal restraint, centralized management, and using research for other social objectives threaten research productivity. The research prioritization and management structure that these trends have created was examined in the microcosm of its application at the Utah Water Research Laboratory. The result indicated that ephemeral prioritization and the failure of research users to target researchers to their own particular needs is diluting productivity. Incremental research prioritization and greater use of advisory councils in facilitating user-researcher interaction are suggested as corrective approaches, but the only firm conclusion at this point in time must be that empirical studies of the performance of alternatives in research management structure are solely needed.     

FOCUSED AND DIFFUSE PATTERNS OF AQUATIC RECREATION BEHAVIOR1

ABSTRACT: Recreation behavior can be examined by identifying characteristics of participants, activities, and places. Two distinct houschold types (social groups) were examined relative to their participation in water based recreation: households whose participation occurs exclusively in water based recreation, and those reporting participation in both water and nonwater activities. These households were compared in terms of preference for and specialization in water recreation, the relationship of water activity selected and resource (place) preference and intensity of participation in water activities. Attention by managers, planners, and social scientists to the interplay of participant group, activity, and place upon behavioral outcomes is important to the future development of recreation opportunities. It is one thing to design a facility for water based recreation; it is another to design a facility knowing the behavioral outcomes occurring and how they will be affected. Similarly, to implement a management strategy without knowing how behavior of participants will be modified as a result of the strategy can lead to failure of the management objective.