Assessing ecological risk on a regional scale

Society needs a quantitative and systematic way to estimate and compare the impacts of environmental problems that affect large geographic areas. This paper presents an approach for regional risk assessment that combines regional assessment methods and landscape ecology theory with an existing framework for ecological risk assessment. Risk assessment evaluates the effects of an environmental change on a valued natural resource and interprets the significance of those effects in light of the uncertainties identified in each component of the assessment process. Unique and important issues for regional risk assessment are emphasized; these include the definition of the disturbance scenario, the assessment boundary definition, and the spatial heterogeneity of the landscape. Although the research described in this article has been funded wholly or in part by the United States Environmental Protection Agency (EPA) through Interagency Agreement Number DW89932112-01-2 to the U.S. Department of Energy, it has not been subjected to EPA review and therefore does not necessarily reflect the views of EPA and no official endorsement should be inferred.     

ECONOMIC EFFECTS OF RIVER RECREATION ON LOCAL ECONOMIES1

ABSTRACT: Outdoor recreation is a major, growing use of water resources in the United States. The economic effects of expenditures by visitors to three recreational river sites on local economies surrounding the sites were estimated using an input-output model (IMPL.AN). Expenditure data were from the Public Area Recreation Visitors Study (PARVS). Results indicate that visitor spending stimulates a considerable amount of economic activity and growth in local economies. Economic effects include increases in total gross output ranging from $2.6 million to $13.4 million, increases in total income ranging from $1.2 million to $5.6 million, and increases in employment ranging from 60 to 292 jobs.     

EFFECTS OF CLIMATIC CHANGE ON THE THORNTHWAITE MOISTURE INDEX1

ABSTRACT: The Thornthwaite moisture index is a useful indicator of the supply of water (precipitation) in an area relative to the demand for water under prevailing climatic conditions (potential evapotranspiration). This study examines the effects of changes in climate (temperature and precipitation) on the Thornthwaite moisture index in the conterminous United States. Estimates of changes in mean annual temperature and precipitation for doubled-atmospheric CO₂ conditions derived from three general circulation models (GCMs) are used to study the response of the moisture index under steady-state doubled-CO₂ conditions. Results indicate that temperature and precipitation changes under doubled-CO₂ conditions generally will cause the Thornthwaite moisture index to decrease, implying a drier climate for most of the United States. The pattern of expected decrease is consistent among the three GCMs, although the amount of decrease depends on which GCM climatic-change scenario is used. Results also suggest that changes in the moisture index are related mainly to changes in the mean annual potential evapotranspiration as a result of changes in the mean annual temperature, rather than to changes in the mean annual precipitation.     

Group utility indifference and resource management decision making

Natural resource managers often rely on the advice of specialists to aid decision making. However, disagreement among these specialists about the relative value of particular management objectives or the risks associated with implementing certain management strategies may complicate the decision effort. Multiattribute utility analysis can facilitate decision making by indicating how attributes of a problem are weighed by individual specialists. This information can then be used to outline bands of potential problem solutions that are acceptable to the advising group and may allow management to further its own objectives (possibly increased efficiency).An example is presented that relates to fire management planning efforts on national forests. Multiattribute utility functions developed from a survey of fire management professionals are used to identify utility-maximizing fire management strategies based on each strategy's level of economic efficiency and risk. Bands of utility-indifferent potential solutions are outlined based on measures of group consensus. It is pointed out that a subset of these would further management's goal (increased efficiency) without significantly altering the value assigned to the risk attribute by the specialists. Finally, the robustness of the technique is discussed with particular reference to environmental management problems and the role that proxy information often plays in decision making.     

HYDROLOGIC EFFECTS OF CLIMATE CHANGE IN THE DELAWARE RWER BASIN1

ABSTRACT: The Thornthwaite water balance and combinations of temperature and precipitation changes representing climate change were used to estimate changes in seasonal soil-moisture and runoff in the Delaware River basin. Winter warming may cause a greater proportion of precipitation in the northern part of the basin to fall as rain, which may increase winter runoff and decrease spring and summer runoff. Estimates of total annual runoff indicate that a 5 percent increase in precipitation would be needed to counteract runoff decreases resulting from a warming of 2°C; a 15 percent increase for a warming of 4°C. A warming of 2° to 4°C, without precipitation increases, may cause a 9 to 25 percent decrease in runoff. The general circulation model derived changes in annual runoff ranged from ?39 to +9 percent. Results generally agree with those obtained in studies elsewhere. The changes in runoff agree in direction but differ in magnitude. In this humid temperate climate, where precipitation is evenly distributed over the year, decreases in snow accumulation in the northern part of the basin and increases in evapotranspiration throughout the basin could change the timing of runoff and significantly reduce total annual water availability unless precipitation were to increase concurrently.     

IDENTIFICATION OF DISSOLVED-CONSTITUENT SOURCES IN MINE-SITE GROUND WATER USING BATCH MIXING1

ABSTRACT: Batch-mixing experiments were used to help identify lithologic and mineralogic sources of increased concentrations of dissolved solids in water affected by surface coal mining in northwestern Colorado. Ten overburden core samples were analyzed for mineral composition and mixed with distilled water for 90 days until mineral-water equilibrium was reached. Between one day and 90 days after initial contact, specific conductance in the sample mixtures had a median increase of 306 percent. Dissolved-solids concentrations ranged from 200 to 8,700 mg/L in water samples extracted from the mixtures after 90 days. Mass. balance simulations were conducted using the geochemical models BALANCE and WATEQF to quantify mineral-water interactions occurring in five selected sample mixtures and in water collected from a spring at a reclaimed mine site. The spring water is affected by mineral-water interactions occurring in all of the lithologic units comprising the overburden. Results of the simulations indicate that oxidation of pyrite, dissolution of dolomite, gypsum, and epsomite, and cation-exchange reactions are the primary mineral-water interactions occurring in the overburden. Three lithologic units in the overburden (a coal, a sandstone, and a shale) probably contribute most of the dissolved solids to the spring water. Water sample extracts from mixtures using core from these three units accounted for 85 percent of the total dissolved solids in the 10 sample extracts. Other lithologic units in the overburden probably contribute smaller quantities of dissolved solids to the spring water.     

REMOVAL OF FLOODWATER SEDIMENTS BY A CLEARCUT TUPELO-CYPRESS WETLAND1

ABSTRACT: A palustrine water tupelo (Nyssa aquatica L.)-baldcy-press (Taxodium distichum (L.) Rich.) swamp in southwestern Alabama was subjected to three types of disturbance, including helicopter logging, rubber-tired skidder logging simulation, and helicopter logging followed by an herbicide application. An adjacent undisturbed stand served as a control area. Post-harvest collection of sedimentation data revealed that the herbaceous and woody vegetation regrowth within the helicopter and skidded clearcut areas trapped more sediments than did the control or herbicide treatment areas. Clearcutting, followed by plant regrowth, improved the wet-land's capacity to remove sediments from overbank flow flood waters.     

Conducting effective audit conferences for improving environmental performance

Both opening and closing conferences are crucial elements of an effective environmental audit program. As many firms reengineer their auditing process, focusing on the beginning and end points of the on-site process makes eminent sense. This article discusses a variety of issues that often arise during the preparation and conduct of opening and closing conferences that can ultimately affect the success of the audit.