SAMPLING FRAME FOR IMPROVING PEBBLE COUNT ACCURACY IN COARSE GRAVEL‐BED STREAMS1

ABSTRACT: Improved sampling techniques are needed to increase the accuracy of pebble‐count particle‐size distributions used for stream studies in gravel‐bed streams. However, pebble counts are prone to operator errors introduced through subjective particle selection, serial correlation, and inaccurate particle‐size measurements. Errors in particle‐size measurements can be minimized by using a gravel template. Operator influence on particle selection can be minimized by using a sampling frame, 60 by 60 cm, in which sampling points are identified by the cross points of thin elastic bands. Serial correlation can be minimized by adjusting the spacing between the cross points and setting it equal to the dominant large particle size (=D₉₅). In a field test in a cobble‐bed stream, the sampling frame developed in this study produced slightly coarser size distributions, particularly in the cobble range, than the traditional heel‐to‐toe walk that selects particles with a blind touch at the tip of the boot. The sampling frame produced more similar sampling results between two operators than heel‐to‐toe walks. The difference between the two sampling methods is attributed to an unbiased selection of fine and coarse particles when using the sampling frame.     

MODELING DRINKING WATER QUALITY VIOLATIONS WITH BAYESIAN NETWORKS1

ABSTRACT: Compliance violations at community water systems are rare but represent significant human health risks. These risks are mediated by the decision schema of human operators at water treatment facilities. However, causal uncertainty among physical and human factors involved in water quality problems complicates assessment of their probability and severity. This study uses a probabilistic Bayesian network modeling approach to explore the causes of compliance violations in a sample of water treatment systems in Pennsylvania. The model presented here is one of several created by treatment system operators during an expert elicitation process. The expert model alone predicts violations poorly, suggesting that experts make inaccurate quantitative estimates. However, Bayesian networks are capable of combining the subjective expertise of treatment system operators with the objective compliance histories of the facilities they manage, and the expert model accurately predicts violations when trained with historical compliance data. Analysis of the trained network reveals those components of the treatment process, including environmental and system characteristics as well as operator decisions, that play the greatest role in determining the likelihood of major violation types. Among operator decisions, coagulant dosing and filter backwash frequency are the most important determinants of violation likelihood.     

Governmental Oversight of Discharges from Concentrated Animal Feeding Operations

As point sources of pollution in the United States, concentrated animal feeding operations (CAFOs) are subject to the National Pollution Discharge Elimination System permitting system requirements. Changes to federal regulations in 2003 and a 2005 court decision have increased the governmental oversight of CAFOs. Manure application to fields from “large CAFOs” that results in unpermitted discharges can be regulated under the Clean Water Act. The U.S. Environmental Protection Agency’s interpretation of agricultural stormwater discharges was approved so that unpermitted discharges may arise if an owner or operator of a CAFO fails to apply manure correctly. Owners and operators do not, however, have a duty to secure governmental permits in the absence of a discharge. Turning to the federal provisions regarding nutrient management plans, a court found that they were deficient. Moreover, the federal government needs to reconsider requirements that would reduce pathogens from entering surface waters. Although these developments should assist in reducing the impairment of U.S. waters, concern still exists. Greater oversight of nutrient management plans and enhanced enforcement efforts offer opportunities to provide greater assurance that CAFO owners and operators will not allow a discharge of pollutants to enter surface waters.     

Simulated wetland conservation-restoration effects on water quantity and quality at watershed scale

Wetlands are one of the most important watershed microtopographic features that affect hydrologic processes (e.g., routing) and the fate and transport of constituents (e.g., sediment and nutrients). Efforts to conserve existing wetlands and/or to restore lost wetlands require that watershed-level effects of wetlands on water quantity and water quality be quantified. Because monitoring approaches are usually cost or logistics prohibitive at watershed scale, distributed watershed models such as the Soil and Water Assessment Tool (SWAT), enhanced by the hydrologic equivalent wetland (HEW) concept developed by Wang [Wang, X., Yang, W., Melesse, A.M., 2008. Using hydrologic equivalent wetland concept within SWAT to estimate streamflow in watersheds with numerous wetlands. Trans. ASABE 51 (1), 55–72.], can be a best resort. However, there is a serious lack of information about simulated effects using this kind of integrated modeling approach. The objective of this study was to use the HEW concept in SWAT to assess effects of wetland restoration within the Broughton's Creek watershed located in southwestern Manitoba, and of wetland conservation within the upper portion of the Otter Tail River watershed located in northwestern Minnesota. The results indicated that the HEW concept allows the nonlinear functional relations between watershed processes and wetland characteristics (e.g., size and morphology) to be accurately represented in the models. The loss of the first 10–20% of the wetlands in the Minnesota study area would drastically increase the peak discharge and loadings of sediment, total phosphorus (TP), and total nitrogen (TN). On the other hand, the justifiable reductions of the peak discharge and loadings of sediment, TP, and TN in the Manitoba study area may require that 50–80% of the lost wetlands be restored. Further, the comparison between the predicted restoration and conservation effects revealed that wetland conservation seems to deserve a higher priority while both wetland conservation and restoration may be equally important.     

Circuit riding for managing small community sewage systems

Providing wastewater treatment services for small communities can be expensive, so many communities have chosen part-time or inadequately trained operators. This can result in neglect and poor plant performance. Indiana County, Pennsylvania, in the USA, has established an authority to provide operation and maintenance through a circuit riding arrangement. Two operators travel to eight plants five days a week. This has resulted in more consistent operation and maintenance at affordable rates. Homeowners pay $12.60–$18.00 and commercial customers pay $25–$150 a month. Even with regular attention, these small plants are not able to meet their effluent requirements at all times.     

The prospects for nickel What price new capacity?

The average LME nickel price in 1988 was $6.26/lb and in 1989 was $6.00/lb. This contrasts with an average price of $2.11/lb over the period 1982–87. The reasons for this run up on price include increased demand for stainless steel (the largest use of nickel), reflecting the period of sustained economic growth in the OECD countries, and the decline in market stocks which reached unusually low levels in 1987 and 1988. Forecasts of nickel supply and demand for 1990 and beyond are presented and the need for additional capacity estimated. In general new greenfield capacity will not be needed until the late 1990s.     

Reducing carbon emissions through improved household energy efficiency in the UK

A number of schemes to increase household energy efficiency have operated in the UK over the last 5–10 years. This paper evaluates their effectiveness in terms of reducing household energy use, carbon emissions and fuel poverty. It then draws on the quantitative results of these schemes, and published plans for their continuation, to model an extended and expanded Household Energy Efficiency Scenario to 2020, using an integrated economy–energy–environment model of the UK. The results suggest that while such schemes can play a significant role in reducing carbon emissions from households, much more ambitious schemes than those currently implemented will be necessary to offset the underlying growth in these emissions. Finally, the results are compared with the UK government's own estimates, in its Climate Change Programme, of carbon emission reductions from such schemes to 2010. The paper concludes that the government's estimates are somewhat optimistic, and that it will need substantial new policy measures beyond those already announced if its carbon reduction targets in this area are to be met. Copyright © 2002 John Wiley & Sons, Ltd.     

The energy,water, and air pollution implications of tapping China's shale gas reserves

China has laid out an ambitious strategy for developing its vast shale gas reserves. This study developed an input–output based hybrid life-cycle inventory model to estimate the energy use, water consumption, and air emissions implications of shale gas infrastructure development in China over the period 2013–2020, including well drilling and operation, land rig and fracturing fleet manufacture, and pipeline construction. Multiple scenarios were analyzed based on different combinations of well development rates, well productivities, and success rates. Results suggest that 700–5100 petajoules (PJ) of primary energy will be required for shale gas infrastructure development, while the net primary energy yield of shale gas production over 2013–2020 was estimated at 1650–7150 PJ, suggesting a favorable energy balance. Associated emissions of CO₂e were estimated at 80–580 million metric tons, and were primarily attributable to coal-fired electricity generation, fugitive methane, and flaring of methane during shale gas processing and transmission. Direct water consumption was estimated at 20–720 million metric tons. The largest sources of energy use and emissions for infrastructure development were the metals, mining, non-metal mineral products, and power sectors, which should be the focus of energy efficiency initiatives to reduce the impacts of shale gas infrastructure development moving forward.     

Solutions for characterising natural landscapes in New Zealand using geographical information systems

This paper explores solutions for characterising naturalness in relation to visual landscapes using Geographical Information System (GIS). It is argued that planners need to identify natural landscapes and monitor changes in their extent. Just like the indices that have been developed to describe the state of the economy, indices need to be developed that monitor the state of natural landscapes. The complications in characterising natural landscapes are outlined but it is argued that there is a need to develop definitions of natural landscapes that can be operationalised with a GIS. This will have the advantages of the efficiency of the technology and that the definition will be explicit and the implementation will be independent of the operator. Several GIS solutions are provided and these are an analysis of landcover, a density analysis of roads and utilities, and an analysis of property sizes. The analysis of property sizes is sensitive to many human modifications of the landscape because many developments begin with the subdivision of properties. However, it is argued in this paper that no one definition will suffice and that all three methods provide different, yet important, insights into natural landscape character. An aggregate classification of naturalness based on the majority value of the indices is demonstrated as well as a range of techniques for expressing the uncertainty of the aggregate classification.     

Establishment of permit limits for mill effluent

Various governmental regulatory agencies are responsible for establishing regulations on the discharge of chlorinated organic compounds from pulp and paper mills. The procedures for setting permit limits are the basic topic of this article. Different methods of determining permit limits are set forth and discussed in a number of references, including documents of the Environmental Protection Agency. This paper discusses in detail the application of one particular methodology—the lognormal model approach. In this paper we utilize a real data set and include the necessary calculations required to set up permit limits. The basic tenets of the permit process are such that if limits are set too low, operators who are in full regulatory compliance will still be frequently cited, and if limits are set too high, operators who are not in compliance will seldom if ever be cited. Thus there is a great need for these effluent limits to be determined with great care, both to protect the environment receiving the wastewater and the industry producing the wastewater.     

The use of choice experiments in the analysis of tourist preferences for ecotourism development in Costa Rica

Many nations promote nature-based tourism in order to promote the dual goals of nature conservation and income generation. To be most effective in providing services that facilitate achievement of these goals, decision makers will need to understand and incorporate tourist preferences for nature appreciation, infrastructure, use restrictions, and other attributes of national parks and protected areas. This paper presents the use of choice experiments as a mechanism to analyze preferences of national and international tourists in relation to the development of Barva Volcano Area in Costa Rica. In this section of the Braulio Carrillo National Park, managers are faced with an immediate need to plan for greatly increased visitation rates due to a new road, which will greatly improve access. Choice sets were developed in collaboration with park managers. A survey was conducted of 171 Costa Rican and 271 foreign tourists who visited Poás Volcano, a well-visited alternative site to Barva Volcano. Survey data was analyzed using conditional multinomial logit models. Results of the study demonstrate, that both sets of tourists preferred: (i) improved infrastructure; (ii) aerial trams with observation towers and picnic areas; (iii) more information; and (iv) low entrance fees. Foreign tourists demonstrated strong preferences for the inclusion of restrictions in the access to some trails, whereas Costa Ricans did not show any significant preference for restrictions. Marginal willingness-to-pay for greater information was estimated to be $1.54 for foreign tourists and $1.01 for Costa Rican visitors. The study concludes that choice experiments are a useful tool in the analyses of tourist preferences for the development of protected areas in developing countries.     

Use of Aquaculture Ponds and Other Habitats by Autumn Migrating Shorebirds Along the Lower Mississippi River

Populations of many shorebird species are declining; habitat loss and degradation are among the leading causes for these declines. Shorebirds use a variety of habitats along interior migratory routes including managed moist soil units, natural wetlands, sandbars, and agricultural lands such as harvested rice fields. Less well known is shorebird use of freshwater aquaculture facilities, such as commercial cat- and crayfish ponds. We compared shorebird habitat use at drained aquaculture ponds, moist soil units, agricultural areas, sandbars and other natural habitat, and a sewage treatment facility in the in the lower Mississippi River Alluvial Valley (LMAV) during autumn 2009. Six species: Least Sandpiper (Calidris minutilla), Killdeer (Charadrius vociferous), Semipalmated Sandpiper (Calidris pusilla), Pectoral Sandpiper (C. melanotos), Black-necked Stilt (Himantopus himantopus), and Lesser Yellowlegs (Tringa flavipes), accounted for 92 % of the 31,165 individuals observed. Sewage settling lagoons (83.4, 95 % confidence interval [CI] 25.3–141.5 birds/ha), drained aquaculture ponds (33.5, 95 % CI 22.4–44.6 birds/ha), and managed moist soil units on public lands (15.7, CI 11.2–20.3 birds/ha) had the highest estimated densities of shorebirds. The estimated 1,100 ha of drained aquaculture ponds available during autumn 2009 provided over half of the estimated requirement of 2,000 ha by the LMAV Joint Venture working group. However, because of the decline in the aquaculture industry, autumn shorebird habitats in the LMAV may be limited in the near future. Recognition of the current aquaculture habitat trends will be important to the future management activities of federal and state agencies. Should these aquaculture habitat trends continue, there may be a need for wildlife biologists to investigate other habitats that can be managed to offset the current and expected loss of aquaculture acreages. This study illustrates the potential for freshwater aquaculture to provide habitat for a taxa at risk. With the rapid growth of aquaculture worldwide, the practices of this industry deserve attention to identify benefits as well as risks to wildlife.     

Tidal wetlands natural and human-made changes from 1973 to 1979 in Delaware: Mapping techniques and results

Coastal wetlands are dynamic ecosystems subject to the manipulative powers of both humans and sea. Areal changes in the tidal wetlands of Delaware were monitored over a six year period with color and color infrared aerial photography. Wetland changes were interpreted directly from the photography and were classified according to natural and legal categories of change. Human activities in tidal wetlands destroyed an average 8.1 ha of wetlands annually from 1973 to 1979. During the same period 3.9 ha of wetlands were eroded and 2.8 ha of wetlands were formed annually by natural processes. A total net loss of 55.1 ha of wetlands was estimated for the six year period. The enactment of state and federal legislation protecting wetlands in 1972–1973 resulted in a decrease of wetlands loss in Delaware from an average of 179.7 ha yr^?1 from 1954 to 1971 to the 8.1 ha yr^?1 determined by this study. The dynamic nature of these wetlands exemplifies the need for frequent monitoring and remapping, if an effective and accurate management program is to remain in operation     

SPATIAL AND TEMPORAL ANALYSIS OF AGRICULTURAL WATER REQUIREMENTS IN THE GULF COAST OF THE UNITED STATES1

ABSTRACT: Competition for water resources is becoming an increasingly important issue in the southeastern U.S. The potential impacts of future precipitation and runoff estimated by a transient global climate model (HADCM2) on competing water resources in the Southeast has been conducted. Issues of agricultural management, irrigation water withdrawals, and water quality were studied over three time periods: 1974–1993, 2020–2039, and 2080–2099 in five water basins identified previously as exhibiting water-related problems. These basins, which encompass the boundary between Alabama and Mississippi, cover four important agricultural counties in Mississippi. Irrigation water requirements generated by crop growth models for corn, soybeans, and winter wheat were coupled with monthly runoff for the impacted basins estimated by the SWAT water balance model. The results of the study reveal that in the next 20–40 years water availability in the southern portions of the study area will decline as much as 10 percent during times when water requirements for agricultural production are crucial. Maintaining or expanding existing crop yields under future climate regimes may require additional irrigation water and increase competition among other uses such as domestic, industrial, recreational, and ecosystem quality.     

EXPANDING WASTE WATER TREATMENT CONSIDERATIONS AT CORPS OF ENGINEERS RECREATION AREAS1

ABSTRACT. There have been many changes in the waste water treatment requirements at St. Louis District Corps of Engineers projects over the past few years. Discussed are the methods considered for treating these wastes. Extended aeration plant, followed by filtration, is the process used in most of the areas. The treatment plant operators have become key members of the project operation team. A discussion of the Districts operator training program is presented along with the operator's job requirements. Through a Spring inspection of all treatment plants in the District, a mechanism has been provided for encouraging feedback to the design engineer from the operator.     

A Comparison of Three Federal Datasets for Thermoelectric Water Withdrawals in the United States for 2010

Historically, thermoelectric water withdrawal has been estimated by the Energy Information Administration (EIA) and the U.S. Geological Survey's (USGS) water‐use compilations. Recently, the USGS developed models for estimating withdrawal at thermoelectric plants to provide estimates independent from plant operator‐reported withdrawal data. This article compares three federal datasets of thermoelectric withdrawals for the United States in 2010: one based on the USGS water‐use compilation, another based on EIA data, and the third based on USGS model‐estimated data. The withdrawal data varied widely. Many plants had three different withdrawal values, and for approximately 54% of the plants the largest withdrawal value was twice the smallest, or larger. The causes of discrepancies among withdrawal estimates included definitional differences, definitional noise, and various nondefinitional causes. The uncertainty in national totals can be characterized by the range among the three datasets, from 5,640 m³/s (129 billion gallons per day [bgd]) to 6,954 m³/s (158 bgd), or by the aggregate difference between the smallest and largest values at each plant, from 4,014 m³/s (92 bgd) to 8,590 m³/s (196 bgd). When used to assess the accuracy of reported values, the USGS model estimates identify plants that need to be reviewed.     

几种神经网络模型在空气质量评价中的应用

人工神经网络是一种利用计算机模拟人脑神经组织的运算模型。作为一种新的研究方法。神经网络在一定程度上可以弥补传统评价方法需要构建隶属函数、无法精确描述级别区间内的变化特征以及设计过程具有一定人为偏好的不足。本文选用BP网络、径向基函数网络、LVQ网络和Elman网络这4种典型的神经网络模型进行实例研究。把国内8个城市的污染物排放数据代入训练好的网络模型，进行空气质量评价，得出的结论对提高神经网络评价结果的准确性和可靠性有一定参考作用。     

Pragmatic Approaches for Water Management Under Climate Change Uncertainty1

Stakhiv, Eugene Z., 2011. Pragmatic Approaches for Water Management Under Climate Change Uncertainty. Journal of the American Water Resources Association (JAWRA) 47(6):1183–1196. DOI: 10.1111/j.1752‐1688.2011.00589.x Abstract: Water resources management is in a difficult transition phase, trying to accommodate large uncertainties associated with climate change while struggling to implement a difficult set of principles and institutional changes associated with integrated water resources management. Water management is the principal medium through which projected impacts of global warming will be felt and ameliorated. Many standard hydrological practices, based on assumptions of a stationary climate, can be extended to accommodate numerous aspects of climate uncertainty. Classical engineering risk and reliability strategies developed by the water management profession to cope with contemporary climate uncertainties can also be effectively employed during this transition period, while a new family of hydrological tools and better climate change models are developed. An expansion of the concept of “robust decision making,” coupled with existing analytical tools and techniques, is the basis for a new approach advocated for planning and designing water resources infrastructure under climate uncertainty. Ultimately, it is not the tools and methods that need to be revamped as much as the suite of decision rules and evaluation principles used for project justification. They need to be aligned to be more compatible with the implications of a highly uncertain future climate trajectory, so that the hydrologic effects of that uncertainty are correctly reflected in the design of water infrastructure.     

Training carbon management engineers: Removing a major hurdle for geologic CO2 storage by increasing educational capacity

Implementing geologic storage of CO₂ at a material scale (ca. 1 Gt C/year) will require an industry comparable in size to the current oil and gas industry and a workforce trained in subsurface engineering. Since the same technologies that apply to hydrocarbon production apply to the subsurface storage of CO₂, petroleum engineering (PE) graduates will be valuable candidates to work in the carbon storage industry. We expect however that the demand for PEs from the oil and gas industry will increase, and that already strained educational capacity will not be sufficient to supply both industries. Thus we advocate building new targeted educational infrastructure. We present a model curriculum based on an existing accredited multidisciplinary degree program. This program combines the fundamentals of petroleum engineering with the subsurface architecture emphasis of geology and the environmental perspective of hydrogeology. We indicate key elements of this program that could be integrated with other, more traditional undergraduate engineering majors that also deal with the subsurface.     

Competition,Sustainability and Packaging Policy in the UK

This paper examines the use of economic instruments in the implementation of environmental policy, based upon a recent study into the European Union Packaging and Packaging Waste Directive (94/62/EC). It explores the introduction of competitionbased models in the UK implementation of the Directive, and assesses their ability to achieve positive environmentaloutcomes in a cost-efficient manner. Several problems for the competition model are discussed, particularly the fear of profiteering within marketbased systems by some economic operators; the behaviour of economic operators towards non-profitable market segments; the ability of free-market models to engender public participation in recycling programmes; and the failure of private sector solutions to consider the full environmental costs of packaging. Neo-liberalist competitive models do not address such problems convincingly, and therefore continued government intervention is required if the UK is to meet its targets under the EU Directive. Whilst economic instruments and competition provide avenues for a more effective environmental policy, there is a continuing need for government regulation rather than unquestioning faith in the benefits of the free market.