Regulated flushing in a gravel-bed river for channel habitat maintenance: A Trinity River fisheries case study

The operation of Trinity and Lewiston Dams on the Trinity River in northern California in the United States, combined with severe watershed erosion, has jeopardized the existence of prime salmonid fisheries. Extreme streamflow depletion and stream sedimentation below Lewiston have resulted in heavy accumulation of coarse sediment on riffle gravel and filling of streambed pools, causing the destruction of spawning, nursery, and overwintering habitat for prized chinook salmon (Salmo gairdnerii) and steelhead trout (Oncorhynchus tschawytscha). Proposals to restore and maintain the degraded habitat include controlled one-time remedial peak flows or annual maintenance peak flows designed to flush the spawning gravel and scour the banks, deltas, and pools. The criteria for effective channel restoration or maintenance by streambed flushing and scouring are examined here, as well as the mechanics involved.The liabilities of releasing mammoth scouring-flushing flows approximating the magnitude that preceded reservoir construction make this option unviable. The resulting damage to fish habitat established under the postproject streamflow regime, as well as damage to human settlements in the floodplain, would be unacceptable, as would the opportunity costs to hydroelectric and irrigation water users. The technical feasibility of annual maintenance flushing flows depends upon associated mechanical and structural measures, particularly instream maintenance dredging of deep pools and construction of a sediment control dam on a tributary where watershed erosion is extreme. The cost effectiveness of a sediment dam with a limited useful economic life, combined with perpetual maintenance dredging, is questionable.     

NEW REQUIREMENTS FOR LOCAL UNITS OF GOVERNMENT IN WATER RESOURCES PLANNING: INSIGHTS FOR IMPLEMENTATION FROM RECENT WATER RESOURCES PLANNING RESEARCH1

ABSTRACT: Recent Federal and some State legislation has enlarged the scope of permitted or required actions of local units of government in water resources management and protection. Much of the legislation encourages local units of government to introduce water resources planning measures which will be preventive instead of corrective. Extensive public works measures, environmental destruction and the threat to human life can thus be eliminated or reduced. Research has developed and tested a method for identifying the elements of a water resources protection program for small urbanizing watersheds which was technically adequate and socially acceptable to the communities implementing such programs. Research results suggest that deliberate efforts will be necessary to inform and educate local units of government as to the usefulness of the legislation; and that the program must reflect local natural resource conditions and local preferences for the method of accomplishing the protection. Successful implementation could be restrained by inertia of local units of government, a lack of tradition in such programs, and hostile existing agencies.     

INSTITUTIONALIZED INEFFICIENCY: THE UNFORTUNATE STRUCTURE OF COLORADO'S WATER RESOURCE MANAGEMENT SYSTEM1

ABSTRACT: This analysis identifies two basic structural features of Colorado's water management system which inhibit constructive reform and perpetuate inefficiencies in water use and distribution patterns. These features are: (1) the fragmentation of authority and influence over water, and (2) the estrangement of interest in reform from formal control over water policy. These interrelated features have continued to produce: sporadic, high conflict battles over proposed changes in the status quo; decision making which tends to exaggerate the importance of narrow, special interests while virtually ignoring legitimate interests of major sectors of the public; an inertia which discourages innovation; and an agglomeration of rules and water rights that are predicated on obsolete social and economic needs. Two radical proposals for reforming the state's water resource management system in order to overcome these problems and to enhance the probability that wise water policy will result are offered. These proposals are: (1) the abolition of the present system of water rights founded on the doctrine of prior appropriation, and (2) the consolidation of authority over water allocation in a single board of governors.     

Trends in passenger exposure to carbon monoxide inside a vehicle on an arterial highway of the San Francisco Peninsula over 30 years: A longitudinal study

This paper describes a long-term trend study of passenger exposure to carbon monoxide (CO) inside a vehicle traveling on an arterial highway in northern California. CO exposure was measured during four field surveys on State Route #82 (El Camino Real) on the San Francisco Peninsula in 1980–1981, 1991–1992, 2001–2002, and 2010–2011. Each field survey took at least 12 months. Fifty trips from each survey—for a total of 200 trips—were matched by date, day of the week, and starting time of the day to facilitate comparisons over three decades. The mean net CO concentration of each trip was obtained by subtracting the background CO level from the average CO concentration for the entire trip. The mean net CO concentration (0.5 ppm) for 2010–2011 was only 5.2% of that (9.7 ppm) for 1980–1981. For the 50 trips, the average travel time for the 1980–1981 period (39.6 min) was only 8.3% higher than during the 2010–2011 period (36.3 min). The estimated round-trip distance on the highway was held constant at 11.8 miles. The reduction in the mean net CO concentration was attributed to more stringent CO emission standards on new vehicles sold in California since 1980. The state’s cold-temperature CO standard implemented in 1996 appeared to reduce high CO concentrations that were observed during the late fall and winter of 1980–1981. In addition, the observed standard deviation in concentration fell from 3.1 ppm in 1980–1981 to 0.2 ppm in 2010–2011, and the range of the 50 mean net CO concentrations narrowed from 14.9 ppm in 1980–1981 to 1.1 ppm in 2010–2011, but the relative variability, as indicated by the geometric standard deviation, remained the same. These results have important scientific implications for regulatory policies designed to control air pollution from motor vehicles.

Implications: Many developing countries launched or expanded their mobile source emission control programs in the 1990s, yet many of them do not have adequate inspection and maintenance (I/M) programs. The El Camino Real study shows the long-term public health benefits of more stringent motor vehicle emission standards for carbon monoxide (CO) on new cars and of an I/M program (Smog Check) on the existing fleet in California. The study provides a protocol for conducting standardized field surveys of in-vehicle exposure on a periodic basis. Such surveys would enable developing countries to assess the progress of their mobile source emission control programs.     

An environmental decision-making tool for evaluating ground-level ozone-related health effects

A computer model called the Ozone Risk Assessment Model (ORAM) was developed to evaluate the health effects caused by ground-level ozone (O3) exposure. ORAM was coupled with the U.S. Environmental Protection Agency's (EPA) Third-Generation Community Multiscale Air Quality model (Models-3/CMAQ), the state-of-the-art air quality model that predicts O3 concentration and allows the examination of various scenarios in which emission rates of O3 precursors (basically, oxides of nitrogen [NOx] and volatile organic compounds) are varied. The principal analyses in ORAM are exposure model performance evaluation, health-effects calculations (expected number of respiratory hospital admissions), economic valuation, and sensitivity and uncertainty analysis through a Monte Carlo simulation. As a demonstration of the system, ORAM was applied to the eastern Tennessee region, and the entire O3 season was simulated for a base case (typical emissions) and three different emission scenarios. The results indicated that a synergism occurs when reductions in NOx emissions from mobile and point sources were applied simultaneously. A 12.9% reduction in asthma hospital admissions is expected when both mobile and point source NOx emissions are reduced (50 and 70%, respectively) versus a 5.8% reduction caused by mobile source and a 3.5% reduction caused by point sources when these emission sources are reduced individually.     

Finding upper-level sets in cellular surface data using echelons and saTScan

Across a spectrum of contemporary contexts from public health to landscape ecology and natural resources, there is need for objective determination of elevated occurrence in phenomena such as disease incidence and biodiversity. Occurrences of such phenomena constitute response surfaces, but data regarding the surface is typically acquired in a cellular framework. The cells may comprise a regular grid, or may be of irregular shapes such as counties in which statistics are collected. Echelons are a topologically based approach to systematic determination of spatial structure in a step surface. Spatial scan statistics are a probability-based approach to the same issue when interest lies in a rate variable. Here we examine the use of echelons both separately and in conjunction with the SaTScan implementation of spatial scan statistics for purposes of determination and visualization of upper-level sets. Consideration is given to both conventional geographic space and to the cellular pseudo-space of contingency tables for ordered categorical variables. Received: August 2002 / Revised: July 2005     

A community classification system for forest evaluation: Development,validation, and extrapolation

A community classification system integrating vegetation and landforms was developed for the 8,054-ha Cheatham Wildlife Management Area (CWMA), located on the Western Highland Rim of Tennessee, USA, to obtain information on which to base multiresource land management decisions. A subjective procedure (synthesis tables) and several objective techniques (factor analysis, cluster analysis, and canonical discrimination) were used to evaluate importance values of overstory and midstory species, coverage values of understory species, and topographic parameters. These procedures were used collectively to guide and to provide evidence for interpretation of vegetational patterns on the landscape. The eight discrete communities identified on a 482-ha compartment within the CWMA were: northern red oak (Quercus rubra L.), chestnut oak (Q. prinus L.), scarlet oak (Q. coccinea Muenchh.), yellow-poplar (Liriodendron tulipifera L.), sycamore-sweetgum (Platanus occidentalis L.-Liquidambar styraciflua L.), black oak-hickory (Q. velutina Lam.-Carya spp.), post oak (Q. stellata Wangenh.), and American beech (Fagus grandifolia Ehrh.) communities. The classification system was validated with an independent data set. The eight communities were successfully extrapolated to an unsampled portion of the CWMA. Clearly, community analysis can become an important facet in forest management and may play a major role where a holistic understanding of vegetative relationships is essential.     

Duck Populations as Indicators of Landscape Condition in the Prairie Pothole Region

The Prairie Pothole Region of the northern GreatPlains is an important region for waterfowl production becauseof the abundance of shallow wetlands. The ecologicalsignificance of the region and impacts from intensiveagriculture prompted the U.S. Environmental Protection Agency to select it as one ofthe first areas for developing and evaluating ecologicalindicators of wetland condition. We examined hypothesizedrelations between indicators of landscape and wetlandconditions and waterfowl abundance on 45 40 km² study sites in North Dakota for1995–1996. Landscape condition was defined a priori as the ratio of cropland area to total upland area surroundingwetlands. Measures of waterfowl abundance included estimatednumbers of breeding pairs (by species and total numbers) and , a species-specific correction factor which effectively adjusts breedingpair estimates for annual or area-related differences in pondsize. Landscape indicators and waterfowl measures varied among regions. Results indicated that most areas in the Coteau region are ofmuch higher quality for ducks than those in the Drift Plain,and areas in the Red River Valley are of the poorest qualityfor ducks. Regression models demonstrated the impact ofagricultural development on breeding duck populations in the PrairiePothole Region. The most consistent landscape indicators ofwaterfowl abundance were percent of cropland and grassland. Models were inconsistent among years and species. Thepotential biotic indicators of landscape and wetland condition examined here wouldbe appropriate for temporal trend analyses, but because ofinherent geographic variability would not be appropriate forsingle-year geographic trend analyses without more extensiveevaluations to improve explanatory models.     

Job engagement,perceived organizational support,high‐performance human resource practices,and cultural value orientations: A cross‐level investigation

Drawing on social exchange theory, we developed and tested a cross‐level model of organizational‐level predictors of job engagement. Specifically, we examined the impact of high‐performance human resource (HR) practices on employee engagement and work outcomes. Based on a sample of 605 employees, their immediate supervisors, and HR managers from 130 companies, our results indicated that high‐performance HR practices were directly related to job engagement as well as indirectly related through employees' perceived organizational support. In turn, job engagement was positively related to in‐role performance and negatively related to intent to quit. Culture was found to act as a critical contextual factor, as our results also revealed that the relationship between HR practices and perceived organizational support was stronger when collectivism was high and when power distance orientation was low. Overall, the findings shed new light on the processes and conditions through which employee work‐related outcomes are enhanced owing to high‐performance HR practices. Copyright © 2015 John Wiley & Sons, Ltd.