The effects of permitting decisions made under Section 404 of the Clean Water Act for which compensatory mitigation was required
were examined. Information was compiled on permits issued in Oregon (January 1977–January 1987) and Washington (1980–1986).
Data on the type of project permitted, wetland impacted, and mitigation project were collected and analyzed. The records of
the Portland and Seattle District Offices of the US Army Corps of Engineers and of Environmental Protection Agency Region
X were the primary sources of information.
The 58 permits issued during the years of concern in Oregon document impacts to 82 wetlands and the creation of 80. The total
area of wetland impacted was 74 ha while 42 ha were created, resulting in a net loss of 32 ha or 43%. The 35 permits issued
in Washington document impacts to 72 wetlands and the creation of 52. The total area of wetland impacted was 61 ha while 45
ha were created, resulting in a net loss of 16 ha or 26%. In both states, the number of permits requiring compensation increased
with time. The area of the impacted and created wetlands tended to be ≤0.40 ha. Permitted activity occurred primarily west
of the Cascade Mountains and in the vicinity of urban centers. Estuarine and palustrine wetlands were impacted and created
most frequently. The wetland types created most often were not always the same as those impacted; therefore, local gains and
losses of certain types occurred. In both states the greatest net loss in area was in freshwater marshes.
This study illustrates how Section 404 permit data might be used in managing a regional wetland resource. However, because
the data readily available were either incomplete or of poor quality, the process of gathering information was very labor
intensive. Since similar analyses would be useful to resource managers and scientists from other areas, development of an
up-to-date standardized data base is recommended. 相似文献
Objective: We compared the differences in the braking response to vehicle collision between an active human emergency braking (control condition) and cruise control (CC) or adaptive cruise control (ACC).
Methods: In 11 male subjects, age 22 to 67 years, we measured the active emergency braking response during manual driving using the accelerator pedal (control condition) or in condition mimicking CC or ACC. In both conditions, we measured the brake reaction time (BRT), delay to produce the peak braking force (PBD), total emergency braking response (BRT + PBD), and peak braking force (PBF). Electromyograms of leg and thigh muscles were recorded during braking. The tonic vibratory response (TVR), Hoffman reflex (HR), and M-waves were recorded in leg muscles to explore the change in sensorimotor control.
Results: No difference in PBF, TVR amplitude, HR latency, and Hmax/Mmax ratio were found between the control and CC/ACC conditions. On the other hand, BRT and PBD were significantly lengthened in the CC/ACC condition (240 ± 13 ms and 704 ± 70 ms, respectively) compared to control (183 ± 7 ms and 568 ± 36 ms, respectively). BRT increased with the age of participants and the driving experience shortened PBD and increased PBF.
Conclusions: In male subjects, driving in a CC/ACC condition significantly delays the active emergency braking response to vehicle collision. This could result from higher amplitude of leg motion in the CC/ACC condition and/or by the age-related changes in motor control. Car and truck drivers must take account of the significant increase in the braking distance in a CC/ACC condition. 相似文献
ABSTRACT: A global predictive real time control strategy minimizing overflow volumes from combined sewers during rainfall was applied to control flows entering the Marigot interceptor (Laval, Canada) for 23 rain events that occurred in this urban area during the summer of 1989. Different surcharge intensities were allowed in the sewer. The duration of the control horizon as well as the location and number of control regulators were varied to assess the impact of these parameters on total overflow volumes and on control safety. Due to the high propagation speed of flow waves in pressurized conduits, it was found that five‐ minute control horizons were sufficient to ensure control performance and safety when important surcharges were permitted in the interceptor and when the controlled regulators were located where pressurized flow occurred. It was also found that it is possible to reduce the number of controlled regulators by placing them at locations intercepting the largest volumes of water during rain periods. 相似文献
Understanding the traits of invasive species may improve the ability to predict, prevent, and manage invasions. I compared morphological and performance traits of five congeneric pairs of invasive and noninvasive Commelinaceae across a factorial experiment using a range of water and nutrient availabilities. Invasive species had greater fecundity and vegetative reproduction than their noninvasive relatives. The invasive species also had higher relative growth rates, greater specific leaf area, and more plastic root-to-shoot ratios than noninvasive species. However, whether a trait was associated with invasiveness often depended on both environment and relatedness. Invasives had greater sexual and vegetative reproduction, higher specific leaf area, and greater relative growth rates than noninvasive congeners, but only in some environments. Differences between invasive and noninvasive taxa were greatest at high nutrient availabilities. These results suggest that studies of invasive species' traits must incorporate information on conditions under which the trait was measured. In addition, incorporating information on relatedness improved our ability to detect associations between species traits, such as specific leaf area and relative growth rate, and invasiveness, suggesting that such information may be required for a complete understanding of what makes a species invasive. 相似文献
Long‐term simulations of agricultural watersheds have often been done assuming constant land use over time, but this is not a realistic assumption for many agricultural regions. This paper presents the soil and water assessment tool (SWAT)‐Landuse Update Tool (LUT), a standalone, user‐friendly desktop‐based tool for updating land use in the SWAT model that allows users to process multi‐year land use data. SWAT‐LUT is compatible with several SWAT model interfaces, provides users with several options to easily prepare and incorporate land use changes (LUCs) over a simulation period, and allows users to incorporate past or emerging land use categories. Incorporation of LUCs is expected to provide realistic model parameterization and scenario simulations. SWAT‐LUT is a public domain interface written in Python programming language. Two applications at the Fort Cobb Reservoir Experimental Watershed located in Oklahoma and pertinent results are provided to demonstrate its use. Incorporating LUCs related to implementation of recommended conservation practices over the years reduced discharge, evapotranspiration, sediment, total nitrogen, and total phosphorus loads by 59%, 9%, 68%, 53%, and 88%, respectively. The user’s manual is included in this article as Supporting Information. The SWAT‐LUT executable file and an example SWAT project with three land use rasters and the user’s manual are available at the United States Department of Agriculture‐Agricultural Research Service Grazinglands Research Laboratory website under Software. Editor’s note: This paper is part of the featured series on Optimizing Ogallala Aquifer Water Use to Sustain Food Systems. See the February 2019 issue for the introduction and background to the series. 相似文献