Roads, bridges, causeways, impoundments, and dikes in the coastal zone often restrict tidal flow to salt marsh ecosystems.
A dike with tide control structures, located at the mouth of the Herring River salt marsh estuarine system (Wellfleet, Massachusetts)
since 1908, has effectively restricted tidal exchange, causing changes in marsh vegetation composition, degraded water quality,
and reduced abundance of fish and macroinvertebrate communities. Restoration of this estuary by reintroduction of tidal exchange
is a feasible management alternative. However, restoration efforts must proceed with caution as residential dwellings and
a golf course are located immediately adjacent to and in places within the tidal wetland. A numerical model was developed
to predict tide height levels for numerous alternative openings through the Herring River dike. Given these model predictions
and knowledge of elevations of flood-prone areas, it becomes possible to make responsible decisions regarding restoration.
Moreover, tidal flooding elevations relative to the wetland surface must be known to predict optimum conditions for ecological
recovery. The tide height model has a universal role, as demonstrated by successful application at a nearby salt marsh restoration
site in Provincetown, Massachusetts. Salt marsh restoration is a valuable management tool toward maintaining and enhancing
coastal zone habitat diversity. The tide height model presented in this paper will enable both scientists and resource professionals
to assign a degree of predictability when designing salt marsh restoration programs. 相似文献
A genetic algorithm (GA) was used to reduce cross section data for a hypothetical example consisting of 41 data points and for 10 cross sections on the Kootenai River. The number of data points for the Kootenai River cross sections ranged from about 500 to more than 2,500. The GA was applied to reduce the number of data points to a manageable dataset because most models and other software require fewer than 100 data points for management, manipulation, and analysis. Results indicated that the program successfully reduced the data. Fitness values from the genetic algorithm were lower (better) than those in a previous study that used standard procedures of reducing the cross section data. On average, fitnesses were 29 percent lower, and several were about 50 percent lower. Results also showed that cross sections produced by the genetic algorithm were representative of the original section and that near‐optimal results could be obtained in a single run, even for large problems. Other data also can be reduced in a method similar to that for cross section data. 相似文献
decision-based scoping —provides an effective methodology for improving the EIS scoping process. Decision-based scoping, in conjunction with a new
tool, the decision-identification tree (DIT), places emphasis on first identifying the potential decisions that may eventually need to be made. The DIT provides
a methodology for mapping alternative courses of action as a function of fundamental decision points. Once these decision
points have been correctly identified, the range of actions, alternatives, and impacts can be more accurately assessed; this
approach can improve the effectiveness of EIS planning, while reducing the risk of future disconnects between the EIS analysis
and reaching a final decision. This approach also has applications in other planning disciplines beyond that of the EIS. 相似文献
To create a truly circular economy requires a shift from the traditional view of waste disposal to one of resource management. This is particularly important in developing countries, where municipal waste generation is increasing, and efficient recovery of economic value from waste is rarely achieved. Conducted in the University of Lagos (UoL), Nigeria, this study investigated the efficiency of a recycling scheme with the goal of making recommendations to improve the process. UoL’s recycling policy centers around source segregation of waste into color-coded bins. Waste audit was carried out using the output method and interviews were conducted with staff from the waste management team to understand practices on campus. Substantial contamination of colored bins with non-target material was observed. Organics (30%), mixed plastics (28%) and paper (24%) were the most abundant materials, hence have the greatest potential for recovery, and income generation, if segregation rates could be improved. Despite its recycling policy and infrastructure, 99% of UoL waste was going to landfill. Poor policy implementation results in low recovery rates. Targeted waste reduction and increased material recovery would enhance efficiency. Improved awareness of recycling benefits, in addition to policy enforcement, could serve as tools to increase stakeholder participation in recycling.
Phosphorus losses from agricultural land can cause accelerated eutrophication of surface water bodies. This study evaluated the use of soil test phosphorus (STP) levels to predict dissolved inorganic phosphorus (DIP) concentrations in runoff water from agricultural soils using laboratory rainfall simulation. The objectives of this study were to determine (i) to what extent STP concentrations can be used as a basis to predict P losses from Alberta soils and (ii) how extended rainfall simulation run times affected DIP losses. Soil samples collected from a total of 38 field sites, widely scattered throughout the southern half of Alberta, were subjected to rainfall simulation in the laboratory. The STP concentrations were determined using Miller-Axley, Norwest, Kelowna, Modified Kelowna Mehlich-III, and distilled water extraction methods. Each rainfall simulation event lasted for at least 90 min. Runoff samples were collected in time series for the duration of each simulation, during two distinct runoff intervals: (i) for the first 30 min of continuous runoff (T30) and (ii) for 40 min during runoff equilibrium (Teq). For all the STP extractants and both runoff intervals, the relationship with DIP-flow-weighted mean concentration (FWMC) was linear and highly significant with r2 values ranging from 0.74 to 0.96. However, the slopes of the resulting regression lines were, on average, 1.85 times greater for the T30 runoff interval over those computed for the Teq interval. Thus experimental methodology greatly influenced regression parameters, suggesting that more work was needed to verify these relationships under natural conditions. In addition, with many of the r2 values greater than 0.90 there would be little, if any, benefit derived by including soil properties in regression analysis. 相似文献