A comparison of current techniques for measuring elevations in the beach and near-shore zones is presented. Techniques considered
include traditional methods such as ground survey along transects and airborne stereophotogrammetry, and also newer methods
based on remote sensing such as airborne scanning laser altimetry (LiDAR). The approach taken was to identify a representative
group of users of beach elevation data, elicit their requirements regarding these data, then assess how well the different
methods met these requirements on both technical and financial grounds.
Potential users of beach height measurements include those concerned with coastal defence, coastal environmental management
economic exploitation of the intertidal zone, and coastal flood forecasting. Three test areas in the UK were identified covering
a range of such users and also different beach types. A total of 17 basic user requirements were elicited. For each requirement
each method was scored according to the degree to which it could meet the requirement. Total scores were calculated and each
method ranked. This was undertaken for all the requirements together, for a subset relating to survey of narrow beaches, and
for a subset relating to survey of wide beaches. Approximate costs were also established for the top six methods.
Airborne stereophotogrammetry proved to be the best method technically, but was also the most expensive. Ground survey provides
very good technical performance on narrower beaches at moderate cost. Airborne LiDAR can achieve good technical performance
on both narrow and wide beaches at lower cost than ground survey. The satellite-based waterline method was also inexpensive
and gave good results on wide beaches. An overall conclusion is that, while the traditional methods of ground survey and airborne
stereophotogrammetry remain the best for engineering-related surveys requiring high levels of accuracy, airborne LiDAR in
particular looks set to have a significant impact on beach survey for applications for which a vertical accuracy of 20 cm
is acceptable, provided that its technology evolves satisfactorily. 相似文献
The use of quantitative data for constructing prognostic maps of the dynamics of ecosystem degradation and restoration by
nonlinear simulation methods is a topical field of landscape ecology. This method of dynamic cartography is based on fiberwise
comparison of data on the state of Chernye Zemli (the Kalmyk Republic, Russia) in different years and the detailed analysis
of the period on which the prognosis was based. For this purpose, materials of repeated aerial and satellite photography obtained
during a long period (1954–1993) were used. Comparison of maps characterizing the dynamics of Chernye Zemli between 1958 and
1993 allows prognostic electronic maps for the next 10–15 years (with a five-year interval) to be drawn and land prognosis
for the next 20–30 years (1998–2023) to be obtained.
Deceased 相似文献
Three-dimensional (3D) models are often utilised to assess the presence of sand and gravel deposits. Expanding these models to provide a better indication of the suitability of the deposit as aggregate for use in construction would be advantageous. This, however, leads to statistical challenges. To be effective, models must be able to reflect the interdependencies between different criteria (e.g. depth to deposit, thickness of deposit, ratio of mineral to waste, proportion of ‘fines’) as well as the inherent uncertainty introduced because models are derived from a limited set of boreholes in a study region. Using legacy borehole data collected during a systematic survey of sand and gravel deposits in the UK, we have developed a 3D model for a 2400 km2 region close to Reading, southern England. In developing the model, we have reassessed the borehole grading data to reflect modern extraction criteria and explored the most suitable statistical modelling technique. The additive log-ratio transform and the linear model of coregionalization have been applied, techniques that have been previously used to map soil texture classes in two dimensions, to assess the quality of sand and gravel deposits in the area. The application of these statistical techniques leads to a model which can be used to generate thousands of plausible realisations of the deposit which fully reflect the extent of model uncertainty. The approach offers potential to improve regional-scale mineral planning by providing an enhanced understanding of sand and gravel deposits and the extent to which they meet current extraction criteria.
Three different sizes of hog farms were selected to analyze the carbon emissions reduction and the cost–benefit of three methane digester systems. The sizes of the digesters are 2,200, 2,200 and 800 m3, respectively. The sales of slaughter hogs from them are 50,000, 35,000 and 10,000 head, respectively. The carbon emissions reductions were 5,237, 4,017, and 1,334 tons, respectively. The results show that while the methane digester systems have a significant effect on carbon emissions reduction, it is difficult to operate the systems sustainably. If the carbon emissions reduction can be traded at high enough prices in the carbon offset markets, then the systems will be profitable and sustainable. Newly established China's domestic carbon offset market could provide this possibility, but more government support is needed. In addition, this study shows that scale economies make the digester adoption relatively more profitable for larger farms than smaller ones. 相似文献