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21.
In Belgium a long process (1999–2005) led to the designation of several marine protected areas (MPAs). In order to analyse the designation process, the ‘policy arrangement approach’ was used as an analytical tool. Attention was given to four dimensions (actors and coalitions, arguments, rules and resources). Particular attention was paid to the switch from an authoritative to a more deliberated policy style in reaction to conflicts with stakeholders. This switch in policy style contributed to a successful legal designation, but does not guarantee the best protection of marine biodiversity. This case study linked science (setting ecological goals) to policy (analysis of a policy process) and led to some more general conclusions on the designation of MPAs and the role of participation in this process. 相似文献
22.
Mountain regions are sensitive to climate changes, which make them good indicators of climate change. The aim of this study is to investigate the spatial and temporal variability of air temperature and precipitation in the Polish Carpathians. This study consists of climatological analyses for the historical period 1851-2010 and future projections for 2021-2100. The results confirm that there has been significant warming of the area and that this warming has been particularly pronounced over the last few decades and will continue in the oncoming years. Climate change is most evident in the foothills; however, these are the highest summits which have experienced the most intensive increases in temperature during the recent period. Precipitation does not demonstrate any substantial trend and has high year-to-year variability. The distribution of the annual temperature contour lines modelled for selected periods provides evidence of the upward shift of vertical climate zones in the Polish Carpathians, which reach approximately 350 meters, on average, what indicates further ecological consequences as ecosystems expand or become extinct and when there are changes in the hydrological cycle. 相似文献
23.
Jewgenij Torizin Li-chao Wang Michael Fuchs Bin Tong Dirk Balzer Li-qin Wan Dirk Kuhn Ang Li Liang Chen 《山地科学学报》2018,15(6):1299-1318
This study presents a statistical landslide susceptibility assessment (LSA) in a dynamic environment. The study area is located in the eastern part of Lanzhou, NW China. The Lanzhou area has exhibited rapid urbanization rates over the past decade associated with greening, continuous land use change, and geomorphic reshaping activities. To consider the dynamics of the environment in the LSA, multitemporal data for landslide inventories and the corresponding causal factors were collected. The weights of evidence (WofE) method was used to perform the LSA. Three time stamps, i.e., 2000, 2012, and 2016, were selected to assess the state of landslide susceptibility over time. The results show a clear evolution of the landslide susceptibility patterns that was mainly governed by anthropogenic activities directed toward generating safer building grounds for civil infrastructure. The low and very low susceptibility areas increased by approximately 10% between 2000 and 2016. At the same time, areas of medium, high and very high susceptibility zones decreased proportionally. Based on the results, an approach to design the statistical LSA under dynamic conditions is proposed, the issues and limitations of this approach are also discussed. The study shows that under dynamic conditions, the requirements for data quantity and quality increase significantly. A dynamic environment requires greater effort to estimate the causal relations between the landslides and controlling factors as well as for model validation. 相似文献
24.
Henning Lorenz David G. Gee Evgeny Korago Galina Kovaleva William C. McClelland Jane A. Gilotti Dirk Frei 《地学学报》2013,25(6):496-503
The Novaya Zemlya fold‐and‐thrust‐belt is the northern continuation of the late Palaeozoic Uralide Orogen. Little is known about its deeper structure and the basement history of the adjacent Barents and Kara shelves. Based on geological evidence and detrital zircon analysis of 28 samples from the northeastern and stratigraphically deepest part of the archipelago, we demonstrate that Cambro‐Ordovician turbidite‐dominated deposition was almost exclusively sourced from rocks consolidated during the Timanian orogeny (Timanian basement). A profound change in provenance occurred near the end of the Ordovician. Over 90% of the zircons from Silurian and about 80% from Devonian strata have ages characteristic of the Sveconorwegian Orogen, implying uplift of these rocks in the vicinity of Novaya Zemlya. The presence of Sveconorwegian and Grenvillian rocks in the high Arctic suggests revision of recent reconstructions of the Rodinia supercontinent, its break‐up and subsequent Caledonian orogeny. 相似文献
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This paper presents an analysis of the accessibility of nodes in the Belgian road network. The intersection of roads are considered as the nodes and their connecting roads as the edges of a network. By means of the Dijkstra algorithm accessibility values are computed for each node by summing shortest travel times to a reference system of 158 nodes spread evenly over the Belgian territory. A comparison of the measured actual accessibility with that determined from an optimal situation provides an indication of the quality of directness of the Belgian road system. Accessibility and directness are shown cartographically. An isochronal map illustrates the access to Brussels. 相似文献
27.
Dirk Goossens 《地球表面变化过程与地形》1985,10(4):353-362
A torn-up road offered the opportunity to sample a dust cloud continuously at different heights during a time interval of 51 hours. In particular the granulometrical characteristics of the dust caught were investigated. It appears that if the air layer in the vicinity of a dust cloud is not too turbulent, the cloud will be clearly granulometrically stratified. The coarse material moves chiefly at the bottom of the cloud, whereas the fine material will occur both at the bottom and at the top. The experiment also shows that the higher the dust in the cloud, the worse it is sorted. Above a critical height, however, the degree of sorting increases again. The variation of the mean dust diameter d50, as a function of the height z, can be expressed in a simple semi-logarithmic equation. The variation of the dust quantity G, as a function of the height z, can also be expressed in a semi-logarithmic form but the correlation is higher when a power equation is used. The ratio of fine silt to coarse silt seems to vary parabolically with height. One can only speak of an optimal transport height in the case of particles > 16 μm. For finer particles, the turbulence of a normal air stream is usually high enough to carry the particles anywhere in the dust cloud, so that one can no longer speak of an optimal transport height. The granulometrical border between aeolian transport in saltation and aeolian transport in suspension lies, according to the results of the experiment, at a diameter of about 63 μm. 相似文献
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29.
Seismic exploration underneath highly heterogeneous layers such as basalt flows is possible by lowering the principal source frequency. Unfortunately this also reduces resolution. Wave‐localization theory is a multiple scattering theory that can be used to study stratigraphic filtering in chaotic lithologies. It predicts the apparent attenuation due to scattering of a plane wave traversing a layer with high velocity fluctuations. It can therefore predict the optimum principle source frequency in the trade‐off between loss of resolution and increased penetration depth. We show how this can be done with the help of a few statistical parameters derived from a well‐log analysis; namely, the average background velocity, the expected standard deviation in the velocity fluctuations, the typical scale length of the heterogeneities and the thickness of the basalt layer. In the likely situation that no local well logs exist, a multitude of scenarios can easily be examined at low cost. 相似文献
30.