Spelling suggestions: "subject:"aphysical geography."" "subject:"2physical geography.""
521 |
När tippen blir toppen -En studie om soptippars omvandling : Hur blir de en tillgång och för vem?Norrby, Viggo January 2015 (has links)
A high degree of urbanization with growing cities has raised a need of transforming closed landfill sites for giving them new uses. This study aims to investigate how old landfills can be re-used, what has lead to the new uses, and for what and whom the transformed site will be an asset. The method used is a case study of four different landfills in Stockholm county, Sweden. The case study is analyzed in the light of former studies regarding re-use of degraded urban areas, so called brownfields, and in particular studies and reports of landfill re-use. The result indicates that old landfill sites is identified as an area with possible values if transformed properly, in the case study area especially as green structure and recreation areas. But for the transformation to take place there has to be a local community which demands a transformation. The transformation is also depending of the surrounding areas’ need of more green structures, which is not always the case in Stockholm. The study also shows that closed landfills which have not been part of any bigger transformation, also can be a valuable place for groups and alternative activities which are not always welcome in other urban environments. Key words: Landfill, land use, land re-use, brownfield, Stockholm.
|
522 |
Från våtmark till våtmark i Ängelholms kommun : Fallstudie kring två våtmarkerHansson, Jonas January 2013 (has links)
Huvudsyftet med denna uppsats är redogöra hur två våtmarker i Ängelholms kommun har kommit till och dess nytta för miljön. För att kunna besvara denna fråga har jag noga studerat beslutsgången, gjort fältstudier, talat med markägare tagit del av opublicerat material och studerat äldre och nya kartor över de båda våtmarkerna, båda belägna i trakten av Höja, ungefär fem kilometer sydost om Ängelholm, och även gjort fältstudier. Utöver detta har jag visat hur Ängelholms och Åstorps kommun arbetar för att främja anläggningen av våtmarker. Båda intresserar sig för att minska övergödningen och med våtmarker så åstadkommer de detta. Utöver vattenrenare så är våtmarker också av intresse rent utbildningsmässigt och bra för att få en heterogen landskapsbild. Slutsatser Det är skillnad på storleken av våtmarker i nordvästra Skåne gentemot i Danmark. Detta beror på att Danmark tidigare var indelade i amt som hade hand om vattenfrågor och kunde genomdriva våtmarksanläggningar i större utsträckning. Våtmarkerna i Skörpinge och Höja fungerar båda som naturliga reningsverk av närsalter. Våtmarken i Skörpinge bör vara mer effektiv när det gäller rening av närsalter då denna har större antal hektar avrinningsområde i förhållandet till våtmarksareal. Till detta skapar våtmarkerna en biologisk mångfald, Våtmarken i Höja visade sig vara väldigt effektiv, 43,4%, när det gällde rening av kväve. Men siffrorna är troligen missvisande i och med att det gjorde för få stickprov under för kort tidsrymd. Andra studier visar en reningseffektivitet på mellan 2 – 20 %. Det som skiljer våtmarkerna åt är dels formen och utförandet och dels antalet markägare. Våtmarken i Höja ägs av bara en markägare medan den andra ägs av fyra. Till detta krävdes det ett godkännande från Miljödomstolen för att våtmarken i Skörpinge skulle få anläggas. Båda våtmarkerna tog lika lång tid att anlägga, ungefär två år. Hur lång tid det tar att anlägga en våtmark kan bero på om markägare vill ha bidrag eller inte och i så fall från vilket myndighet. Så det kan säkerligen ta kortare tid att anlägga en våtmark. För att följa upp nyttan av våtmarkerna i Höja och Skörpinge bör det göras fler stickprov under längre tid och med dessa avgöra hur effektiva våtmarkerna egentligen är. Till detta bör det göras en inventering av flora och fauna för att undersöka den biologiska mångfalden.
|
523 |
Dynamics of surging tidewater glaciers in Tempelfjorden, SpitsbergenFlink, Anne January 2013 (has links)
Terrestrial glacial geomorphology has long been used to evaluate the extent, chronology and dynamics of former glaciers and ice sheets. New marine geophysical methods provide an opportunity to study the glacial submarine morphology of modern continental shelves and fjord systems. This makes it possible to study landform assemblages in the submarine settings that are often better preserved than their terrestrial counterparts. This study focuses mainly on the recent surge history of the tidewater glacier Tunabreen, which calves into Tempelfjorden in Western Spitsbergen. Tunabreen is a small outlet glacier of the Lomonosovfonna ice cap and has experienced severalsurges and terminal retreats during the last century. The multiple surge events havemost likely removed or reworked landform assemblages created by earlier surges,resulting in a complex geomorphological imprint on the bed of Tempelfjorden. Tunabreen has left a specific morphological imprint on the sea floor, consisting of iceflow‐parallel lineations and generally flow‐transverse retreat moraines. Comparisonof retreat moraines mapped from high resolution multibeam bathymetric data andglacier terminal positions, established using remote sensing imagery suggest that themoraines in the inner part of Tempelfjorden are annually formed recessionalmoraines, formed during winter still stands of the glacier margin or during its minorreadvances. Although detailed reconstruction of glacier surge dynamics based solelyon the landform distribution is challenging, it is evident that Tunabreen hasexperienced fast flow during surges and semiannual retreat of the margin after thesurges. The main achievements of this study are a spatial reconstruction of the dynamics ofTunabreen, which has experienced three surges during the last hundred years.Together with the Little Ice Age surge of the adjacent von Postbreen, four recentsurges have been recorded in Tempelfjorden since 1870, which distinguishes thestudy area from earlier studied Svalbard tidewater surge glacier settigs, where theglaciers have been known to surge only once or twice. However a detailedunderstanding of surge triggering mechanisms and their role in controlling thedynamics of the tidewater glaciers in Svalbard is still poor and requires furtherinvestigations. Svalbard, where most of the small outlet glaciers are believed to be ofsurge type, is an excellent natural laboratory for such investigations.
|
524 |
Karst hydrogeology of the southern catchment of the River Wye, DerbyshireBanks, Vanessa Jane January 2007 (has links)
A conceptual model of the regional hydrogeology of the White Peak, considered fundamental to the understanding of the local (Wye) catchment has been presented. Specific to the local catchment, an investigation of the karst hydrogeology has been carried out in the context of its geological setting using results from: tracer experiments, chemical analyses of spring water, and hydrograph analyses; alongside detailed consideration of speleogenetic processes and terrain evaluation. Derived from these studies, a conceptual model has been developed, which represents the catchment hydrogeology in a number of hydrogeological units. Their attribution reflects the lithological differences and material responses to both stress and mineralization that have exerted significant influence on speleogenetic processes in the catchment. The units exhibit different recharge, through-flow and resurgence characteristics. Speleogenetic processes in some of the bedrock units support the inception horizon hypothesis. Flow paths typically pass through more than one hydrogeological unit. Lead-zinc-fluorite-baryte mineralization is associated with the dominant hydrogeological unit on the eastern side of the catchment. The mineral deposits were subject to several phases of exploitation facilitated by dewatering via drainage adits (soughs). Records pertaining to the soughs have been used to contribute to an understanding of the changes in groundwater levels as a consequence of mineral exploitation. A case study focused on Lathkill Dale has been used to test the catchment model and further explore human impacts on the hydrogeology. The major contribution of this work is in furthering the understanding of the hydrogeology and speleogenetic processes operating in the catchment. This is supplemented by additional contributions to the understanding of the distribution of superficial deposits within the catchment. Speculation regarding mineralizing processes; geomorphology; functioning of karst aquifers; seasonality of the groundwater chemistry; climate change, and the engineering properties of the bedrock may encourage further research in these areas.
|
525 |
The provenance of the Norber erratics, and the formation of post-Devensian-deglaciation pedestal rocks with Carboniferous limestone pedestals in England, Ireland and WalesParry, Brian January 2007 (has links)
This study investigates a Devensian glacial conundrum, the provenance of the Norber erratics in North Yorkshire, and the origins of a post-Devensian-deglaciation landform, pedestal rocks with Carboniferous limestone pedestals in England, Ireland and Wales. Investigations to determine the provenance of the Norber erratics were undertaken in a study area of about 2000ha. Mapping erratic dispersal and measuring striae strike revealed that the provenance is Crummackdale, and that Devensian ice crossed over only the Crummack, Sowerthwaite and Austwick formations en route to Norber. Petrographical and physical surveys further revealed that the erratics are derived from the Austwick Formation only, and that provenance is a glacially-plucked ‘amphitheatre’ in the vicinity of the Old Limekiln (SD 770707). Investigations to determine the formation of post-Devensian-deglaciation pedestal rocks with Carboniferous limestone pedestals were undertaken at 19 sites in England, Ireland and Wales, where 162 pedestal rocks and a pedestal rock field were examined. The study was divided into two, the formation of perched and mushroom pedestal rocks. An examination of weathering and erosion processes at Norber, where only perched pedestal rocks with vertical sidewalls are found, revealed that lowering of the inter-pedestal limestone surface has taken place primarily in a sub-regolith karstic environment, and that little or no pedestal formation occurred prior to ca.10000BP. In contrast, the lowering of the inter-pedestal limestone surface about perched pedestal rocks with sloping sidewalls, such as at Scales Moor (North Yorkshire) and the Burren (County Clare), has taken place primarily in a subaerial environment. Moreover, pedestal formation commenced in ca.14500BP in England and Wales, and ca.13700BP in Ireland. The pedestals of mushroom pedestal rocks have formed due to lateral dissolution under regolith that has largely been eroded, probably following deforestation in ca.3000BP.
|
526 |
The Holocene palaeoenvironments of the rift margin in Southern Jordan (Wadi Faynan)Mohamed, Hwedi Abdulsalam January 2000 (has links)
No description available.
|
527 |
Modern distribution of freshwater ostracodes in the southwest Yukon Territory and northern British Columbia, CanadaBunbury, Joan January 2004 (has links)
This biogeographical study documents the modern distribution of ostracodes in the southwest Yukon Territory and northern British Columbia, Canada. The study tested the hypothesis that dissolved ion composition and concentrations of the lake water are the primary determinants of the distribution of modern ostracodes in this region. A total of 28 freshwater species representing 8 genera were identified in the 33 study lakes. Species common in the southwest Yukon are widely distributed throughout North America, and include Cyclocypris ampla, Candona candida, Cypria turneri, Cypria ophtalmica, and Candona protzi. Concentrations of ostracode valves were highest in four lakes with moderate conductivity values ranging between 330 and 397 muS/cm. Rarefaction estimated species richness was low (3 to 8), and the highest estimated species richness was found in four lakes, three of which were within 1 km of each other. Conductivities in these lakes ranged between 320 and 397 muS/cm. There is little geographic pattern in either species richness or in the distribution of common species. The dissolved ion composition is the primary control determining the species that will be present in a particular lake.
|
528 |
The impact of forest fire on permafrost slopes Klondike area, Yukon TerritoryCoates, James January 2008 (has links)
Numerous forest fires occurred during the summer of 2004 in the Klondike Goldfields region of the Yukon Territory, an area of extensive discontinuous permafrost. More than 35 shallow detachment failure landslides developed in subsequent weeks in Steele Creek, a small drainage basin located about 60 km south of Dawson City.
Preliminary observations of the failures and near-surface thermal regime were made through freeze-up of 2004 and continued in the summers of 2005 and 2006. Detachment failures were mapped and individual sites were surveyed. Air and ground temperatures were measured in burned and unburned areas. In addition, two-dimensional DC resistivity transects were used to examine subsurface conditions in the area.
Forest fire contributed to detachment failure activity on permafrost slopes by destroying the surface organic mat, causing burned surface temperatures to rise, thawing active layers by up to 20 cm (+31%) deeper than unburned slopes and weakening the surface root structures. Deeper thaw melted transient layer ground ice, raising soil porewater pressures. The thermal differences between burned and unburned sites were greater at the north-facing than south-facing sites, and active layer freezing and thawing processes varied according to both aspect and burned status. More southerly-facing and/or burned sites generally thawed earlier, refroze later and had warmer temperatures than more northerly and/or unburned sites. Thaw of burned areas with high ground surface temperatures can be expected to continue, depending on climatic conditions, until sufficient revegetation occurs to shade the surface and rebuild the insulating organic mat.
The detachment failures occurred from a few weeks to two years after forest fire, and only on slopes where permafrost was extensive. They were not similar to others in the literature in that almost all occurred in coarse-gained soils and had failure planes elevated above the permafrost table. These landslides were flow-type failures that rafted portions of the organic mat on top of deforming, non-cohesive sediment. They occurred in areas of deeper thaw but their distribution and the resistivity data suggest that they were associated with supra-permafrost taliks which concentrated groundwater flow.
In an unglaciated area like the Klondike region this landsliding process has likely occurred thousands of times during the Pleistocene and may be responsible for elements of the form of the region's slopes. Predicted increases in the frequency and magnitude of forest fire in the boreal forest due to warming climates may increase incidence of these types of failures.
|
529 |
Incorporation of Vegetation into Mountain Permafrost Distribution Models, Southern Yukon TerritoryKremer, Marian January 2010 (has links)
Three groups of variables (Digital Elevation Model [DEM]-derived variables, fieldwork-derived vegetation variables, and satellite imagery-derived vegetation variables) were combined in Classification and Regression Tree (CART) models to determine the utility of vegetation-based variables for mountain permafrost distribution modelling in the southern half of the Yukon Territory. Four variables were measured in the field: canopy openness, vegetation height, organic mat thickness, and dominant species. Using Landsat TM and ETM+ imagery, three variables were calculated: a Normalized Difference Vegetation Index (NDVI), a vegetation classification, and a canopy closure classification. Individual variables were also examined to determine the one most useful for representing vegetation when modelling permafrost presence or absence. Additionally, models for each of five study areas spread across 5° of latitude were compared to examine the transferability of each variable.
The addition of vegetation variables to the CART models created with DEM-derived variables resulted in only a minimal increase in the overall accuracy. Dominant species proved to be the most useful variable, but the relationship between permafrost and each species differed among study areas. Only black spruce (Picea mariana) was consistently classified as permafrost probable and lodgepole pine (Pinus contorta var. latifolia) and trembling aspen (Populus tremuloides) were classified as permafrost improbable over all study areas. These results indicate that models of permafrost distribution across large areas are not likely to be enriched sufficiently by the inclusion of vegetation variables while models covering smaller areas may benefit from the inclusion of vegetation variables. The CART models tended to show a high accuracy in the prediction of areas with no permafrost which could be useful for the purposes of infrastructure development. CART models have not previously been used in permafrost modelling and the high accuracies they produced may indicate their utility for modelling the complex relationships among the variables affecting permafrost.
|
530 |
Changes in Multiyear Landfast Sea Ice in the Northern Canadian Arctic ArchipelagoPope, Sierra Grace January 2010 (has links)
For most of the 20th century, multiyear landfast sea ice (MLSI) existed in semi-permanent plugs across Nansen Sound and Sverdrup Channel and formed an incipient ice shelf in Yelverton Bay, Ellesmere Island in the northern CAA. Both plugs broke in 1962 and 1998, and several breakups within the last decade indicate that the plugs are becoming temporary seasonal features. The history of the plugs is reviewed using Canadian Ice Service ice charts, satellite imagery and a literature review. The weather systems associated with plug breakup events are related to a sequence of synoptic patterns, with most breakups occurring when low pressure centers over the Asian side of the Arctic Ocean and a warm pressure ridge develops over the QEI, creating warm temperatures, clear skies, and frequent wind reversals. The 2005 simultaneous breakup of the plugs was accompanied by the removal of 690 km2 of 55-60 year old MLSI from Yelverton Bay. Ground Penetrating Radar (GPR) and ice cores taken in June 2009 provide the first detailed assessment of the remaining MLSI in Yelverton Inlet, which in turn provides ground-truthing of satellite scenes and air photos used to chart historical changes in the MLSI. The last of the Yelverton Bay MLSI was removed in August 2010. The removal of these MLSI features in recent years aligns with the larger trend of reductions in age and thickness of sea ice in the Canadian Arctic Archipelago.
|
Page generated in 0.0679 seconds