Spelling suggestions: "subject:"aphysical geography."" "subject:"2physical geography.""
431 |
Urban morphology and ecosystem services : a historico-geographical study of fringe belts and urban green spaces in Birmingham, UKZhang, Yiting January 2018 (has links)
Cities have tended to be treated by ecologists as essentially physical entities unconnected to the concerns of historical geographers. In contrast, urban morphologists have tended to focus on how urban physical expressions of culture have changed over time: such an approach has stimulated research on the characteristics and planning of the form of cities that has been largely divorced from concerns about ecosystem services. This is somewhat paradoxical in light of the significant areas of most cities that are vegetated and the increasing evidence of the value to society of these green spaces. This thesis examines the connection between urban morphological research on the fringe-belt concept, as developed by M. R. G. Conzen and others, and the character and distribution within cities of major areas of green space. The principal focus is on how green spaces within fringe belts that are embedded within cities (for example, parks, allotment gardens, golf courses, and land attached to educational and medical institutions) have changed over time, especially during the past 100 years. Detailed studies of fringe-belt sites in Birmingham reveal a decline in green space over time but maturation of surviving green space towards mature wood-grassland. Comparisons are made with residential areas.
|
432 |
A national coastal erosion risk assessment for ScotlandFitton, James Michael January 2015 (has links)
The geography of Scotland, with a highly undulating hinterland, long and indented coastline, together with a large number of islands, means that much social and economic activity is largely located at the coast. The importance of the coast is further highlighted by the large number of ecosystem services derived from the coast. The threat posed by climate change, particularly current and future sea level rise, is of considerable concern and the associated coastal erosion and coastal flooding has the potential to have a substantial effect on the socioeconomic activity of the whole country. Currently, the knowledge base of coastal erosion is poor, which serves to hinder the current and future management of the coast. This research reported here aimed to establish four key aspects of coastal erosion within Scotland: the physical susceptibility of the coast to erosion; the assets exposed to coastal erosion; the vulnerability of communities to coastal erosion; and the coastal erosion risk to those communities. Coastal erosion susceptibility was modelled here within a GIS, using data for ground elevation, rockhead elevation, wave exposure and proximity to the open coast. Combining these data produced the Underlying Physical Susceptibility Model (UPSM), in the form of a 50 m2 raster of national coverage. The Coastal Erosion Susceptibility Model (CESM) was produced with the addition of sediment supply and coastal defence data, which then moderates the outputs of the UPSM. Asset data for dwellings, key assets, transport infrastructure, historic assets, and natural assets were used along with the UPSM and CESM to assess their degree of exposure to coastal erosion. A Coastal Erosion Vulnerability Model (CEVM) was produced using Experian Mosaic Scotland (a geodemographic classification which identifies 44 different social groups within Scotland) to classify populations based upon 11 vulnerability variables. Dwellings were assigned a CESM and CEVM score in order to establish their coastal erosion risk. This research demonstrated that the issue of coastal erosion will impact on a relatively low number of properties compared to those impacted by flooding (both coastal and fluvial) as many dwellings are already protected by coastal defences. There is therefore, a considerable future liability, and great pressure for coastal defences to be maintained and upgraded in their current form. The use of the CEVM is a novel inclusion within a coastal erosion assessment for Scotland. Use of the CEVM established that coastal erosion risk is not distributed equally amongst the Scottish coastal population and highlighted that risk can be reduced by either reducing exposure or reducing vulnerability. Thus far in Scotland, reducing exposure has been the primary management approach, which has a number of implications with regards social justice. This research identified the existing data gaps that should be addressed by future research in order to further improve coastal management in Scotland. Future research should focus on assessing historical coastal change rates on a national scale, improve modelling of national scale wave exposure, enhance the information held about current coastal defences and, determine the direct and indirect economic cost associated with the loss of different asset types. It is also necessary to clarify the social justice implications of using adaptation approaches to manage coastal erosion as well as establishing a method to communicate the susceptibility, exposure, vulnerability and risk aspects whilst minimising the potential negative impacts (e.g. property blight) of releasing such information.
|
433 |
River transport 1189-1600Caffyn, Douglas John Morris January 2011 (has links)
The purpose of this thesis is to establish the extent of river transportation in the period 1189 - 1600. Investigation is made as to which rivers were physically usable, which were legally usable and the comparative cost of land and river transport. The evidence of historic use is examined and these records are compared with the recent limits of use of the rivers. Hence an estimate is made as to which sections of rivers were probably used during that period. The principles of fluvial geomorphology have been used to estimate past channel changes. The legal records have been studied and analysed. Considerable evidence of the use of rivers has been found which materially increases the lengths of rivers for which there are records of historic use. It is concluded that:- 1. all rivers which were physically usable were legally usable, 2. there is a high probability that each section of a river which is now physically usable was usable by small boats in the period 1189-1600, 3. on the balance of probabilities each section of a river which is now physically usable was used during that period. Finally the implication of this research for the present day law relating to public access on rivers is considered.
|
434 |
Analysing and modelling the effects of galactic cosmic rays on the Earth’s atmosphere over daily timescalesLaken, Benjamin A. January 2010 (has links)
In recent years, a range of detailed palaeoclimatic reconstructions have shown indications of a connection between changes in solar activity and Earth's climate. However, a process that may explain such a relationship has yet to be reliably demonstrated. One proposed mechanism concerns the theoretical link between the solar-modulated galactic cosmic ray (GCR) flux and Earth's cloud cover. Several microphysical pathways have been suggested which could account for this relationship, including (i) changes in the concentration of cloud condensation nuclei by an ion-mediated growth of aerosol particles, and (ii) the accumulation of charge at cloud boundaries predicted to influence the ability of cloud droplets to grow by scavenging processes. This work uses an original epoch-superpositional (composite) methodology to present new indications of statistically significant relationships between the rate of GCR flux (measured from neutron monitor sites across the globe) and changes in the rate of numerous large-scale atmospheric parameters (derived from satellite, reanalysis and weather station datasets) over daily timescales. Attempts are made to reproduce the observed anomalous atmospheric responses within a general circulation model. The results strongly suggest that some of the observed anomalies may be causally related to cloud changes and, furthermore, provide some support for possible links between the GCR flux, cloud anomalies and atmospheric responses. This relationship appears to be sensitive to changes in the rate of GCR flux and is also likely constrained by internal conditions.
|
435 |
Examining the use of the partition coefficient in quantifying sorption of heavy metals in Permo-Triassic sandstone aquifersBatty, Timothy Alexander January 2016 (has links)
Hydrogeologists using the partition coefficient, or K\(_d\) approach, to quantify attachment (sorption and / or ion exchange) of heavy metal(s) in aquifers have expressed reservations about its oversimplification of the geochemistry involved, potentially undermining predictions of contaminant fate and therefore jeopardising effective remediation efforts. The aims of this project were to determine the validity of the K\(_d\) approach for the Permo-Triassic sandstone – a common aquifer type worldwide – and to propose a better way of quantifying attachment for metal ions. After characterising a sample of Permo-Triassic sandstone by way of a suite of batch experiments, the geochemical code PHREEQC was used to interpret the results using simulations incorporating both surface complexation theory and ion exchange. These demonstrated, by approximately matching attachment isotherm plots of Zn, that the model was a robust representation of the sandstone. This model was then adapted to simulate transport of Zn through a representative aquifer in a range of conditions to determine the potential importance of sorption in metal transport. The results confirmed the variability in the system with regard to pH influences, the fluctuating dominance of ion exchange and sorption, the presence of competing ions, and the resultant outcomes for Zn transport. It is expected that these results are similar for metals with chemistry similar to that of Zn.
|
436 |
Modelling the impact of urbanisation on the regional climate of the Greater London areaThompson, Heather Louise January 2009 (has links)
Urban areas have well documented effects on climate, such as the urban heat island effect, reduction of wind speeds, enhanced turbulence and boundary layer heights, and changes in cloud cover and precipitation. This PhD examines the impact of the urban surface on the major agglomeration of London on local and regional climate by means of the numerical mesoscale model METRAS (Schlünzen 1988) coupled for the first time with the sophisticated urban canopy scheme BEP, developed by Martilli et al. (2002). The robustness of the new model is demonstrated through a series of simulations and sensitivity studies for an idealised urban domain. The model is then configured for the London region, and evaluated using data from a range of meteorological monitoring sites. Implementation of the urban canopy scheme results in a marked improvement in model performance. Under ideal meteorological conditions, peak urban heat island intensities of up to 2.5 K are found during night time hours, with the timing and magnitude of the peak showing good agreement with previous experimental studies for London. The new model is then used to investigate how growth of the Greater London urban area affects the urban heat island intensity. The results show that the relative fractions of urban land cover and of vegetation within the urban area have important implications for the near surface temperature, diurnal temperature range, wind speed and urban heat island intensity. The results also suggest that extensive future growth of the London urban area has the potential to increase temperatures, with significant increases for both daytime and night time. The specific forms of urban development, such as densification and spatial expansion, have an impact on these fields. These results have important implications for the design of cities and the management of urban climate.
|
437 |
Total radical production and degradation products from Alkene OzonolysisAlam, Mohammed Salim January 2011 (has links)
The gas-phase reactions of ozone with alkenes can be significant sources of free radicals (OH, HO2 and RO2) in the Earth’s atmosphere. While there are a number of quantitative indirect OH and HO2 yield measurements from ozonolysis in the literature, obtained, for example, through the use of radical tracer / scavenger species, few direct observations have been reported. This thesis presents the first direct measurements of OH and HO2 by Laser Induced Fluorescence for a homologous series of alkenes. The radical and stable products from ethene, propene, 1-butene, 2 methylpropene, cis-2-butene, trans-2-butene and 2,3-dimethyl-2-butene ozonolysis have been observed. The experiments were carried out in the EUPHORE atmospheric simulation chamber, utilising various instrumentation including Fourier Transform Infrared Spectroscopy and Peroxy Radical Chemical Amplification. The alkene-ozone reaction systems were investigated with and without an OH radical scavenger and as a function of humidity. The results were interpreted through detailed chemical chamber box modelling, incorporating the Master Chemical Mechanism degradation scheme for each specific alkene, supplemented with a more explicit representation of the alkene-ozone reaction mechanism. The observed yields are interpreted in terms of branching ratios for each channel within the postulated alkene ozonolysis mechanism, and their implications for atmospheric radical production were considered.
|
438 |
Continental break-up at the Galicia marginCresswell, Derren James Franklyn January 2018 (has links)
The Galicia margin has been at the forefront the development and testing of models on the break-up of magma-poor passive margins. However the current paradigm of continental break-up is still largely based on two dimensional observations. The data presented here from a high resolution 3D seismic reflection data reveal in unprecedented detail the complexity of continental break-up. Using the 3D geometry of the faults, analysing fault displacement at a number of different levels, and mapping syn-rift sediments it has been possible to offer a new model of break-up. This model combines elements of previous models but offers a new degree of clarity over the mechanism including fault linkage. Slip initiates at different points on the a weakened serpentinised mantle forming a slip surface that propagates up through a network of faults forming the S reflector, a detachment fault whilst also dissecting the crust, allowing further water ingress and weakening. Progressive slip and weakening rotates slip surfaces, eventually new sites of slip initiation form that propagate through the crust forming a new fault network and ceasing slip on the previous network. Continued weakening and slip eventually leads to break-up.
|
439 |
Distinguishing flood frequency and magnitude in the morphodynamics and sedimentology of rivers : insights from the South Saskatchewan River, CanadaParker, Natalie Olwyn January 2010 (has links)
The impact of a 1 in 40 year flood on the morphology and sedimentology of the sandy braided South Saskatchewan River, Canada was assessed. Comparison of 2004 - 2007 repeat GPR surveys and the production of DEMs of difference allowed quantification of the initial and long-term 2005 flood impact on reach morphology and sedimentology. Main results show that even though a significant initial morphological impact was caused due to the flood through net erosion and channel incision across Bar A, subsequent low-magnitude high-frequency floods were able to rework morphology due to the ability to transport the medium sized sand bed load. In the subsurface, no distinct flood signature has been left, as flood deposits are similar to the scale and composition of deposits produced by low-magnitude high-frequency floods. Consequently, little evidence of such a flood event will be preserved in the sedimentary record. The research has also highlighted some important findings with respect to linking morphological processes to sedimentary deposits. In particular they have suggested the revision of depositional models for braided rivers, and further research on the relationship between bedform geometry and flow depth in natural rivers. The results have wider applications to other sand bed braided rivers and may aid interpretation and modelling of such deposits on a wider scale.
|
440 |
The oxidation of dissolved organic compounds by redbed sandstonesAl Azzo, Omar Nabhan January 2016 (has links)
The aim of this research was to provide a basis for quantifying the ability of red sandstone to oxidise dissolved organic carbon (DOC), and determine if results of experiments on synthetic minerals can be applied to geological materials. Ascorbic acid (H\(_2\)A) was used as a probe. Preliminary experiments revealed that it can reductively dissolve sandstone hematite and Mn oxide as research on synthetic minerals had previously shown. Sorption of H\(_2\)A to sandstone was similar to that seen for synthetic hematite (a two-slope linear isotherm). Anoxic batch experiments were undertaken under biotic and abiotic conditions. Release of Fe and Mn was found to be dependent on the concentration of H\(_2\)A and pH. Decrease in H\(_2\)A concentration exceeded increase in Fe and Mn concentrations corrected for sorption, and this was modelled by sorption of both ascorbate and dehydroascorbic acid. The rate of H\(_2\)A oxidation was higher in biotic experiments than in abiotic experiments, probably due to the differences in pH rather than bacterial presence. The rate of ascorbic acid oxidation by natural oxides was higher than found by previous researchers for synthetic hematite. This result was not expected, and only in part can be ascribed to the effect of Mn oxides. However, the mechanism of reductive dissolution determined by the synthetic mineral studies appear relevant also to the sandstone system. Many questions remain but the study shows that the sandstone provides a significant natural oxidative attenuation capacity and that the results of experimentation on synthetic minerals can only be applied qualitatively.
|
Page generated in 0.0732 seconds