Spelling suggestions: "subject:"aphysical geography."" "subject:"2physical geography.""
671 |
Characterization of Weathering Effects in Holocene Loess and Paleosol, Kluane Lake, Yukon, Canada.Lagerbäck Adolphi, Emma January 2014 (has links)
When measuring weathering intensity of paleosols there arevarious methods and ratios that can be used. This studyexamines several weathering indicators too see which are bestapplied and most effective on loess and paleosols from Yukon,Canada. This region today is considered sub-arctic, but duringpast time this area and its soils has been characterized byglaciations and interglaciations. These changes are the origin ofthe unweathered Kluane loess and the weathered Slims Soilthat are analyzed in the study. Methods used to determine themost sensitive weathering indicator was; CIA (the ChemicalIndex of Alteration), CPA (the Chemical Proxy of Alteration),oxide ratios ((CaO + Na2O + MgO)/TiO2 and (CaO + Na2O +K2O)/TiO2), and elemental ratios (Rb/Sr, Ba/Sr, Ti/Sr). Theresults from the CIA and oxide ratios show that calcium is thevarying factor, and thereby a good weathering indicator forthese samples. The elemental ratios showed a great variationbetween weathered and unweathered samples, and a cleardecrease strontium is apparent. These ratios would also beuseful indicators, but since Sr is associated with Ca, it isprobably calcium that is the main feature. The methods withoutcalcium as a factor did not give any clear separation betweenKluane loess and Slims Soil. Thereby it is concluded that proxyscontaining Ca are the most useful indicators of weathering inthis area.
|
672 |
Katastrof eller avkylning? : En stuide om framtiden för Yellowstone vulkaniska fältTobias, Fredriksson January 2014 (has links)
No description available.
|
673 |
Assessment of carbon and nutrient export from a peatland windfarm construction siteSmith, Benjamin Anthony Visocchi January 2016 (has links)
The full extent of a landscape’s resilience to the environmental impact of siting wind-based renewables on peats is currently unknown. This research explores if windfarm construction activities have caused disturbance by investigating; time series of fluvial carbon (C) and nutrient concentrations; constructing aquatic organic C fluxes, before, during and after the windfarm construction period. Additionally, C sequestration rates of peat and nearby lake sediments (Loch Brora) were calculated to provide a historical context to, i) calculated aquatic C fluxes and ii) sediment export from surrounding catchments, considering both a catchment hosting the windfarm construction and one that does not. Furthermore, the effectiveness of a peatland restoration technique, drain-blocking, was assessed as a means of undertaking a whole system approach to assessing the potential impact of the windfarm development, considering how these management strategies can help mitigate potential C losses associated with construction. The research field site was located on the Gordonbush Estate, near Brora, where construction started in July 2010 (the same time this research began) on Scottish and Sothern Energy Renewables (SSER) 35 turbine windfarm. Construction work finished in May 2012 and data collection continued until September 2014. Throughout this period, fieldwork was focussed on storm event sampling (collecting samples for dissolved organic carbon (DOC), particulate organic carbon (POC), total phosphorous (TP), soluble reactive phosphorous (SRP) and total oxidised nitrogen (TON)), collecting peat and lake sediment cores, samples of modern day sediment export and monitoring water table depth in an area where old drainage channels were blocked as part of a peatland restoration initiative. Three river catchments were studied, two affected by windfarm construction activities (GB10 and GB11) and one control site (GB12), DOC concentrations ranged from 1.1 mg l-1 to 48.3 mg l-1, POC from <0.1 mg l-1 to 21.3 mg l-1, TP from <0.5 µg l-1 to 264 µg l-1, SRP from <0.5 µg l-1 to 39 µg l-1 and TON from <1 µg l-1 to 141 µg l-1. These were all within ranges of macronutrient concentrations measured at other northern temperate peatland sites. Comparing macronutrient concentrations between catchments, generally GB10 > GB11 > GB12 for all determinants. Seasonal patterns in fluvial macronutrient concentrations were observed at Gordonbush: summer maxima and winter minima in DOC and TP concentrations and the opposite trend in TON concentrations. SRP data collected indicates a legacy of forest felling in the Bull Burn Plantation has contributed to increased concentration in the Allt Mhuilin river (GB10) compared to the two other catchments, Allt Smeorail (GB11) and Old Town Burn (GB12) where no forest felling occurred during the data collection period. Differences in DOC and TP concentration in Allt Mhuilin compared to other catchments could also be related to forest felling activities but catchment characteristics such as peat coverage may have also influenced results. For all relevant measures of water quality, macronutrient concentrations from Gordonbush shows studied streams consistently achieved “Good” or “High” status throughout the data collection period. Apart from the legacy of forest felling, a discernible impact of windfarm construction was not observed from macronutrient concentration time series. Calculating annual aquatic C fluxes from studied catchments offered a means of assessing potential impact. Various techniques of estimating fluxes were explored but splitting storm event DOC and POC data based on time of year and whether samples were collected on the rising or falling limbs were concluded to give the best estimates. Calculated fluxes ranged from 3 – 38 g C m-2 yr-1 and DOC consistently accounted for ~90% of total aquatic C export. These values were within limits of other C flux based studies from peatlands but the time series constructed at Gordonbush suggested windfarm construction, between July 2010 and May 2012, may have contributed to an increase in aquatic C export from affected catchments during this time, relative to the control site. Long term C sequestration rates from within the Gordonbush estate were 20-25 g C m-2 yr-1, the same magnitude as aquatic organic C fluxes. However, peat C sequestration was shown to be variable over the last ~9000 years since Scottish peatlands became established, with rates ranging from 10-60 g C m-2 yr-1. Controls on this variation are likely climatic with delivery of moisture influenced by the North Atlantic Oscillation (NAO) a key factor. Calculated lake C sequestration also varied over time, 22-82 g C m-2 yr-1 but an inconclusive radiocarbon dating chronology meant historical comparison of C export dynamics between the, C ‘source’, peatland to the, C ‘sink’, lake was unfortunately not possible. Modern day sedimentary export data showed higher sediment yields from windfarm affected catchment than the control site. Physical characteristics varied considerably between the two catchments so although this observation could not definitively be attributed to a direct windfarm impact, it remains a possibility. Whilst studying and quantifying the impact of drain blocking, manual measurements of water table depth (WTD) ranged between -53 cm to +14 cm in dip-wells and -36 cm to +20 cm in automated logging pressure transducers. The response of WTD throughout both data sets indicates meteorological conditions were more influential as a factor controlling peat hydrology across the site compared to topography. Manual measurements from dip-wells shows the drainage channels investigated (~0.5-0.7 m deep and ~0.5 m wide) had the greatest influence on effect WTD 0-2 m from the main channel but no statistically significant difference was detected in mean WTDs measurements before or after blocking, in relation to distance from the drainage channels themselves or comparisons between drained and un-drained (control) areas. However, data from PTs indicate the net effect of multiple parallel drains can cause water table drawdown at a significant distance, ~ 25 m, from the drainage channel. This is an important finding as methodology used to calculate the C ‘payback time’ of windfarms utilises the lateral drainage extent of peat when turbines bases are excavated. Drain blocking had no obvious effect (either positive or negative) on WTDs however it is acknowledged positive effects can take up to five years, after blocking has taken place, to be observed. Maximum DOC concentrations increased the year after blocking however this result has been recorded at other sites and the exceptionally dry summer of 2013 could have contributed to the noticed increased by promoting more peat oxidation and subsequently DOC production. There was no statistically significant difference between [DOC] collected up and downstream of the drainage channel inputs for samples collected before and after blocking. This suggests drain-blocking has had little impact on the larger site [DOC] signature one year after drain-blocking. However, as discharge from drainage channels was not measured, a potential reduction in overall DOC export could not be fully assessed and this is a highlighted future research need. Combining averages of aquatic organic C fluxes and peat C sequestration rates calculated it is estimated net ecosystem exchange would have to be between -30 to -50 g C m-2 yr-1 for Gordonbush to be classed as a C ‘sink’. If the observed increases in sedimentary export could be attributed to windfarm construction, Loch Brora is unlikely to act as a strong C sink for any potential increased losses as it is estimated ~90% of POC exported is not sequestered on a long-term basis in the lake sediments. It has recently been recommended windfarms should not be developed on peatlands due to the marginal C savings achieved as our future energy mix changes (Smith et al., 2014). However, if similar projects are granted planning permission then findings from this research support the following recommendations: installation of buffer zones around areas of felled forestry to reduce nutrient export into surrounding streams; implementation of a water quality monitoring programme to assess impact of windfarm construction during construction and a period afterwards as it is still unclear from this research if there will be any lasting effects; installation of silt traps to reduce aquatic sediment export and disturbance; limit any high density excavation of drainage channels as the effects of water draw-down could be quite extensive; in addition, blocking all historical drainage channels and retaining as much moisture as possible within, and surrounding, areas of degraded peatland can increase long-term peat C sequestration rates and offset C losses experienced during construction. This research has been funded by SSER, Engineering and Physical Sciences Research Council (EPSRC) and Energy Technology Partnership (ETP). This research has been undertaken and supported at the University of Glasgow within the College of Science and Engineering, specifically aligned to the work of the Carbon Landscapes and Drainage (CLAD) research group headed by Prof. Susan Waldron in the School of Geographical and Earth Sciences. Finally, this research has also been supported in partnership with Stirling University.
|
674 |
The changing governance of UK flood management policies 1998-2010 : a comparative analysis of local approaches in Scotland and EnglandLafinhan, Dipo January 2016 (has links)
The governments of Scotland and England have responded to the increase in flood risk by introducing legislation intended to manage present day flood risk and to avoid future flood risk. This thesis evaluates how the new policy regime has evolved and been implemented in Scotland and England, focusing particularly in Local Authorities, and using contrasts in rural and urban settings to reveal how the policy has had to be adapted to apply effectively in these different physical and administrative environments. Based on discourse theory and the institutionalisation features of policy networks, it is argued first that the new policy regime is subject to multiple interpretations and, second that policy change occurs as a result of the transformation of institutional practices of the multiple flood governance discourses by policy narratives in the policy process. The concept of the advocacy coalition framework is applied to reveal how contrasting local governance approaches result from continuous interactions between national policies and distinctive, local factors. These arguments are supported by the results of empirical research that examined policy change and local governance interpretation through textual analysis of relevant policy documents, interviews with key institutional stakeholders and participant observation of a local stakeholder meeting. Research findings reveal how the more pro-active local governance approaches serve as innovators in informing future national policies. This process stems from local interpretation of existing national policy through the mediating effects of distinctive local policy factors that result in the introduction of new policy ideas and actors. These ideas and the involvement of new actors are in turn transferred through revisions to national policies of flood risk governance. Consequently the policy mediating features of Local Authorities are manifest through first, the utility of policy narratives in driving national policy change and second, in shaping policies in local governance approaches.
|
675 |
An investigation of talus slope development in the Similkameen Valley near Keremeos, B.C.Worobey , George A. January 1972 (has links)
Talus form and development in the Similkameen Valley near Keremeos, British Columbia was investigated. Initial observations suggested that talus formation in the region was entering a passive stage and subsequent analysis has confirmed that the talus slopes are tending towards stability. Volcanic ash exposed on one talus slope allowed the calculation of relative rates of past and recent talus accumulation which supported a 'diminishing sediment yield' concept.
Analysis of climate data recorded at Keremeos since 1930 revealed a high frequency of frost cycles. This suggests the importance of frost action as a mechanism of weathering along the exposed headwalls and it is thought that the occurrence of abundant and massive talus forms in the region is basically the result of frost weathering in association with lithologic controls. A fence structure designed to capture rockfall debris yielded fair results and substantiated the validity of using vegetation as an index of stability on talus slopes.
A weak but not monotonic increase in sediment size down slope was detected on a number of slopes, contradicting an initial visual impression. Debris sampled along lateral profiles on one talus cone is significantly larger at the 1% level than debris sampled along the central profile. Some correlation between size and angle is implied, since the lateral profiles are also steeper; it is hypothesized that transport mechanisms down the sides are different from those along the center of the cone. Readily observable cross-slope sorting, resulting in the development of longitudinal strips of fine and coarse debris, is explained in terms of differential mass movement mechanisms. It is concluded that the talus slopes studied are complex and influenced by a variety of processes in addition to primary deposition.
The mapping of one talus cone at a five foot contour interval provided the basis for a detailed analysis of talus form. A sample of the debris size taken simultaneously with the mapping of the surface allowed for the calculation and establishment of a fourth degree trend surface, an examination of which is made in conjunction with the map and photos of the cone. Practical implications of the development of talus as applied to this region are discussed. / Arts, Faculty of / Geography, Department of / Graduate
|
676 |
Arctic Loess as an Environmental Archive : Identifying Weathering with XRF Analysis in West Greenland / Arktiska lössjordar som miljöarkiv : Identifiering av vittring med XRF-analys på västra GrönlandKarnik, Isabelle January 2019 (has links)
Loess from west Greenland was studied to evaluate Holocene paleoclimate in the Arctic region. Deposits of loess are formed over long time scales through deposition of fine aeolian sediment and they exist in several places in the world. The main aeolian dust source in the study area is glaciofluvial material derived from the Greenland Ice Sheet (GrIS). Studying and understanding paleoclimate can help to make better predictions about the future in this sensitive region. Apart from sea level rise, melting of the GrIS also leads to an increase of aeolian dust as it gets released from the ice, which influences atmospheric and metrological phenomenon as well as the ice sheet’s albedo. This creates negative feedback mechanisms through increasing melting rates of glaciers and warming of the Arctic. Loess samples from two sites in the Kangerlussuaq area were analyzed and the mineral composition was measured with X-Ray Florescence Spectroscopy (XRF). With the measured mineral content, weathering indices were calculated to identify rates of weathering during the Holocene. Increased weathering intensities indicate warmer and more humid climate. The deposits in Greenland are relatively thin. Radiocarbon dating of the sediment suggests that the oldest parts of the profiles are about 4000 cal. yr B.P. (calibrated years before present). Arctic loess has not been studied very extensively. Weathering indices and ratios developed for classical loess, that had not been tested on Arctic loess, was used. The results were plotted by depth and age to visually identify changes over time. By considering the geology, climate and local conditions of the study area, some weathering indices seemed to be suitable, generating matching trends between the two sites. Compared with results from previous studies, the results also seemed credible. / Löss från västra Grönland studerades för att utvärdera holocent paleoklimat i Arktis. Lössjordar bildas över långa tidsskalor genom avsättning av fint vindburet sediment och de finns på flera platser i världen. Den huvudsakliga källan till det vindburna sedimentet i studieområdet är glaciofluvialt material härstammande från Grönlandsisen (GrIS). Att studera och förstå paleoklimat kan underlätta skapandet av bättre prognoser om framtiden i denna känsliga region. Bortsett från höjning av de globala havsnivåerna leder smältningen av GrIS också till en ökning av vindburet sediment då det frigörs från isen, vilket påverkar atmosfäriska och metrologiska fenomen samt isens albedo. Detta skapar negativa återkopplingsmekanismer genom ökande smälthastighet av glaciärer och uppvärmning av Arktis. Lössprover från två ställen i Kangerlussuaq-området analyserades och mineralsammansättningen mättes med röntgenstrålningsspektroskopi (XRF). Med det uppmätta mineralinnehållet beräknades vittringssindex för att identifiera vittringshastigheter under Holocen. Ökad vittringsintesitet indikerar varmare och fuktigare klimat. Avlagringarna på Grönland är relativt tunna. Kol-14-datering av sedimentet antyder att de äldsta delarna är cirka 4000 cal. yr B.P. (kalibrerade år före nutid). Arktisk löss är relativt ostuderad. Vittringsindex som har utvecklats för klassisk löss i tempererade regioner, och tidigare inte testats på arktisk löss, användes. Resultaten ritades i grafer efter djup och ålder för att visuellt identifiera förändringar över tid. Genom att ta hänsyn till geologin, klimatet och lokala förhållanden i studieområdet, verkade några av vittringsindexen ge trovärdiga resultat då matchande trender mellan bägge profiler kunde utläsas. I jämförelse med resultat från tidigare studier verkade resultaten också trovärdiga.
|
677 |
“I am fighting the best I can” : Women’s adaptive capacity when facing rain variability in Paje,Zanzibar (Tanzania)Folkeryd, Felicia January 2020 (has links)
Many of the world’s most impoverished populations rely on farming, hunting and gathering to eat and earn a living where people often have just enough food and assets to last through the next season, and ultimately inadequate reserves to fall back on in the event of a poor harvest. Rural resource-dependent livelihoods are embedded in high risks, as climate variability and climate extremes are additional stressors to poverty. They often have limited livelihood options and few economic opportunities to adapt and compensate for unforeseen events. This research is a contribution to the limited and narrowed research of Zanzibari coastal people’s livelihoods’ exposure to rainy seasons. Based on women’s distinctively vulnerable position towards poverty, this research addresses single mothers, and their experiences of forming and maintaining their livelihoods during rainy seasons, in the coastal village of Paje, on Zanzibar, Tanzania. The intention is to outline these women’s exposure to rainy seasons and their range of adaptive capacity to maintain a sustainable livelihood. The research method is semistructured interviews with 30 single mothers living in Paje village, Zanzibar. The analysis is guided by the sustainable livelihoods framework to conceptualise the complex dynamic systems of poor rural livelihoods. The results reveal that seasonal transition to rainy season generates several constraints for single mothers to sustain their livelihood security throughout the rainy season. Women experience instability in their livelihood security, with extensive shortfalls in their income levels. These losses are further linked to food insecurity, destruction of homes, health issues and many other socioeconomic disadvantages. The women’s most persuasive survival strategy relies on their social capital of donations or loans from friends, families and neighbours. Hence, their level of adaptive capacity is affected by several other factors, such as inadequate institutional support and infrastructure, poor education and issues of gender inequality.
|
678 |
Grain-Size Analysis of Loess Deposits of the Last Glacial Period, NW France / Analys av kornstorlek av lössjord från senaste istiden, nordvästra FrankrikeRodin Borne, Linnéa January 2021 (has links)
Loess is an unique record of the paleoclimate of the Quaternary. Because it is directly deposited from the atmosphere, it can be used as a proxy for wind speed and circulation patterns. It can also be directly dated using luminescence. The site of the loess being investigated for this paper is PrimelTrégastel (Brittany), which lies in north-western France of the shore to the English Channel. The English Channel may be one of the sources for loess of the last glaciation, the Wichselian, and is the reason for choosing Primel-Trégastel to investigate. It is the purpose of this paper to investigate the climate of the time the loess was formed at Primel-Trégastel using grain-size distribution analysis, as well as comparing its properties to other loess sites in north-western Europe. The results show that the loess of Primel-Trégastel is coarse and have a relatively high sand content. That may imply that the loess was deposited during cold and arid conditions by high wind speeds, and at that it may have had a relatively close source. The results also exhibit cycles in the coarseness of the grain-size, indicative of the climate varying between cold and relatively warmer, resulting in relatively higher and lower wind speeds respectively. The loess of Nantois and Pegwell Bay are also relatively coarse, and the loess of Pegwell Bay also have a high sand content. The loess of Nussloch was in comparison more unlike the one of Primel-Trégastel, possibly due to the lack of a local source of sand at Nussloch.
|
679 |
Functions of Wetlands in Sweden : a literature reviewToth, Gergely Istvan January 2021 (has links)
The lack of cultural and economic recognition of the significance of wetlands arguably led to theirdevastating and rapid loss compared to other ecosystems. To reverse this trend and establish a reasonablevaluation of wetlands, the foundations of socio-ecological concepts were laid in late 20th century thatsuggested the acknowledgement of the functions, values, and services of ecosystems. Subsequently, inthe 21st century the scientific interest in wetland functionality is driven beyond mere conservationalefforts and includes the appropriation of their values for sustainable development, and the utilization oftheir functions as nature-based solutions to humanity’s growing environmental problems. In light of thistrend, this literature review outlines the most critical functions of Swedish wetlands and places them intheir contexts of significance. A meta-analysis of the scientific literature on Swedish wetlandswas conducted with the assessment of wetland functions, wetland types, and the drivers that motivatedeach study. To identify the most critical functions and their contexts, patterns and trends wereinvestigated among these categories. Results show that the most recognised functions of Swedishwetlands are their nutrient-pollutant retention, ecosystem maintenance, and carbon sink functions.Their connections to distinct drivers suggest that their values mainly lie in their potential tomitigate negative impacts of anthropogenic activities, such as eutrophication and global warming,and to support local and regional biodiversity. Synergies among these functions are alsodiscussed, as exemplified by dual-purpose constructed wetlands. Moreover, understudiedhydrological functions are thought to reflect their undervaluation and indicate possible risksattached to associated knowledge gaps. By summarising and contextualising the most importantfunctions, this literature review sheds light on the contemporary understanding and valuation ofwetland functions in Sweden. It is suggested that these novel perceptions effectively drive wetlandconstruction and restoration, the ever-more popular strategies to mitigate climate- and industryrelated risks. Consequently, the recognition, interpretation, and application of wetland functionswill all contribute to the future landscape composition of Sweden.
|
680 |
Recent climate warming impact on the firn layers at Lomonosovfonna and Penny Ice CapWinander Schönning, Christoffer January 2014 (has links)
Current climate warming has a disproportionally large impact on Arctic glaciers and ice caps. In this thesis, I examined stratigraphic changes observed in the top ~15 m of two Arctic ice caps: one located at Svalbard (Lomonosovfonna) and the eastern Canadian Arctic Archipelago (Penny). The objective was to find out if and how the increasing regional temperatures have impacted the stratigraphy and densification rates of these ice caps, and particularly since the 1990s when Arctic warming accelerated. This was accomplished by analyzing and comparing recent (2000s) and earlier (1990s) ice-core density and stratigraphic measurements from these two ice caps, and also regional temperature data from Svalbard and the eastern Canadian Arctic over the period 1995-2013. Data over the amount and thickness of ice layers in the ice cores are also used and compared with the density development. A decrease in elevation for the formation of infiltration ice layers at Lomonsovfonna is concluded as well as a strong increase in temperature where the winter temperatures increase the most. In the ice cores it ́s also seen that each core has certain spatial variability when it comes to the distribution of infiltration ice.
|
Page generated in 0.0634 seconds