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Alteration of rainfall patterns is one major impact of climate change. Rainfall events with big precipitation volumes under short periods of time are predicted to become even more frequent in higher latitude regions, including Sweden. One characteristic example of such an intense rainfall occurred between the 5th and 6th of September 2015 in Hallsberg, a city in central Sweden, where approximately 105 mm of rain fell under 24 hours, causing severe flooding in the city. In order to be able to predict flood cases like the aforementioned one, hydrodynamic models are employed to simulate floods and investigate rainfall scenarios so that the competent authorities can take precaution measures. However, due to lack of calibration data most of flood models are not validated and are comprised of substantial uncertainty. This report aims to study the Hallsberg flood event in September 2015 by calibrating a hydrodynamic model using aerial photographs for the flood inundation extent. The utilized model is MIKE 21, which is a 2D overland flow model developed by DHI. Contrary to the common practice in flood studies where inclusion of the infiltration capacity is implemented with an arbitrary reduction of the rain volume, the infiltration module of MIKE 21, which is a new development in the model, was utilized. Apart from the inundation extent, the outputs were also evaluated for the water depth in two points based on a photograph captured from the streets of the affected area, the description of the course of events for the timing of flood’s culmination and the water volume on the pixels that were erroneously simulated as flooded. The results presented a high degree of agreement with the observations. The parameter of surface resistance, expressed as Manning’s “M”, was found to be of paramount importance with the suitable values for undeveloped areas being below 5. In addition, the culverts’ limited capacity played an important role in the flooding of the city and hence including them in the simulations is crucial. Finally, utilization of the infiltration module resulted in a higher accuracy of 8.3% although it can be considered more of an arbitrary deduction of water as some of the parameters used in it are not physically well justified. / Ändringar i nederbördsmönster är en tydlig konsekvens av klimatförändringen. Regnhändelser med stora volymer nederbörd under korta tidsperioder förutses bli alltmer frekventa i regioner vid högre breddgrader, däribland Sverige. Ett karaktäristiskt exempel av en sådan händelse skedde mellan den femte och sjätte september 2015 i Hallsberg. Ca 105 mm regn föll inom loppet av 24 timmar vilket orsakade stora översvämningar i staden. För att kunna förutse översvämningar så som den tidigare nämnd och möjliggöra vidtagning av förebyggande åtgärder används hydrodynamiska modeller för att simulera vattenflöden och undersöka möjliga scenarion av nederbörd. Emellertid, på grund av avsaknaden av data för kalibrering av modellerna medför användandet av dem en signifikant osäkerhet. Syftet med den här rapporten är att undersöka översvämningen i Hallsberg i september 2015 genom att kalibrera en hydrodynamisk modell med hjälp av flygbilder för översvämningens utbredning. Den använda modellen, MIKE 21, är en 2D modell över ytavrinningen utvecklad av DHI. Praxis vid studiet av översvämningar är att inkludera infiltrationsförmåga med ett godtyckligt avdrag av nederbörden. Här används istället infiltreringsmodulen för MIKE 21, vilket är en ny del som har utvecklats i modellen. Förutom översvämningens utbredning utvärderades även resultaten utifrån vattendjupet vid två punkter baseras på ett fotografi från gatorna i det drabbade området. Utvärdering av resultaten gjordes också mot tid av översvämnings kulm från beskrivning av händelses förlopp samt vattenvolym vid pixlarna som felaktigt simulerades som översvämmade. Resultatet visade på en hög grad av samstämmighet med gjorda observationer. Parametern ytans råhet, uttryckt som Mannings ”M”, visade sig vara av stor betydelse med lämpliga värden för underutvecklade områden under 5. Därtill spelade kulvertarnas begränsade kapacitet en viktig roll vid översvämmandet av staden. Att inkludera dessa i simuleringarna var därför avgörande. Slutligen, användandet av infiltreringsmodulen resulterade i en högre noggrannhet av 8.3 %, även om det kan anses vara ett godtyckligt vattenavdrag då vissa av de använda parametrarna inte är fysiskt välmotiverade.

Altitudinal treeline advance represents a sensitive and well-studied example of species response to climate warming. Although a great deal of work has been conducted globally, few studies have considered subtropical alpine treelines and little is known about their structure and function. This research aims to investigate the response of high altitude forests in Taiwan to climate variation by characterising treeline advance in the area, exploring the mechanisms driving the advance, and considering the consequences of advance for the wider community. The thesis consists of a general introduction to the topic followed by a series of papers, exploring: (1) Possible consequences of treeline shifts for biodiversity and ecosystem function. (2) The advance of the Abies kawakamii treeline through aerial photograph analysis. (3) The changes in growth rate of Abies kawakamii at treeline and the influence of altitude and temperature on growth. (4) Regeneration patterns at treeline and the importance of microclimate and topographic sheltering. (5) Consequences of the range shift for the wider forest community. The work is then concluded with a general discussion and synthesis. The main aims of this work are therefore to characterise and understand the pattern and pace of treeline advance and forest structural change throughout the Central Mountain Range of Taiwan. Treeline advance is characterised through the study of repeat aerial photographs and the mechanisms behind the observed shift are explored through the study of two key responses associated with forest advance: tree growth at treeline and seedling establishment beyond treeline. The consequences of treeline advance for the wider subalpine community are investigated through the study of epiphytic lichen communities at treeline sites. This investigation of an understudied region will allow for improved understanding of treeline response at a global scale.

A produção de mosaicos fotográficos é uma atividade de apoio bastante importante em diversas áreas tais como a geração de mapas, o monitoramento ambiental e o gerenciamento agrícola. A fotogrametria, e em especial a aerofotogrametria, é a ciência que trata, entre outros tópicos, da geração de mosaicos através de procedimentos trabalhosos, o que torna sua manutenção uma tarefa difícil e de alto custo. O Projeto ARARA (Aeronaves de Reconhecimento Assistidas por Rádio e Autônomas) representa uma alternativa de baixo custo para a aquisição de fotografias aéreas. Câmeras digitais de pequeno formato a bordo das aeronaves permitem a obtenção automática das fotografias necessárias para a geração de mosaicos. Este trabalho propõe uma metodologia para a geração e a atualização de mosaicos compostos por fotografias aéreas oblíquas digitais e de pequeno formato, adquiridas com o auxílio das aeronaves do Projeto ARARA. As fotografias podem ser submetidas a procedimentos que associam técnicas de ortoretificação e processamento digital de imagens para corrigir suas distorções geométricas e radiométricas. A metodologia apresentada neste trabalho procura evitar a necessidade de pontos de controle no solo e focaliza a geração automática ou semi-automática dos mosaicos. Procedimentos automáticos têm o potencial de permitir a utilização de uma grande quantidade de fotografias de pequeno formato em substituição às fotografias normalmente utilizadas pela aerofotogrametria convencional. / The generation of photographic mosaics is an important activity in many areas such as map production, environment monitoring and agricultural management. Photogrammetry, and specially aero-photogrammetry, are the sciences that deal, among other subjects, with mosaic generation using time consuming procedures, making the maintenance and updating of photographic mosaics a difficult and high-cost task. The ARARA Project (Autonomous and Radio Assisted Reconaissance Aircrafts), presents a low cost alternative to acquire aerial photographs. An onboard, small format digital camera can take automatically the photographs used for the mosaic generation. This work proposes a methodology for mosaic generation and updating using oblique, digital, small format aerial photographs taken by ARARA aircraft. Photographs can be corrected both geometrically and radiometrically by orthorectification and digital image processing procedures. The methodology presented in this work avoids the use of ground control points, focusing on the automatic and semi-automatic mosaic generation. An automatic procedure make possible the use of a large number of small format photographs to replace the photographs normally used in conventional aerophotogrammetry.

This doctoral thesis examines the history of the Iraqw’ar Da/aw area in the Mbulu Highlands of northern Tanzania. Since the late nineteenth century this area has been known for its intensive cultivation, and referred to as an “island” within a matrix of less intensive land use. The conventional explanation for its characteristics has been high population densities resulting from the prevention of expansion by hostility from surrounding pastoral groups, leading to a siegelike situation. Drawing on an intensive programme of interviews, detailed field mapping and studies of aerial photographs, early travellers’ accounts and landscape photographs, this study challenges that explanation. The study concludes that the process of agricultural intensification has largely been its own driving force, based on self-reinforcing processes of change, and not a consequence of land scarcity.

The boreal forest in Fennoscandia has been subjected to major loss and fragmentation of natural forests due to intensive forestry. This has resulted in that forest edges are now abundant and important landscape features. Edges have documented effects on the structure, function and biodiversity in forests. Edge influence on biodiversity is complex and depends on interactions between many local and regional factors. This thesis focuses on sharp forest edges and their potential to influence biodiversity at the landscape-level. I have developed a method for quantification and characterization of sharp forest edges by interpretation of colour infrared (CIR) aerial photographs in combination with line intersect sampling (LIS) and sample plots. The method was used to estimate density of forest edge in 28 landscapes (each 1600 ha) in northern Sweden, differing in management intensity, landscape composition and geographical location. Forest edges were described in detail using edge, canopy and neighbourhood attributes. By combining these attributes it was possible to classify edges with respect to levels of exposure. A field experiment was conducted to examine the effect of edge contrast on growth of the old forest lichen Usnea longissima. The edge quantification method is accurate and efficient for estimating the length of sharp forest edges on an area basis (edge density, m ha-1) and for collecting detailed attributes of edges and their surroundings. In northern Sweden, the forest edge density is high (54 m ha-1) but varies extensively (12-102 m ha-1) between landscapes. Edge density is strongly correlated with the level of human disturbance and increases towards the southern part of the study area, at lower altitudes were management intensity is highest. Edge orientation, contrast and neighbourhood size shows an immense variation between edges and also varies between edge types. Regenerating edges are generally of higher contrast and face larger neighbourhoods than natural edges. Maintained edges had high contrast but small neighbourhoods. A larger proportion of edges in mature forests are highly exposed to microclimatic edge influence than edges in general. The field experiment revealed that growth of U. longissima was highest near edges where the vegetation on the adjacent area was sheltering, but not shading, the lichen. In the present thesis, I have provided a valuable tool for estimating density of forest edges with potential to yield information on important factors determining edge influence at landscape-level. The large variability in edge density, edge and neighbourhood attributes imply large differences in microclimate anf thus in the potential for ede influence. Management and conservation strategies must incorporate these factors to realistically address edge influence on biota at the landscape-level.

A produção de mosaicos fotográficos é uma atividade de apoio bastante importante em diversas áreas tais como a geração de mapas, o monitoramento ambiental e o gerenciamento agrícola. A fotogrametria, e em especial a aerofotogrametria, é a ciência que trata, entre outros tópicos, da geração de mosaicos através de procedimentos trabalhosos, o que torna sua manutenção uma tarefa difícil e de alto custo. O Projeto ARARA (Aeronaves de Reconhecimento Assistidas por Rádio e Autônomas) representa uma alternativa de baixo custo para a aquisição de fotografias aéreas. Câmeras digitais de pequeno formato a bordo das aeronaves permitem a obtenção automática das fotografias necessárias para a geração de mosaicos. Este trabalho propõe uma metodologia para a geração e a atualização de mosaicos compostos por fotografias aéreas oblíquas digitais e de pequeno formato, adquiridas com o auxílio das aeronaves do Projeto ARARA. As fotografias podem ser submetidas a procedimentos que associam técnicas de ortoretificação e processamento digital de imagens para corrigir suas distorções geométricas e radiométricas. A metodologia apresentada neste trabalho procura evitar a necessidade de pontos de controle no solo e focaliza a geração automática ou semi-automática dos mosaicos. Procedimentos automáticos têm o potencial de permitir a utilização de uma grande quantidade de fotografias de pequeno formato em substituição às fotografias normalmente utilizadas pela aerofotogrametria convencional. / The generation of photographic mosaics is an important activity in many areas such as map production, environment monitoring and agricultural management. Photogrammetry, and specially aero-photogrammetry, are the sciences that deal, among other subjects, with mosaic generation using time consuming procedures, making the maintenance and updating of photographic mosaics a difficult and high-cost task. The ARARA Project (Autonomous and Radio Assisted Reconaissance Aircrafts), presents a low cost alternative to acquire aerial photographs. An onboard, small format digital camera can take automatically the photographs used for the mosaic generation. This work proposes a methodology for mosaic generation and updating using oblique, digital, small format aerial photographs taken by ARARA aircraft. Photographs can be corrected both geometrically and radiometrically by orthorectification and digital image processing procedures. The methodology presented in this work avoids the use of ground control points, focusing on the automatic and semi-automatic mosaic generation. An automatic procedure make possible the use of a large number of small format photographs to replace the photographs normally used in conventional aerophotogrammetry.