TY - THES A1 - Fekete, Alexander T1 - Massenbewegungen im Elbursgebirge, Iran - im Spannungsfeld zwischen natürlicher Stabilität und anthropogener Beeinflussung T1 - Mass Movements in Alborz Mountains, Iran - an area of conflict between natural stability and human impact N2 - Massenbewegungen (in englischer Literatur landslides, in französischer Literatur glissements de terre) sind das Symptom von Hanginstabilitäten in einem Naturraum. Die Wahl des Überbegriffs Massenbewegungen und die Untergliederung der einzelnen Stadien des Prozessablaufs wurden im Rahmen eines pragmatischen Ansatzes dieser Arbeit neu festgelegt. Im Untersuchungsgebiet im Elbursgebirge im Norden des Iran stellen Massenbewegungen ein Phänomen dar, welches die Kulturlandschaft bedroht, aber auch durch sie selbst bedingt ist. In dieser Arbeit wurden Abhängigkeitsbeziehungen zwischen menschlichem Eingriff und natürlichem Stabilitätspotential untersucht. In einem heuristischen Ansatz wurden Faktoren analysiert, welche Massenbewegungen bedingen oder auslösen. Faktoren wie geologischer Untergrund, Bodenauflage, Hangneigung, Exposition, Hydrologie, Vegetationsbedeckung oder Straßenbau wirken in unterschiedlicher Weise auf die Verursachung von Massenbewegungen ein. Die Analyse der Tragweite und Relevanz dieser Faktoren erfolgte mittels einer Faktorenüberlagerung in einem Geographischen Informationssystem (GIS). Das GIS bildete die Schnittstelle für Fernerkundungsdaten, Kartenmaterial, Geländeaufnahme und das digitale Geländemodell (DEM, bzw. DTM). Neben Photos, Beschreibungen, GPS-Punkten und Bodenproben aus der Geländeaufnahme im Iran wurden CORONA- und LANDSAT-ETM+ - Satellitendaten sowie Klimaaufzeichnungen, Topographische und Geologische Karten auf ihre Aussagekraft hin analysiert. Durch Verschneidung der Datenebenen konnten Gefährdungszonen hinsichtlich Massenbewegungen ausgewiesen werden. Die Ergebnisse wurden mit den vorhandenen Befunden über aufgetretene Massenbewegungen überprüft. Die Übereinstimmung der Gefährdungszonen mit der Verteilung vorgefundener Massenbewegungsformen bestätigte die Richtigkeit des methodischen Vorgehens. Bei der Auswahl und Bearbeitung von Daten und Methodik lagen die Schwerpunkte im Anwendungsbezug und in der Qualitätssicherung. Zur Erstellung des digitalen Höhenmodells wurde ein eigener Ansatz zur Extraktion von Höhenlinien aus Topographischen Karten verfolgt. Das Ergebnis der Arbeit ist ein kostengünstiger, pragmatischer und übertragbarer Ansatz zur Bewertung des Gefährdungspotentials von Massenbewegungen. N2 - Mass movements (in English literature often referred to as landslides, in French Literature as glissements de terre) are symptoms of instability in natural environments. Within the scope of a pragmatic approach the key word 'mass movements' and its processual steps were newly defined. Mass movements are a phenomenon in the study area in Alborz mountains, Iran. They threaten human environments while at the same time they display results of human activity. The focus of this paper is directed on interdependences between human impact and areas that are prone to slope instability. In a heuristic approach factors that influence or trigger mass movements were analysed. These determining factors include the geology, soil cover, slope, aspect, hydrology, vegetationcover and roads. Analysis of intensity, extent and relevance was compiled by factor overlay technique in a Geographical Information System (GIS). Under the GIS environment, CORONA and LANDSAT-ETM+ satellite images, climatic data, topographical and geological maps, ground truth data and the digital elevation model (DEM) could be integrated. This resulted in a hazard zonation map of mass movements. The hazard zonation map was cross referenced with a sample of real occurences of mass movements. This step served to validate the derived model for mass movement hazard. Data and methods were selected and tested on the basis of quality and application ability. Extraction of contour lines from topographical maps was used as a faster and better way of creating the digital elevation model compared to digitalization. All methodical ways resulted into a pragmatic cost-effective and transferable approach of evaluating the hazard of mass movements. KW - Elbursgebirge KW - Massenbewegung KW - Massenbewegungen KW - Rutschungen KW - Gefahrenkarten KW - GIS KW - Höhenmodell KW - landslides KW - digital elevation model KW - Landsat KW - remote sensing KW - Iran Y1 - 2004 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-13576 ER - TY - THES A1 - Walz, Yvonne T1 - Measuring burn severity in forests of South-West Western Australia using MODIS N2 - Burn severity was measured within the Mediterranean sclerophyll forests of south-west Western Australia (WA) using remote sensing data from the Moderate Resolution Imaging Spectroradiometer (MODIS). The region of south-west WA is considered as a high fire prone landscape and is managed by the state government’s Department of Conservation and Land Management (CALM). Prescribed fuel reduction burning is used as a management tool in this region. The measurement of burn severity with remote sensing data focused on monitoring the success and impact of prescribed burning and wildfire in this environment. The high temporal resolution of MODIS with twice daily overpasses in this area was considered highly favourable, as opportunities for prescribed burning are temporally limited by climatic conditions. The Normalised Burn Ratio (NBR) was investigated to measure burn severity in the forested area of south-west WA. This index has its heritage based on data from the Landsat TM/ETM+ sensors (Key and Benson, 1999 [1],[2]) and was transferred from Landsat to MODIS data. The measurement principally addresses the biomass consumption due to fire, whereas the change detected between the pre-fire image and the post-fire image is quantified by the ÄNBR. The NBR and the Normalised Difference Vegetation Index (NDVI) have been applied to MODIS and Landsat TM/ETM+ data. The spectral properties and the index values of the remote sensing data have been analysed within different burnt areas. The influence of atmospheric and BRDF effects on MODIS data has been investigated by comparing uncorrected top of atmosphere reflectance and atmospheric and BRDF corrected reflectance. The definition of burn severity classes has been established in a field trip to the study area. However, heterogeneous fire behaviour and patchy distribution of different vegetation structure made field classification difficult. Ground truth data has been collected in two different types of vegetation structure present in the burnt area. The burn severity measurement of high resolution Landsat data was assessed based on ground truth data. However, field data was not sufficient for rigorous validation of remote sensing data. The NBR index images of both sensors have been calibrated based on training areas in the high resolution Landsat image. The burn severity classifications of both sensors are comparable, which demonstrates the feasibility of a burn severity measurement using moderate spatial resolution 250m MODIS data. The normalisation through index calculation reduced atmospheric and BRDF effects, and thus MODIS top of at-mosphere data has been considered suitable for the burn severity measurement. The NBR could not be uniformly applied, as different structures of vegetation influenced the range of index values. Furthermore, the index was sensitive to variability in moisture content. However, the study concluded that the NBR on MODIS data is a useful measure of burn severity in the forested area of south-west WA. KW - Westaustralien KW - Waldbrand KW - Fernerkundung KW - MODIS KW - Waldbraende KW - Fernerkundung KW - Australien KW - MODIS KW - mediterranes Oekosystem KW - burn severity KW - MODIS KW - Normalised Burn Ratio (NBR) KW - Mediterranean sclerophyll forest KW - prescribed burning Y1 - 2004 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-14745 ER -