TY - JOUR A1 - Geyer, Gerd A1 - Pais, Miguel Caldeira A1 - Wotte, Thomas T1 - Unexpectedly curved spines in a Cambrian trilobite: considerations on the spinosity in Kingaspidoides spinirecurvatus sp. nov. from the Anti-Atlas, Morocco, and related Cambrian ellipsocephaloids JF - PalZ N2 - The new ellipsocephaloid trilobite species Kingaspidoides spinirecurvatus has a spectacular morphology because of a unique set of two long and anteriorly recurved spines on the occipital ring and the axial ring of thoracic segment 8. Together with the long genal spines this whimsical dorsally directed spine arrangement is thought to act as a non-standard protective device against predators. This is illustrated by the body posture during different stages of enrolment, contrasting with the more sophisticated spinosities seen in later trilobites, which are discussed in brief. Kingaspidoides spinirecurvatus from the lower–middle Cambrian boundary interval of the eastern Anti-Atlas in Morocco has been known for about two decades, with specimens handled as precious objects on the fossil market. Similar, but far less spectacular, spine arrangements on the thoracic axial rings are known from other ellipsocephaloid trilobites from the Anti-Atlas of Morocco and the Franconian Forest region of Germany. This suggests that an experimental phase of spine development took place within the Kingaspi-doides clade during the early–middle Cambrian boundary interval. KW - Cambrian KW - Trilobita KW - Systematics KW - Biostratigraphy KW - West Gondwana KW - Morocco Y1 - 2020 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-231873 SN - 0031-0220 VL - 94 ER - TY - THES A1 - Emmert, Adrian Alexander T1 - The Internal Structure of Periglacial Landforms - Assessments of Subsurface Variations in Permafrost-related and Frost-related Phenomena by Multi-dimensional Geophysical Investigations T1 - Der innere Aufbau Periglazialer Landformen N2 - The internal structure of periglacial landforms contains valuable information on past and present environmental conditions. To benefit from this archive, however, an enhanced understanding of subsurface variations is crucial. This enables to assess the influence of the internal structure on prevailing process regimes and to evaluate the sensitivity of different landform units to environmental changes. This thesis investigates structural variations in the subsurface of (i) rock glaciers,(ii) solifluction lobes, (iii) palsas/ lithalsas and (iv) patterned ground, which occur between the different landform types, but also between landform units of the same type. Investigated variables comprise (i) the spatial distribution of permafrost, (ii) ground ice content, (iii) the origin of ground ice, (iv) thickness of the active layer and (v) frost table topography. Multi-dimensional investigations by the geophysical methods Electrical Resistivity Imaging (ERI) and Ground-Penetrating Radar (GPR) were performed in six study areas (a–f): four of them are located in high-alpine environments in Switzerland and two of them are located in the subarctic highlands of Iceland. Additionally, surface and subsurface temperature values were continuously recorded at selected study sites. At one study site, pF-values, representing the matric potential (or water potential), were recorded. From a methodological view, this thesis focuses on the application of quasi-3-D ERI, an approach in which many two-dimensional data sets are combined to create one three-dimensional data set. This permits e.g., a three-dimensional delimitation of subsurface structures and a spatial investigation of the distribution of ground ice. Besides the analysis of field data, this thesis incudes a comparison between inversion models produced with different software products, based on two synthetic data sets. The detection of resistivity structures and reflection patterns provides valuable insights into the internal structure of the investigated landform units: At the high-alpine study site at (a) Piz Nair, a highly variable ice content indicates a complex development of the investigated rock glacier assembly. The local formation of ground ice is attributed to an embedding of surface patches of snow or ice into the subsurface by rockfall. Results of geoelectric monitoring surveys on selected rock glaciers show the influence of seasonal alterations in the internal structure on subsurface meltwater flow. At the study site at (b) Piz Üertsch, results indicate the occurrences of isolated ground ice patches in a significantly larger rock glacier. Detected characteristics of the internal structure enable to reconstruct the development of the rock glacier, in which a temporary override of an adjacent glacier tongue on the rock glacier is considered crucial for the current distribution of ground ice. However, results of this thesis clearly show the absence of buried glacier ice in the subsurface of the rock glacier. Results from a rock glacier near the (c) Las Trais Fluors mountain ridge affirm the existence of a water-permeable frozen layer, which was assumed in previous studies. Furthermore, results show that the rock glacier contains large amounts of rockfall deposits. A joint interpretation of ERI and GPR results from the investigated scree slope at the mountain (d) Blauberg (Furka Pass) reveals characteristic structures in the subsurface, which enable a differentiation between solifluction lobes and pebbly rock glaciers. At the subarctic study site (e) Orravatnsrústir, results show that the internal structure of palsas can be used to deduce their current development stage and to assess past and future developments. Presented results affirm a long history of palsa development at the study site, as assumed in previous studies, but indicate recently changing environmental conditions. The investigated occurrences of patterned ground in the proglacial area of the glacier (f) Hofsjökull are currently not influenced by the detected occurrence of permafrost, according to the presented results. Therefore, a temporary formation of pattered ground is assumed, which is linked to the retreat of the glacier. This thesis shows discrepancies between the internal structure of some of the investigated landform units and the recent environmental conditions. This indicates a delayed adaption and a low sensitivity of the landform units to environmental changes. Findings indicate that the future development of permafrost will be strongly affected by variations in snowfall. Furthermore, the detection of isolated occurrences of ground ice at several study sites contradicts the widely assumed effectivity of balancing heat fluxes to create homogenous subsurface conditions in relatively fine-grained subsurface materials. N2 - Der strukturelle Aufbau periglazialer Landformen beinhaltet wertvolle Informationen über vergangene und heutige Umweltbedingungen. Um diese Informationen nutzen zu können, muss jedoch ein vertieftes Verständnis für den Zustand der inneren Struktur und möglicher Variationen entwickelt werden. Dieses Wissen ermöglicht beispielsweise eine Abschätzung des Einflusses der inneren Struktur auf das momentan dominierende Prozess-Regime und eine Beurteilung der Sensitivität gegenüber sich verändernden Umweltbedingungen. Die vorliegende Arbeit untersucht Unterschiede im Aufbau von (i) Blockgletschern, (ii) Solifluktionsloben, (iii) Palsas/ Lithalsas und (iv) Frostmusterböden, die zwischen den Landformtypen, aber auch zwischen einzelnen Einheiten desselben Typs bestehen. Betrachtet werden dabei (i) die räumliche Verbreitung von Permafrost,(ii) der Eisgehalt im Untergrund, (iii) die Entstehung von Untergrundeis, (iv) die Mächtigkeit der Auftauschicht sowie (v) die Formung der Frosttafel. In sechs Untersuchungsgebieten (a–f), davon vier in Hochgebirgsregionen der Schweiz und zwei im subarktischen Hochland Islands, wurden Untersuchungen mittels mehr-dimensionaler geophysikalischer Verfahren, Widerstandsgeoelektrik (ERI) und Bodenradar (GPR), durchgeführt. Zudem wurden an ausgewählten Standorten kontinuierlich Temperaturwerte der Oberfläche und des Untergrunds aufgezeichnet. An einem Standort wurden ergänzend pF-Werte, die die Saugspannung des Porenwassers angeben, aufgezeichnet. Methodischer Schwerpunkt der vorliegenden Arbeit ist die Anwendung von quasi-3-D ERI, einem Ansatz bei dem Datenpunkte mehrerer zweidimensionaler Datensätze zu einem dreidimensionalen Datensatz vereinigt werden. Dies erlaubt beispielsweise eine dreidimensionale Abgrenzung von Untergrundstrukturen und damit eine räumliche Untersuchung der Verbreitung von Untergrundeis. Ergänzend zur Arbeit mit Felddaten enthält die vorliegende Arbeit einen Vergleich zwischen Inversionsmodellen, die auf Basis von zwei identischen, synthetischen Datensätzen mit unterschiedlichen Softwareprodukten generiert wurden. Durch die Detektion von Widerstandsstrukturen und Reflektionsmustern lassen sich wertvolle Erkenntnisse über den strukturellen Aufbau der untersuchten Einheiten gewinnen: Im hochalpinen Untersuchungsgebiet am (a) Piz Nair weisen stark schwankende Eisgehalte auf eine komplexe Entwicklungsgeschichte der untersuchten Blockgletschergruppe hin. Die lokale Entstehung von Untergrundeis wird auf Verschüttungen oberflächlicher Schnee- oder Eisfelder durch Steinschlag zurückgeführt. An einem Blockgletscher der Gruppe wird mittels geoelektrischer Wiederholungsmessungen der saisonale Einfluss der inneren Struktur auf den Schmelzwasserabfluss im Untergrund durch Veränderungen der Permafrosttafel gezeigt. An einem deutlich größeren Blockgletscher im Untersuchungsgebiet am (b) Piz Üertsch zeigen die Ergebnisse dieser Arbeit isolierte Vorkommen von Untergrundeis. Hier kann anhand der inneren Struktur die Entwicklung des Blockgletschers nachvollzogen werden, wobei insbesondere eine zeitweilige Überdeckung des Blockgletschers durch eine benachbarte Gletscherzunge als ausschlaggebend für die lokale Verteilung von Untergrundeis angesehen wird. Die Ergebnisse zeigen, dass kein Gletschereis in den Block gletscher eingebettet wurde. Die vorgestellten Ergebnisse der Untersuchungen an einem Blockgletscher nahe des Bergkamms (c) Las Trais Fluors bestätigen die dort in vorherigen Studien angenommene Wasserdurchlässigkeit der Frosttafel. Zudem zeigt der Aufbau des Blockgletschers das Auftreten großer Mengen von Steinschlagablagerungen. Am untersuchten Schutthang am (d) Blauberg (Furkapass) können durch eine gemeinsame Auswertung der Ergebnisse von ERI und GPR charakteristische Strukturen detektiert werden, durch die sich die dort auftretenden Lobenstrukturen in Solifluktionsloben und Feinmaterial-Blockgletscher (Pebbly Rock Glaciers) unterscheiden lassen. Im subarktischen Untersuchungsgebiet (e) Orravatnsrústir zeigen die Ergebnisse, dass vom strukturellen Aufbau von Palsas auf deren gegenwärtiges Entwicklungsstadium geschlossen werden kann und dass Rückschlüsse auf vergangene und zukünftige Entwicklungen möglich sind. Die vorgestellten Ergebnisse bestätigen die in vorherigen Studien getroffene Annahme einer lange zurückreichenden Entwicklungsgeschichte der Palsas, weisen aber auch auf sich seit kurzem verändernde Umweltbedingungen hin. Die untersuchten Frostmusterböden im Gletschervorfeld des (f) Hofsjökull zeigen gegenwärtig keine Beeinflussung durch Permafrost, obwohl ein rezentes Vorkommen von Permafrost angenommen wird. Daher wird eine temporäre Bildung der untersuchten Oberflächenstrukturen angenommen, die an den Rückzug des Gletschers gebunden ist. Die vorliegende Arbeit zeigt, dass die innere Struktur einiger der untersuchten Landform-Einheiten Diskrepanzen zu den momentanen Umweltbedingungen aufweist. Dies deutet auf eine geringe Sensitivität, beziehungsweise eine verzögerte Anpassung der Landschaftsformung auf sich verändernde Umweltbedingungen hin. Des Weiteren zeigt die vorliegende Arbeit, dass besonders Veränderungen im Schneedeckenauf- und abbau wesentlich zur zukünftigen Entwicklung von Permafrost in den untersuchten Gebieten beitragen werden. Die Beobachtung isolierter Vorkommen von Untergrundeis in mehreren Untersuchungsgebieten steht in Kontrast zur verbreiteten Annahme, dass die ausgleichende Wirkung von Wärmeströmen im Untergrund in feinkörnigem Material besonders stark ist N2 - Periglacial environments are facing dramatic changes. Warming air temperatures and strong snow cover variations fundamentally affect landforming processes in this hotspot region of Climate Change. But before we can assess the response of landform development to a changing climate, we need to enhance our understanding of the internal structure of those landforms. Within this study, a broad scope of landform types from alpine and subarctic regions is investigated: rock glaciers, solifluction lobes, palsas and patterned ground. By using the geophysical methods 2-D and 3-D ERI, as well as GPR surveying, structural differences and similarities between landform units of different or the same landform types are highlighted. This enables a reconstruction of their past and a projection of their future development. KW - Permafrost KW - Geophysik KW - permafrost KW - internal structure KW - applied geophysics KW - periglacial landform Y1 - 2020 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-202437 SN - 978-3-95826-138-9 SN - 978-3-95826-139-6 N1 - Parallel erschienen als Druckausgabe in Würzburg University Press, 978-3-95826-138-9, 34,90 EUR. PB - Würzburg University Press CY - Würzburg ET - 1. Auflage ER - TY - JOUR A1 - Ziegler, Katrin A1 - Pollinger, Felix A1 - Böll, Susanne A1 - Paeth, Heiko T1 - Statistical modeling of phenology in Bavaria based on past and future meteorological information JF - Theoretical and Applied Climatology N2 - Plant phenology is well known to be affected by meteorology. Observed changes in the occurrence of phenological phases arecommonly considered some of the most obvious effects of climate change. However, current climate models lack a representationof vegetation suitable for studying future changes in phenology itself. This study presents a statistical-dynamical modelingapproach for Bavaria in southern Germany, using over 13,000 paired samples of phenological and meteorological data foranalyses and climate change scenarios provided by a state-of-the-art regional climate model (RCM). Anomalies of severalmeteorological variables were used as predictors and phenological anomalies of the flowering date of the test plantForsythiasuspensaas predictand. Several cross-validated prediction models using various numbers and differently constructed predictorswere developed, compared, and evaluated via bootstrapping. As our approach needs a small set of meteorological observationsper phenological station, it allows for reliable parameter estimation and an easy transfer to other regions. The most robust andsuccessful model comprises predictors based on mean temperature, precipitation, wind velocity, and snow depth. Its averagecoefficient of determination and root mean square error (RMSE) per station are 60% and ± 8.6 days, respectively. However, theprediction error strongly differs among stations. When transferred to other indicator plants, this method achieves a comparablelevel of predictive accuracy. Its application to two climate change scenarios reveals distinct changes for various plants andregions. The flowering date is simulated to occur between 5 and 25 days earlier at the end of the twenty-first century comparedto the phenology of the reference period (1961–1990). KW - statistical modeling KW - phenology KW - Bavaria Y1 - 2020 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-232717 SN - 0177-798X VL - 140 ER - TY - JOUR A1 - Usman, Muhammad A1 - Mahmood, Talha A1 - Conrad, Christopher A1 - Bodla, Habib Ullah T1 - Remote Sensing and modelling based framework for valuing irrigation system efficiency and steering indicators of consumptive water use in an irrigated region JF - Sustainability N2 - Water crises are becoming severe in recent times, further fueled by population increase and climate change. They result in complex and unsustainable water management. Spatial estimation of consumptive water use is vital for performance assessment of the irrigation system using Remote Sensing (RS). For this study, its estimation is done using the Soil Energy Balance Algorithm for Land (SEBAL) approach. Performance indicators including equity, adequacy, and reliability were worked out at various spatiotemporal scales. Moreover, optimization and sustainable use of water resources are not possible without knowing the factors mainly influencing consumptive water use of major crops. For that purpose, random forest regression modelling was employed using various sets of factors for site-specific, proximity, and cropping system. The results show that the system is underperforming both for Kharif (i.e., summer) and Rabi (i.e., winter) seasons. Performance indicators highlight poor water distribution in the system, a shortage of water supply, and unreliability. The results are relatively good for Rabi as compared to Kharif, with an overall poor situation for both seasons. Factors importance varies for different crops. Overall, distance from canal, road density, canal density, and farm approachability are the most important factors for explaining consumptive water use. Auditing of consumptive water use shows the potential for resource optimization through on-farm water management by the targeted approach. The results are based on the present situation without considering future changes in canal water supply and consumptive water use under climate change. KW - consumptive water use KW - performance assessment KW - indicator importance assessment KW - water management KW - Pakistan Y1 - 2020 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-219358 SN - 2071-1050 VL - 12 IS - 22 ER - TY - THES A1 - Büdel, Christian T1 - Quaternary alluvial fan morphodynamics and basin sedimentation in North Iran N2 - Several hundred meter thick alluvial fans are dominating the landscape of semiarid plains of north-eastern Iranian mountain-talus. These fans developed since Miocene times and are still prograding today. They are storing and transporting major amount of weathered debris from the mountain ranges and sediments are directed to the depressions of the endorheic basins. In this course, the debris gets increasingly weathered and abraded to sand silt and clay fractions, which finally constitute the fine loamy layers of the typical central playa lakes and playas. The study focused on the detailed investigation of a characteristic section of this prominent sediment cascades. The sediments were planned be comprehensively documented by using a fully analytical geomorphological mapping approach, also suitable for the classification of the sediment’s geomorphological system contexts. Therefore, a geodatabase structure was developed, which is capable of managing and analyzing geomorphological data. The corresponding data was acquired using remote sensing imagery, digital elevation models and field mapping campaigns. Additionally, mapped sediments were selected and analyzed to reveal representative stratigraphic and sedimentologic characteristics. The fieldwork was conducted in Damghan Basin on sections in geomorphologically subdivided alluvial apron sediments. The corresponding, more regularly layered and partly laminated sediments from the central playa, were also investigated and comparably described. Attending to the preparation of profile sections and the percussion core probing, samples from both origins were taken. Detailed lithostratigraphical and geochemical analyses were carried out in the laboratory, in order to develop sound comparable sediment and sediment alteration indices. In addition, OSL sampling was done on distinct alluvial fan surfaces, and the samples were measured and dated in the laboratory in order to develop a functional chronostratigraphy. The results of the geomorphological and stratigraphical investigations reveal five classes of surface ages on the alluvial apron. Parallel to that observation, the ramming core samples exhibit four main phases of sediment development in the playa, each with internal differentiation. This brings up opportunities for a valid correlation of continuously deposited playa sediments, with widespread alluvial surfaces. By considering the OSL ages of selected terrestrial and lacustrine layers, the stratigraphy and relative chronological order of the studied sediments, are aligned to Pleistocene and mid to late Holocene periods. This is also confirmed by proxy ages from the chronological framework of the landscape development, within the basin. Geophysical and geochemical data reveals roughly cyclic sedimentation and sediment alteration that can also be observed in genetically differing geoarchives from alluvial fan surfaces to the playa sediments. These parallel developments are confirmed by the sequence-stratigraphic order of the archives which is derived from geomorphological mapping. We postulate a time span covered by the playa sediments from today to late Pleistocene times. Drying and Lake level retreat at the end of Pleistocene is documented in parallel geoarchives of terrestrial and lacustrine origin. Thus, geomorphologic landform-succession and alluvial fan morphogenesis, as well as geochemical and geophysical fingerprinting data of playa sediments characterize this development. Therefore, it is present in the two youngest generations of alluvial fans, which deposited at the toe of the alluvial apron and which incorporate reworked still water deposits of a former lake level terrace. The geochemical parameters, like pH-value and Ca/S-ratio, in both, sediments of a former lake level and those from the recent playa extent exhibit a similar development. In addition, Ti/Al-ratio shows the potential for quantifying lake level retreat, as it seems to be tightly depending on lake level and increasing transportation distances along the sediment cascade. Major Findings - Analytical geomorphological mapping is a key tool for understanding the sedimentation history of the Iranian Quaternary and for describing Quaternary stratigraphic units of North Iran. - The younger playa deposits in Damghan Basin cover a time span from today to late Pleistocene. They are 10 meters thick and reveal very low organic matter contents throughout the core. - Drying and Lake level retreat is documented in parallel geoarchives (1) in geomorphologic landform-succession and alluvial fan morphogenesis and (2) in geochemical and geophysical fingerprinting data of playa sediments - Sequences of torrential sedimentation are detectable signals and can be correlated in both: playa sediments and landform morphology N2 - Die nordostiranische Gebirgsabdachung wird maßgeblich von mehrere hundert Meter mächtigen Schwemmfächern gebildet. Die Aufschüttung der Schwemmfächer setze im Miozän ein und bis heute progradieren die Fächer ins Beckeninnere. Dabei transportieren und speichern sie den Großteil des Verwitterungsschutts der Gebirgszone und die Sedimente werden von hier weiter in die zentralen Depressionen der endorheischen Beckenlandschaften geleitet. Auf ihrem Weg wird der Schutt weiter zerkleinert und verwittert, und bildet schließlich in feinen Sand-, Schluff- und Tongemengelagen die Lehmschichten der typischen zentralen Playaseen und Playas. Mit der vorliegenden Studie wurde ein charakteristischer Abschnitt dieser bedeutenden Sedimentkaskade detailliert untersucht. Durch einen vollanalytischen geomorphologischen Kartieransatz sollten die Sedimente umfangreich erfasst und in ihren geomorphologischen Systemzusammenhang gebracht werden. Zu diesem Zweck wurde eine Geodatenbankstruktur entwickelt, die die Verwaltung und Analyse geomorphologischer Daten ermöglicht. Die entsprechenden Dateneinträge wurden aus spektralen Fernerkundungsdaten, digitalen Geländemodellen und den Feldkartierungen mehrerer Expeditionen extrahiert. Für die kartierten Sedimente wurden an repräsentativen Standorten zusätzlich die stratigraphischen und sedimentologischen Charakteristika ermittelt und mit den Kartenelementen verknüpft. Für die Feldarbeiten wurden die Sedimente einer typischen Schwemmfächerschürze des Damghan Beckens geomorphologisch untergegliedert und ergraben. Entsprechend wurden die, das Ende der Sedimentkaskade bildenden, regelmäßiger geschichteten und zum Teil laminierten Sedimente der Playa sondiert und vergleichbar beschrieben. Die Landformen wurden als Kartenelemente im Vektorformat gespeichert und nach standardisierten geomorphologischen Konzepten in Systemelemente aus Form, Material und Prozess klassifiziert. Spezifiziert wurden die Landformen und Landformelemente dann in den Klassen Moprhometrie und Morphographie (Form), Morphostruktur (Material), Morphodynamik und Morphogenese (Prozess), sowie Geomorphologie (System Synthese). Begleitend zu den Kartierungen und der Bearbeitung der Profilschnitte und Rammkernsondagen, wurden die Schichten beider Sedimentationsräume detailliert beprobt. Weitere Untersuchungen zu Lithostratigraphie, Geochronologie und Geochemie der Sedimente wurden im Labor ausgeführt und sollten aussagekräftige Indizes zu Sedimenteigenschaften und Art und Alter der Sedimentvariation erbringen. Neben pH- und Leitfähigkeitsmessungen, sowie der Ionenchromatographie leicht löslicher Salze, wurde für alle Proben die Granulometrie mittels Laserdiffraktometrie ermittelt. Die mineralogische Zusammensetzung wurde röntgendiffraktometrisch bestimmt. Haupt- und Nebenelemente wurden im Wesentlichen mit einer Kombination aus Röntgenfluoreszenzmessungen (XRF) und optischer Emissionsspektrometrie von Königswasseraufschlüssen mittels induktiv gekoppeltem Plasma (ICP-OES) analysiert. Altersbestimmungen konnten lediglich an ausgewählten Proben der terrestrischen Sedimente durchgeführt werden; dabei wurden im Labor Dosimetrie und Optisch Stimulierte Lumineszenz gemessen (OSL) und daraus die Alter modelliert. Die Ergebnisse der geomorphologischen und stratigraphischen Untersuchungen zeigen fünf Hauptphasen vergangener Schwemmfächeroberflächenaktivität. Parallel dazu konnten in den Rammkernen der zentralen Playa vier in sich gegliederte Hauptsedimentationsphasen nachgewiesen werden. Die kontinuierlichen Akkumulationsphasen der Playasedimente bieten aussagekräftige Korrelationen mit den Aktivitätsphasen auf den ausgedehnten Flächen der Schwemmfächerschürze. Über die OSL-Alter der ausgewählten terrestrischen und lakustrinen Sedimentschichten können Stratigraphie und relative Chronologie der untersuchten Sedimente Pleistozänen und mittel- bis spätholozänen Perioden zugeordnet und in die allgemeine Chronostratigraphy des Beckens eingefügt werden. Die geophysikalischen und geochemischen Messungen lassen auf zyklische Sedimentationsphasen schließen, die sich über Geoarchive verschiedenen Ursprungs von der Schwemmfächerschürze bis in die zentrale Playa koppeln lassen. Diese stratigraphische Entwicklung wurde über die historisch-genetische Systemrekonstruktion im Zuge der geomorphologischen Kartierung in ihren sequenzstratigraphischen Zusammenhang gebracht und bestätigt so die parallele Entwicklung der verschiedenen Geoarchive. Die untersuchten Playasedimente belegen somit eine Zeitspanne vom Spätpleistozän bis zur aktuell anhaltenden Phase. Die Entwicklung der verschiedenen Sedimentkörper zeigt auch den Wechsel zu trockeneren Bedingungen und die Austrocknung eines früher ausgedehnten (Playa-)Sees in spätpleistozäner Zeit an. Sowohl die geomorphologische Landformensukzession und Schwemmfächermorphogenese, wie auch das Elementsignal und die veränderten geophysikalischen und geochemischen Eigenschaften der Playasedimente charakterisieren diese Entwicklung. So ist diese präsent in den beiden jüngsten Schwemmfächergenerationen, die am Fuß der Schwemmfächerschürze liegen und erodierte Sedimente einer ehemaligen Seeterrasse beinhalten. Auch geochemische Parameter, hier die pH-Werte und das Ca/S-Verhältnis, der Schichten in Position der ehemaligen Seeterrasse, und der Schichtung innerhalb der rezenten Playaausdehnung weisen auf die zunehmende Salinität des ehemaligen Sees im Zuge der Austrocknung hin. Ergänzend hat das Ti/Al-Verhältnis Potential den Seespiegelrückzug zu quantifizieren, indem es als Indikator für zunehmende Transportdistanzen entlang der Sedimentkaskade genutzt wird. Der beobachtete Seespiegelrückgang und die Phasen der Schwemmfächeraktivität können weiterhin mit Humiditätsphasen korreliert werden, die aus verschiedenen See- und Sumpfsedimenten des Nordiran bekannt sind. So beginnt in Damghan mit der Jüngeren Dyas eine intensive Trockenphase mit veränderten klimatischen Bedingungen. Nach einer folgenden Humiditätsphase mit neuerlichem Seehochstand können zwei weitere Trockenphasen im Frühholozän ausgemacht werden. Die letzte Trockenphase setzt somit nach einer mittelholozänen Phase relativer Stabilität ein. Wesentliche Erkenntnisse - Die analytisch geomorphologische Kartierung bildet ein essentielles Werkzeug zur Untersuchung der Sedimentation im iranischen Quartär und zur Beschreibung der quartären stratigraphischen Einheiten des Nordiran - Die jüngeren Playasedimente des Damghan Beckens repräsentieren einen Zeitabschnitt der von heute bis in das Spätpleistozän reicht. Sie weisen eine Mächtigkeit von 10 Meter auf und enthalten durchweg sehr geringe Anteile an organischer Substanz. - Austrocknung und Seespiegelrückgang sind in Damghan parallel in zwei Geoarchivtypen dokumentiert. Sie zeigen sich (1) in der geomorphologischen Landformenfolge und Schwemmfächerentwicklung und (2) im Wandel der geochemischen und geophysikalischen Charakteristika der Playasedimente. - Sequenzen mit torrentieller Sedimentation konnten ebenfalls in beiden Sedimentationsräumen erkannt und korreliert werden. N2 - Availability of water and desiccation of important water reservoirs is a vital challenge in semi-arid to arid climates with growing economy and population. Low quantities of precipitation and high evaporation rates leave the water supply vulnerable to human activity and climatic variations. Endorheic basins of Northern Iran were hydrologically landlocked within geological timescales and thus bear evidence of past variations of water resources in generations of water related landforms, like abandoned lake level shorelines, alluvial fans and stream terraces. Understanding the development of these landforms reveals crucial information about past water reservoirs and landscape history. This study offers a comprehensive approach on understanding the geomorphological development of the landscape throughout Late Pleistocene and Holocene times. It integrates remote sensing and geographic information system analysis, with geomorphological and stratigraphical mapping fieldwork and detailed sedimentological investigations. The work shows the importance of analytical geomorphological mapping for delineating stratigraphic units of the Iranian Quaternary. Thus, several phases of drying and lake level retreat were identified in parallel geoarchives and could be dated to a time span from today to Late Pleistocene. The findings link the fate of the citizens of the ancient city of "Tepe Hissar" to their access to water and to the power of geomorphological processes, which started changing their environment. T2 - Quartäre Schwemmfächerdynamik und Beckensedimentation im Nordiran T3 - Würzburger Geographische Arbeiten - 123 KW - Quartärgeomorphologie KW - Quartär KW - Trockengebiet KW - Schwemmfächer KW - Playa KW - Sedimentarchiv KW - Quaternary KW - drylands KW - alluvial fan KW - basin geomorphology Y1 - 2020 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-184508 SN - 978-3-95826-114-3 SN - 978-3-95826-115-0 SN - 0510-9833 SN - 2194-3656 N1 - Parallel erschienen als Druckausgabe in Würzburg University Press, 978-3-95826-114-3, 29,80 EUR PB - Würzburg University Press CY - Würzburg ET - 1. Auflage ER - TY - JOUR A1 - Ulloa-Torrealba, Yrneh A1 - Stahlmann, Reinhold A1 - Wegmann, Martin A1 - Koellner, Thomas T1 - Over 150 years of change: object-oriented analysis of historical land cover in the Main river catchment, Bavaria/Germany JF - Remote Sensing N2 - The monitoring of land cover and land use change is critical for assessing the provision of ecosystem services. One of the sources for long-term land cover change quantification is through the classification of historical and/or current maps. Little research has been done on historical maps using Object-Based Image Analysis (OBIA). This study applied an object-based classification using eCognition tool for analyzing the land cover based on historical maps in the Main river catchment, Upper Franconia, Germany. This allowed land use change analysis between the 1850s and 2015, a time span which covers the phase of industrialization of landscapes in central Europe. The results show a strong increase in urban area by 2600%, a severe loss of cropland (−24%), a moderate reduction in meadows (−4%), and a small gain in forests (+4%). The method proved useful for the application on historical maps due to the ability of the software to create semantic objects. The confusion matrix shows an overall accuracy of 82% for the automatic classification compared to manual reclassification considering all 17 sample tiles. The minimum overall accuracy was 65% for historical maps of poor quality and the maximum was 91% for very high-quality ones. Although accuracy is between high and moderate, coarse land cover patterns in the past and trends in land cover change can be analyzed. We conclude that such long-term analysis of land cover is a prerequisite for quantifying long-term changes in ecosystem services. KW - historical KW - land cover change KW - object-based classification KW - eCognition Y1 - 2020 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-220029 SN - 2072-4292 VL - 12 IS - 24 ER - TY - JOUR A1 - Forkuor, Gerald A1 - Ullmann, Tobias A1 - Griesbeck, Mario T1 - Mapping and monitoring small-scale mining activities in Ghana using Sentinel-1 time series (2015−2019) JF - Remote Sensing N2 - Illegal small-scale mining (galamsey) in South-Western Ghana has grown tremendously in the last decade and caused significant environmental degradation. Excessive cloud cover in the area has limited the use of optical remote sensing data to map and monitor the extent of these activities. This study investigated the use of annual time-series Sentinel-1 data to map and monitor illegal mining activities along major rivers in South-Western Ghana between 2015 and 2019. A change detection approach, based on three time-series features — minimum, mean, maximum — was used to compute a backscatter threshold value suitable to identify/detect mining-induced land cover changes in the study area. Compared to the mean and maximum, the minimum time-series feature (in both VH and VV polarization) was found to be more sensitive to changes in backscattering within the period of investigation. Our approach permitted the detection of new illegal mining areas on an annual basis. A backscatter threshold value of +1.65 dB was found suitable for detecting illegal mining activities in the study area. Application of this threshold revealed illegal mining area extents of 102 km\(^2\), 60 km\(^2\) and 33 km\(^2\) for periods 2015/2016–2016/2017, 2016/2017–2017/2018 and 2017/2018–2018/2019, respectively. The observed decreasing trend in new illegal mining areas suggests that efforts at stopping illegal mining yielded positive results in the period investigated. Despite the advantages of Synthetic Aperture Radar data in monitoring phenomena in cloud-prone areas, our analysis revealed that about 25% of the Sentinel-1 data, mostly acquired in March and October (beginning and end of rainy season respectively), were unusable due to atmospheric effects from high intensity rainfall events. Further investigation in other geographies and climatic regions is needed to ascertain the susceptibility of Sentinel-1 data to atmospheric conditions. KW - Sentine-1 KW - mining KW - image artifacts KW - time-series features KW - galamsey KW - Ghana Y1 - 2020 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-203204 SN - 2072-4292 VL - 12 IS - 6 ER - TY - JOUR A1 - Thonfeld, Frank A1 - Steinbach, Stefanie A1 - Muro, Javier A1 - Kirimi, Fridah T1 - Long-term land use/land cover change assessment of the Kilombero catchment in Tanzania using random forest classification and robust change vector analysis JF - Remote Sensing N2 - Information about land use/land cover (LULC) and their changes is useful for different stakeholders to assess future pathways of sustainable land use for food production as well as for nature conservation. In this study, we assess LULC changes in the Kilombero catchment in Tanzania, an important area of recent development in East Africa. LULC change is assessed in two ways: first, post-classification comparison (PCC) which allows us to directly assess changes from one LULC class to another, and second, spectral change detection. We perform LULC classification by applying random forests (RF) on sets of multitemporal metrics that account for seasonal within-class dynamics. For the spectral change detection, we make use of the robust change vector analysis (RCVA) and determine those changes that do not necessarily lead to another class. The combination of the two approaches enables us to distinguish areas that show (a) only PCC changes, (b) only spectral changes that do not affect the classification of a pixel, (c) both types of change, or (d) no changes at all. Our results reveal that only one-quarter of the catchment has not experienced any change. One-third shows both, spectral changes and LULC conversion. Changes detected with both methods predominantly occur in two major regions, one in the West of the catchment, one in the Kilombero floodplain. Both regions are important areas of food production and economic development in Tanzania. The Kilombero floodplain is a Ramsar protected area, half of which was converted to agricultural land in the past decades. Therefore, LULC monitoring is required to support sustainable land management. Relatively poor classification performances revealed several challenges during the classification process. The combined approach of PCC and RCVA allows us to detect spatial patterns of LULC change at distinct dimensions and intensities. With the assessment of additional classifier output, namely class-specific per-pixel classification probabilities and derived parameters, we account for classification uncertainty across space. We overlay the LULC change results and the spatial assessment of classification reliability to provide a thorough picture of the LULC changes taking place in the Kilombero catchment. KW - land-use/land-cover change KW - robust change vector analysis KW - Kilombero KW - wetland KW - food production KW - random forest KW - multitemporal metrics KW - Landsat KW - post-classification comparison Y1 - 2020 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-203513 SN - 2072-4292 VL - 12 IS - 7 ER - TY - JOUR A1 - Heinemann, Sascha A1 - Siegmann, Bastian A1 - Thonfeld, Frank A1 - Muro, Javier A1 - Jedmowski, Christoph A1 - Kemna, Andreas A1 - Kraska, Thorsten A1 - Muller, Onno A1 - Schultz, Johannes A1 - Udelhoven, Thomas A1 - Wilke, Norman A1 - Rascher, Uwe T1 - Land surface temperature retrieval for agricultural areas using a novel UAV platform equipped with a thermal infrared and multispectral sensor JF - Remote Sensing N2 - Land surface temperature (LST) is a fundamental parameter within the system of the Earth’s surface and atmosphere, which can be used to describe the inherent physical processes of energy and water exchange. The need for LST has been increasingly recognised in agriculture, as it affects the growth phases of crops and crop yields. However, challenges in overcoming the large discrepancies between the retrieved LST and ground truth data still exist. Precise LST measurement depends mainly on accurately deriving the surface emissivity, which is very dynamic due to changing states of land cover and plant development. In this study, we present an LST retrieval algorithm for the combined use of multispectral optical and thermal UAV images, which has been optimised for operational applications in agriculture to map the heterogeneous and diverse agricultural crop systems of a research campus in Germany (April 2018). We constrain the emissivity using certain NDVI thresholds to distinguish different land surface types. The algorithm includes atmospheric corrections and environmental thermal emissions to minimise the uncertainties. In the analysis, we emphasise that the omission of crucial meteorological parameters and inaccurately determined emissivities can lead to a considerably underestimated LST; however, if the emissivity is underestimated, the LST can be overestimated. The retrieved LST is validated by reference temperatures from nearby ponds and weather stations. The validation of the thermal measurements indicates a mean absolute error of about 0.5 K. The novelty of the dual sensor system is that it simultaneously captures highly spatially resolved optical and thermal images, in order to construct the precise LST ortho-mosaics required to monitor plant diseases and drought stress and validate airborne and satellite data. KW - UAV KW - thermal infrared KW - multispectral VNIR KW - LST KW - emissivity KW - NDVI thresholds KW - atmospheric correction KW - agricultural mapping KW - low-cost applications Y1 - 2020 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-203557 SN - 2072-4292 VL - 12 IS - 7 ER - TY - JOUR A1 - Akhundzadah, Noor Ahmad A1 - Soltani, Salim A1 - Aich, Valentin T1 - Impacts of climate change on the water resources of the Kunduz River Basin, Afghanistan JF - Climate N2 - The Kunduz River is one of the main tributaries of the Amu Darya Basin in North Afghanistan. Many communities live in the Kunduz River Basin (KRB), and its water resources have been the basis of their livelihoods for many generations. This study investigates climate change impacts on the KRB catchment. Rare station data are, for the first time, used to analyze systematic trends in temperature, precipitation, and river discharge over the past few decades, while using Mann–Kendall and Theil–Sen trend statistics. The trends show that the hydrology of the basin changed significantly over the last decades. A comparison of landcover data of the river basin from 1992 and 2019 shows significant changes that have additional impact on the basin hydrology, which are used to interpret the trend analysis. There is considerable uncertainty due to the data scarcity and gaps in the data, but all results indicate a strong tendency towards drier conditions. An extreme warming trend, partly above 2 °C since the 1960s in combination with a dramatic precipitation decrease by more than −30% lead to a strong decrease in river discharge. The increasing glacier melt compensates the decreases and leads to an increase in runoff only in the highland parts of the upper catchment. The reduction of water availability and the additional stress on the land leads to a strong increase of barren land and a reduction of vegetation cover. The detected trends and changes in the basin hydrology demand an active management of the already scarce water resources in order to sustain water supply for agriculture and ecosystems in the KRB. KW - climate change KW - Kunduz River Basin KW - trend analysis KW - river discharge KW - landcover changes Y1 - 2020 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-213199 SN - 2225-1154 VL - 8 IS - 10 ER -