@article{SchuesslerSkinnerRoland1990, author = {Sch{\"u}ssler, Ulrich and Skinner, D. N. B. and Roland, N.}, title = {Basischer bis intermedi{\"a}rer Plutonismus im NW-Teil des Wilson Terrane, Nordvictorialand, Antarktis}, url = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-81850}, year = {1990}, abstract = {no abstract available}, subject = {Wilson Terrane}, language = {de} } @article{Sponholz1988, author = {Sponholz, Barbara}, title = {Beobachtungen zur Morphodynamik an Koris des s{\"u}dlichen Air-Vorlandes (Niger)}, url = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-53579}, year = {1988}, abstract = {Am Beispiel von vier Koris l) (T{\´e}loua, Barghot, Tazol{\´e}, Oufagu{\´e}dout) des s{\"u}dlichen Air-Vorlandes werden Beobachtungen zum aktuellen morphodynamischen Geschehen dieser Region vorgestellt. Durch die regionalen Unterschiede der durchschnittlichen j{\"a}hrlichen Niederschlagsh{\"o}hen und durch unterschiedliche Charakteristika ihrer Einzugsgebiete k{\"o}nnen diese vier Koris als typische Vertreter verschiedener fluviatil/{\"a}olischer Formungsgruppen angesehen werden. Der {\"U}bergang von vorherrschend fluviatiler zu vorherrschend {\"a}olischer Formung liegt dabei im Bereich des Kori Oufagu{\´e}dout, im {\"o}stlichen Teil des Untersuchungsraumes. Hier konnte durch mehrere Sch{\"u}rfe auch der zeitliche {\"U}bergang zwischen beiden Formungskreisen in der j{\"u}ngeren Reliefgeschichte nachgewiesen werden.}, subject = {Geographie}, language = {de} } @article{PaethPollinger2019, author = {Paeth, Heiko and Pollinger, Felix}, title = {Changes in mean flow and atmospheric wave activity in the North Atlantic sector}, series = {Quarterly Journal of the Royal Meteorological Society}, volume = {145}, journal = {Quarterly Journal of the Royal Meteorological Society}, number = {725}, doi = {10.1002/qj.3660}, url = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-208079}, pages = {3801-3818}, year = {2019}, abstract = {In recent years, the midlatitudes are characterized by more intense heatwaves in summer and sometimes severe cold spells in winter that might emanate from changes in atmospheric circulation, including synoptic-scale and planetary wave activity in the midlatitudes. In this study, we investigate the heat and momentum exchange between the mean flow and atmospheric waves in the North Atlantic sector and adjacent continents by means of the physically consistent Eliassen-Palm flux diagnostics applied to reanalysis and forced climate model data. In the long-term mean, momentum is transferred from the mean flow to atmospheric waves in the northwest Atlantic region, where cyclogenesis prevails. Further downstream over Europe, eddy fluxes return momentum to the mean flow, sustaining the jet stream against friction. A global climate model is able to reproduce this pattern with high accuracy. Atmospheric variability related to atmospheric wave activity is much more expressed at the intraseasonal rather than the interannual time-scale. Over the last 40 years, reanalyses reveal a northward shift of the jet stream and a weakening of intraseasonal weather variability related to synoptic-scale and planetary wave activity. This pertains to the winter and summer seasons, especially over central Europe, and correlates with changes in the North Atlantic Oscillation as well as regional temperature and precipitation. A very similar phenomenon is found in a climate model simulation with business-as-usual scenario, suggesting an anthropogenic trigger in the weakening of intraseasonal weather variability in the midlatitudes.}, language = {en} } @article{YangYaoLietal.2022, author = {Yang, Xuting and Yao, Wanqiang and Li, Pengfei and Hu, Jinfei and Latifi, Hooman and Kang, Li and Wang, Ningjing and Zhang, Dingming}, title = {Changes of SOC content in China's Shendong coal mining area during 1990-2020 investigated using remote sensing techniques}, series = {Sustainability}, volume = {14}, journal = {Sustainability}, number = {12}, issn = {2071-1050}, doi = {10.3390/su14127374}, url = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-278939}, year = {2022}, abstract = {Coal mining, an important human activity, disturbs soil organic carbon (SOC) accumulation and decomposition, eventually affecting terrestrial carbon cycling and the sustainability of human society. However, changes of SOC content and their relation with influential factors in coal mining areas remained unclear. In the study, predictive models of SOC content were developed based on field sampling and Landsat images for different land-use types (grassland, forest, farmland, and bare land) of the largest coal mining area in China (i.e., Shendong). The established models were employed to estimate SOC content across the Shendong mining area during 1990-2020, followed by an investigation into the impacts of climate change and human disturbance on SOC content by a Geo-detector. Results showed that the models produced satisfactory results (R\(^2\) > 0.69, p < 0.05), demonstrating that SOC content over a large coal mining area can be effectively assessed using remote sensing techniques. Results revealed that average SOC content in the study area rose from 5.67 gC·kg\(^{-1}\) in 1990 to 9.23 gC·kg\(^{-1}\) in 2010 and then declined to 5.31 gC·Kg\(^{-1}\) in 2020. This could be attributed to the interaction between the disturbance of soil caused by coal mining and the improvement of eco-environment by land reclamation. Spatially, the SOC content of farmland was the highest, followed by grassland, and that of bare land was the lowest. SOC accumulation was inhibited by coal mining activities, with the effect of high-intensity mining being lower than that of moderate- and low-intensity mining activities. Land use was found to be the strongest individual influencing factor for SOC content changes, while the interaction between vegetation coverage and precipitation exerted the most significant influence on the variability of SOC content. Furthermore, the influence of mining intensity combined with precipitation was 10 times higher than that of mining intensity alone.}, language = {en} } @article{Ibebuchi2021, author = {Ibebuchi, Chibuike Chiedozie}, title = {Circulation pattern controls of wet days and dry days in Free State, South Africa}, series = {Meteorology and Atmospheric Physics}, volume = {133}, journal = {Meteorology and Atmospheric Physics}, number = {5}, issn = {1436-5065}, doi = {10.1007/s00703-021-00822-0}, url = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-268552}, pages = {1469-1480}, year = {2021}, abstract = {Atmospheric circulation is a vital process in the transport of heat, moisture, and pollutants around the globe. The variability of rainfall depends to some extent on the atmospheric circulation. This paper investigates synoptic situations in southern Africa that can be associated with wet days and dry days in Free State, South Africa, in addition to the underlying dynamics. Principal component analysis was applied to the T-mode matrix (variable is time series and observation is grid points at which the field was observed) of daily mean sea level pressure field from 1979 to 2018 in classifying the circulation patterns in southern Africa. 18 circulation types (CTs) were classified in the study region. From the linkage of the CTs to the observed rainfall data, from 11 stations in Free State, it was found that dominant austral winter and late austral autumn CTs have a higher probability of being associated with dry days in Free State. Dominant austral summer and late austral spring CTs were found to have a higher probability of being associated with wet days in Free State. Cyclonic/anti-cyclonic activity over the southwest Indian Ocean, explained to a good extent, the inter-seasonal variability of rainfall in Free State. The synoptic state associated with a stronger anti-cyclonic circulation at the western branch of the South Indian Ocean high-pressure, during austral summer, leading to enhanced low-level moisture transport by southeast winds was found to have the highest probability of being associated with above-average rainfall in most regions in Free State. On the other hand, the synoptic state associated with enhanced transport of cold dry air, by the extratropical westerlies, was found to have the highest probability of being associated with (winter) dryness in Free State.}, language = {en} } @article{LatifiValbuena2019, author = {Latifi, Hooman and Valbuena, Ruben}, title = {Current trends in forest ecological applications of three-dimensional remote sensing: Transition from experimental to operational solutions?}, series = {Forests}, volume = {10}, journal = {Forests}, number = {10}, issn = {1999-4907}, doi = {10.3390/f10100891}, url = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-193282}, year = {2019}, abstract = {The alarming increase in the magnitude and spatiotemporal patterns of changes in composition, structure and function of forest ecosystems during recent years calls for enhanced cross-border mitigation and adaption measures, which strongly entail intensified research to understand the underlying processes in the ecosystems as well as their dynamics. Remote sensing data and methods are nowadays the main complementary sources of synoptic, up-to-date and objective information to support field observations in forest ecology. In particular, analysis of three-dimensional (3D) remote sensing data is regarded as an appropriate complement, since they are hypothesized to resemble the 3D character of most forest attributes. Following their use in various small-scale forest structural analyses over the past two decades, these sources of data are now on their way to be integrated in novel applications in fields like citizen science, environmental impact assessment, forest fire analysis, and biodiversity assessment in remote areas. These and a number of other novel applications provide valuable material for the Forests special issue "3D Remote Sensing Applications in Forest Ecology: Composition, Structure and Function", which shows the promising future of these technologies and improves our understanding of the potentials and challenges of 3D remote sensing in practical forest ecology worldwide.}, language = {en} } @article{BucheltBloetheKuenzeretal.2023, author = {Buchelt, Sebastian and Bl{\"o}the, Jan Henrik and Kuenzer, Claudia and Schmitt, Andreas and Ullmann, Tobias and Philipp, Marius and Kneisel, Christof}, title = {Deciphering small-scale seasonal surface dynamics of rock glaciers in the Central European Alps using DInSAR time series}, series = {Remote Sensing}, volume = {15}, journal = {Remote Sensing}, number = {12}, issn = {2072-4292}, doi = {10.3390/rs15122982}, url = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-362939}, year = {2023}, abstract = {The Essential Climate Variable (ECV) Permafrost is currently undergoing strong changes due to rising ground and air temperatures. Surface movement, forming characteristic landforms such as rock glaciers, is one key indicator for mountain permafrost. Monitoring this movement can indicate ongoing changes in permafrost; therefore, rock glacier velocity (RGV) has recently been added as an ECV product. Despite the increased understanding of rock glacier dynamics in recent years, most observations are either limited in terms of the spatial coverage or temporal resolution. According to recent studies, Sentinel-1 (C-band) Differential SAR Interferometry (DInSAR) has potential for monitoring RGVs at high spatial and temporal resolutions. However, the suitability of DInSAR for the detection of heterogeneous small-scale spatial patterns of rock glacier velocities was never at the center of these studies. We address this shortcoming by generating and analyzing Sentinel-1 DInSAR time series over five years to detect small-scale displacement patterns of five high alpine permafrost environments located in the Central European Alps on a weekly basis at a range of a few millimeters. Our approach is based on a semi-automated procedure using open-source programs (SNAP, pyrate) and provides East-West displacement and elevation change with a ground sampling distance of 5 m. Comparison with annual movement derived from orthophotos and unpiloted aerial vehicle (UAV) data shows that DInSAR covers about one third of the total movement, which represents the proportion of the year suited for DInSAR, and shows good spatial agreement (Pearson R: 0.42-0.74, RMSE: 4.7-11.6 cm/a) except for areas with phase unwrapping errors. Moreover, the DInSAR time series unveils spatio-temporal variations and distinct seasonal movement dynamics related to different drivers and processes as well as internal structures. Combining our approach with in situ observations could help to achieve a more holistic understanding of rock glacier dynamics and to assess the future evolution of permafrost under changing climatic conditions.}, language = {en} } @article{KleemannZamoraVillacisChiluisaetal.2022, author = {Kleemann, Janina and Zamora, Camilo and Villacis-Chiluisa, Alexandra Belen and Cuenca, Pablo and Koo, Hongmi and Noh, Jin Kyoung and F{\"u}rst, Christine and Thiel, Michael}, title = {Deforestation in continental Ecuador with a focus on protected areas}, series = {Land}, volume = {11}, journal = {Land}, number = {2}, issn = {2073-445X}, doi = {10.3390/land11020268}, url = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-262078}, year = {2022}, abstract = {Forest conservation is of particular concern in tropical regions where a large refuge of biodiversity is still existing. These areas are threatened by deforestation, forest degradation and fragmentation. Especially, pressures of anthropogenic activities adjacent to these areas significantly influence conservation effectiveness. Ecuador was chosen as study area since it is a globally relevant center of forest ecosystems and biodiversity. We identified hotspots of deforestation on the national level of continental Ecuador between 1990 and 2018, analyzed the most significant drivers of deforestation on national and biome level (the Coast, the Andes, The Amazon) as well as inside protected areas in Ecuador by using multiple regression analysis. We separated the national system of protected areas (SNAP) into higher and lower protection levels. Besides SNAP, we also considered Biosphere Reserves (BRs) and Ramsar sites. In addition, we investigated the rates and spatial patterns of deforestation in protected areas and buffer zones (5 km and 10 km outwards the protected area boundaries) using landscape metrics. Between 1990 and 2018, approximately 4\% of the accumulated deforestation occurred within the boundaries of SNAP, and up to 25.5\% in buffer zones. The highest rates of deforestation have been found in the 5 km buffer zone around the protected areas with the highest protection level. Protected areas and their buffer zones with higher protection status were identified as the most deforested areas among SNAP. BRs had the highest deforestation rates among all protected areas but most of these areas just became BRs after the year 2000. The most important driver of deforestation is agriculture. Other relevant drivers differ between the biomes. The results suggest that the SNAP is generally effective to prevent deforestation within their protection boundaries. However, deforestation around protected areas can undermine conservation strategies to sustain biodiversity. Actions to address such dynamics and patterns of deforestation and forest fragmentation, and developing conservation strategies of their landscape context are urgently needed especially in the buffer zones of areas with the highest protection status.}, language = {en} } @article{RoeschPlank2022, author = {R{\"o}sch, Moritz and Plank, Simon}, title = {Detailed mapping of lava and ash deposits at Indonesian volcanoes by means of VHR PlanetScope change detection}, series = {Remote Sensing}, volume = {14}, journal = {Remote Sensing}, number = {5}, issn = {2072-4292}, doi = {10.3390/rs14051168}, url = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-262232}, year = {2022}, abstract = {Mapping of lava flows in unvegetated areas of active volcanoes using optical satellite data is challenging due to spectral similarities of volcanic deposits and the surrounding background. Using very high-resolution PlanetScope data, this study introduces a novel object-oriented classification approach for mapping lava flows in both vegetated and unvegetated areas during several eruptive phases of three Indonesian volcanoes (Karangetang 2018/2019, Agung 2017, Krakatau 2018/2019). For this, change detection analysis based on PlanetScope imagery for mapping loss of vegetation due to volcanic activity (e.g., lava flows) is combined with the analysis of changes in texture and brightness, with hydrological runoff modelling and with analysis of thermal anomalies derived from Sentinel-2 or Landsat-8. Qualitative comparison of the mapped lava flows showed good agreement with multispectral false color time series (Sentinel-2 and Landsat-8). Reports of the Global Volcanism Program support the findings, indicating the developed lava mapping approach produces valuable results for monitoring volcanic hazards. Despite the lack of bands in infrared wavelengths, PlanetScope proves beneficial for the assessment of risk and near-real-time monitoring of active volcanoes due to its high spatial (3 m) and temporal resolution (mapping of all subaerial volcanoes on a daily basis).}, language = {en} } @article{RiyasSyedKumaretal.2021, author = {Riyas, Moidu Jameela and Syed, Tajdarul Hassan and Kumar, Hrishikesh and Kuenzer, Claudia}, title = {Detecting and analyzing the evolution of subsidence due to coal fires in Jharia coalfield, India using Sentinel-1 SAR data}, series = {Remote Sensing}, volume = {13}, journal = {Remote Sensing}, number = {8}, issn = {2072-4292}, doi = {10.3390/rs13081521}, url = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-236703}, year = {2021}, abstract = {Public safety and socio-economic development of the Jharia coalfield (JCF) in India is critically dependent on precise monitoring and comprehensive understanding of coal fires, which have been burning underneath for more than a century. This study utilizes New-Small BAseline Subset (N-SBAS) technique to compute surface deformation time series for 2017-2020 to characterize the spatiotemporal dynamics of coal fires in JCF. The line-of-sight (LOS) surface deformation estimated from ascending and descending Sentinel-1 SAR data are subsequently decomposed to derive precise vertical subsidence estimates. The most prominent subsidence (~22 cm) is observed in Kusunda colliery. The subsidence regions also correspond well with the Landsat-8 based thermal anomaly map and field evidence. Subsequently, the vertical surface deformation time-series is analyzed to characterize temporal variations within the 9.5 km\(^2\) area of coal fires. Results reveal that nearly 10\% of the coal fire area is newly formed, while 73\% persisted throughout the study period. Vulnerability analyses performed in terms of the susceptibility of the population to land surface collapse demonstrate that Tisra, Chhatatanr, and Sijua are the most vulnerable towns. Our results provide critical information for developing early warning systems and remediation strategies.}, language = {en} } @article{MayrKleinRutzingeretal.2021, author = {Mayr, Stefan and Klein, Igor and Rutzinger, Martin and Kuenzer, Claudia}, title = {Determining temporal uncertainty of a global inland surface water time series}, series = {Remote Sensing}, volume = {13}, journal = {Remote Sensing}, number = {17}, issn = {2072-4292}, doi = {10.3390/rs13173454}, url = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-245234}, year = {2021}, abstract = {Earth observation time series are well suited to monitor global surface dynamics. However, data products that are aimed at assessing large-area dynamics with a high temporal resolution often face various error sources (e.g., retrieval errors, sampling errors) in their acquisition chain. Addressing uncertainties in a spatiotemporal consistent manner is challenging, as extensive high-quality validation data is typically scarce. Here we propose a new method that utilizes time series inherent information to assess the temporal interpolation uncertainty of time series datasets. For this, we utilized data from the DLR-DFD Global WaterPack (GWP), which provides daily information on global inland surface water. As the time series is primarily based on optical MODIS (Moderate Resolution Imaging Spectroradiometer) images, the requirement of data gap interpolation due to clouds constitutes the main uncertainty source of the product. With a focus on different temporal and spatial characteristics of surface water dynamics, seven auxiliary layers were derived. Each layer provides probability and reliability estimates regarding water observations at pixel-level. This enables the quantification of uncertainty corresponding to the full spatiotemporal range of the product. Furthermore, the ability of temporal layers to approximate unknown pixel states was evaluated for stratified artificial gaps, which were introduced into the original time series of four climatologic diverse test regions. Results show that uncertainty is quantified accurately (>90\%), consequently enhancing the product's quality with respect to its use for modeling and the geoscientific community.}, language = {en} } @article{HolzwarthThonfeldAbdullahietal.2020, author = {Holzwarth, Stefanie and Thonfeld, Frank and Abdullahi, Sahra and Asam, Sarah and Da Ponte Canova, Emmanuel and Gessner, Ursula and Huth, Juliane and Kraus, Tanja and Leutner, Benjamin and Kuenzer, Claudia}, title = {Earth Observation based monitoring of forests in Germany: a review}, series = {Remote Sensing}, volume = {12}, journal = {Remote Sensing}, number = {21}, issn = {2072-4292}, doi = {10.3390/rs12213570}, url = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-216334}, year = {2020}, abstract = {Forests in Germany cover around 11.4 million hectares and, thus, a share of 32\% of Germany's surface area. Therefore, forests shape the character of the country's cultural landscape. Germany's forests fulfil a variety of functions for nature and society, and also play an important role in the context of climate levelling. Climate change, manifested via rising temperatures and current weather extremes, has a negative impact on the health and development of forests. Within the last five years, severe storms, extreme drought, and heat waves, and the subsequent mass reproduction of bark beetles have all seriously affected Germany's forests. Facing the current dramatic extent of forest damage and the emerging long-term consequences, the effort to preserve forests in Germany, along with their diversity and productivity, is an indispensable task for the government. Several German ministries have and plan to initiate measures supporting forest health. Quantitative data is one means for sound decision-making to ensure the monitoring of the forest and to improve the monitoring of forest damage. In addition to existing forest monitoring systems, such as the federal forest inventory, the national crown condition survey, and the national forest soil inventory, systematic surveys of forest condition and vulnerability at the national scale can be expanded with the help of a satellite-based earth observation. In this review, we analysed and categorized all research studies published in the last 20 years that focus on the remote sensing of forests in Germany. For this study, 166 citation indexed research publications have been thoroughly analysed with respect to publication frequency, location of studies undertaken, spatial and temporal scale, coverage of the studies, satellite sensors employed, thematic foci of the studies, and overall outcomes, allowing us to identify major research and geoinformation product gaps.}, language = {en} } @article{AppelHardaker2022, author = {Appel, Alexandra and Hardaker, Sina}, title = {Einzelhandel als Katalysator f{\"u}r nachhaltige urbane Radlogistik? - W{\"u}Livery, ein Fallbeispiel aus W{\"u}rzburg}, series = {Standort}, volume = {46}, journal = {Standort}, number = {1}, issn = {1432-220X}, doi = {10.1007/s00548-021-00758-y}, url = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-268437}, pages = {9-15}, year = {2022}, abstract = {Die Covid-19-Pandemie gilt in vielen gesellschaftlichen Teilbereichen als Beschleuniger f{\"u}r Transformationsprozesse. Auch im Bereich der Organisation urbaner Logistik und Einzelhandelslandschaften etablieren sich neue Akteur*innen und Funktionen. Logistiker*innen integrieren lokale Onlinemarktpl{\"a}tze in ihre Profile und der station{\"a}re Einzelhandel generiert Wettbewerbsf{\"a}higkeit gegen{\"u}ber großen Onlineh{\"a}ndler*innen {\"u}ber die Nutzung lokaler Radlogistiknetzwerke, mittels derer Lieferungen noch am Tag der Bestellung (Same-Day-Delivery) verteilt werden k{\"o}nnen. Damit leisten die involvierten Akteur*innen potenziell auch einen Beitrag zur Nachhaltigkeitstransformation im Bereich urbaner Logistiksysteme. Im Fokus steht das Fallbeispiel W{\"u}Livery, ein Kooperationsprojekt des Stadtmarketingvereins, der Wirtschaftsf{\"o}rderung, Radlogistiker*innen sowie Einzelh{\"a}ndler*innen in W{\"u}rzburg, welches w{\"a}hrend des zweiten coronabedingten Lockdowns im November 2020 umgesetzt wurde. Die entstehenden Dynamiken und Organisationsformen werden auf Basis von 11 Expert*inneninterviews dargestellt und analysiert. Es kann gezeigt werden, dass st{\"a}dtische Akteur*innen grundlegende Mediator*innen f{\"u}r Transformationsprozesse darstellen und Einzelh{\"a}ndler*innen und lokale Onlinemarktpl{\"a}tze als Katalysator*innen fungieren k{\"o}nnen. Das ist auch vor dem Hintergrund planerischer und politischer Kommunikationsprozesse zur Legitimation neuer Verkehrsinfrastrukturen nutzbar, da die einzelnen Akteur*innengruppen in Austausch kommen und ein gesteigertes Bewusstsein f{\"u}r die jeweiligen Bedarfe entsteht.}, language = {de} } @article{AnsahAbuKleemannetal.2022, author = {Ansah, Christabel Edena and Abu, Itohan-Osa and Kleemann, Janina and Mahmoud, Mahmoud Ibrahim and Thiel, Michael}, title = {Environmental contamination of a biodiversity hotspot — action needed for nature conservation in the Niger Delta, Nigeria}, series = {Sustainability}, volume = {14}, journal = {Sustainability}, number = {21}, issn = {2071-1050}, doi = {10.3390/su142114256}, url = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-297214}, year = {2022}, abstract = {The Niger Delta belongs to the largest swamp and mangrove forests in the world hosting many endemic and endangered species. Therefore, its conservation should be of highest priority. However, the Niger Delta is confronted with overexploitation, deforestation and pollution to a large extent. In particular, oil spills threaten the biodiversity, ecosystem services, and local people. Remote sensing can support the detection of spills and their potential impact when accessibility on site is difficult. We tested different vegetation indices to assess the impact of oil spills on the land cover as well as to detect accumulations (hotspots) of oil spills. We further identified which species, land cover types, and protected areas could be threatened in the Niger Delta due to oil spills. The results showed that the Enhanced Vegetation Index, the Normalized Difference Vegetation Index, and the Soil Adjusted Vegetation Index were more sensitive to the effects of oil spills on different vegetation cover than other tested vegetation indices. Forest cover was the most affected land-cover type and oil spills also occurred in protected areas. Threatened species are inhabiting the Niger Delta Swamp Forest and the Central African Mangroves that were mainly affected by oil spills and, therefore, strong conservation measures are needed even though security issues hamper the monitoring and control.}, language = {en} } @article{GlaserSponholz1993, author = {Glaser, R{\"u}diger and Sponholz, Barbara}, title = {Erste Untersuchungen von Hangrutschungen an der Frankenh{\"o}he}, url = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-53615}, year = {1993}, abstract = {Der vorliegende Beitrag faßt den derzeitigen Stand der Untersuchungen von Hangrutschungen im Bereich der Frankenh{\"o}he, die im Rahmen des EPOCH-Programmes durchgef{\"u}hrt wurden, zusammen. Nach einer Inventarisierung der regionalen Rutschungsereignisse wird die Rutschung bei Obergailnau in einer geomorphologischen Detailkartierung vorgestellt. F{\"u}r die Ausl{\"o}sung der Rutschung kommen mehrere Faktoren in Betracht: neben einer erh{\"o}hten Rutschungsanf{\"a}lligkeit aufgrund der geologisch-tektonischen Verh{\"a}ltnisse muß v.a. auch eine Einflußnahme durch die Landnutzung mit ber{\"u}cksichtigt werden. Dazu z{\"a}hlen Steinbrucharbeiten in unmittelbarer N{\"a}he der Rutschung, aber auch Wasserbaumaßnahmen am Schloßberg. In diesem potentielllabilisierten Gebiet kam es nach {\"u}berdurchschnittlichen Niederschl{\"a}gen Anfang 1958 zu einer {\"U}berschreitung der Belastungsgrenze des Hanges, die sich in einer großfl{\"a}chigen Rutschung {\"a}ußerte. Die weiteren Untersuchungen sollen zeigen, ob sich die f{\"u}r Obergailnau herausgestellten Faktorenkomplexe im regionalen Rahmen verifizieren lassen.}, subject = {Geographie}, language = {de} } @article{AbdullahiWesselHuberetal.2019, author = {Abdullahi, Sahra and Wessel, Birgit and Huber, Martin and Wendleder, Anna and Roth, Achim and Kuenzer, Claudia}, title = {Estimating penetration-related X-band InSAR elevation bias: a study over the Greenland ice sheet}, series = {Remote Sensing}, volume = {11}, journal = {Remote Sensing}, number = {24}, issn = {2072-4292}, doi = {10.3390/rs11242903}, url = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-193902}, year = {2019}, abstract = {Accelerating melt on the Greenland ice sheet leads to dramatic changes at a global scale. Especially in the last decades, not only the monitoring, but also the quantification of these changes has gained considerably in importance. In this context, Interferometric Synthetic Aperture Radar (InSAR) systems complement existing data sources by their capability to acquire 3D information at high spatial resolution over large areas independent of weather conditions and illumination. However, penetration of the SAR signals into the snow and ice surface leads to a bias in measured height, which has to be corrected to obtain accurate elevation data. Therefore, this study purposes an easy transferable pixel-based approach for X-band penetration-related elevation bias estimation based on single-pass interferometric coherence and backscatter intensity which was performed at two test sites on the Northern Greenland ice sheet. In particular, the penetration bias was estimated using a multiple linear regression model based on TanDEM-X InSAR data and IceBridge laser-altimeter measurements to correct TanDEM-X Digital Elevation Model (DEM) scenes. Validation efforts yielded good agreement between observations and estimations with a coefficient of determination of R\(^2\) = 68\% and an RMSE of 0.68 m. Furthermore, the study demonstrates the benefits of X-band penetration bias estimation within the application context of ice sheet elevation change detection.}, language = {en} } @article{TaubenboeckWurmNetzbandetal.2011, author = {Taubenb{\"o}ck, H and Wurm, M and Netzband, M and Zwenzner, H and Roth, A and Rahman, A and Dech, S}, title = {Flood risks in urbanized areas - multi-sensoral approaches using remotely sensed data for risk assessment}, series = {NATURAL HAZARDS AND EARTH SYSTEM SCIENCES}, volume = {11}, journal = {NATURAL HAZARDS AND EARTH SYSTEM SCIENCES}, number = {2}, doi = {10.5194/nhess-11-431-2011}, url = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-139605}, pages = {431-444}, year = {2011}, abstract = {Estimating flood risks and managing disasters combines knowledge in climatology, meteorology, hydrology, hydraulic engineering, statistics, planning and geography - thus a complex multi-faceted problem. This study focuses on the capabilities of multi-source remote sensing data to support decision-making before, during and after a flood event. With our focus on urbanized areas, sample methods and applications show multi-scale products from the hazard and vulnerability perspective of the risk framework. From the hazard side, we present capabilities with which to assess flood-prone areas before an expected disaster. Then we map the spatial impact during or after a flood and finally, we analyze damage grades after a flood disaster. From the vulnerability side, we monitor urbanization over time on an urban footprint level, classify urban structures on an individual building level, assess building stability and quantify probably affected people. The results show a large database for sustainable development and for developing mitigation strategies, ad-hoc coordination of relief measures and organizing rehabilitation.}, language = {en} } @article{KoehlerKuenzer2020, author = {Koehler, Jonas and Kuenzer, Claudia}, title = {Forecasting spatio-temporal dynamics on the land surface using Earth Observation data — a review}, series = {Remote Sensing}, volume = {12}, journal = {Remote Sensing}, number = {21}, issn = {2072-4292}, doi = {10.3390/rs12213513}, url = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-216285}, year = {2020}, abstract = {Reliable forecasts on the impacts of global change on the land surface are vital to inform the actions of policy and decision makers to mitigate consequences and secure livelihoods. Geospatial Earth Observation (EO) data from remote sensing satellites has been collected continuously for 40 years and has the potential to facilitate the spatio-temporal forecasting of land surface dynamics. In this review we compiled 143 papers on EO-based forecasting of all aspects of the land surface published in 16 high-ranking remote sensing journals within the past decade. We analyzed the literature regarding research focus, the spatial scope of the study, the forecasting method applied, as well as the temporal and technical properties of the input data. We categorized the identified forecasting methods according to their temporal forecasting mechanism and the type of input data. Time-lagged regressions which are predominantly used for crop yield forecasting and approaches based on Markov Chains for future land use and land cover simulation are the most established methods. The use of external climate projections allows the forecasting of numerical land surface parameters up to one hundred years into the future, while auto-regressive time series modeling can account for intra-annual variances. Machine learning methods have been increasingly used in all categories and multivariate modeling that integrates multiple data sources appears to be more popular than univariate auto-regressive modeling despite the availability of continuously expanding time series data. Regardless of the method, reliable EO-based forecasting requires high-level remote sensing data products and the resulting computational demand appears to be the main reason that most forecasts are conducted only on a local scale. In the upcoming years, however, we expect this to change with further advances in the field of machine learning, the publication of new global datasets, and the further establishment of cloud computing for data processing.}, language = {en} } @article{KacicKuenzer2022, author = {Kacic, Patrick and Kuenzer, Claudia}, title = {Forest biodiversity monitoring based on remotely sensed spectral diversity — a review}, series = {Remote Sensing}, volume = {14}, journal = {Remote Sensing}, number = {21}, issn = {2072-4292}, doi = {10.3390/rs14215363}, url = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-290535}, year = {2022}, abstract = {Forests are essential for global environmental well-being because of their rich provision of ecosystem services and regulating factors. Global forests are under increasing pressure from climate change, resource extraction, and anthropologically-driven disturbances. The results are dramatic losses of habitats accompanied with the reduction of species diversity. There is the urgent need for forest biodiversity monitoring comprising analysis on α, β, and γ scale to identify hotspots of biodiversity. Remote sensing enables large-scale monitoring at multiple spatial and temporal resolutions. Concepts of remotely sensed spectral diversity have been identified as promising methodologies for the consistent and multi-temporal analysis of forest biodiversity. This review provides a first time focus on the three spectral diversity concepts "vegetation indices", "spectral information content", and "spectral species" for forest biodiversity monitoring based on airborne and spaceborne remote sensing. In addition, the reviewed articles are analyzed regarding the spatiotemporal distribution, remote sensing sensors, temporal scales and thematic foci. We identify multispectral sensors as primary data source which underlines the focus on optical diversity as a proxy for forest biodiversity. Moreover, there is a general conceptual focus on the analysis of spectral information content. In recent years, the spectral species concept has raised attention and has been applied to Sentinel-2 and MODIS data for the analysis from local spectral species to global spectral communities. Novel remote sensing processing capacities and the provision of complementary remote sensing data sets offer great potentials for large-scale biodiversity monitoring in the future.}, language = {en} } @article{KacicThonfeldGessneretal.2023, author = {Kacic, Patrick and Thonfeld, Frank and Gessner, Ursula and Kuenzer, Claudia}, title = {Forest structure characterization in Germany: novel products and analysis based on GEDI, Sentinel-1 and Sentinel-2 data}, series = {Remote Sensing}, volume = {15}, journal = {Remote Sensing}, number = {8}, issn = {2072-4292}, doi = {10.3390/rs15081969}, url = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-313727}, year = {2023}, abstract = {Monitoring forest conditions is an essential task in the context of global climate change to preserve biodiversity, protect carbon sinks and foster future forest resilience. Severe impacts of heatwaves and droughts triggering cascading effects such as insect infestation are challenging the semi-natural forests in Germany. As a consequence of repeated drought years since 2018, large-scale canopy cover loss has occurred calling for an improved disturbance monitoring and assessment of forest structure conditions. The present study demonstrates the potential of complementary remote sensing sensors to generate wall-to-wall products of forest structure for Germany. The combination of high spatial and temporal resolution imagery from Sentinel-1 (Synthetic Aperture Radar, SAR) and Sentinel-2 (multispectral) with novel samples on forest structure from the Global Ecosystem Dynamics Investigation (GEDI, LiDAR, Light detection and ranging) enables the analysis of forest structure dynamics. Modeling the three-dimensional structure of forests from GEDI samples in machine learning models reveals the recent changes in German forests due to disturbances (e.g., canopy cover degradation, salvage logging). This first consistent data set on forest structure for Germany from 2017 to 2022 provides information of forest canopy height, forest canopy cover and forest biomass and allows estimating recent forest conditions at 10 m spatial resolution. The wall-to-wall maps of the forest structure support a better understanding of post-disturbance forest structure and forest resilience.}, language = {en} } @article{KhareLatifiRossietal.2019, author = {Khare, Siddhartha and Latifi, Hooman and Rossi, Sergio and Ghosh, Sanjay Kumar}, title = {Fractional cover mapping of invasive plant species by combining very high-resolution stereo and multi-sensor multispectral imageries}, series = {Forests}, volume = {10}, journal = {Forests}, number = {7}, issn = {1999-4907}, doi = {10.3390/f10070540}, url = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-197250}, year = {2019}, abstract = {Invasive plant species are major threats to biodiversity. They can be identified and monitored by means of high spatial resolution remote sensing imagery. This study aimed to test the potential of multiple very high-resolution (VHR) optical multispectral and stereo imageries (VHRSI) at spatial resolutions of 1.5 and 5 m to quantify the presence of the invasive lantana (Lantana camara L.) and predict its distribution at large spatial scale using medium-resolution fractional cover analysis. We created initial training data for fractional cover analysis by classifying smaller extent VHR data (SPOT-6 and RapidEye) along with three dimensional (3D) VHRSI derived digital surface model (DSM) datasets. We modelled the statistical relationship between fractional cover and spectral reflectance for a VHR subset of the study area located in the Himalayan region of India, and finally predicted the fractional cover of lantana based on the spectral reflectance of Landsat-8 imagery of a larger spatial extent. We classified SPOT-6 and RapidEye data and used the outputs as training data to create continuous field layers of Landsat-8 imagery. The area outside the overlapping region was predicted by fractional cover analysis due to the larger extent of Landsat-8 imagery compared with VHR datasets. Results showed clear discrimination of understory lantana from upperstory vegetation with 87.38\% (for SPOT-6), and 85.27\% (for RapidEye) overall accuracy due to the presence of additional VHRSI derived DSM information. Independent validation for lantana fractional cover estimated root-mean-square errors (RMSE) of 11.8\% (for RapidEye) and 7.22\% (for SPOT-6), and R\(^2\) values of 0.85 and 0.92 for RapidEye (5 m) and SPOT-6 (1.5 m), respectively. Results suggested an increase in predictive accuracy of lantana within forest areas along with increase in the spatial resolution for the same Landsat-8 imagery. The variance explained at 1.5 m spatial resolution to predict lantana was 64.37\%, whereas it decreased by up to 37.96\% in the case of 5 m spatial resolution data. This study revealed the high potential of combining small extent VHR and VHRSI- derived 3D optical data with larger extent, freely available satellite data for identification and mapping of invasive species in mountainous forests and remote regions.}, language = {en} } @article{RemelgadoSafiWegmann2020, author = {Remelgado, Ruben and Safi, Kamran and Wegmann, Martin}, title = {From ecology to remote sensing: using animals to map land cover}, series = {Remote Sensing in Ecology and Conservation}, volume = {6}, journal = {Remote Sensing in Ecology and Conservation}, number = {1}, doi = {10.1002/rse2.126}, url = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-225200}, pages = {93-104}, year = {2020}, abstract = {Land cover is a key variable in monitoring applications and new processing technologies made deriving this information easier. Yet, classification algorithms remain dependent on samples collected on the field and field campaigns are limited by financial, infrastructural and political boundaries. Here, animal tracking data could be an asset. Looking at the land cover dependencies of animal behaviour, we can obtain land cover samples over places that are difficult to access. Following this premise, we evaluated the potential of animal movement data to map land cover. Specifically, we used 13 White Storks (Cicona cicona) individuals of the same population to map agriculture within three test regions distributed along their migratory track. The White Stork has adapted to foraging over agricultural lands, making it an ideal source of samples to map this land use. We applied a presence-absence modelling approach over a Normalized Difference Vegetation Index (NDVI) time series and validated our classifications, with high-resolution land cover information. Our results suggest White Stork movement is useful to map agriculture, however, we identified some limitations. We achieved high accuracies (F1-scores > 0.8) for two test regions, but observed poor results over one region. This can be explained by differences in land management practices. The animals preferred agriculture in every test region, but our data showed a biased distribution of training samples between irrigated and non-irrigated land. When both options occurred, the animals disregarded non-irrigated land leading to its misclassification as non-agriculture. Additionally, we found difference between the GPS observation dates and the harvest times for non-irrigated crops. Given the White Stork takes advantage of managed land to search for prey, the inactivity of these fields was the likely culprit of their underrepresentation. Including more species attracted to agriculture - with other land-use dependencies and observation times - can contribute to better results in similar applications.}, language = {en} } @article{SponholzBaumhauerFelixHennignsen1993, author = {Sponholz, Barbara and Baumhauer, Roland and Felix-Hennignsen, P.}, title = {Fulgurites in the southern central Sahara, Republic of Niger and their palaeoenvironmental significance}, url = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-63337}, year = {1993}, abstract = {The mineralogical and chemical characteristics of fulgurites ( = natural glasses forrned by lightning strikes to the ground) from the southern Centrat Sahara (Niger) are presented. The fulgurites are indicators of thunderstorms. The northernmost important fulgurite formation in the study area reached up to about l8°N, with decreasing fulgurite concentration from south to north. Their distribution pattern and the relative dating of their formation in relation to Iandscape history from the Late Pleistocene onwards (e.g., palaeolakes, palaeosols), and to Neolithic settlement reveals their value as palaeoenvironmental indicators. They indicate: (1) local palaeoenvironmental conditions depending on the topographical situation in a complex dune relief; (2) climatic change during the mid-Holocene from northerly rains to southerly rains; and (3) the northernmost Iimit of important thunderstorrns and rainfall activity since this time in the southern Centrat Sahara.}, subject = {Sahara}, language = {en} } @article{HaggMayrMannigetal.2018, author = {Hagg, Wilfried and Mayr, Elisabeth and Mannig, Birgit and Reyers, Mark and Schubert, David and Pinto, Joaquim G. and Peters, Juliane and Pieczonka, Tino and Juen, Martin and Bolch, Tobias and Paeth, Heiko and Mayer, Christoph}, title = {Future climate change and its impact on runoff generation from the debris-covered Inylchek glaciers, Central Tian Shan, Kyrgyzstan}, series = {Water}, volume = {10}, journal = {Water}, number = {11}, issn = {2073-4441}, doi = {10.3390/w10111513}, url = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-197592}, pages = {1513}, year = {2018}, abstract = {The heavily debris-covered Inylchek glaciers in the central Tian Shan are the largest glacier system in the Tarim catchment. It is assumed that almost 50\% of the discharge of Tarim River are provided by glaciers. For this reason, climatic changes, and thus changes in glacier mass balance and glacier discharge are of high impact for the whole region. In this study, a conceptual hydrological model able to incorporate discharge from debris-covered glacier areas is presented. To simulate glacier melt and subsequent runoff in the past (1970/1971-1999/2000) and future (2070/2071-2099/2100), meteorological input data were generated based on ECHAM5/MPI-OM1 global climate model projections. The hydrological model HBV-LMU was calibrated by an automatic calibration algorithm using runoff and snow cover information as objective functions. Manual fine-tuning was performed to avoid unrealistic results for glacier mass balance. The simulations show that annual runoff sums will increase significantly under future climate conditions. A sensitivity analysis revealed that total runoff does not decrease until the glacier area is reduced by 43\%. Ice melt is the major runoff source in the recent past, and its contribution will even increase in the coming decades. Seasonal changes reveal a trend towards enhanced melt in spring, but a change from a glacial-nival to a nival-pluvial runoff regime will not be reached until the end of this century.}, language = {en} } @article{SchuesslerKreuzerVejnaretal.1989, author = {Sch{\"u}ssler, Ulrich and Kreuzer, H.. and Vejnar, Z. and Okrusch, M. and Seidel, E. and Kopeck{\´y}, L. and Patzak, M.}, title = {Geochemische Untersuchungen und K-Ar Datierungen in der Zone Tepl-Taus}, url = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-81840}, year = {1989}, abstract = {no abstract available}, subject = {Tepl-Taus}, language = {de} } @article{TrappeKneisel2019, author = {Trappe, Julian and Kneisel, Christof}, title = {Geophysical and sedimentological investigations of Peatlands for the assessment of lithology and subsurface water pathways}, series = {Geosciences}, volume = {9}, journal = {Geosciences}, number = {3}, doi = {10.3390/geosciences9030118}, url = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-201699}, pages = {118}, year = {2019}, abstract = {Peatlands located on slopes (herein called slope bogs) are typical landscape units in the Hunsrueck, a low mountain range in Southwestern Germany. The pathways of the water feeding the slope bogs have not yet been documented and analyzed. The identification of the different mechanisms allowing these peatlands to originate and survive requires a better understanding of the subsurface lithology and hydrogeology. Hence, we applied a multi-method approach to two case study sites in order to characterize the subsurface lithology and to image the variable spatio-temporal hydrological conditions. The combination of Electrical Resistivity Tomography (ERT) and an ERT-Monitoring and Ground Penetrating Radar (GPR), in conjunction with direct methods and data (borehole drilling and meteorological data), allowed us to gain deeper insights into the subsurface characteristics and dynamics of the peatlands and their catchment area. The precipitation influences the hydrology of the peatlands as well as the interflow in the subsurface. Especially, the geoelectrical monitoring data, in combination with the precipitation and temperature data, indicate that there are several forces driving the hydrology and hydrogeology of the peatlands. While the water content of the uppermost layers changes with the weather conditions, the bottom layer seems to be more stable and changes to a lesser extent. At the selected case study sites, small differences in subsurface properties can have a huge impact on the subsurface hydrogeology and the water paths. Based on the collected data, conceptual models have been deduced for the two case study sites.}, language = {en} } @article{StereńczakLaurinChiricietal.2020, author = {Stereńczak, Krzysztof and Laurin, Gaia Vaglio and Chirici, Gherardo and Coomes, David A. and Dalponte, Michele and Latifi, Hooman and Puletti, Nicola}, title = {Global Airborne Laser Scanning Data Providers Database (GlobALS) — a new tool for monitoring ecosystems and biodiversity}, series = {Remote Sensing}, volume = {12}, journal = {Remote Sensing}, number = {11}, issn = {2072-4292}, doi = {10.3390/rs12111877}, url = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-207819}, year = {2020}, abstract = {Protection and recovery of natural resource and biodiversity requires accurate monitoring at multiple scales. Airborne Laser Scanning (ALS) provides high-resolution imagery that is valuable for monitoring structural changes to vegetation, providing a reliable reference for ecological analyses and comparison purposes, especially if used in conjunction with other remote-sensing and field products. However, the potential of ALS data has not been fully exploited, due to limits in data availability and validation. To bridge this gap, the global network for airborne laser scanner data (GlobALS) has been established as a worldwide network of ALS data providers that aims at linking those interested in research and applications related to natural resources and biodiversity monitoring. The network does not collect data itself but collects metadata and facilitates networking and collaborative research amongst the end-users and data providers. This letter describes this facility, with the aim of broadening participation in GlobALS.}, language = {en} } @article{SchuesslerTalarico1991, author = {Sch{\"u}ssler, Ulrich and Talarico, F.}, title = {Granulite facies rocks from the Ross orogenic belt, Northern-Victoria-Land, Antarctica}, url = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-81889}, year = {1991}, abstract = {no abstract available}, subject = {Geographie}, language = {en} } @article{StanleyUllmannLangeAthinodorou2021, author = {Stanley, Jean-Daniel and Ullmann, Tobias and Lange-Athinodorou, Eva}, title = {Holocene aridity-induced interruptions of human activity along a fluvial channel in Egypt's northern delta}, series = {Quaternary}, volume = {4}, journal = {Quaternary}, number = {4}, issn = {2571-550X}, doi = {10.3390/quat4040039}, url = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-250285}, year = {2021}, abstract = {Geoarchaeological information presented here pertains to a subsidiary Nile channel that once flowed west of the main Sebennitic distributary and discharged its water and sediments at Egypt's then north-central deltaic coast. Periodical paleoclimatic episodes during the later Middle and Upper Holocene included decreased rainfall and increased aridity that reduced the Nile's flow levels and thus likely disrupted nautical transport and anthropogenic activity along this channel. Such changes in this deltaic sector, positioned adjacent to the Levantine Basin in the Eastern Mediterranean, can be attributed to climatic shifts triggered as far as the North Atlantic to the west, and African highland source areas of the Egyptian Nile to the south. Of special interest in a study core recovered along the channel are several sediment sequences without anthropogenic material that are interbedded between strata comprising numerous potsherds. The former are interpreted here as markers of increased regional aridity and reduced Nile flow which could have periodically disrupted the regional distribution of goods and nautical activities. Such times occurred ~5000 years B.P., ~4200-4000 years B.P., ~3200-2800 years B.P., ~2300-2200 years B.P., and more recently. Periods comparable to these are also identified by altered proportions of pollen, isotopic and compositional components in different radiocarbon-dated Holocene cores recovered elsewhere in the Nile delta, the Levantine region to the east and north of Egypt, and in the Faiyum depression south of the delta.}, language = {en} } @article{AkhundzadahSoltaniAich2020, author = {Akhundzadah, Noor Ahmad and Soltani, Salim and Aich, Valentin}, title = {Impacts of climate change on the water resources of the Kunduz River Basin, Afghanistan}, series = {Climate}, volume = {8}, journal = {Climate}, number = {10}, issn = {2225-1154}, doi = {10.3390/cli8100102}, url = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-213199}, year = {2020}, abstract = {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.}, language = {en} } @article{AtaeeMaghsoudiLatifietal.2019, author = {Ataee, Mohammad Sadegh and Maghsoudi, Yasser and Latifi, Hooman and Fadaie, Farhad}, title = {Improving estimation accuracy of growing stock by multi-frequency SAR and multi-spectral data over Iran's heterogeneously-structured broadleaf Hyrcanian forests}, series = {Forests}, volume = {10}, journal = {Forests}, number = {8}, issn = {1999-4907}, doi = {10.3390/f10080641}, url = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-197212}, year = {2019}, abstract = {Via providing various ecosystem services, the old-growth Hyrcanian forests play a crucial role in the environment and anthropogenic aspects of Iran and beyond. The amount of growing stock volume (GSV) is a forest biophysical parameter with great importance in issues like economy, environmental protection, and adaptation to climate change. Thus, accurate and unbiased estimation of GSV is also crucial to be pursued across the Hyrcanian. Our goal was to investigate the potential of ALOS-2 and Sentinel-1's polarimetric features in combination with Sentinel-2 multi-spectral features for the GSV estimation in a portion of heterogeneously-structured and mountainous Hyrcanian forests. We used five different kernels by the support vector regression (nu-SVR) for the GSV estimation. Because each kernel differently models the parameters, we separately selected features for each kernel by a binary genetic algorithm (GA). We simultaneously optimized R\(^2\) and RMSE in a suggested GA fitness function. We calculated R\(^2\), RMSE to evaluate the models. We additionally calculated the standard deviation of validation metrics to estimate the model's stability. Also for models over-fitting or under-fitting analysis, we used mean difference (MD) index. The results suggested the use of polynomial kernel as the final model. Despite multiple methodical challenges raised from the composition and structure of the study site, we conclude that the combined use of polarimetric features (both dual and full) with spectral bands and indices can improve the GSV estimation over mixed broadleaf forests. This was partially supported by the use of proposed evaluation criterion within the GA, which helped to avoid the curse of dimensionality for the applied SVR and lowest over estimation or under estimation.}, language = {en} } @article{EmmertKneisel2021, author = {Emmert, Adrian and Kneisel, Christof}, title = {Internal structure and palsa development at Orravatnsr{\´u}stir Palsa Site (Central Iceland), investigated by means of integrated resistivity and ground-penetrating radar methods}, series = {Permafrost and Periglacial Processes}, volume = {32}, journal = {Permafrost and Periglacial Processes}, number = {3}, doi = {10.1002/ppp.2106}, url = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-238933}, pages = {503 -- 519}, year = {2021}, abstract = {The natural cyclical development of palsas makes it difficult to use visible signs of decay as reference points for environmental change. Thus, to determine the actual development stage of a palsa, investigations of the internal structure are crucial. Our study presents 2-D and 3-D electrical resistivity imaging (ERI) and 2-D ground-penetrating radar (GPR) results, measurements of surface and subsurface temperatures, and of the soil matric potential from Orravatnsr{\´u}stir Palsa Site in Central Iceland. By a joint interpretation of the results, we deduce the internal structure (i.e., thickness of thaw zone and permafrost, ice/water content) of five palsas of different size and shape. The results differentiate between initial and mature development stages and show that palsas of different development stages can exist in close proximity. While internal characteristics indicate undisturbed development of four palsas, one palsa shows indications of environmental change. Our study shows the value of the multimethod geophysical approach and introduces measurements of the soil matric potential as a promising method to assess the current state of the subsurface.}, language = {en} } @article{UsmanReimannLiedletal.2018, author = {Usman, Muhammad and Reimann, Thomas and Liedl, Rudolf and Abbas, Azhar and Conrad, Christopher and Saleem, Shoaib}, title = {Inverse parametrization of a regional groundwater flow model with the aid of modelling and GIS: test and application of different approaches}, series = {ISPRS International Journal of Geo-Information}, volume = {7}, journal = {ISPRS International Journal of Geo-Information}, number = {1}, doi = {10.3390/ijgi7010022}, url = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-175721}, pages = {22}, year = {2018}, abstract = {The use of inverse methods allow efficient model calibration. This study employs PEST to calibrate a large catchment scale transient flow model. Results are demonstrated by comparing manually calibrated approaches with the automated approach. An advanced Tikhonov regularization algorithm was employed for carrying out the automated pilot point (PP) method. The results indicate that automated PP is more flexible and robust as compared to other approaches. Different statistical indicators show that this method yields reliable calibration as values of coefficient of determination (R-2) range from 0.98 to 0.99, Nash Sutcliffe efficiency (ME) range from 0.964 to 0.976, and root mean square errors (RMSE) range from 1.68 m to 1.23 m, for manual and automated approaches, respectively. Validation results of automated PP show ME as 0.969 and RMSE as 1.31 m. The results of output sensitivity suggest that hydraulic conductivity is a more influential parameter. Considering the limitations of the current study, it is recommended to perform global sensitivity and linear uncertainty analysis for the better estimation of the modelling results.}, language = {en} } @article{KreuzerSeidelSchuessleretal.1989, author = {Kreuzer, Hans and Seidel, Eberhard and Sch{\"u}ssler, Ulrich and Okrusch, Martin and Lenz, Karl-Ludwig and Raschka, Helmut}, title = {K-Ar geochronology of different tectonic units at the northeastern margin of the Bohemian Massif}, url = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-31811}, year = {1989}, abstract = {No abstract available}, language = {en} } @article{BuscheSponholz1988, author = {Busche, Detlef and Sponholz, Barbara}, title = {Karsterscheinungen in nichtkarbonatischen Gesteinen der Republik Niger}, url = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-55858}, year = {1988}, abstract = {Vorgestellt werden L{\"o}sungsformen in karbonatfreien Sandsteinen und Eisenkrusten der {\"o}stlichen Republik Niger. Diese Formen haben eine außerordentlich weite Verbreitung und sind wesentliche Elemente der Landschaft. Beschrieben werden sowohl auf den Dachfl{\"a}chen der s{\"u}dsaharisch/sahelischen Schichtstufen entwickelte Depressionen mit subterraner Entw{\"a}sserung als auch an Wadi h{\"a}ngen und steilen Stufenabschnitten gekappte, horizontal bis schr{\"a}g verlaufende H{\"o}hlen und R{\"o}hren. Viele dieser L{\"o}sungsformen sind zumindest in Resten noch von einer Eisen- oder Kieselkruste ausgekleidet, die u.a. als Indiz f{\"u}r eine Entstehung der Formen im Grundwasserbereich angesehen werden kann. Die Anlage der Karstformen w{\"a}re demnach noch vor die Herauspr{\"a}parierung der Stufen und Inselberge im ausgehenden Terti{\"a}r zu stellen. Die Karstformen in nichtkarbonatischen Gesteinen gleichen bis ins Detail denen des Karbonatkarstes. Eine initiale Formung durch {\"a}olische oder fluviatile Prozesse oder durch Piping kann ausgeschlossen werden.}, subject = {Geographie}, language = {de} } @article{Sponholz1992, author = {Sponholz, Barbara}, title = {Karstverf{\"u}llungen in Ostniger}, url = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-53866}, year = {1992}, abstract = {Die Karstdepressionen auf den Dachfl{\"a}chen der Schichtstufen in Sahara und Sahel sind im allgemeinen von allochthonen quart{\"a}ren Lockermaterialien verf{\"u}llt. Die tieferen Verf{\"u}llungsschichten zeigen eine von Norden nach S{\"u}den zunehmende {\"U}berpr{\"a}gung durch Verwitterungs- und Bodenbildungsprozesse. Die obersten ca. 10 cm der Verf{\"u}llungen sind dagegen im ganzen Untersuchungsgebiet relativ uniform ausgebildet. Sie repr{\"a}sentieren die {\"a}olischen Ablagerungen seit der mittelholoz{\"a}nen Aridisierung. Drei Verfiillungsprofile (Seggedim, Termit-Dougoule und Koutous) werden vorgestellt und hinsichtlich ihrer pal{\"a}oklimatischen Aussagekraft {\"u}berpr{\"u}ft.}, subject = {Karst}, language = {de} } @article{HeinemannSiegmannThonfeldetal.2020, author = {Heinemann, Sascha and Siegmann, Bastian and Thonfeld, Frank and Muro, Javier and Jedmowski, Christoph and Kemna, Andreas and Kraska, Thorsten and Muller, Onno and Schultz, Johannes and Udelhoven, Thomas and Wilke, Norman and Rascher, Uwe}, title = {Land surface temperature retrieval for agricultural areas using a novel UAV platform equipped with a thermal infrared and multispectral sensor}, series = {Remote Sensing}, volume = {12}, journal = {Remote Sensing}, number = {7}, issn = {2072-4292}, doi = {10.3390/rs12071075}, url = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-203557}, year = {2020}, abstract = {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.}, language = {en} } @article{RemelgadoLeutnerSafietal.2018, author = {Remelgado, Ruben and Leutner, Benjamin and Safi, Kamran and Sonnenschein, Ruth and Kuebert, Carina and Wegmann, Martin}, title = {Linking animal movement and remote sensing - mapping resource suitability from a remote sensing perspective}, series = {Remote Sensing in Ecology and Conservation}, volume = {4}, journal = {Remote Sensing in Ecology and Conservation}, number = {3}, doi = {10.1002/rse2.70}, url = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-225199}, pages = {211-224}, year = {2018}, abstract = {Optical remote sensing is an important tool in the study of animal behavior providing ecologists with the means to understand species-environment interactions in combination with animal movement data. However, differences in spatial and temporal resolution between movement and remote sensing data limit their direct assimilation. In this context, we built a data-driven framework to map resource suitability that addresses these differences as well as the limitations of satellite imagery. It combines seasonal composites of multiyear surface reflectances and optimized presence and absence samples acquired with animal movement data within a cross-validation modeling scheme. Moreover, it responds to dynamic, site-specific environmental conditions making it applicable to contrasting landscapes. We tested this framework using five populations of White Storks (Ciconia ciconia) to model resource suitability related to foraging achieving accuracies from 0.40 to 0.94 for presences and 0.66 to 0.93 for absences. These results were influenced by the temporal composition of the seasonal reflectances indicated by the lower accuracies associated with higher day differences in relation to the target dates. Additionally, population differences in resource selection influenced our results marked by the negative relationship between the model accuracies and the variability of the surface reflectances associated with the presence samples. Our modeling approach spatially splits presences between training and validation. As a result, when these represent different and unique resources, we face a negative bias during validation. Despite these inaccuracies, our framework offers an important basis to analyze species-environment interactions. As it standardizes site-dependent behavioral and environmental characteristics, it can be used in the comparison of intra- and interspecies environmental requirements and improves the analysis of resource selection along migratory paths. Moreover, due to its sensitivity to differences in resource selection, our approach can contribute toward a better understanding of species requirements.}, language = {en} } @article{ThonfeldSteinbachMuroetal.2020, author = {Thonfeld, Frank and Steinbach, Stefanie and Muro, Javier and Kirimi, Fridah}, title = {Long-term land use/land cover change assessment of the Kilombero catchment in Tanzania using random forest classification and robust change vector analysis}, series = {Remote Sensing}, volume = {12}, journal = {Remote Sensing}, number = {7}, issn = {2072-4292}, doi = {10.3390/rs12071057}, url = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-203513}, year = {2020}, abstract = {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.}, language = {en} } @article{ForkuorUllmannGriesbeck2020, author = {Forkuor, Gerald and Ullmann, Tobias and Griesbeck, Mario}, title = {Mapping and monitoring small-scale mining activities in Ghana using Sentinel-1 time series (2015-2019)}, series = {Remote Sensing}, volume = {12}, journal = {Remote Sensing}, number = {6}, issn = {2072-4292}, doi = {10.3390/rs12060911}, url = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-203204}, year = {2020}, abstract = {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.}, language = {en} } @article{OttingerBachoferHuthetal.2021, author = {Ottinger, Marco and Bachofer, Felix and Huth, Juliane and Kuenzer, Claudia}, title = {Mapping aquaculture ponds for the coastal zone of Asia with Sentinel-1 and Sentinel-2 time series}, series = {Remote Sensing}, volume = {14}, journal = {Remote Sensing}, number = {1}, issn = {2072-4292}, doi = {10.3390/rs14010153}, url = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-252207}, year = {2021}, abstract = {Asia dominates the world's aquaculture sector, generating almost 90 percent of its total annual global production. Fish, shrimp, and mollusks are mainly farmed in land-based pond aquaculture systems and serve as a primary protein source for millions of people. The total production and area occupied for pond aquaculture has expanded rapidly in coastal regions in Asia since the early 1990s. The growth of aquaculture was mainly boosted by an increasing demand for fish and seafood from a growing world population. The aquaculture sector generates income and employment, contributes to food security, and has become a billion-dollar industry with high socio-economic value, but has also led to severe environmental degradation. In this regard, geospatial information on aquaculture can support the management of this growing food sector for the sustainable development of coastal ecosystems, resources, and human health. With free and open access to the rapidly growing volume of data from the Copernicus Sentinel missions as well as machine learning algorithms and cloud computing services, we extracted coastal aquaculture at a continental scale. We present a multi-sensor approach that utilizes Earth observation time series data for the mapping of pond aquaculture within the entire Asian coastal zone, defined as the onshore area up to 200 km from the coastline. In this research, we developed an object-based framework to detect and extract aquaculture at a single-pond level based on temporal features derived from high-spatial-resolution SAR and optical satellite data acquired from the Sentinel-1 and Sentinel-2 satellites. In a second step, we performed spatial and statistical data analyses of the Earth-observation-derived aquaculture dataset to investigate spatial distribution and identify production hotspots at various administrative units at regional, national, and sub-national scale.}, language = {en} } @article{DuerigGudmundssonKarmannetal.2015, author = {D{\"u}rig, Tobias and Gudmundsson, Magn{\´u}s Tumi and Karmann, Sven and Zimanowski, Bernd and Dellino, Pierfrancesco and Rietze, Martin and B{\"u}ttner, Ralf}, title = {Mass eruption rates in pulsating eruptions estimated from video analysis of the gas thrust-buoyancy transition-a case study of the 2010 eruption of Eyjafjallaj{\"o}kull, Iceland}, series = {Earth, Planets and Space}, volume = {67}, journal = {Earth, Planets and Space}, number = {180}, doi = {10.1186/s40623-015-0351-7}, url = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-138635}, year = {2015}, abstract = {The 2010 eruption of Eyjafjallajokull volcano was characterized by pulsating activity. Discrete ash bursts merged at higher altitude and formed a sustained quasi-continuous eruption column. High-resolution near-field videos were recorded on 8-10 May, during the second explosive phase of the eruption, and supplemented by contemporary aerial observations. In the observed period, pulses occurred at intervals of 0.8 to 23.4 s (average, 4.2 s). On the basis of video analysis, the pulse volume and the velocity of the reversely buoyant jets that initiated each pulse were determined. The expansion history of jets was tracked until the pulses reached the height of transition from a negatively buoyant jet to a convective buoyant plume about 100 m above the vent. Based on the assumption that the density of the gas-solid mixture making up the pulse approximates that of the surrounding air at the level of transition from the jet to the plume, a mass flux ranging between 2.2 and 3.5 . 10\(^4\) kg/s was calculated. This mass eruption rate is in good agreement with results obtained with simple models relating plume height with mass discharge at the vent. Our findings indicate that near-field measurements of eruption source parameters in a pulsating eruption may prove to be an effective monitoring tool. A comparison of the observed pulses with those generated in calibrated large-scale experiments reveals very similar characteristics and suggests that the analysis of near-field sensors could in the future help to constrain the triggering mechanism of explosive eruptions.}, language = {en} } @article{SchuesslerRichterOkrusch1989, author = {Sch{\"u}ssler, Ulrich and Richter, P. and Okrusch, Martin}, title = {Metabasites from the KTB Oberpfalz target area, Bavaria - geochemical characteristics and examples of mobile behaviour of "immobile" elements}, url = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-31021}, year = {1989}, abstract = {No abstract available}, language = {en} } @article{vonGehlenMatthesOkruschetal.1990, author = {von Gehlen, K. and Matthes, S. and Okrusch, Martin and Richter, P. and R{\"o}hr, C. and Sch{\"u}ssler, Ulrich}, title = {Metapyroxenite in der KTB-Vorbohrung}, url = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-87539}, year = {1990}, abstract = {No abstract available.}, subject = {Kontinentales Tiefbohrprogramm der Bundesrepublik Deutschland}, language = {de} } @article{SchuesslerWilhelm1992, author = {Sch{\"u}ssler, Ulrich and Wilhelm, G.}, title = {Mikrosondenanalytische Untersuchungen eines Kupfer-Rollsiegels des fr{\"u}hen 3. Jahrtausends v. Ch. vom Tell Karrana-3 bei Mosul, Irak}, url = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-86747}, year = {1992}, abstract = {No abstract available}, subject = {Mikrosonde}, language = {de} } @article{Schuessler1988, author = {Sch{\"u}ssler, Ulrich}, title = {Mobilisation einzelner Elemente in Amphiboliten aus der Umgebung der KTB-Lokation, Zone Erbendorf-Vohenstrauss, n{\"o}rdliche Oberpfalz}, url = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-39248}, year = {1988}, abstract = {No abstract available}, subject = {Mineralogie}, language = {de} } @article{LibandaPaeth2023, author = {Libanda, Brigadier and Paeth, Heiko}, title = {Modelling wind speed across Zambia: Implications for wind energy}, series = {International Journal of Climatology}, volume = {43}, journal = {International Journal of Climatology}, number = {2}, doi = {10.1002/joc.7826}, url = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-312134}, pages = {772 -- 786}, year = {2023}, abstract = {Wind energy is a key option in global dialogues about climate change mitigation. Here, we combined observations from surface wind stations, reanalysis datasets, and state-of-the-art regional climate models from the Coordinated Regional Climate Downscaling Experiment (CORDEX Africa) to study the current and future wind energy potential in Zambia. We found that winds are dominated by southeasterlies and are rarely strong with an average speed of 2.8 m·s\(^{-1}\). When we converted the observed surface wind speed to a turbine hub height of 100 m, we found a ~38\% increase in mean wind speed for the period 1981-2000. Further, both simulated and observed wind speed data show statistically significant increments across much of the country. The only areas that divert from this upward trend of wind speeds are the low land terrains of the Eastern Province bordering Malawi. Examining projections of wind power density (WPD), we found that although wind speed is increasing, it is still generally too weak to support large-scale wind power generation. We found a meagre projected annual average WPD of 46.6 W·m\(^{-2}\). The highest WPDs of ~80 W·m\(^{-2}\) are projected in the northern and central parts of the country while the lowest are to be expected along the Luangwa valley in agreement with wind speed simulations. On average, Zambia is expected to experience minor WPD increments of 0.004 W·m\(^{-2}\) per year from 2031 to 2050. We conclude that small-scale wind turbines that accommodate cut-in wind speeds of 3.8 m·s\(^{-1}\) are the most suitable for power generation in Zambia. Further, given the limitations of small wind turbines, they are best suited for rural and suburban areas of the country where obstructions are few, thus making them ideal for complementing the government of the Republic of Zambia's rural electrification efforts.}, language = {en} } @article{GhazaryanRienowOldenburgetal.2021, author = {Ghazaryan, Gohar and Rienow, Andreas and Oldenburg, Carsten and Thonfeld, Frank and Trampnau, Birte and Sticksel, Sarah and J{\"u}rgens, Carsten}, title = {Monitoring of urban sprawl and densification processes in Western Germany in the light of SDG indicator 11.3.1 based on an automated retrospective classification approach}, series = {Remote Sensing}, volume = {13}, journal = {Remote Sensing}, number = {9}, issn = {2072-4292}, doi = {10.3390/rs13091694}, url = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-236671}, year = {2021}, abstract = {By 2050, two-third of the world's population will live in cities. In this study, we develop a framework for analyzing urban growth-related imperviousness in North Rhine-Westphalia (NRW) from the 1980s to date using Landsat data. For the baseline 2017-time step, official geodata was extracted to generate labelled data for ten classes, including three classes representing low, middle, and high level of imperviousness. We used the output of the 2017 classification and information based on radiometric bi-temporal change detection for retrospective classification. Besides spectral bands, we calculated several indices and various temporal composites, which were used as an input for Random Forest classification. The results provide information on three imperviousness classes with accuracies exceeding 75\%. According to our results, the imperviousness areas grew continuously from 1985 to 2017, with a high imperviousness area growth of more than 167,000 ha, comprising around 30\% increase. The information on the expansion of urban areas was integrated with population dynamics data to estimate the progress towards SDG 11. With the intensity analysis and the integration of population data, the spatial heterogeneity of urban expansion and population growth was analysed, showing that the urban expansion rates considerably excelled population growth rates in some regions in NRW. The study highlights the applicability of earth observation data for accurately quantifying spatio-temporal urban dynamics for sustainable urbanization and targeted planning.}, language = {en} } @article{Hardaker2022, author = {Hardaker, Sina}, title = {More Than Infrastructure Providers - Digital Platforms' Role and Power in Retail Digitalisation in Germany}, series = {Tijdschrift voor Economische en Sociale Geografie}, volume = {113}, journal = {Tijdschrift voor Economische en Sociale Geografie}, number = {3}, doi = {10.1111/tesg.12511}, url = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-287297}, pages = {310 -- 328}, year = {2022}, abstract = {Digital platforms, such as Amazon, represent the major beneficiaries of the Covid-19 crisis. This study examines the role of digital platforms and their engagement in digitalisation initiatives targeting (small) brick-and-mortar retailers in Germany, thereby contributing to a better understanding of how digital platforms augment, substitute or reorganise physical retail spaces. This study applies a mixed-method approach based on qualitative interviews, participant observation as well as media analysis. First, the study illustrates the controversial role of digital platforms by positioning themselves as supporting partners of the (offline) retailers, while simultaneously shifting power towards the platforms themselves. Second, digital platforms have established themselves not only as infrastructure providers but also as actors within these infrastructures, framing digital as well as physical retail spaces, inter alia due to their role as publicly legitimised retail advisers. Third, while institutions want to help retailers to survive, they simultaneously enhance retailers' dependency on digital platforms.}, language = {en} } @article{BuscheSponholz1992, author = {Busche, Detlef and Sponholz, Barbara}, title = {Morphological and micromorphological aspects of the sandstone karst of eastern Niger}, url = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-56672}, year = {1992}, abstract = {Die Arbeit beschreibt im ersten Teil die Auswirkung der Sandstein- und Eisenkrustenverkarstung auf das Plateaurelief des {\"o}stlichen Niger. Angesprochen werden die abflußlosen Karstdepressionen auf den Plateaudachfl{\"a}chen, die Rolle intensiver Verkarstung bei der Herauspr{\"a}parierung von Sandsteins{\"a}ulen an H{\"a}ngen, von Plateauspornen und Inselbergen, die Mitwirkung bei der Talbildung sowie Einsturzdolinen an H{\"a}ngen. Im zweiten Teil wird die Mikromorphologie von Karsth{\"o}hlen{\"u}berz{\"u}gen aus der Endphase der phreatischen Karstl{\"o}sung beschrieben. Oberfl{\"a}chennahe K{\"o}rner weisen starke Korrosion auf. Phosphor in der wiederausgef{\"a}llten Matrix und eingekieselte Bakterien deuten auf eine organische Komponente bei der Ausbildung des terti{\"a}ren Silikatkarsts.}, subject = {Geographie}, language = {de} }