Inhaltsverzeichnis
Auswahl der wissenschaftlichen Literatur zum Thema „Braided fluvial“
Geben Sie eine Quelle nach APA, MLA, Chicago, Harvard und anderen Zitierweisen an
Machen Sie sich mit den Listen der aktuellen Artikel, Bücher, Dissertationen, Berichten und anderer wissenschaftlichen Quellen zum Thema "Braided fluvial" bekannt.
Neben jedem Werk im Literaturverzeichnis ist die Option "Zur Bibliographie hinzufügen" verfügbar. Nutzen Sie sie, wird Ihre bibliographische Angabe des gewählten Werkes nach der nötigen Zitierweise (APA, MLA, Harvard, Chicago, Vancouver usw.) automatisch gestaltet.
Sie können auch den vollen Text der wissenschaftlichen Publikation im PDF-Format herunterladen und eine Online-Annotation der Arbeit lesen, wenn die relevanten Parameter in den Metadaten verfügbar sind.
Zeitschriftenartikel zum Thema "Braided fluvial"
Wang, H., und X. Jia. „Selective deposition response to aeolian-fluvial sediment supply in the desert braided channel of the Upper Yellow River, China“. Natural Hazards and Earth System Sciences Discussions 3, Nr. 2 (10.02.2015): 1269–90. http://dx.doi.org/10.5194/nhessd-3-1269-2015.
Der volle Inhalt der QuelleWang, H., X. Jia, Y. Li und W. Peng. „Selective deposition response to aeolian–fluvial sediment supply in the desert braided channel of the upper Yellow River, China“. Natural Hazards and Earth System Sciences 15, Nr. 9 (02.09.2015): 1955–62. http://dx.doi.org/10.5194/nhess-15-1955-2015.
Der volle Inhalt der QuelleSigdel, Ashok, und Tetsuya Sakai. „Sedimentary facies analysis of the fluvial systems in the Siwalik Group, Karnali River section, Nepal Himalaya, and their significance for understanding the paleoclimate and Himalayan tectonics“. Journal of Nepal Geological Society 51 (31.12.2016): 11–26. http://dx.doi.org/10.3126/jngs.v51i0.24084.
Der volle Inhalt der QuelleLu, Zhiyuan, Zhiliang He, Shizhong Ma und Yu He. „Sedimentary characteristics and sand-body distributions in the Lower Permian He 8 Member, Ordos Basin, China“. Interpretation 10, Nr. 2 (22.02.2022): T223—T236. http://dx.doi.org/10.1190/int-2021-0101.1.
Der volle Inhalt der QuelleJu, Xiaoyu, Xiaodong Zhao, Boyu Zhou, Ruixue Zhang, Xinyu Wu und Dafa Guo. „Identification of Reservoir Water-Flooding Degrees via Core Sizes Based on a Drip Experiment of the Zhenwu Area in Gaoyou Sag, China“. Energies 16, Nr. 2 (04.01.2023): 608. http://dx.doi.org/10.3390/en16020608.
Der volle Inhalt der QuelleZawri, Nurul Fahana, Abdul Hadi Abd Rahman, Numair Ahmed Siddiqui und Norizam Md Nor. „Geomorphological evolution of the Group I fluvial system, AX field, Malay Basin“. IOP Conference Series: Earth and Environmental Science 1003, Nr. 1 (01.04.2022): 012009. http://dx.doi.org/10.1088/1755-1315/1003/1/012009.
Der volle Inhalt der QuelleSun, Yu, Xiu Li Zhang, Jin Yan Zhang und Chen Chen. „Analysis on Grain-Size Characteristics and Sedimentary Environment of Conglomerate Reservoirs in Ying-4 Section of Xingcheng Gas Field of Songliao Basin“. Advanced Materials Research 734-737 (August 2013): 286–89. http://dx.doi.org/10.4028/www.scientific.net/amr.734-737.286.
Der volle Inhalt der QuelleLiu, Yuming, Luxing Dou, Xiaoxu Ren und Jiagen Hou. „Sedimentary characteristics of muddy deposits in sandy braided fluvial system: A case study from outcrops of the Jurassic Yungang Formation in the Datong Basin, Central China“. Interpretation 8, Nr. 3 (01.07.2020): SM139—SM149. http://dx.doi.org/10.1190/int-2019-0174.1.
Der volle Inhalt der QuelleCui, Kunning. „Characteristics of sedimentary system evolution and sequence stratigraphy boundary of Denglouku group in Xujiaweizi fault depression, Songliao Basin“. IOP Conference Series: Earth and Environmental Science 1087, Nr. 1 (01.10.2022): 012073. http://dx.doi.org/10.1088/1755-1315/1087/1/012073.
Der volle Inhalt der QuelleCandeiro, Carlos Roberto, Rodrigo Pinto De Azevedo und Priscila Maria Da Silva. „PRELIMINARY APPROACH ON DEPOSITIONAL ENVIRONMENTAL OF THE UBERABA FORMATION (UPPER CRETACEOUS), PEIRÓPOLIS SITE, MINAS GERAIS STATE, BRAZIL: AN INTRODUCTION“. Caminhos de Geografia 8, Nr. 22 (22.09.2007): 81–85. http://dx.doi.org/10.14393/rcg82215625.
Der volle Inhalt der QuelleDissertationen zum Thema "Braided fluvial"
Pinisetti, Moe. „Integrated numerical well test modelling in braided fluvial reservoirs“. Thesis, Heriot-Watt University, 1999. http://hdl.handle.net/10399/609.
Der volle Inhalt der QuelleSalas, Carlos J. „Braided fluvial architecture within a rapidly subsiding basin the Pennsylvanian Cumberland group southwest of Sand River, Nova Scotia“. Thesis, University of Ottawa (Canada), 1986. http://hdl.handle.net/10393/5416.
Der volle Inhalt der QuelleReis, Adriano Domingos dos. „Análise arquitetural de depósitos fluviais da Formação Guará (Jurássico Superior-Cretáceo Inferior) na borda sudeste da Bacia do Paraná, RS, Brasil“. reponame:Biblioteca Digital de Teses e Dissertações da UFRGS, 2016. http://hdl.handle.net/10183/133638.
Der volle Inhalt der QuelleA Formação Guará (Jurássico Superior) aflora na porção oeste do Rio Grande do Sul ao longo de uma faixa com orientação norte-sul, sendo a sua porção setentrional constituída essencialmente por depósitos fluviais com paleocorrente para sudoeste. Apesar da existência de afloramentos com boa exposição vertical e uma alta continuidade lateral, não haviam sido realizados até o presente momento estudos detalhados da arquitetura fluvial desta unidade. Por meio da análise de fácies, com a elaboração de perfis verticais e seções laterais, foram descritos e interpretados 9 litofácies que compõem 8 elementos arquiteturais. Estes elementos se agrupam em corpos arenosos de dois estilos fluviais: (1) Rios entrelaçados perenes profundos – compostos por elementos de acresção frontal simples e compostas, hollows de pequeno e grande porte, sets isolados com estratificações cruzadas e fácies arenosas e finas externas aos canais – e (2) Rios entrelaçados efêmeros fracamente canalizados – caracterizados por arenitos horizontalmente estratificados e sets isolados com estratificações cruzadas. Dois ou mais corpos arenosos de mesmo estilo se amalgamam em pacotes de 10 a 15 m que representam intervalos de tempo com o domínio de um estilo fluvial. Estes pacotes se alternam verticalmente separados por superfícies de centenas de metros de extensão lateral, refletindo intervalos com descarga aquosa maior e mais contínua (com corpos arenosos de rios perenes e profundos) ou com descarga episódica e de alta energia (com corpos arenosos de rios efêmeros fracamente canalizados). Os sistemas fluviais da porção proximal da Formação Guará refletem variações de descarga de baixa frequência, de controle climático.
Picco, Lorenzo. „Long period morphological dynamics in regulated braided gravel-bed rivers: comparison between Piave River (Italy) and Waitaki River (New Zealand)“. Doctoral thesis, Università degli studi di Padova, 2010. http://hdl.handle.net/11577/3426981.
Der volle Inhalt der QuelleObbiettivo della presente ricerca è quello di eseguire un’analisi di lungo e medio periodo sulla dinamica della morfologia fluviale riguardante fiumi a canali intrecciati a fondo ghiaioso, sottoposti a regolazione dei regimi idrici, come il fiume Piave (Italia) e il fiume Waitaki (Nuova Zelanda). Il fiume Piave (area del bacino di circa 4000 km2), è uno dei principali fiumi del nord-est d’Italia; il tratto analizzato ha una lunghezza di circa 37 km e si trova nella parte centrale del bacino montano. Inoltre, sono stati studiati diversi sottotratti fino ad un minimo di 1.5 km di lunghezza. Il fiume Waitaki (area del bacino di circa 11000 km2) è il più importante fiume delle Nuova Zelanda per valori di portata, scorre dal versante est delle Alpi del Sud dell’isola del Sud della Nuova Zelanda; il tratto analizzato ha una lunghezza di circa 13 km. Il regime delle portate e l’apporto di sedimenti di questi due fiumi sono stati considerevolmente alterati dalla presenza di dighe per la produzione di energia idroelettrica e dalla presenza di opere trasversali e di difesa spondale. Per studiare le variazioni che si sono succedute nel tempo si è eseguita una ricostruzione storica con l’ausilio di fotografie aeree, dati storici di rilievi topografici e un set di dati LiDAR. Le caratteristiche che si sono analizzate sono l’estensione dell’alveo attivo, la larghezza massima dei canali, la profondità massima dei canali, l’area bagnata dei canali, il numero di canali e le caratteristiche altimetriche del letto del fiume. Si sono, anche, condotte analisi sulla variazione e la dinamica della vegetazione presente in alveo, attraverso la misurazione dell’area delle isole fluviali e l’estensione delle diverse tipologie di vegetazione presente nell’area perifluviale. I risultati ottenuti indicano come nel corso degli anni considerati vi siano stati delle variazioni considerevoli. In entrambi i fiumi c’è stata una marcata tendenza alla diminuzione dei numeri di canali e dell’estensione de corridoio attivo, solamente a seguito di eventi di piene rilevanti è stato possibile osservare un aumento dell’estensione del corridoio attivo. Lungo il corso del fiume Piave è stato possibile osservare una marcata tendenza all’incisione del canale durante gli ultimi 80 anni. Le isole fluviali tendono a maturare e stabilizzarsi per molti anni, occupando così il corridoio attivo. L’estensione delle isole diminuisce solamente a seguito di eventi di piena con tempi di ritorno marcati (> 10 anni), oppure a seguito di eventi che si succedono frequentemente, anche se di intensità minore. Infine si è potuto notare una tendenza delle isole fluviali a fondersi con la vegetazione perifluviale circostante, limitando ancor più l’estensione del corridoio attivo.
Bofill, Lucas. „From outcrop to fluid-flow : sedimentary architecture, permeability heterogeneity, and effect of sedimentary facies in fluid-flow modelling : a case study of the middle buntstandstein continental sandstones (lower triassic, eastern France)“. Electronic Thesis or Diss., Strasbourg, 2024. http://www.theses.fr/2024STRAH006.
Der volle Inhalt der QuelleAt the Upper Rhine Graben, in Eastern France, the Lower Triassic Buntsandstein serves as an important reservoir of groundwater and lithium-rich geothermal brines. The scientific objective of this study is to comprehend the architecture of the Lower Grès Vosgien Formation (LGV), Middle Buntsandstein; how sedimentological processes, at different scales, generate significant permeability heterogeneities; and the effect of such heterogeneity in fluid-flow modelling results. The study employs high-resolution sedimentological characterisation, through vertical profile descriptions, digital outcrop model, and petrographic analysis. Subsequently, permeability measurements are coupled with sedimentological data, to identify different scales of sedimentary controls on permeability distribution. Finally, a realistic 2D hydrostratigraphyc conceptual model is generated as a reference, to evaluate how different scenarios of heterogeneity simplification impact fluid-flow modelling, concerning particle residence time, macro-dispersivity and upscaled anisotropy.Results indicate that 93% of the LGV is composed of sandstones deposited by a braided fluvial system, with evidence suggesting that discharge variability was a main depositional controlling factor of sedimentary facies and heterogeneity distribution. The LGV stacking pattern reveals periods when fluvial processes were absent, and aeolian processes dominated sediment transport and deposition, constituting 7% of the total LGV thickness. The aeolian deposits record indications of persistent water in the system, either due to water table rise or ephemeral floods In the fluvial channel facies association, an inverse relationship between fluvial flow regime conditions and the permeability of its facies is observed. In the wind- and water-laid facies association (WWL), permeability distribution is directly influenced by climatic conditions, where low permeability hybrid sand sheets were deposited in more humid conditions, and high permeability aeolian dunes in more arid conditions. However, despite the high permeability of the AD, the architecture of the WWL implies low connectivity potential. Compaction is the main process influencing the permeability and porosity of the LGV. Samples with a higher proportion of lithoclasts and infiltrated clay recorded a more advanced degree of compaction, whereas samples with a higher percentage of quartz overgrowth exhibited a lower degree of compaction. The diagenetic overprint affected the distinct facies differently, indicating that primary sedimentary processes and architecture govern the distribution of permeability heterogeneity in the LGV. Permeability data from outcrops exhibited median values up to three orders of magnitude higher than those from subsurface data. However, the same facies, and similar trends of relative porosity-permeability responses to the distinct facies, are observed between outcrops and borehole samples, highlighting sedimentology as an indispensable proxy for reservoir heterogeneity studies[...]
Tacon, Sandrine. „Spatio-temporal analysis of braided river morphology with airborne LiDAR“. Thesis, Lyon 2, 2015. http://www.theses.fr/2015LYO20054/document.
Der volle Inhalt der QuelleBraided rivers form complex floodplains composed of sedimentary deposits mosaics, which differ in term of spatial and time scales, in function of hydrologic forcing and sediment supply. The goal of this thesis is to use airborne LiDAR to improve our understanding of braided channel morphological responses at different spatial and time scales.In a first time, two sequential airborne LiDAR surveys were used to reconstruct morphological changes of a 7-km-long braided river channel following a 14-year return period flood. This was done on the Bès River, a tributary of the Bléone River in southeastern France. Results highlighted the importance of different data processing steps in sediment budget computation (surface matching, bathymetry assessment, spatially distributed propagation of uncertainty). Analysis of these data also shows that the braided channel pattern was highly disturbed by the flood owing to the occurrence of several channel avulsions.In a second time, LiDAR data were used to look at longitudinal signatures of cross-sectional morphology at the scale of several kilometers. This study was done on 9 study reaches distributed on five braided rivers in Drôme, Drac and Bléone catchments. These data highlighted the effect of braided river confinement/obstruction on morphologic signature with upstream widening pattern. Secondly, two characteristic wavelengths have been identified from these signals: 3-4 and 10 times the active channel width. The first could be link to the dynamics of macroforms. The second could be associated to the dynamics of megaforms and long term sediment transfer.Finally, airborne LiDAR data were associated with archived aerial photos to reconstruct floodplain formation and relate this geomorphic organisation with vegetation patch characters. This is achieved on 3 different braided rivers in French Alps with an increasing degree of activity: the Bouinenc Torrent, the Drôme River and the Bès River. This methodology allowed us to establish the timing of channel incision with the identification of two major periods: before 1948 and second part of 20th century. Impacts of flood history on channel incision and widening pattern were also highlighted. These long term changes are playing a significant role to explain vegetation mosaics with a well-developed vegetated floodplain mainly composed of mature units following long term narrowing and incision. Rivers with higher activity show an equi-diversity of floodplain vegetation units. Finally, presence of shrubland patches seems to be good indicator of incision periods
Krapf, Carmen. „Ephemeral river systems at the Skeleton Coast, NW-Namibia sedimentological and geomorphological studies on the braided river dominated Koigab Fan, the cenozoic succession in the Uniabmond area and comparative studies on fluvio-aeolian interaction between ephemeral rivers and the Skeleton Coast erg /“. Doctoral thesis, [S.l. : s.n.], 2003. http://deposit.ddb.de/cgi-bin/dokserv?idn=968609740.
Der volle Inhalt der QuellePICCO, LORENZO. „Long period morphological dynamics in regulated braided gravel-bed rivers: comparison between Piave River (Italy) and Waitaki River (New Zealand)“. Doctoral thesis, 2010. http://hdl.handle.net/11577/3033851.
Der volle Inhalt der QuelleKrapf, Carmen [Verfasser]. „Ephemeral river systems at the Skeleton Coast, NW-Namibia : sedimentological and geomorphological studies on the braided river dominated Koigab Fan, the cenozoic succession in the Uniabmond area and comparative studies on fluvio-aeolian interaction between ephemeral rivers and the Skeleton Coast erg / vorgelegt von Carmen Krapf“. 2003. http://d-nb.info/968609740/34.
Der volle Inhalt der QuelleBücher zum Thema "Braided fluvial"
E&G Quaternary Science Journal Vol. 60 No 4: Quaternary landscape evolution in the Peribaltic region. Geozon Science Media, 2011.
Den vollen Inhalt der Quelle findenBuchteile zum Thema "Braided fluvial"
Surian, Nicola. „Fluvial Processes in Braided Rivers“. In Rivers – Physical, Fluvial and Environmental Processes, 403–25. Cham: Springer International Publishing, 2015. http://dx.doi.org/10.1007/978-3-319-17719-9_15.
Der volle Inhalt der QuelleAshmore, P., und J. T. Gardner. „Unconfined Confluences in Braided Rivers“. In River Confluences, Tributaries and the Fluvial Network, 119–47. Chichester, UK: John Wiley & Sons, Ltd, 2008. http://dx.doi.org/10.1002/9780470760383.ch7.
Der volle Inhalt der QuelleGardiner, Scott, David V. Thomas, E. Dale Bowering und Larry S. McMinn. „A Braided Fluvial Reservoir, Peco Field, Alberta, Canada“. In Casebooks in Earth Sciences, 31–56. New York, NY: Springer New York, 1990. http://dx.doi.org/10.1007/978-1-4613-8988-0_3.
Der volle Inhalt der QuelleSurian, Nicola, und Alessandro Fontana. „The Tagliamento River: The Fluvial Landscape and Long-Term Evolution of a Large Alpine Braided River“. In World Geomorphological Landscapes, 157–67. Cham: Springer International Publishing, 2017. http://dx.doi.org/10.1007/978-3-319-26194-2_13.
Der volle Inhalt der QuelleMomin, Hassan, und Gorky Chakraborty. „Missing Fluvio-Social Dynamics of a Braided River: A Study on a Select Stretch of the Brahmaputra in Assam“. In Indigeneity, Development and Sustainability, 245–74. Singapore: Springer Nature Singapore, 2024. http://dx.doi.org/10.1007/978-981-97-1436-0_12.
Der volle Inhalt der Quelle„Braided Fluvial Reservoirs“. In Oil Field Production Geology, 273–77. American Association of Petroleum Geologists, 2009. http://dx.doi.org/10.1306/13161222m913372.
Der volle Inhalt der QuelleMAIZELS, JUDITH K. „LARGE-SCALE FLOOD DEPOSITS ASSOCIATED WITH THE FORMATION OF COARSE-GRAINED, BRAIDED TERRACE SEQUENCES“. In Recent Developments in Fluvial Sedimentology, 135–48. SEPM (Society for Sedimentary Geology), 1987. http://dx.doi.org/10.2110/pec.87.39.0135.
Der volle Inhalt der QuelleMcvey, R., B. Rumsby und J. Brasington. „The potential for high resolution fluvial archives in braided rivers“. In River Basin Sediment Systems - Archives of Environmental Change. Taylor & Francis, 2001. http://dx.doi.org/10.1201/9781439824672.ch16.
Der volle Inhalt der QuelleKINGSLEY, CHARLES S. „FACIES CHANGES FROM FLUVIAL CONGLOMERATE TO BRAIDED SANDSTONE OF THE EARLY PROTEROZOIC ELDORADO FORMATION, WELKOM GOLDFIELD, SOUTH AFRICA“. In Recent Developments in Fluvial Sedimentology, 359–70. SEPM (Society for Sedimentary Geology), 1987. http://dx.doi.org/10.2110/pec.87.39.0359.
Der volle Inhalt der QuelleBarineau*, Clinton, und Diana Ortega-Ariza*. „An Upper Cretaceous paleodrainage system on the Coastal Plain unconformity of Alabama-Georgia“. In Field Excursions from the 2021 GSA Section Meetings, 35–60. Geological Society of America, 2021. http://dx.doi.org/10.1130/2021.0061(03).
Der volle Inhalt der QuelleKonferenzberichte zum Thema "Braided fluvial"
Toro-Rivera, M. L. E., P. W. M. Corbett und George Stewart. „Well Test Interpretation in a Heterogeneous Braided Fluvial Reservoir“. In European Petroleum Conference. Society of Petroleum Engineers, 1994. http://dx.doi.org/10.2118/28828-ms.
Der volle Inhalt der QuelleEttema, R., D. Armstrong, C. Thornton, S. Hughes und S. Abt. „Hydraulic modeling of braided channels self-formed in an alluvial plain“. In The International Conference On Fluvial Hydraulics (River Flow 2016). Taylor & Francis Group, 6000 Broken Sound Parkway NW, Suite 300, Boca Raton, FL 33487-2742: CRC Press, 2016. http://dx.doi.org/10.1201/9781315644479-176.
Der volle Inhalt der QuelleTaylor, D., D. Hodgetts, J. Redfern und J. Richardson. „Quantification and Prediction of Braided Fluvial Systems Using Digital Outcrop Models“. In 80th EAGE Conference and Exhibition 2018. Netherlands: EAGE Publications BV, 2018. http://dx.doi.org/10.3997/2214-4609.201801689.
Der volle Inhalt der QuelleBiswas, Robin, A. Yorozuya und S. Egashira. „Monitoring of sandbars migration process in mega-sized braided river using MODIS“. In The International Conference On Fluvial Hydraulics (River Flow 2016). Taylor & Francis Group, 6000 Broken Sound Parkway NW, Suite 300, Boca Raton, FL 33487-2742: CRC Press, 2016. http://dx.doi.org/10.1201/9781315644479-99.
Der volle Inhalt der QuelleLi, S. L., und X. H. Yu. „The Response of Architectural Elements to Sequence Stratigraphy in Braided Fluvial System“. In Saint Petersburg 2012. Netherlands: EAGE Publications BV, 2012. http://dx.doi.org/10.3997/2214-4609.20143720.
Der volle Inhalt der QuelleUnsworth, C., A. Nicholas, P. Ashworth, C. Simpson, J. Best, S. Lane, D. Parsons und G. Sambrook. „Using bedform migration and orientation to infer sediment transport pathways in a sandy braided river“. In The International Conference On Fluvial Hydraulics (River Flow 2016). Taylor & Francis Group, 6000 Broken Sound Parkway NW, Suite 300, Boca Raton, FL 33487-2742: CRC Press, 2016. http://dx.doi.org/10.1201/9781315644479-180.
Der volle Inhalt der QuelleBecker, Mauro R., Larry W. Lake und Noel Tyler. „Fractal Properties of Braided Fluvial Deposits for Characterization and Simulation of Reservoir Heterogeneity“. In Latin American and Caribbean Petroleum Engineering Conference. Society of Petroleum Engineers, 1997. http://dx.doi.org/10.2118/38951-ms.
Der volle Inhalt der QuelleLabourdette, R., und R. Jones. „Characterisation of Fluvial Architectural Elements Using a Three Dimensional Outcrop Dataset – Escanilla Braided System“. In 69th EAGE Conference and Exhibition incorporating SPE EUROPEC 2007. European Association of Geoscientists & Engineers, 2007. http://dx.doi.org/10.3997/2214-4609.201401722.
Der volle Inhalt der QuelleDavies, D. K., B. P. J. Williams und R. K. Vessell. „Models for Meandering and Braided Fluvial Reservoirs With Examples From the Travis Peak Formation, East Texas“. In SPE Annual Technical Conference and Exhibition. Society of Petroleum Engineers, 1992. http://dx.doi.org/10.2118/24692-ms.
Der volle Inhalt der QuelleZhongbo, Xu, Huang Kai, Shen Chunsheng, Luo Xianbo, He Bin, Kang Kai, Chen Yukun et al. „Architecture Characterization of Sandy Braided Fluvial Reservoir: A Case Study of P Oilfield (Neogene), Bohai Offshore, China“. In SPE Annual Technical Conference and Exhibition. Society of Petroleum Engineers, 2015. http://dx.doi.org/10.2118/174886-ms.
Der volle Inhalt der QuelleBerichte der Organisationen zum Thema "Braided fluvial"
Devaney, J. R., und P. W. Fralick. Regional sedimentology of the Namewaminikan group, northern Ontario: archean fluvial fans, braided rivers, deltas, and an aquabasin. Natural Resources Canada/ESS/Scientific and Technical Publishing Services, 1985. http://dx.doi.org/10.4095/120237.
Der volle Inhalt der Quelle