TY - JOUR A1 - Rasigraf, Olivia A1 - Wagner, Dirk T1 - Landslides BT - an emerging model for ecosystem and soil chronosequence research JF - Earth science reviews : the international geological journal bridging the gap between research articles and textbooks N2 - Erosion by landslides is a common phenomenon in mountain regions around the globe, affecting all climatic zones. Landslides facilitate bedrock weathering, pedogenesis and ecological succession, being key drivers of biodiversity. Landslide chronosequences have long been used for studies of vegetation succession in initial ecosystems, but they further offer ideal model systems for studies of soil development and microbial community succession. In this review we synthesize the state of knowledge on the role of landslides in ecosystems, their influence on element cycles and interactions with biota. Further, we discuss feedback mechanisms between global warming, landslide activity and greenhouse gas emissions. In the view of increasing anthropogenic influence and climate change, soils are becoming a critical resource. Due to their ubiquity, landslide chronosequences have the potential to provide critical insights into soil development under different climates and thereby contribute to future soil restoration efforts. KW - Landslides KW - Greenhouse gas emissions KW - Landslide chronosequences KW - Soil KW - microbial community KW - Erosion KW - Biodiversity KW - Microbial processes KW - Climate KW - change Y1 - 2022 U6 - https://doi.org/10.1016/j.earscirev.2022.104064 SN - 0012-8252 SN - 1872-6828 VL - 231 PB - Elsevier CY - Amsterdam ER - TY - JOUR A1 - Pena-Angulo, D. A1 - Nadal-Romero, E. A1 - Gonzalez-Hidalgo, J. C. A1 - Albaladejo, J. A1 - Andreu, V A1 - Bagarello, V A1 - Barhi, H. A1 - Batalla, R. J. A1 - Bernal, S. A1 - Bienes, R. A1 - Campo, J. A1 - Campo-Bescos, M. A. A1 - Canatario-Duarte, A. A1 - Canton, Y. A1 - Casali, J. A1 - Castillo, V A1 - Cerda, Artemi A1 - Cheggour, A. A1 - Cid, Patricio A1 - Cortesi, N. A1 - Desir, G. A1 - Diaz-Pereira, E. A1 - Espigares, T. A1 - Estrany, Joan A1 - Fernandez-Raga, M. A1 - Ferreira, Carla S. S. A1 - Ferro, Vito A1 - Gallart, Francesc A1 - Gimenez, R. A1 - Gimeno, E. A1 - Gomez, J. A. A1 - Gomez-Gutierrez, A. A1 - Gomez-Macpherson, H. A1 - Gonzalez-Pelayo, O. A1 - Hueso-Gonzalez, P. A1 - Kairis, O. A1 - Karatzas, G. P. A1 - Klotz, S. A1 - Kosmas, C. A1 - Lana-Renault, Noemi A1 - Lasanta, T. A1 - Latron, J. A1 - Lazaro, R. A1 - Le Bissonnais, Y. A1 - Le Bouteiller, C. A1 - Licciardello, F. A1 - Lopez-Tarazon, José Andrés A1 - Lucia, A. A1 - Marin, C. A1 - Marques, M. J. A1 - Martinez-Fernandez, J. A1 - Martinez-Mena, M. A1 - Martinez-Murillo, J. F. A1 - Mateos, L. A1 - Mathys, N. A1 - Merino-Martin, L. A1 - Moreno-de las Heras, M. A1 - Moustakas, N. A1 - Nicolau, J. M. A1 - Novara, A. A1 - Pampalone, V A1 - Raclot, D. A1 - Rodriguez-Blanco, M. L. A1 - Rodrigo-Comino, Jesús A1 - Romero-Diaz, A. A1 - Roose, E. A1 - Rubio, J. L. A1 - Ruiz-Sinoga, J. D. A1 - Schnabel, S. A1 - Senciales-Gonzalez, J. M. A1 - Simonneaux, V A1 - Sole-Benet, A. A1 - Taguas, E. A1 - Taboada-Castro, M. M. A1 - Taboada-Castro, M. T. A1 - Todisco, Francesca A1 - Ubeda, X. A1 - Varouchakis, E. A. A1 - Vericat, Damia A1 - Wittenberg, L. A1 - Zabaleta, A. A1 - Zorn, M. T1 - Spatial variability of the relationships of runoff and sediment yield with weather types throughout the Mediterranean basin JF - Journal of hydrology N2 - Soil degradation by water is a serious environmental problem worldwide, with specific climatic factors being the major causes. We investigated the relationships between synoptic atmospheric patterns (i.e. weather types, WTs) and runoff, erosion and sediment yield throughout the Mediterranean basin by analyzing a large database of natural rainfall events at 68 research sites in 9 countries. Principal Component Analysis (PCA) was used to identify spatial relationships of the different WTs including three hydro-sedimentary variables: rainfall, runoff, and sediment yield (SY, used to refer to both soil erosion measured at plot scale and sediment yield registered at catchment scale). The results indicated 4 spatial classes of rainfall and runoff: (a) northern sites dependent on North (N) and North West (NW) flows; (b) eastern sites dependent on E and NE flows; (c) southern sites dependent on S and SE flows; and, finally, (d) western sites dependent on W and SW flows. Conversely, three spatial classes are identified for SY characterized by: (a) N and NE flows in northern sites (b) E flows in eastern sites, and (c) W and SW flows in western sites. Most of the rainfall, runoff and SY occurred during a small number of daily events, and just a few WTs accounted for large percentages of the total. Our results confirm that characterization by WT improves understanding of the general conditions under which runoff and SY occur, and provides useful information for understanding the spatial variability of runoff, and SY throughout the Mediterranean basin. The approach used here could be useful to aid of the design of regional water management and soil conservation measures. KW - Synoptic weather types KW - Erosion KW - Sediment yield KW - Runoff KW - Mediterranean basin Y1 - 2019 U6 - https://doi.org/10.1016/j.jhydrol.2019.01.059 SN - 0022-1694 SN - 1879-2707 VL - 571 SP - 390 EP - 405 PB - Elsevier CY - Amsterdam ER - TY - JOUR A1 - van der Meij, Marijn W. A1 - Temme, Arnaud J. A. M. A1 - Wallinga, J. A1 - Hierold, W. A1 - Sommer, Michael T1 - Topography reconstruction of eroding landscapes - A case study from a hummocky ground moraine (CarboZALF-D) JF - Geomorphology : an international journal on pure and applied geomorphology N2 - Erosion processes, aggravated by human activity, have a large impact on the spatial variation of soil and topographic properties. Knowledge of the topography prior to human-induced erosion (paleotopography) in naturally stable landscapes is valuable for identifying vulnerable landscape positions and is required as starting point for erosion modelling exercises. However, developing accurate reconstructions of paleotopography provide a major challenge for geomorphologists. Here, we present a set of paleotopographies for a closed kettle hole catchment in north-east Germany (4 ha), obtained through different reconstruction approaches. Current soil and colluvium thickness, estimated from a dataset of 264 soil descriptions using Ordinary Kriging, were used as input for a mass balance, or were compared with a set of undisturbed soil thicknesses to estimate the amount of erosion. The performance of the different approaches was assessed with cross-validation and the count of mispredicted eroded, depositional or stable landscape positions. The paleotopographic reconstruction approach based on the average thickness of undisturbed soils in the study area showed the best performance. This thickness (1.00 m) is comparable to the average undisturbed soil thickness in the region and in line with global correlations of soil thickness as a function of rainfall and initial CaCO3 content. The performance of the different approaches depended more on mispredictions of landscape position due to the assumption of a spatially constant initial soil depth than on small variations in this depth. To conclude, we mention several methodological and practical points of attention for future topography reconstruction studies, concerning data quality and availability, spatial configuration of data and other processes affecting topography. (C) 2017 Elsevier B.V. All rights reserved. KW - Topography reconstruction KW - Erosion KW - Tillage KW - Landscape change Y1 - 2017 U6 - https://doi.org/10.1016/j.geomorph.2017.08.015 SN - 0169-555X SN - 1872-695X VL - 295 SP - 758 EP - 772 PB - Elsevier CY - Amsterdam ER - TY - THES A1 - Behrens, Ricarda T1 - Causes for slow weathering and erosion in the steep, warm, monsoon-subjected Highlands of Sri Lanka T1 - Ursache von langsamer Verwitterung und Erosion im steilen, warmen und Monsun-beeinflussten Hochland von Sri Lanka N2 - In the Highlands of Sri Lanka, erosion and chemical weathering rates are among the lowest for global mountain denudation. In this tropical humid setting, highly weathered deep saprolite profiles have developed from high-grade metamorphic charnockite during spheroidal weathering of the bedrock. The spheroidal weathering produces rounded corestones and spalled rindlets at the rock-saprolite interface. I used detailed textural, mineralogical, chemical, and electron-microscopic (SEM, FIB, TEM) analyses to identify the factors limiting the rate of weathering front advance in the profile, the sequence of weathering reactions, and the underlying mechanisms. The first mineral attacked by weathering was found to be pyroxene initiated by in situ Fe oxidation, followed by in situ biotite oxidation. Bulk dissolution of the primary minerals is best described with a dissolution – re-precipitation process, as no chemical gradients towards the mineral surface and sharp structural boundaries are observed at the nm scale. Only the local oxidation in pyroxene and biotite is better described with an ion by ion process. The first secondary phases are oxides and amorphous precipitates from which secondary minerals (mainly smectite and kaolinite) form. Only for biotite direct solid state transformation to kaolinite is likely. The initial oxidation of pyroxene and biotite takes place in locally restricted areas and is relatively fast: log J = -11 molmin/(m2 s). However, calculated corestone-scale mineral oxidation rates are comparable to corestone-scale mineral dissolution rates: log R = -13 molpx/(m2 s) and log R = -15 molbt/(m2 s). The oxidation reaction results in a volume increase. Volumetric calculations suggest that this observed oxidation leads to the generation of porosity due to the formation of micro-fractures in the minerals and the bedrock allowing for fluid transport and subsequent dissolution of plagioclase. At the scale of the corestone, this fracture reaction is responsible for the larger fractures that lead to spheroidal weathering and to the formation of rindlets. Since these fractures have their origin from the initial oxidational induced volume increase, oxidation is the rate limiting parameter for weathering to take place. The ensuing plagioclase weathering leads to formation of high secondary porosity in the corestone over a distance of only a few cm and eventually to the final disaggregation of bedrock to saprolite. As oxidation is the first weathering reaction, the supply of O2 is a rate-limiting factor for chemical weathering. Hence, the supply of O2 and its consumption at depth connects processes at the weathering front with erosion at the surface in a feedback mechanism. The strength of the feedback depends on the relative weight of advective versus diffusive transport of O2 through the weathering profile. The feedback will be stronger with dominating diffusive transport. The low weathering rate ultimately depends on the transport of O2 through the whole regolith, and on lithological factors such as low bedrock porosity and the amount of Fe-bearing primary minerals. In this regard the low-porosity charnockite with its low content of Fe(II) bearing minerals impedes fast weathering reactions. Fresh weatherable surfaces are a pre-requisite for chemical weathering. However, in the case of the charnockite found in the Sri Lankan Highlands, the only process that generates these surfaces is the fracturing induced by oxidation. Tectonic quiescence in this region and low pre-anthropogenic erosion rate (attributed to a dense vegetation cover) minimize the rejuvenation of the thick and cohesive regolith column, and lowers weathering through the feedback with erosion. N2 - Erosions- und chemische Verwitterungsraten im srilankischen Hochland gehören zu den langsamsten der globalen Gebirgsdenudationsraten. In diesem tropischen, humiden Gebiet entwickelten sich mächtige Verwitterungsprofile – sogenannte Saprolite – auf spheroidal verwittertem, hochgradig metamorphen Charnockit. Spheroidale Verwitterung führt zu abgerundeten „corestones“ mit abgesplitterten Rinden („rindlets“) an der Gesteins – Saprolit Grenze. Zur Identifizierung der ratenlimitierenden Faktoren des Fortschreiten der Verwitterungsfront, der Sequenz der Verwitterungsreaktionen und der dahinterliegenden Mechanismen nutzte ich detaillierte gesteinsstrukturelle, mineralogische, chemische und elektronenmikroskopische (SEM, FIB, TEM) Analysemethoden. Die initiale Verwitterung beginnt mit lokal begrenzter in situ Oxidation in Pyroxen, gefolgt von in situ Oxidation von Biotit. Die Auflösung der Minerale wird am besten durch einen Auflöse – Wiederausfällungs-prozess beschrieben, da zur Mineralgrenze hin keine chemischen Gradienten, dafür aber auf der nm-Skala scharfe strukturelle Grenzen zu beobachten sind. Die ersten ausfallenden Sekundärphasen sind Oxide und amorphe Phasen aus denen sich Sekundärmineral (hauptsächlich Smectit und Kaolinit) bilden. Für Biotit ist auch eine direkte Umwandlung im Festzustand zu Kaolinit möglich. Die initiale Pyroxen- und Biotitoxidation ist relativ schnell: log J = -11 molmin/(m2 s). Berechnete Oxidationsraten auf der corestone-Skala (cm) sind vergleichbar zu Auflöseraten auf derselben Skala: log R = -13 molpx/(m2 s) und log R = -15 molbt/(m2 s). Volumetrische Berechnungen führen zum Schluss, dass die Oxidation mit einhergehender Volumenzunahme zur Entwicklung von Mikrofrakturen in den Mineralen und dem Gesamtgestein führt. Diese begünstigen Fluidtransport und damit einhergehende Plagioklasverwitterung. Des Weiteren ist diese Oxidationsreaktion verantwortlich für die Entstehung der Frakturen bei spheroidaler Verwitterung des Gesteins, welche die „rindlets“ vom „corestone“ abgrenzen. Daraus kann geschlossen werden, dass in situ Oxidation der ratenlimitierende Prozess bei der Verwitterung ist. Plagioklasverwitterung führt zu einer hohen Porositätszunahme und der endgültigen Umwandlung von Gestein zu Saprolit. Da Oxidation die erste Verwitterungsreaktion ist, verbinden die Zuführung und der Verbrauch von O2 zur, beziehungsweise an die Verwitterungsfront Erosion an der Oberfläche mit Prozessen an der Verwitterungsfront über einen Feedbackmechanismus. Daher hängt die langsame Verwitterungsrate letztlich vom Sauerstofftransport durch das Verwitterungsprofil und von lithologischen Faktoren des Charnockit wie zum Beispiel geringe Gesteinsporosität und/oder wenige Fe(II)-haltige Primärminerale ab. Des Weiteren ist der einzige Prozess im Charnockit der frische verwitterbare Oberflächen (eine Voraussetzung für chemische Verwitterung) generiert die oxidations-induzierte Frakturierung. Darüber hinaus minimieren die Abwesenheit von tektonischer Aktivität und geringe prä-anthropogene Erosionsraten in dieser Region den Abtrag des mächtigen und kohäsiven Verwitterungsprofils und somit über den beschriebenen Feedback auch die chemische Verwitterungsrate. KW - Sri Lanka KW - chemical weathering KW - erosion KW - saprolite KW - weathering feedback KW - charnockite KW - critical zone KW - mineral weathering reactions KW - Sri Lanka KW - chemische Verwitterung KW - Erosion KW - Saprolit KW - Verwitterungsfeedback KW - Charnockit KW - kritische Zone KW - Mineralverwitterungsreaktionen Y1 - 2018 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:kobv:517-opus4-408503 ER - TY - THES A1 - Weege, Stefanie T1 - Climatic drivers of retrogressive thaw slump activity and resulting sediment and carbon release to the nearshore zone of Herschel Island, Yukon Territory, Canada T1 - Einfluss des Klimas auf das Auftauen einer rückschreitenden Erosionsfront und die daraus resultierende Sediment- und Kohlenstofffreigabe in den Küstenbereich von Herschel Island, Kanada N2 - The Yukon Coast in Canada is an ice-rich permafrost coast and highly sensitive to changing environmental conditions. Retrogressive thaw slumps are a common thermoerosion feature along this coast, and develop through the thawing of exposed ice-rich permafrost on slopes and removal of accumulating debris. They contribute large amounts of sediment, including organic carbon and nitrogen, to the nearshore zone. The objective of this study was to 1) identify the climatic and geomorphological drivers of sediment-meltwater release, 2) quantify the amount of released meltwater, sediment, organic carbon and nitrogen, and 3) project the evolution of sediment-meltwater release of retrogressive thaw slumps in a changing future climate. The analysis is based on data collected over 18 days in July 2013 and 18 days in August 2012. A cut-throat flume was set up in the main sediment-meltwater channel of the largest retrogressive thaw slump on Herschel Island. In addition, two weather stations, one on top of the undisturbed tundra and one on the slump floor, measured incoming solar radiation, air temperature, wind speed and precipitation. The discharge volume eroding from the ice-rich permafrost and retreating snowbanks was measured and compared to the meteorological data collected in real time with a resolution of one minute. The results show that the release of sediment-meltwater from thawing of the ice-rich permafrost headwall is strongly related to snowmelt, incoming solar radiation and air temperature. Snowmelt led to seasonal differences, especially due to the additional contribution of water to the eroding sediment-meltwater from headwall ablation, lead to dilution of the sediment-meltwater composition. Incoming solar radiation and air temperature were the main drivers for diurnal and inter-diurnal fluctuations. In July (2013), the retrogressive thaw slump released about 25 000 m³ of sediment-meltwater, containing 225 kg dissolved organic carbon and 2050 t of sediment, which in turn included 33 t organic carbon, and 4 t total nitrogen. In August (2012), just 15 600 m³ of sediment-meltwater was released, since there was no additional contribution from snowmelt. However, even without the additional dilution, 281 kg dissolved organic carbon was released. The sediment concentration was twice as high as in July, with sediment contents of up to 457 g l-1 and 3058 t of sediment, including 53 t organic carbon and 5 t nitrogen, being released. In addition, the data from the 36 days of observations from Slump D were upscaled to cover the main summer season of 1 July to 31 August (62 days) and to include all 229 active retrogressive thaw slumps along the Yukon Coast. In total, all retrogressive thaw slumps along the Yukon Coast contribute a minimum of 1.4 Mio. m³ sediment-meltwater each thawing season, containing a minimum of 172 000 t sediment with 3119 t organic carbon, 327 t nitrogen and 17 t dissolved organic carbon. Therefore, in addition to the coastal erosion input to the Beaufort Sea, retrogressive thaw slumps additionally release 3 % of sediment and 8 % of organic carbon into the ocean. Finally, the future evolution of retrogressive thaw slumps under a warming scenario with summer air temperatures increasing by 2-3 °C by 2081-2100, would lead to an increase of 109-114% in release of sediment-meltwater. It can be concluded that retrogressive thaw slumps are sensitive to climatic conditions and under projected future Arctic warming will contribute larger amounts of thawed permafrost material (including organic carbon and nitrogen) into the environment. N2 - Die Yukon Küste in Kanada ist eine eisreiche Permafrost Küste und reagiert hoch sensibel auf verändernde Umweltbedingungen. Rückschreitende auftaubedingte Rutschungen sind vielzählig entlang der Küste und entstehen, wenn exponierter eisreicher Permafrost an Hängen auftaut und der daraus resultierende Schlamm abtransportiert wird. Diese Rutschungen tragen große Mengen von Sediment, inklusive organischen Kohlenstoff und Stickstoff, in den küstennahen Bereich. Das Ziel dieser Studie war 1) die klimatischen und geomorphologischen Antriebskräfte für die Freisetzung von Sediment-Schmelzwasser zu identifizieren 2) die Mengen an Schmelzwasser, Sediment, organischen Kohlenstoff und Stickstoff zu quantifizieren und 3) die Entwicklung der Sediment-Schmelzwasser-Freigabe von rückschreitenden Rutschungen unter zukünftigen klimatischen Veränderungen abzuschätzen. Die größte rückschreitende Rutschung auf Herschel Island wird als „Slump D“ bezeichnet und steht im Fokus dieser Arbeit. Die Analysen basierten auf den Daten, die über 18 Tage im Juli (2013) und 18 Tage im August (2012) erhoben wurden. Eine Abfluss-Messrinne wurde in den Haupt-Sediment-Schmelzwasser-Kanal eingebaut, um die Sediment-Schmelzwassermassen zu erfassen. Zusätzlich wurden zwei Wetterstationen aufgebaut (auf der unberührten Tundra und innerhalb der Erosionsfläche), die Sonneneinstrahlung, Lufttemperatur, Windgeschwindigkeit und Niederschlagsmenge aufzeichneten. Das Abflussvolumen, das vom auftauenden, eisreichen Permafrost und den schmelzenden Schneebänken ablief, wurde gemessen und mit den meteorologischen Daten in Echtzeit mit einer Auflösung von einer Minute verglichen. Die Ergebnisse zeigen, dass eine Freigabe von Sediment-Schmelzwasser beim Auftauen der eisreichen Permafrost-Steilklippe stark von Schneeschmelze, Sonneneinstrahlung und Lufttemperatur abhängen. Die Schneeschmelze führt zu saisonalen Unterschieden, besonders durch den zusätzlichen Betrag von Wasser zu dem erodierenden Sediment-Schmelzwasser der auftauenden Steilklippe. Dies führt zu einer Verdünnung des Sediment-Schmelzwassers. Sonneneinstrahlung und Lufttemperaturen waren die Hauptantriebskräfte für die Schwankungen im Tagesverlauf und die Unterschiede zwischen den Tagen. Die rückschreitende Rutschung gab im Juli (2013) ungefähr 25 000 m³ Sediment-Schmelzwasser frei, welches 225 kg gelösten organischen Kohlenstoff, 2050 t Sediment, inklusive 33 t organischen Kohlenstoff und 4 t Stickstoff enthielt. Im August (2012) fehlte der zusätzliche Eintrag der Schneeschmelze und das Sediment-Schmelzwasser-Volumen war geringer mit 15 600 m³. Dennoch, ohne die zusätzliche Verdünnung, wurden 281 kg gelöster organischer Kohlenstoff freigesetzt. Die Sedimentkonzentration war doppelt so hoch und führte zu einem Sedimentgehalt mit bis zu 457 g l-1 zu 3058 t Sediment, inklusive 53 t organischen Kohlenstoff und 5 t Stickstoff. Zusätzlich wurden die Daten der 36-tägigen Abflussmessung der rückschreitenden Rutschung auf 62 Tage, von 1. Juli bis 31. August auf alle 229 aktiven Rutschungen entlang der Yukon Küste hochgerechnet. Es wurde diskutiert, dass alle rückschreitenden Rutschungen entlang der Yukon Küste zusammen mindestens 1,4 Mio. m³ Sediment-Schmelzwasser während jeder Auftausaison freigeben. Diese enthalten ein Minimum von 172 000 t Sediment, 3119 t organischen Kohlenstoff, 327 t Stickstoff und 17 t gelösten organischen Kohlenstoff. Daher kann zusammengefasst werden, dass zusätzlich zur Küstenerosion von allen Rutschungen noch ein zusätzlicher Beitrag von 3 % Sediment und 8 % organischen Kohlenstoff in die Beaufort See eingetragen wird. Schließlich wurde die zukünftige Entwicklung dieser rückschreitenden Rutschungen bei einem Temperaturanstieg von 2-3 °C bis 2081-2100 diskutiert. Dies könnte zu einem Anstieg der Sediment-Schmelzwasser-Freigabe von 109-114 % führen. Es kann daraus geschlossen werden, dass rückschreitende Rutschungen sensibel auf Klimabedingungen reagieren und mit der Arktischen Erwärmung größere Mengen an auftauenden Permafrost (inklusive organischen Kohlenstoff und Stickstoff) in die Umwelt freigeben werden. KW - permafrost KW - arctic KW - Canada KW - coast KW - erosion KW - Permafrost KW - Arktik KW - Kanada KW - Küste KW - Erosion Y1 - 2017 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:kobv:517-opus4-397947 ER - TY - JOUR A1 - Bloethe, Jan H. A1 - Munack, Henry A1 - Korup, Oliver A1 - Fuelling, Alexander A1 - Garzanti, Eduardo A1 - Resentini, Alberto A1 - Kubik, Peter W. T1 - Late Quaternary valley infill and dissection in the Indus River, western Tibetan Plateau margin JF - Quaternary science reviews : the international multidisciplinary research and review journal N2 - The Indus, one of Earth's major rivers, drains large parts of the NW Himalaya and the Transhimalayan ranges that form part of the western Tibetan Plateau margin. In the western Himalayan syntaxis, where local topographic relief exceeds 7 km, the Indus has incised a steep bedrock gorge at rates of several mm yr(-1). Upstream, however, the upper Indus and its tributaries alternate between bedrock gorges and broad alluvial flats flanked by the Ladakh and Zanskar ranges. We review the late Quaternary valley history in this region with a focus on the confluence of the Indus and Zanskar Rivers, where vast alluvial terrace staircases and lake sediments record major episodes of aggradation and incision. New absolute dating of high-level fluvial terrace remnants using cosmogenic Be-10, optically and infrared stimulated luminescence (OSL, IRSL) indicates at least two phases of late Quaternary valley infilling. These phases commenced before similar to 200 ka and similar to 50-20 ka, judging from terrace treads stranded >150 m and similar to 30-40 m above modern river levels, respectively. Numerous stacks of lacustrine sediments that straddle the Indus River >200 km between the city of Leh and the confluence with the Shyok River share a distinct horizontal alignment. Constraints from IRSL samples of lacustrine sequences from the Leh-Spituk area reveal a protracted lake phase from >177 ka to 72 ka, locally accumulating >50-m thick deposits. In the absence of tectonic faulting, major lithological differences, and stream capture, we attribute the formation of this and other large lakes in the region to natural damming by large landslides, glaciers, and alluvial fans. The overall patchy landform age constraints from earlier studies can be reconciled by postulating a major deglacial control on sediment flux, valley infilling, and subsequent incision that has been modulated locally by backwater effects of natural damming. While comparison with Pleistocene monsoon proxies reveals no obvious correlation, a lateor post-glacial sediment pulse seems a more likely source of this widespread sedimentation that has partly buried the dissected bedrock topography. Overall, the long residence times of fluvial, alluvial and lacustrine deposits in the region (>500 ka) support previous studies, but remain striking given the dominantly steep slopes and deeply carved valleys that characterise this high-altitude mountain desert. Recalculated late Quaternary rates of fluvial bedrock incision in the Indus and Zanskar of 1.5 +/- 0.2 mm yr(-1) are at odds with the longevity of juxtaposed valley-fill deposits, unless a lack of decisive lateral fluvial erosion helps to preserve these late Pleistocene sedimentary archives. We conclude that alternating, similar to 10(4)-yr long, phases of massive infilling and incision have dominated the late Quaternary history of the Indus valley below the western Tibetan Plateau margin. (C) 2014 Elsevier Ltd. All rights reserved. KW - Himalaya KW - Indus KW - Valley fills KW - Glaciation KW - Erosion KW - Lake sediment Y1 - 2014 U6 - https://doi.org/10.1016/j.quascirev.2014.04.011 SN - 0277-3791 VL - 94 SP - 102 EP - 119 PB - Elsevier CY - Oxford ER - TY - JOUR A1 - Korup, Oliver A1 - Hayakawa, Yuichi A1 - Codilean, Alexandru T. A1 - Matsushi, Yuki A1 - Saito, Hitoshi A1 - Oguchi, Takashi A1 - Matsuzaki, Hiroyuki T1 - Japan's sediment flux to the Pacific Ocean revisited JF - Earth science reviews : the international geological journal bridging the gap between research articles and textbooks N2 - Quantifying volumes and rates of delivery of terrestrial sediment from island arcs to subduction zones is indispensable for refining estimates of the thickness of trench fills that may eventually control the location and timing of submarine landslides and tsunami-generating mega-earthquakes. Despite these motivating insights, knowledge about the rates of erosion and sediment export from the Japanese islands to their Pacific subduction zones remains patchy regardless of the increasing availability of highly resolved data on surface deformation, climate, geology, and topography. Traditionally, natural erosion rates across the island arc have been estimated from regression of topographic catchment metrics and reservoir sedimentation rates that were recorded over several years to decades. We review current research in this context, correct for a systematic bias in one of the most widely used predictions, and present new estimates of decadal to millennial-scale erosion rates of Japan's terrestrial inner forearc. We draw on several independent and unprecedented inventories of mass wasting, reservoir sedimentation, and concentrations of cosmogenic Be-10 in river sands. We find that natural Be-10-derived denudation rates of several mm yr(-1) in the Japanese Alps have been sustained over several centuries to millennia, and are, within error, roughly consistent with sediment yields inferred from artificial reservoir sedimentation. Local exceptions may likely result from release of sediment storage or regional landsliding episodes that trigger transient sediment pulses. Our synopsis further reveals that catchments draining Japan's eastern seaboard differ distinctly in their tectonic, lithological, topographic, and climatic characteristics between the Tohoku, Japanese Alps, and Nankai inner forearc segments, which is underscored by a marked asymmetric pattern of erosion rates along the island arc. Erosion rates are highest (up to at least 3 mm yr(-1)) in the Japanese Alps that mark the collision of two subduction zones, where high topographic relief, hillslope and bedrock-channel steepness foster rapid denudation by mass wasting. Comparable, if slightly lower, erosion rates characterise the Nankai inner forearc in southwest Japan, most likely due to higher typhoon-driven rainfall totals and variability rather than its high topographic relief. In contrast, our estimated erosion and flux rates are lowest in the Tohoku inner forearc catchments that feed sediment into the Japan Trench. We conclude that collisional mountain building of the Japanese Alps drives some of the highest erosion rates in the island arc despite similar uplift and precipitation controls in southwest Japan. We infer that, prior to extensive river damming, reservoir construction, and coastal works, the gross of Japan's total sediment export to the Pacific Ocean entered the accretionary margin of the Nankai Trough as opposed to the comparatively sediment-starved Japan Trench. Compared to documented contemporary rates of sediment flux from mountainous catchments elsewhere in the Pacific, the rivers draining Japan's inner forearc take an intermediate position despite high relief, steep slopes, very high seismicity, and frequent rainstorms. However, the average rates of millennial-scale denudation in the Japanese Alps particularly are amongst the highest reported worldwide. Local mismatches between these late Holocene and modern rates emphasise the anthropogenic fingerprint on sediment retention that may have significantly reduced the island arc's mass flux to its subduction zones, as is the case elsewhere in east and southeast Asia. (C) 2014 Elsevier B.V. All rights reserved. KW - Erosion KW - Japan KW - Subduction zone KW - Landslides KW - Cosmogenic nuclides KW - Sediment budget Y1 - 2014 U6 - https://doi.org/10.1016/j.earscirev.2014.03.004 SN - 0012-8252 SN - 1872-6828 VL - 135 SP - 1 EP - 16 PB - Elsevier CY - Amsterdam ER - TY - JOUR A1 - Bronstert, Axel A1 - de Araujo, Jose-Carlos A1 - Batalla Villanueva, Ramon J. A1 - Costa, Alexandre Cunha A1 - Delgado, José Miguel Martins A1 - Francke, Till A1 - Förster, Saskia A1 - Guentner, Andreas A1 - Lopez-Tarazon, José Andrés A1 - Mamede, George Leite A1 - Medeiros, Pedro Henrique Augusto A1 - Mueller, Eva A1 - Vericat, Damia T1 - Process-based modelling of erosion, sediment transport and reservoir siltation in mesoscale semi-arid catchments JF - Journal of soils and sediments : protection, risk assessment and remediation N2 - To support scientifically sound water management in dryland environments a modelling system has been developed for the quantitative assessment of water and sediment fluxes in catchments, transport in the river system, and retention in reservoirs. The spatial scale of interest is the mesoscale because this is the scale most relevant for management of water and land resources. This modelling system comprises process-oriented hydrological components tailored for dryland characteristics coupled with components comprising hillslope erosion, sediment transport and reservoir deposition processes. The spatial discretization is hierarchically designed according to a multi-scale concept to account for particular relevant process scales. The non-linear and partly intermittent run-off generation and sediment dynamics are dealt with by accounting for connectivity phenomena at the intersections of landscape compartments. The modelling system has been developed by means of data from nested research catchments in NE-Spain and in NE-Brazil. In the semi-arid NE of Brazil sediment retention along the topography is the main process for sediment retention at all scales, i.e. the sediment delivery is transport limited. This kind of deposition retains roughly 50 to 60 % of eroded sediment, maintaining a similar deposition proportion in all spatial scales investigated. On the other hand, the sediment retained in reservoirs is clearly related to the scale, increasing with catchment area. With increasing area, there are more reservoirs, increasing the possibility of deposition. Furthermore, the area increase also promotes an increase in flow volume, favouring the construction of larger reservoirs, which generally overflow less frequently and retain higher sediment fractions. The second example comprises a highly dynamic Mediterranean catchment in NE-Spain with nested sub-catchments and reveals the full dynamics of hydrological, erosion and deposition features. The run-off modelling performed well with only some overestimation during low-flow periods due to the neglect of water losses along the river. The simulated peaks in sediment flux are reproduced well, while low-flow sediment transport is less well captured, due to the disregard of sediment remobilization in the riverbed during low flow. This combined observation and modelling study deepened the understanding of hydro-sedimentological systems characterized by flashy run-off generation and by erosion and sediment transport pulses through the different landscape compartments. The connectivity between the different landscape compartments plays a very relevant role, regarding both the total mass of water and sediment transport and the transport time through the catchment. KW - Connectivity KW - Deposition KW - Erosion KW - Modelling KW - Sediment transfer KW - Semi-arid Y1 - 2014 U6 - https://doi.org/10.1007/s11368-014-0994-1 SN - 1439-0108 SN - 1614-7480 VL - 14 IS - 12 SP - 2001 EP - 2018 PB - Springer CY - Heidelberg ER - TY - JOUR A1 - Zimmermann, Alexander A1 - Francke, Till A1 - Elsenbeer, Helmut T1 - Forests and erosion: Insights from a study of suspended-sediment dynamics in an overland flow-prone rainforest catchment JF - Journal of hydrology N2 - Forests seem to represent low-erosion systems, according to most, but not all, studies of suspended-sediment yield. We surmised that this impression reflects an accidental bias in the selection of monitoring sites towards those with prevailing vertical hydrological flowpaths, rather than a tight causal link between vegetation cover and erosion alone. To evaluate this conjecture, we monitored, over a 2-year period, a 3.3 ha old-growth rainforest catchment prone to frequent and widespread overland flow. We sampled stream flow at two and overland flow at three sites in a nested arrangement on a within-event basis, and monitored the spatial and temporal frequency of overland flow. Suspended-sediment concentrations were modeled with Random Forest and Quantile Regression Forest to be able to estimate the annual yields for the 2 years, which amounted to 1 t ha(-1) and 2 t ha(-1) in a year with below-average and with average precipitation, respectively. These estimates place our monitoring site near the high end of reported suspended-sediment yields and lend credence to the notion that low yields reflect primarily the dominance of vertical flowpaths and not necessarily and exclusively the kind of vegetative cover. Undisturbed forest and surface erosion are certainly no contradiction in terms even in the absence of mass movements. KW - Rainforest KW - Overland flow KW - Erosion KW - Suspended-sediment yield KW - Quantile Regression Forest model KW - Panama Canal watershed Y1 - 2012 U6 - https://doi.org/10.1016/j.jhydrol.2012.01.039 SN - 0022-1694 VL - 428 IS - 7 SP - 170 EP - 181 PB - Elsevier CY - Amsterdam ER - TY - JOUR A1 - Korup, Oliver T1 - Earth's portfolio of extreme sediment transport events JF - Earth science reviews : the international geological journal bridging the gap between research articles and textbooks N2 - Quantitative estimates of sediment flux and the global cycling of sediments from hillslopes to rivers, estuaries, deltas, continental shelves, and deep-sea basins have a long research tradition. In this context, extremely large and commensurately rare sediment transport events have so far eluded a systematic analysis. To start filling this knowledge gap I review some of the highest reported sediment yields in mountain rivers impacted by volcanic eruptions, earthquake- and storm-triggered landslide episodes, and catastrophic dam breaks. Extreme specific yields, defined here as those exceeding the 95th percentile of compiled data, are similar to 10(4) t km(-2) yr(-1) if averaged over 1 yr. These extreme yields vary by eight orders of magnitude, but systematically decay with reference intervals from minutes to millennia such that yields vary by three orders of magnitude for a given reference interval. Sediment delivery from natural dam breaks and pyroclastic eruptions dominate these yields for a given reference interval. Even if averaged over 10(2)-10(3) yr, the contribution of individual disturbances may remain elevated above corresponding catchment denudation rates. I further estimate rates of sediment (re-)mobilisation by individual giant terrestrial and submarine mass movements. Less than 50 postglacial submarine mass movements have involved an equivalent of similar to 10% of the contemporary annual global flux of fluvial sediment to Earth's oceans, while mobilisation rates by individual events rival the decadal-scale sediment discharge from tectonically active orogens such as Taiwan or New Zealand. Sediment flushing associated with catastrophic natural dam breaks is non-stationary and shows a distinct kink at the last glacial-interglacial transition, owing to the drainage of very large late Pleistocene ice-marginal lakes. Besides emphasising the contribution of high-magnitude and low-frequency events to the global sediment cascade, these findings stress the importance of sediment storage for fuelling rather than buffering high sediment transport rates. KW - Sediment yield KW - Erosion KW - Extreme event Y1 - 2012 U6 - https://doi.org/10.1016/j.earscirev.2012.02.006 SN - 0012-8252 VL - 112 IS - 3-4 SP - 115 EP - 125 PB - Elsevier CY - Amsterdam ER -