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Evening Lecture and Keynotes

Evening Lecture - Human origins: 7 million years of diversity

Monday September 24, 2018 - 19:00

Prof. Dr. Friedemann Schrenk

Senckenberg Gesellschaft für Naturforschung (Paleoanthropology Section) - Frankfurt am Main


Humanity originated in Africa about 350.000 generations ago. The fossil record is constantly growing, and reveals a complex history of our earliest ancestors together with a large geographic diversity of pre-humans and early humans. The search for our earliest history involves questions about the origin of upright walking, of culture, of expansions out of Africa and on the origin of worldwide geographical variants. Ecological and climatological data highlight the relationship between climate change and the critical stages of human evolution. The lecture also discusses how our new knowledge can assist in the de-construction of racism  and the creation of a new understanding of human history.


Keynote 1 - The Rhine delta: from upland sediment delivery to a living landscape

Monday September 24, 2018 - 14:15

Prof. Dr. Hans Middelkoop

Utrecht University (Department of Physical Geography)

 

The Rhine-Meuse delta in the Netherlands has been functioning as an efficient and near-complete trap of sediment from the upstream basin during the past 8000 years. Over the past decades we have disclosed this record in high resolution, which has brought major insights in the timing and amounts of sediments that were trapped in the delta, shifting deposition hotspots within the delta, as well as the likely causes for these. In addition, the delta contains high-resolution records of Rhine discharge extremes over the past millennia, which has revealed several periods with increased peak flows.

 

The resulting build-up of the trapped sediment has had major consequences for the delta morphology, in particular in times of human interaction with the delta landscape. Our detailed database, and 3D-time models of the delta substrate, and new GIS-based landscape analyses have enabled us to understand how the inherited build-up and changing sediment loads determined sea ingressions and land loss in the coastal region, facilitated natural levee building and human occupation within the central delta, triggered a remarkable avulsion across the delta, and have led to serious land subsidence in the flood basins.

 

These Holocene-Anthropocene developments demonstrate the linkages between Quaternary and Geomorphologic research, but their understanding is also highly relevant to modern delta management.

 

Keynote 2 - Subaquatic geomorphology of perualpine lakes: exploring a hidden frontier

Tuesday September 25, 2018 - 14:15

Prof. Dr. Flavio Anselmetti

University of Bern (Institute of Geological Sciences)

 

To date, most underwater landscapes in lakes remain unexplored and represent a hidden frontier in geomorphologic research. Quality of existing bathymetric data mostly lags well behind the terrestrial counterparts (i.e. from airborne laser scanning) preventing detailed analysis of lake-floor processes. In the last ten years, however, application of state-of-the-art surveying techniques, including swath bathymetry in deep-water areas and green-laser technology in shallow-water zones, produce digital elevation models that are equal or better than what is available on land allowing novel exploration or previously unmapped areas. This wealth of data provides spectacular insights into key processes including recurrence rates and impacts of natural hazards (mass movements, earthquakes, tsunamis), subglacial erosion and deposition, lake-physical processes, neotectonis, and human impact.

Most perialpine lakes lie within glacially overdeepened basins that formed during repeated glaciations, when subglacial erosion produced deep incisions in the bedrock. Underwater remains of this glacial activity can be mapped still today, in particular when bathymetric data are combined with reflections seismic surveys. Subaquatic moraines provide critical insights into deglaciation processes for periods when the overall retreating glacier remained stable or readvanced. Once that a glacier left the overdeepened basin, lacustrine sedimentation infills the basin with rates depending on the clastic supply through river-delta systems and on in situ lake productivity. Inherited glacial morphology thus becomes infilled, often accompanied by seismic or aseismic underwater slope instabilities that mobilize million of cubic meters of lake sediments. Such mass movement often are tsunamogenic and leave dramatic traces in the lake-floor morphology. High-resolution bathymetric data is necessary to compile complete mass-movement catalogues so that reliable underwater hazard maps and related natural hazard assessments can be made. Moreover, bathymetric data allows to identify traces of neotectonic fault lines and various forms of archeological remains that were not known prior to the surveys.

In areas of rapid sedimentation or erosion, repeated bathymetric surveys allow a high-resolution 4D quantification of positive or negative mass balances. This is in particular useful in highly dynamic zones such as on delta slopes or in coastal waters where nearshore erosion is critical. Sedimentation rates can be calculated and can be considered in the context of mass fluxes from catchment sources to the basinal sinks. This quantitative knowledge provides well-needed time series of sediment yield reflecting transient states of erosion, mobilization and deposition.

 

Keynote 3 - Modelling future surface topographies and land forming processes in deglaciating areas - an emerging research field

Wednesday September 26, 2018 - 14:15

Prof. Dr. Wilfried Haeberli (em.)

University of Zurich (Department of Geography)

 

As a consequence of continued global warming, glaciers in many mountain regions are likely to essentially disappear within the coming decades.  So far glacier-covered areas are thereby rapidly but probably for generations to come transforming into periglacial landscapes of bedrock, loose debris, scarce vegetation, numerous lakes and slowly degrading permafrost (Haeberli et al. 2017). Pronounced and long-lasting disequilibria are likely to affect slope stability, sediment cascades or vegetation cover. Corresponding effects from such developments relating to possible options and risks for human activities and infrastructure must be anticipated and quantitatively modelled (Haeberli 2017).

 

Modelling ice thicknesses and bed topographies for still existing glaciers constitutes the first step, providing future surface topographies exposed after ice vanishing. A number of 3D slope-related approaches have become available during recent years. They apply the principle of a generalized inverted ice flow consideration where mass fluxes determine slope-dependent stresses and ice thicknesses. Simple as well as complex, stress-driven as well as flux-driven approaches exist. Simple stress-driven approaches (constant driving stress along individual glaciers) have the advantage of being robust, transparent, fast, using easily available input and needing no tuning. Complex flux-driven approaches depend on sophisticated input information and must be heavily tuned (whereby they largely loose their originally envisaged complexity). An international inter-comparison study (Farinotti et al. 2017) reveals that simple as well as complex/tuned models perform about equally well with the uncertainty level concerning absolute values of local ice-depths being generally high (about ± 30% of the estimated value). The main cause of this uncertainty is the difficulty of parameterizing mass fluxes (mass balance, flow), a basic scientific difficulty which cannot easily be overcome. Calculated relative bed topographies, however, much more directly depend on variable glacier surface slopes and, hence, are more robust. As a consequence, they provide a quite realistic impression of future surface topographies and topologies (overdeepenings, riegels, steep lateral slopes, etc.).

 

Based on so-anticipated surface topographies, future landforming processes and resulting landscapes can be modelled. First accomplishments concern the possible formation of future lakes in exposed glacier-bed overdeepenings or steep/debuttressed lateral slopes (Haeberli et al. 2017). More integrated analyses are needed with modelling bio-geomorphological interactions, sediment transfer processes, or hazard/risk assessment in relation to slope instability and complex chains of processes such as impact/flood waves from rock/ice avalanches into new lakes at the foot of oversteepened icy peaks. A wide new research field is open and growing for geomorphology and quaternary sciences. Combining modern quantitative process understanding with documented experience about the past from these two scientific domains will thereby play a key role (cf. for instance Eichel et al. 2015).

 

References:

 

Eichel, J., Corenblit, D. and Dikau, R. (2015): Conditions for feedbacks between geomorphic and vegetation dynamics on lateral moraine slopes: a biogeomorphic feedback window. Earth Surface Processes and Landforms 41, 406-419. doi:10.1002/esp.3859

Farinotti, D. and 35 co-authors (2017): How accurate are estimates of glacier ice thickness? Results from ITMIX, the Ice Thickness Models Intercomparison eXperiment. The Cryosphere 11, 949–970. doi.org/10.5194/tc-11-949-2017 

Haeberli, W. (2017): Integrative modelling and managing new landscapes and environments in de-glaciating mountain ranges: An emerging trans-disciplinary research field. Forestry Research and Engineering: International Journal 1(1). doi:10.15406/freij.2017.01.00005

Haeberli, W., Schaub, Y. and Huggel, C. (2017): Increasing risks related to landslides from degrading permafrost into new lakes in de-glaciating mountain ranges. Geomorphology 293, 405-417. doi:10.1016/j.geomorph.2016.02.009