The specific aims of the focus area "Palaeohydrology and fluvial archives - extreme and critical events" are:

The Focus Group aims at a local but also a continental perspective, which consequently requires further international collaboration. To achieve this multidisciplinary research it is proposed to focus on palaeohydrological research initiatives that will incorporate timely topics and each involve new cross-boundary research groups including:

  1. Extreme hydrological events, addressing the spatial and temporal patterns of extremes in different world regions and from a multidisciplinary perspective. A hydrological event is defined as having a magnitude higher (flood) or lower (drought) than a critical threshold, including extreme events of significantly differing magnitudes. Events may be unique or clustered in time and tend to last longer going back in time in the geological record. Eventually, a succession of extreme events may lead to river incision and alluvial terrace formation in addition to the traces of a distinct event itself, which can be well illustrated by outburst floods. One of the challenging question concerns the recognition of the conditions and the methods related to the definition of extreme events in a contest characterised by a different past climate.

  2. Collation and presentation of palaeohydrological research results that are relevant for understanding and managing global environmental change. The study of palaeohydrological critical events requires knowledge on their original causes, either by climatic change related triggers or due to geophysical processes such as dam failures of natural impounded lakes. Clustering of floods in a continental perspectives can be a potential tool for correlation of continental stratigraphic record.

  3. Human perception and impact. For Holocene and historical events human perception including consequences like abandonments or shifting of settlements are important to figure extreme events' impacts. Quantification of duration and magnitude of previous drought and flood periods is of primary importance to assess the resilience of cultural groups and their capability to react the natural forcing. Interaction and feedback between extreme palaeohydrological events and human societies has a key role in understanding the resilience of the groups to perturbation of landscape and available water. Moreover, the geoarchaeological approach supports the collection of very detailed chronological information that constraint of the floods and droughts periods. For the late Holocene the palaeoenvironmental record preserved in some archaeological sites allows to recognize single events and clustering of them. For the last centuries the historical sources a wealth of descriptions and data can be exploited. Crisis or collapse of cultural groups are often linked to environmental cause, but the proofs are rarely strong and often an undemonstrated direct link between natural crisis and collapse of civilization is claimed without clear proofs.

  4. New methods and techniques for palaeohydrological reconstruction like remote sensing, geochronology, modelling, numerical simulation, geochemical and isotopic analysis are constantly developed and further improved. The necessary quantification of discharge associated with abandoned landforms (e.g. palaeochannels) has attracted the work of researchers at the beginning of palaeohydrology but, despite the impressive improvement of available data (e.g. remote sensed images, LiDAR altimetry) very few attention has been paid to update and to develop further the related techniques in the last decades. The combined use of stratigraphy, palaeobotany and numerical models can largely improve our knowledge and reconstruction of palaeodischarges.

Historic flood levels of the River Main at Eibelstadt (near W├╝rzburg) dating back up to five centuries