An Atlas of Past and Present Pollen Maps for Europe: 0-13000 Years Ago, and The Overlay Maps.

A comprehensive database of radiocarbon dated fluvial units in Great Britain, Poland and Spain has been compiled to investigate the relationship between environmental change, flooding and Holocene river dynamics. Following the methodology recently developed by Macklin and Lewin [Macklin, M.G., Lewin, J., 2003. River sediments, great floods and centennial-scale Holocene climate change. Journal of Quaternary Science 18, 101–105], radiocarbon dates in fluvial sequences that coincide with a modification in sedimentation rate, or style, have been highlighted, allowing geomorphologically significant changes in Holocene river activity to be identified. Data analysis has been undertaken at both national and sub-national scales, and on catchments of different size, type and land-use history. Multiple phases of higher flood frequency, characterized by accelerated erosion and sediment deposition on floodplains, are recognized and compared with a range of climate proxies. The relative and varying roles of climate and land-use on river dynamics are considered and the value of the database for reconstructing past hydrological events, as well as for predicting river response to future environmental change, is assessed.

Past hydrological events reflected in the Holocene fluvial record of Europe

Flood estimation and flood management have traditionally been the domain of hydrologists, water resources engineers and statisticians, and disciplinary approaches abound. Dominant views have been shaped; one example is the catchment perspective: floods are formed and influenced by the interaction of local, catchment-specific characteristics, such as meteorology, topography and geology. These traditional views have been beneficial, but they have a narrow framing. In this paper we contrast traditional views with broader perspectives that are emerging from an improved understanding of the climatic context of floods. We come to the following conclusions: (1) extending the traditional system boundaries (local catchment, recent decades, hydrological/hydraulic processes) opens up exciting possibilities for better understanding and improved tools for flood risk assessment and management. (2) Statistical approaches in flood estimation need to be complemented by the search for the causal mechanisms and dominant processes in the atmosphere, catchment and river system that leave their fingerprints on flood characteristics. (3) Natural climate variability leads to time-varying flood characteristics, and this variation may be partially quantifiable and predictable, with the perspective of dynamic, climate-informed flood risk management. (4) Efforts are needed to fully account for factors that contribute to changes in all three risk components (hazard, exposure, vulnerability) and to better understand the interactions between society and floods. (5) Given the global scale and societal importance, we call for the organization of an international multidisciplinary collaboration and data-sharing initiative to further understand the links between climate and flooding and to advance flood research.

/pdf/floods-and-climate-emerging-perspectives-for-flood-risk-2qu8rc4z53.pdf

Floods and climate: emerging perspectives for flood risk assessment and management

This contribution analyses the processes involved in the generation of sinkholes from the study of paleokarst features exposed in four Spanish Tertiary basins. Bedrock strata are subhorizontal evaporites, and in three of the basins they include halite and glauberite in the subsurface. Our studies suggest that formation of dolines in these areas results from a wider range of subsidence processes than those included in the most recently published sinkhole classifications; a new genetic classification of sinkholes applicable to both carbonate and evaporite karst areas is thus proposed. With the exception of solution dolines, it defines the main sinkhole types by use of two terms that refer to the material affected by downward gravitational movements (cover, bedrock or caprock) and the main type of process involved (collapse, suffosion or sagging). Sinkholes that result from the combination of several subsidence processes and affect more than one type of material are described by combinations of the different terms with the dominant material or process followed by the secondary one (e.g. bedrock sagging and collapse sinkhole). The mechanism of collapse includes any brittle gravitational deformation of cover and bedrock material, such as upward stoping of cavities by roof failure, development of well-defined failure planes and rock brecciation. Suffosion is the downward migration of cover deposits through dissolutional conduits accompanied with ductile settling. Sagging is the ductile flexure of sediments caused by differential corrosional lowering of the rockhead or interstratal karstification of the soluble bedrock. The paleokarsts we analysed suggest that the sagging mechanism (not included in previous genetic classifications) plays an important role in the generation of sinkholes in evaporites. Moreover, collapse processes are more significant in extent and rate in areas underlain by evaporites than in carbonate karst, primarily due to the greater solubility of the evaporites and the lower mechanical strength and ductile rheology of gypsum and salt rocks.

A genetic classification of sinkholes illustrated from evaporite paleokarst exposures in Spain

http://www.ugr.es/~grupo179/pdf/Moreno%202012.pdf

The Medieval Climate Anomaly in the Iberian Peninsula reconstructed from marine and lake records

Palaeoflood record of the Tagus River (Central Spain) during the Late Pleistocene and Holocene

Geomorphological and sedimentological features in Quaternary fluvial systems affected by solution-induced subsidence (Ebro Basin, NE-Spain)

Geoarqueología y patrimonio en la Península Ibérica y el entorno mediterráneo

Trabajo presentado en el Congreso Ex AQUA, celebrado en Padua (Italia), del 26 de septiembre al 1 de octubre de 2016

Historical Palaeohydrology and landscape resilience of a mediterranean Rambla (Castellón, NE Spain)

Climate change implies changes in the frequency and magnitude of flood events. The influence of climate variability on flooding was evaluated by an analysis of sedimentary (palaeofloods) and documentary archives. A 500-year palaeoflood record at Montlleo River (657 km2 in catchment area), eastern Spain, revealed up to 31 palaeofloods with a range of discharges of 20–950 m3 s−1, and with at least five floods exceeding 740–950 m3 s−1. This information contrasts with the available gauged flood registers (since year 1971) with an annual maximum daily discharge of 129 m3 s−1. Our palaeoflood dataset indicates flood cluster episodes at (1) 1570–1620, (2) 1775–1795, (3) 1850–1890, and (4) 1920–1969. Flood rich periods 1 and 3 corresponded to cooler than usual (about 0.3 °C and 0.2 °C) climate oscillations, whereas 2 and 4 were characterised by higher inter-annual climatic variability (floods and droughts). This high inter-annual rainfall variability increased over the last 150 years, leading to a reduction of annual maximum flow. Flood quantiles (>50 years) calculated from palaeoflood+gauged data showed 30%–40% higher peak discharges than those using only instrumental records, whereas when increasing the catchment area (1500 km2) the discharge estimation variance decreased to ~15%. The results reflect the higher sensitivity of small catchments to changes on flood magnitude and frequency due to climate variability whereas a larger catchment buffers the response due to the limited extent of convective storms. Our findings show that extended flood records provide robust knowledge about hazardous flooding that can assist in the prioritization of low-regret actions for flood-risk adaptation to climate change.

https://www.mdpi.com/2073-4441/12/4/1008/pdf

María José Machado

Papers

Palaeoflood record of the Tagus River (Central Spain) during the Late Pleistocene and Holocene

Geomorphological and sedimentological features in Quaternary fluvial systems affected by solution-induced subsidence (Ebro Basin, NE-Spain)

Geoarqueología y patrimonio en la Península Ibérica y el entorno mediterráneo

Historical Palaeohydrology and landscape resilience of a mediterranean Rambla (Castellón, NE Spain)

Extreme Floods in Small Mediterranean Catchments: Long-Term Response to Climate Variability and Change