• Energy Research

Fluvial records contain evidence of past hydrological changes in terms of water/sediment fluxes and extreme hydrological events (floods), which can be linked to Earth's climate variability. Sedimentological records of hydrological extremes can be complemented with historical documentary information and botanical records. In recent years, fluvial and palaeoflood records supported with excellent chronological data have become available for many rivers worldwide (Gregory et al., 2006), but still regional and global palaeohydrological reconstructions and syntheses have yet to be fully developed. Related to the interpretation of alluvial records, a major recent achievement has been the development of new combined analysis of large radiometrically dated fluvial databases, which allow fluvial activity periods to be more precisely defined and to be characterized in terms of forcing hydrological conditions (Macklin et al., 2006). The approach also serves for comparison of records of fluvial activity in different countries, regions and sites with a range of climate proxies and, for the more recent record, land-use change indicators. The meta-analyses demonstrate the value of the growing spatial coverage and increasing chronological precision of fluvial archives for reconstructing past hydrological events, as well as for understanding river response to environmental/climate change in the past and the future. This special issue brings together a range of papers that reconstruct regional fluvial chronologies of extreme events based on multiple proxies and documentary information, which evaluate the relationship between river hydrology, climate and atmospheric circulation variability. The research presented in this volume was drawn together within the framework of the INQUA Project 1220 on Hydrological EXtreme Events in Changing Climate (HEX Events), and the 1st Workshop on HEX Events held at Utrecht University on November 29th–30th, 2012. Peer reviewed

Abstract The basis for attribution assessments of current extreme weather and climatic events such as droughts and floods is that the record of such events is of sufficient length to be able to compare the occurrence and severity of recent events with those in the past. If this assumption holds, then the magnitude and frequency of extreme hydrological events in the current anthropogenically forced climate can be compared with those in the past under an unforced climate. Attempts to attribute recent floods to anthropogenically-forced climate change have been made, but we argue that such assessments have failed to correctly analyse the true frequency and magnitude of past floods, when anthropogenic Greenhouse Gas (GHG) forcing was low. In this paper we use well-dated, multi-millennial and multi-centennial length records of large floods from multiple sites across Western and Southwestern Europe that demonstrate past floods were occasionally of much higher magnitudes than those of the present-day, and that attribution studies are presently unable to claim that human-created greenhouse gas emissions have increased flood magnitude. We show that flood magnitude was significantly higher before the 20th century, despite there being a negligible greenhouse gas contribution from humans, which means that natural variability might be significantly higher than assumed by climate modellers. This has profound implications for flood planning and climate adaptation policy, as many recent floods cannot be viewed as unprecedented, even in the historical record.

Abstract. In the coal mining districts of the Netherlands, Belgium and Germany, we identified 662 previously unidentified depressions at the land surface using LIDAR data. Their density decreases westwards along with deepening of the Carboniferous coal layers, while not changing in dimensions. The timing of their formation based on historical maps and landowner reports, suggests that they mostly formed during the period 1920–1970, the peak of mining activity. Based on their position, density and age, we link the formation of depressions to the coal-mining activities in South Limburg, Germany and Belgium. Our working hypothesis tentatively explains the origin, mechanism of formation and timing of these local subsidence features.

High-resolution continuous core material, geophysical measurements, and hundreds of archived core descriptions enabled to identify 13 Late Pleistocene Rhine-Meuse sedimentary units in the infill of the southern part of the North Sea basin (the Netherlands, northwestern Europe). This sediment record and a large set of Optical Stimulated Luminescence dates,

AbstractClimate change is expected to significantly affect flooding regimes of river systems in the future. For Western Europe, flood risk assessments generally assume an increase in extreme events and flood risk, and as a result major investments are planned to reduce their impacts. However, flood risk assessments for the present day and the near future suffer from uncertainty, coming from short measurements series, limited precision of input data, arbitrary choices for particular statistical and modelling approaches, and climatic non‐stationarities. This study demonstrates how historical and sedimentary information can extend data records, adds important information on extremes, and generally improves flood risk assessments. The collection of specific data on the occurrence and magnitude of extremes and the natural variability of the floods is shown to be of paramount importance to reduce uncertainty in our understanding of flooding regime changes in a changing climate. For the Lower Rhine (the Netherlands and Germany) estimated recurrence times and peak discharges associated with the current protection levels correlate poorly with historical and sedimentary information and seem biased towards the recent multi‐decadal period of increased flood activity. Multi‐decadal and centennial variability in flood activity is recorded in extended series of discharge data, historical information and sedimentary records. Over the last six centuries that variability correlates with components of the Atlantic climate system such as the North Atlantic Oscillation (NAO) and Atlantic Multi‐decadal Oscillation (AMO). These climatic non‐stationarities importantly influence flood activity and the outcomes of flood risk assessments based on relatively short measurement series. Copyright © 2016 John Wiley & Sons, Ltd.