The development and application of a database of radiocarbon-dated Holocene fluvial deposits in Great Britain

This paper reports on the development of a British database of 14C dated Holocene fluvial units over the last 15 years. Since its inception in 1989, the database has undergone substantial expansion, refinement and improvement together with considerable methodological development, so that today it serves as a powerful research tool for investigating the spatial and temporal dynamics of Holocene river development and flooding in Great Britain. The improved analytical method is here applied to the currently existing database by examining datasets of 14C dated fluvial units from river basins that lie within and beyond the limits of Late Devensian glaciation. This analysis indicates how the contrasted conditions in these two types of river environment have, to an extent, led to divergent records of flooding in response to Holocene climate and land-use change. However, even in the contrasting sedimentary records of upland glaciated, and lowland unglaciated river basins, six corresponding episodes of increased flood frequency are identified at c. 5730, c. 3540, c. 2730, c. 2280, c. 660 and c. 570 cal. BP. These represent widespread common responses from British river systems to large-scale changes in climate. The method of database construction and analysis outlined and demonstrated in this paper could be readily adopted in other parts of the world to improve our understanding of Holocene river behaviour at the continental- and global-scale.