How floods determine river landscapes with examples from the Himalaya and Scottish Highlands. Talk by Professor Hugh Sinclair – University of Edinburgh.
Rivers adjust their width, depth and slope to the climate (mainly rainfall), vegetation and underlying rock types in their upstream catchment, and, once adjusted, are able to support a diverse range of fauna and flora. However, when any of these factors are perturbed, such as through agriculture, damming or flood protection, adjustment can take many years to decades, and this provides a major challenge for freshwater ecosystems. Climate change is now adding another challenge for our rivers. A critical question is what determines the ability of a river to settle back to a more steady or ‘natural’ condition following a change in its environment. The key here is the ability of the river to adjust its channel through erosion and deposition of sediment, and all of this is fundamentally controlled by the magnitude and frequency of flood events.
In this talk, Prof Sinclair will first look at extreme examples from the Himalaya where devastating floods appear to be increasing and where engineered flood protection and hydropower dams are being swept away by huge, sediment laden flood waters; we will consider how flood risk can be managed in these settings. Secondly, we will explore examples from the Highlands of Scotland where rewilding and nature-based engineering solutions are attempting to return rivers to their more natural state and encourage greater numbers and diversity of insects, birds and fish. In both settings we find the ability of floods to reconfigure a river channel through erosion and sedimentation as the principal determinant of a river’s response to climatic or anthropogenic perturbations. The underlying message is that the nature of any river channel is a direct reflection of the health of its upstream catchment and its impact on flooding.
Hugh Sinclair is a geologist by training having received degrees from Aberystwyth and Oxford Universities. He has worked in numerous mountain ranges studying how their geological growth is recorded in the stratigraphic record. Having recognised the value of understanding ‘deep time’, he increasingly studied modern processes such as sand transport in rivers in order to better understand the geological record. Having been a researcher and lecturer at Durham and Birmingham Universities, he moved to Edinburgh University in 1999 where he has remained since. At Edinburgh, opportunities to work in large teams enabled Hugh to consider interdisciplinary approaches to understanding the nature of modern rivers in the Himalaya and elsewhere and has focused on the extreme events that cause severe changes to the landscapes. He has recently been involved in innovative ways to monitor the transport of gravels and sand in big rivers of Scotland and the Himalaya.
He currently leads the Global Change Institute at Edinburgh University and is Principal Investigator on an interdisciplinary project looking at risk sensitive planning for ‘Tomorrow’s Cities’:
https://www.ed.ac.uk/geosciences/research/institutes-centres/institutes/global-change