Geomorphic and sedimentary evolution of an extreme event: testing a sediment-based palaeoflood record

GSTDTAP

项目编号	NE/P000118/1
	Geomorphic and sedimentary evolution of an extreme event: testing a sediment-based palaeoflood record
	[unavailable]
主持机构	University of Liverpool
项目开始年	2016
	2016-05-01
项目结束日期	2016-12-31
资助机构	UK-NERC
项目类别	Research Grant
国家	英国
语种	英语
英文摘要	This project will use the December 2015 extreme flooding in Cumbria to critically test the integrity and responsiveness of our unique, long (>600 year) lake sedimentary records of flood magnitude and frequency by quantifying the initial sedimentary event, its' diagenetic evolution and the impacts of a sediment-rich post-flood catchment. The recent flooding, following previous extreme flood events in 2005 and 2009, has highlighted the inadequacies of flood magnitude / return-frequency models developed using recorded river flows (30-50 year), which are too short to address societal requirements for accurate measures of flood risk and to address questions regarding the role of climate forcing of recent events. Lake sedimentary archives developed by our research teams at Liverpool and Durham Universities provide the length of record necessary to address this research gap. This includes a sediment magnitude (event particle size) signature at Bassenthwaite that correlates well with river discharges (for 40 years) and identifies that the largest 3 floods in 600 years have occurred in the past decade. We have three specific aims: 1. To establish the deep water sedimentary event signature for lakes with differing water retention times (21-350 days) and to use repeat sampling into the summer period of peak organic productivity in the lake to test the evolution of this and high magnitude events in the recent past (11/2009) into the palaeoflood record. 2. To establish and monitor how post-flood conditioning of catchment-to-lake and within-lake processes modifies or augments the lake sediment flood signal for 2015 event. 3. To improve confidence in our existing palaeoflood series by placing this recent extreme event in that longer term context, and to establish flood frequency models that use integrated sediment and river flow data. The proposed project will use the unique opportunity afforded by contrasting pre- and post-flood sedimentary records and fluxes to establish the sedimentary signature of one of NW England's most extreme floods; crucially to engender confidence in the use of our lake sediment records as genuine flood series, thus contributing to calls for enhanced flood records to accurately define flood risk in these and potentially wider UK and world river systems. Our team has existing sediment traps at Brotherswater and Buttermere, together with lake sediment surface gravity cores sampled before the flood (2012-2015) at key sites impacted by the recent events in the Eden catchment (Brotherswater and Ullswater (Glenridding)) and Cocker-Derwent catchment (Bassenthwaite and Buttermere). Our research methodology is designed to characterise the sediment signal (grain size, geochemistry, mass accumulation) of the flood deposits and repeat this sampling at 6 week intervals to establish the progression of the event into the palaeo-record. We will also monitor the post-flood sediment dynamics in the lake (monthly sediment trapping and continuous turbidity monitoring) and the catchment to quantify the supply of sediments from catchment slopes (6 weekly UAV drone surveys) through key nodes in the sediment cascade to the lake (source-to-sink). This will enable us to contrast the sedimentary characteristics (grain size, geochemistry) of the December 2015 flood with events in the longer palaeoflood record, and incorporate these data in our novel flood frequency modelling using combined sediment and river flow records. This provides an unparalleled opportunity to investigate directly recent flood sedimentation across a variety of lake environments. Uniquely, we have the opportunity to contrast the pre- and post-flood sedimentary records and place our developing long-term data on both flood magnitude and frequency on a robust footing, which will allow us at our stakeholder workshop to encourage national organisations, hydrologists and engineers to use these records with confidence in flood risk management.
来源学科分类	Natural Environment Research
文献类型	项目
条目标识符	http://119.78.100.173/C666/handle/2XK7JSWQ/86151
专题	环境与发展全球科技态势
推荐引用方式 GB/T 7714	[unavailable].Geomorphic and sedimentary evolution of an extreme event: testing a sediment-based palaeoflood record.2016.