TY - JOUR

T1 - Sediment dynamics in an upland temperate catchment : changing sediment sources, rates and deposition.

AU - Hatfield, Robert

AU - Maher, Barbara

AU - Pates, Jackie

AU - Barker, Philip

PY - 2008/11

Y1 - 2008/11

N2 - Accelerated erosion and transport of fine sediment from upland temperate catchments can reflect increased erosivity and/or erodibility, due in turn to climatic and/or human forcing. Identification of sediment fluxes and sources over Holocene timescales can both enable understanding of the relative impacts of these forcings, and provide perspective on recent sediment fluxes. Here we present a ~ 5,500 year record of sediment fluxes and sources from Lake Bassenthwaite utilising magnetic measurements and fuzzy clustering, coupled with independent pollen and archaeological records, to identify the timing and impact of catchment disturbance. This record shows that recent sediment flux increases (i.e., within the last 150 years) are unprecedented in scale throughout the mid-late Holocene and appear to be in response to specific human changes occurring within the catchment. Earlier episodes of human activity, from the mid-Holocene onwards, show no link with increased lake sediment fluxes, indicating either limited catchment impact and/or ‘buffering’ through within-catchment sediment storage. Increasingly intensive land use and reduction of sediment storage through revetment construction on a key inflow, Newlands Beck, have resulted in 3 x increases in lake sediment flux. These data may be significant for other upland temperate areas, as increasing land use pressures and reduced sediment storage capacity may not only increase contemporary sediment flux, but increase sensitivity to predicted increases in rainfall and storminess as a result of global warming.

AB - Accelerated erosion and transport of fine sediment from upland temperate catchments can reflect increased erosivity and/or erodibility, due in turn to climatic and/or human forcing. Identification of sediment fluxes and sources over Holocene timescales can both enable understanding of the relative impacts of these forcings, and provide perspective on recent sediment fluxes. Here we present a ~ 5,500 year record of sediment fluxes and sources from Lake Bassenthwaite utilising magnetic measurements and fuzzy clustering, coupled with independent pollen and archaeological records, to identify the timing and impact of catchment disturbance. This record shows that recent sediment flux increases (i.e., within the last 150 years) are unprecedented in scale throughout the mid-late Holocene and appear to be in response to specific human changes occurring within the catchment. Earlier episodes of human activity, from the mid-Holocene onwards, show no link with increased lake sediment fluxes, indicating either limited catchment impact and/or ‘buffering’ through within-catchment sediment storage. Increasingly intensive land use and reduction of sediment storage through revetment construction on a key inflow, Newlands Beck, have resulted in 3 x increases in lake sediment flux. These data may be significant for other upland temperate areas, as increasing land use pressures and reduced sediment storage capacity may not only increase contemporary sediment flux, but increase sensitivity to predicted increases in rainfall and storminess as a result of global warming.

KW - environmental magnetism

KW - magnetic susceptibility

KW - sediment tracing

KW - pollen

KW - climate change

KW - Holocene

KW - sediment storage

UR - http://www.scopus.com/inward/record.url?scp=52549131552&partnerID=8YFLogxK

U2 - 10.1007/s10933-008-9221-7

DO - 10.1007/s10933-008-9221-7

M3 - Journal article

VL - 40

SP - 1143

EP - 1158

JO - Journal of Paleolimnology

JF - Journal of Paleolimnology

SN - 0921-2728

IS - 4

ER -