TY - JOUR

T1 - Pathways of runoff and sediment transfer in small agricultural catchments.

AU - Deasy, Clare

AU - Heathwaite, A. Louise

AU - Brazier, R. E.

AU - Hodgkinson, R.

PY - 2009/4/30

Y1 - 2009/4/30

N2 - Simultaneous field monitoring of runoff and suspended sediment loads from a 30 ha, artificially-drained, mixed-agricultural catchment in Herefordshire, UK indicates field drains are the dominant pathway for the transfer of runoff and sediment to the stream. Surface runoff pathways draining 6·2% of the catchment area transported around 1% of the catchment sediment load, while subsurface runoff in field drains draining 26·5% of the catchment transported around 24% of the sediment load. The explanations offered here for the dominance of drainflow - the spatial limitation of surface runoff generation and low hillslope-stream connectivity of surface runoff compared with subsurface runoff - are also likely to apply to other artificially-drained lowland agricultural catchments in the UK. These catchments are usually on poorly-drained soils, and land management can have a considerable effect on the operation of runoff pathways and the transfer of sediment from hillslope to stream. As a result, subsurface inputs may also dominate sediment transfers in other underdrained catchments. The focus on sediment and pollutant losses via surface runoff pathways means that pollution inputs from subsurface, preferential pathways have been unfairly neglected, and it may be more important to focus on subsurface sediment and sediment-associated pollution inputs for mitigation rather than inputs from surface pathways.

AB - Simultaneous field monitoring of runoff and suspended sediment loads from a 30 ha, artificially-drained, mixed-agricultural catchment in Herefordshire, UK indicates field drains are the dominant pathway for the transfer of runoff and sediment to the stream. Surface runoff pathways draining 6·2% of the catchment area transported around 1% of the catchment sediment load, while subsurface runoff in field drains draining 26·5% of the catchment transported around 24% of the sediment load. The explanations offered here for the dominance of drainflow - the spatial limitation of surface runoff generation and low hillslope-stream connectivity of surface runoff compared with subsurface runoff - are also likely to apply to other artificially-drained lowland agricultural catchments in the UK. These catchments are usually on poorly-drained soils, and land management can have a considerable effect on the operation of runoff pathways and the transfer of sediment from hillslope to stream. As a result, subsurface inputs may also dominate sediment transfers in other underdrained catchments. The focus on sediment and pollutant losses via surface runoff pathways means that pollution inputs from subsurface, preferential pathways have been unfairly neglected, and it may be more important to focus on subsurface sediment and sediment-associated pollution inputs for mitigation rather than inputs from surface pathways.

KW - sediment transfer

KW - surface runoff

KW - drainflow

KW - connectivity

KW - hillslope

KW - catchment

U2 - 10.1002/hyp.7257

DO - 10.1002/hyp.7257

M3 - Journal article

VL - 23

SP - 1349

EP - 1358

JO - Hydrological Processes

JF - Hydrological Processes

SN - 0885-6087

IS - 9

ER -