UPLAND ENVIRONMENTS RESEARCH UNIT. Evidence for the occurrence of infiltration excess overland flow in an eroded peatland catchment: implications for connectivity. Claire S. Goulsbra and Martin G. Evans.
Claire S. Goulsbra andMartin G. Evans
Upland Environments Research Unit, School of Environment and Development, University of Manchester, UK
Overland flow and Connectivity
OLF in peatlands
North Pennines (in tact)
OLF occurs most frequently on footslopes from return flow and least frequently on steep mid-slopes
Daniels et al. (2008) JoH
South Pennines (eroded)
Water table drawdown at the gully edge, esp within 2 m (‘erosional acrotelm’ effect)Models of peatland OLF generation
What are the key controls on OLF generation in peatlands in space and time?
Flow – high conductivity
ER sensorMonitoring OLF using ER sensors
> Binary flow/no-flow distinction(Blasch et al., 2002 Vadose Zone Journal)
Drainage holes and a small gap at the bottom of the lid allow the entry of surface flow.
Minimise chances of false positives.
Installed at the ground surface.
Sensor ‘lid’ with plastic at either end to prevent entry of rain/sediment
Small gap to allow surface flow to enter sensor
Holes in bottom of sensor for free drainage Ø 3mm
Sensor electrodes ~3 mm long
Holes through which nails are driven to secure sensor to the ground Ø 6mm
Insulated wire connecting electrodes to data logger
Sensor base-plateOLF sensor design
In UNG catchment, the average distance to a gully is just 10.3 m; 13.7% of the intact peat mass lies within 2 m of a gully
May to July 2008
September to November 2008
Readings at 1 minute intervals > 36 days of continuous logging
MetersOLF at the gully edge
CatotelmDifferences in OLF