Hampshire Avon
Demonstration Test Catchment (DTC) Project

Hampshire Avon Demonstration Test Catchment (DTC) Project
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River Sem


The River Sem lies 5 miles north of Shaftesbury.  It is underlain by Kimmeridge clay; a fault in the north of the catchment is though to be the main source of the water.  There are two monitored sub-catchments in the River Sem: Priors Farm (manipulated) and Cools Cottage (control).

Priors Farm is entirely underlain by Kimmeridge clay and therefore is a surface water dominated catchment with low permeability.  There are some limestone beds under the catchment, but it is currently not known if they provide a source of water to the river. 

Cools Cottage is located in higher ground to the north-east of the catchment and only 20% underlain by clay.  There are also areas of limestone and greensands forming layers.  This catchment is fed by springs formed in the junctions between the limestone and the clay.

The predominant farm types for these sub-catchments are low intensity grazing (lowland), dairy, cereals and mixed.