Hampshire Avon
Demonstration Test Catchment (DTC) Project

Hampshire Avon Demonstration Test Catchment (DTC) Project
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Target sub-catchments and Experimental Design

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Hampshire Avon experimental sub-catchments:

 

All of the experimental sub-catchments in the Hampshire Avon DTC fall within Catchment Sensitive Farming (CSF) priority areas (except the Upper Ebble).  These sub-catchments cover chalk, clay and greensand geology and thereby cover all principle outcrops in the broader study area.

There are five target sub-catchments in the Avon: Ebbesbourne Wake on the River Ebble, Priors Farm (manipulated) and Cools Cottage (control) on the River Sem, Kingston Deverill (control) and Brixton Deverill (manipulated) on the River Wylye.  Figure 1 shows the target sub-catchments that are being monitored:

Sem
Ebble
Wylye

  
 

Figure 1 Map showing the location of the target sub-catchments in the Hampshire Avon
Please click on the map to show a larger image

 Tamar experimental sub-catchments:

  
Three sites have been secured in the Tamar catchment:

Caudworthy Outlet, Caudworthy Water
Winnacott Bridge, Caudworthy Water
Burracott Bridge, River Neet

Caudworthy Outlet and Winnacott Bridge are both manipulated target sub-catchments, Burracott Bridge on the river Neet is the control target sub-catchment.		  
  Figure 2 Map showing the location of three of the target sub-catchments in the Tamar
Please click on the map to show a larger image

Experimental desgin:

The basic experimental design uses the ‘Before-After Control-Impact’ (BACI) approach to monitor water quality.  This design compares a manipulated stream with a non-manipulated stream before and after implementation of a mitigation measure (figure 2a).  Measurements taken pre-mitigation provide a baseline against which to compare post-mitigation conditions in the focal stream.  The adjacent control stream provides additional spatial reference that can be used to factor out confounding effects of changes in land use, rainfall, flow etc. 

A variant on the BACI approach is to use a monitoring point upstream of the mitigation area as the control (figure 2b).  This acts to isolate part of the stream that is subject to the mitigation measures and means that a separate control stream is no longer necessary. 

Both BACI version 1 and version 2 will be used in this project.
   
 Figure 2a BACI version 1 Figure 2b BACI version 2 


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