Flow Pathways, Soil Erosion Risk and Watercoure Pollution in the Cober Catchment

The River Cober provides drinking water to the Helston area. It has been recognised by the Environment Agency that the raw water quality in the Cober catchment is poor. This diffuse pollution is largely from an agricultural source and consists of sediment, phosphate and  pesticides.

This study identifies sites of high pollution risk and the modes of transport to the
watercourse. This was achieved through fieldwork analysis across a number of landcover  types, to identify the causes behind soil loss from farmland and how this reaches the  watercourse.

Sediment transport risk map

Sediment transport risk map of the Cober Catchment, overlain by runoff pathways to highlight connectivity with the watercourse

A complex variety of parameters were found to influence soil stability, causing
soil detachment along flow pathways. From the study it was identified that slope steepness  and crop type are the two key factors in runoff and sediment transport.

Other influential factors identified include: soil compaction, vegetation cover and farming practices (e.g. cultivation direction). Field data was used to create a risk map of the catchment, highlighting high risk sites and the connectivity of these with the watercourse through runoff pathways.

This information would be valuable for farmers and growers to assist in crop planning and land management, enabling them to avoid putting high risk crops on high risk sites.

You can read the full Dissertation here: 2016 – Evaluating flow pathways in an agricultural setting in relation to the risk of soil erosion and watercourse pollution in the Cober Catchment, Helston, Cornwall.

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