Research and analysis

Impact of agricultural soil conditions on floods: Autumn 2000

A targeted survey to investigate the conditions of a range of soils under different cropping systems in selected areas of the large Severn and Yorkshire Ouse catchments.

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The year 2000 was the wettest in Great Britain since records began in the eighteenth century. It has been repeatedly claimed in statements to the media that catchments such as the Severn, Yorkshire Ouse and Medway flooded because they were “saturated” by the first rain storms in October and were unable to absorb more rainfall. Some modern farming practices can lead to a reduction in soil water storage and infiltration capacity, particularly on certain types of soil. These “degraded” soil conditions can reduce the soil’s inherent ability to absorb rain and thus lead to increased runoff to surface waters, particularly during storm events. However, there is little quantified data available to corroborate this possibility. As a consequence, the National Soil Resources Institute (formerly the Soil Survey and Land Research Centre) were commissioned to undertake a targeted survey to investigate the conditions of a range of soils under different cropping systems in selected areas of the large Severn and Yorkshire Ouse catchments and also the smaller catchments of the rivers Uck and Bourne in the south-east of England. The catchments of the Severn and the Yorkshire Ouse were too large to investigate in detail and field visits were therefore focussed on three selected representative 100 km2 areas within each catchment.