Bridget Flanagan, trustee of the Great Ouse Valley Trust, explains how flooding is a natural phenomenon and why its nature is changing and what we can do about it

Newcomers could be forgiven for finding it puzzling that there are frequent floods in the Great Ouse Valley – despite the area having one of the lowest annual rainfalls in the UK.

Average precipitation is below 600 mm (23.6 in) per year compared to 838 mm (33 in) for England, yet, on a few occasions most years, the valley landscape is transformed with vast tracts of water, and has done so for centuries.

The reality of floods is a very serious matter. If, as a layman like me, you read the Environment Agency’s Great Ouse Catchment Flood Management Plan, you will begin to grasp the scale of this river and its catchment area.

The part that flows past Huntingdon and St Ives is referred to as the Bedford Ouse, stretching from Brackley to Earith. Its main tributaries are the Rivers Tove, Ouzel, Ivel and Kym, plus the Brampton and Alconbury Brooks.

The CFMP details how the tributaries show a rapid response to rainfall by gathering run-off which can then accumulate into floods. Between Huntingdon and Earith we are lucky that the natural topography mitigates the potentially disastrous effects of great quantities of fast flowing water – the wide floodplain provides significant storage for the flood waters and also helps reduce the flow.

Several days of heavy rainfall on already saturated ground brought a high flood over the recent Christmas period. Waters naturally flowed out over the floodplain meadows; they were also held by man-made defences.

Many communities felt extremely grateful for the investment in flood defence schemes. However, these combined systems were unable to cope with excessive run-off overwhelming storm drains, poorly maintained ditches and faulty pumps.

I think we are all aware that our climate is changing. Storms bring increased intensity of heavy rain. The 2020 Christmas floods were of similar height to the 1998 Easter floods - a 1-in-25 year event, but only 23 years ago.

We are also aware that there has been inappropriate development in floodplains and high groundwater risk areas.

Floods are not solely natural disasters. Man is closely linked in their making and we urgently need to extricate ourselves from this.

INFO: www.gov.uk/government/publications/great-ouse-catchment-flood-management-plan.

www.greatousevalleytrust.org.uk.