The latest Water Situation report from the EA shows elevated river flows and groundwater levels for the time of year were common this month as the persistently wet weather of June and July subsided into more typical conditions for August. 

Rainfall

Rainfall in August was 84% of long term average for South East Region, contrasting with the wet conditions in June and July. The rainfall this month was generally convective in nature with some heavy downpours. As a result rainfall distribution was very uneven within catchments, for example on the 13 th at Basingstoke in the Loddon catchment the highest daily total of 27mm was recorded, while a few miles away in Camberley less than 2mm was measured. Regional rainfall patterns also varied widely with the Cotswolds, Upper Thames, Cherwell, Thame and Berkshire Downs receiving above average rainfall for the month, whilst areas to the South and East had for the most part below average rainfall. The extremely wet conditions since April mean that total rainfall for April to August is the highest for the South East during summer months in the past 102 years.

Soil Moisture Deficit

Recharge and Groundwater Levels Soil moisture deficits are generally lower than average for the time of year, particularly in the Thames catchment. This is due to the wet weather in past months. Recharge during the summer is usually minimal and only has the effect of slowing declining groundwater levels. This year the unprecedented rainfall has caused recharge on a scale more typical of winter conditions for many areas. Groundwater levels are within their normal range at 7 of the 16 key monitoring sites. Stonor Manor in the Chilterns near Henley-on-Thames is the only remaining monitoring point with below normal levels for the time of year, and levels here are still rising. Many of the key monitoring locations have notably or exceptionally high levels for the end of August, and levels are at the highest they have been for at least 12 months in many areas, when usually levels would be nearing their lowest point. Levels, though unusual for August, are still well below the maximum annual levels at the key sites which generally occur between December and March.

River Flows

River flows decreased this month with the lower rainfall, with only small rises in flows due to the thundery showers, however flows were still the highest on record for August at Allbrook and Highbridge gauging stations on the Itchen. The Coln at Bibury in the Cotswolds and the River Thames at Eynsham were both the second highest on record after August 2007. Flows were above average for the time of year for all but 5 of the key sites. The Great Stour at Horton was the only key site with below normal flows – the 11 th lowest on record for August. Five flood alerts were issued during the month for the Rivers Cole and Ray – rapidly responding urban tributaries of the Upper Thames.

Reservoir Storage/Water Resource Zone Stocks

Reservoir storage remains above average in South East England, and is higher than at the same time last year.

Full report from the Environment Agency is available here