The Environment Agency Southeast water report for September shows the rivers responded to the heavy rainfall, but flows declined at the end of the month,the region received average rainfall for September.

Rainfall

Although September recorded average rainfall, it was a dry month with little rainfall until the 23 rd of the month, when an area of low pressure brought a few days of persistent rain and showers to the South East. The wettest day was the 23 rd when Efford raingauge near Lymington in the New Forest recorded 68mm. On average, 80% of the rainfall for September fell between the 23 rd and 26 th of the month. The north of the Region was slightly drier than the south. Average rainfall in September rounded off an exceptional 6 month Summer period with over 150% of average rainfall. A number of catchments in the south and west of the Region had the wettest summer period on record. Examples of this are the Adur and West Sussex Chalk catchments which received 191% and 185% average summer rainfall respectively.

Soil Moisture Deficit & Recharge and Groundwater Levels

The soil moisture deficits continue to be lower than average for September as a result of the rainfall in the second half of the month. This contrasts with this time last year when the deficit was about 150% average. There has been some recharge this month, and unusually, about 240% average recharge across the Region since April. Groundwater levels are within their normal range at 5 key sites; 9 are higher than the normal range with 2 of these at exceptionally high levels for September (Jackaments in Cotswolds West – 3 rd highest and Rockley in the Berkshire Downs – 4 th highest on record for September). Levels at both Stonor in Chilterns East catchment and Little Bucket in the Stour catchment remain below normal. Chalk groundwater levels across the Region are falling, with the exception of Riddles Lane in the North Downs. Levels in the Cotswolds have responded quickly to the rainfall and have risen slightly at Jackaments.

River Flows

Although all rivers responded to the heavy rainfall on the 23 rd ; the general trend was declining flows across the Region during September with flows at key sites remaining within their normal range for September or higher. A number of sites had their highest September flows since 2008. The Coln at Bibury and the Thames at Eynsham were exceptionally high, supported by the high groundwater levels in the Cotswolds. Both these sites had the third highest September flow on record. The Itchen at Allbrook and Highbridge also had the third highest flows and is exceptionally high for September. Three flood alerts (Cole, Evenlode and Dikler) were issued in West Thames for the 24 th and one in Solent and South Downs (Cuckmere) on the 26 th of the month.

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 is available Here