Hydrological Summary for September 2017 published

September was a predominantly unsettled month with Atlantic low pressure systems bringing persistent and sometimes heavy rainfall, particularly to the west. Rainfall was moderately above average at the national scale, with only parts of northern Scotland and south-east England registering below average rainfall. It was particularly wet in Northern Ireland and western Britain, with large swathes registering more than 150% of average. Soil Moisture Deficits (SMDs) generally decreased during September and soils mostly remained wetter than average for the time of year. River flows were generally in the normal range or above across the UK, with some western catchments registering more than twice the September average. Flows in the less responsive rivers in southern England were below normal, and in some cases were notably low. Reservoir stocks generally increased relative to average and were substantially above average in some impoundments in northern England and Northern Ireland. Following the wet summer and early autumn, the short-term water resources outlook is healthy with above average reservoir stocks and SMDs across much of the UK. However, groundwater levels generally continued their seasonal recession and remained below normal or notably low across much of the Chalk in south-east England, reflecting longer-term rainfall deficiencies. The long‑term outlook is very dependent on recharge over the winter half-year, which will commence from a below-normal baseline in these areas.

Read the full summary here.