Upper Bulbourne Readings for June 2020 submitted by Bob Farrer

Here are the readings for June, with a few comments:-

  1. Dudswell Bridge (highest datum point).

The stream is now dry at Dudswell. Reading is 1.36 metres below datum. Further south there is water in the stream bed but no flow until approximately 250 metres north of Northchurch Cricket Club.

  1. Northchurch Recreation Ground.

No reading was possible here. The casing is broken. The stream varies between 2-4 metres wide. There is a steady gentle flow of clear water, about 10 cm deep. Stream bed is mostly now silt rather than gravel, as the flow rate diminishes.

  1. Northchurch Primary School.

Reading is 80cm below datum. Stream is approx 3 metres wide with a good flow of clear water about 15 cm deep. The Environment Agency has cleared much weed from the stream bed here.

  1. Billet Lane, Berkhamsted (lowest datum point)

Reading is 1.28 below datum. There is a powerful flow through a weed and cress-choked bed. Water is clear. Flow is mainly confined to the centre channel. A depth assessment was impossible because of the thick weed.

COMMENTS:-

A wetter month, with 85 mm of rain falling at Dudswell. (May = 1mm). Half of the June total fell during the 24 hour period between the 17th to 18th. Two very heavy showers produced temporary flooding of roads and some gardens, as the road run-off reached the already swollen stream.
The resumption of boating on the canal has necessitated a return to pumping of ground water at Cowroast to maintain sufficient depth for navigation. The Cowroast pump was in use on the day of these measurements (30th June) but the Northchurch pump, which has now been repaired, was not in use.
The short video shows swans at Dudswell Lock, (GUC 48)

Best wishes to you all, stay safe,

Bob