Brook Levels

The Pillhill Brook Association are curious to find out how groundwater level affects the winterbourne sections of the brook throughout the year. With PBA volunteers recording water depth at 9 locations along the brook and groundwater level in a number of boreholes in the north of the catchment we can start to create a flow map of the brook.

Play the slide presentation below to see how brook flow changes with groundwater level. 

First watch the top left hand corner of the slide presentation as the blue line (showing the course of the Pillhill Brook) slowly turn red as the brook dries from Kimpton southwards and Thruxton eastwards. 

Then watch as the dry watercourse slowly returns to blue as flow returns.

The Environment Agency use groundwater levels at Clanville Gate and Kimpton High View boreholes to help them assess flood or drought risk in our area. So the table in the top left hand corner of the map shows how groundwater levels at both these boreholes has changed as the brook ebbs and flows. 

Although the brook had dried to Mullens Pond, just north of the A303, by 22 August 2025 it did not dry any further even though groundwater level at Clanville Gate continued to fall. In fact groundwater level at Clanville Gate fell by another 3.36 m before it started to rise again on 14 November 2025. In this case you might have expected groundwater level to have to rise by some 3 m before brook flows would start to return. In fact groundwater level had only risen by 19 cm at Clanville Gate when flow started to return in Amport Fen leat and only by another 7 cm before flow started to return in the main brook! Interesting observational data that we can use next groundwater season.

As of 27 Januray 2026 the Pillhill Brook is in full flow from its known source in Kimpton. The Fyfield and Thruxton winterbournes and the leat in Amport Fen are also flowing freely.