Bristol Avon Little Avon Axe and North Somerset St catchment
• Ashley • Wiltshire • ID: 53130 • Level
(32m ago) • 3 readings/hr • 201 views
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⤴Unusual rise — FloodRadar+Top 1% rise rate for this gauge.
Height for "Above a height"
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You'll be notified when this gauge is rising more than 0.10 m/hr — a sign of rapidly increasing water levels.
You'll be notified when a new storm-overflow (sewage) discharge starts within ~3 km of this gauge, based on the water companies' near-real-time feeds.
Get notified when recent rainfall near this gauge crosses its learnt rise trigger — an early "watch"
signal, typically hours before a rise. Experimental; not an official flood warning.
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Not an emergency service — if in danger call 999. Alerts rely on
EA/SEPA/NRW data and are best-efforts. Terms
Current Level
0.153 mASD
▬ Steady
24h Max
0.160 mASD
24h Min
0.152 mASD
Typical Range
0.19 - 0.77
mASD
Highest Recorded
2.41 mASD
EA official record
2.41 in our data (since Dec 1981)
Current level is 6% of this
🚽Sewage overflows nearby
Recent Water Levels
🌍 floodradar.co.uk
1 day
EA forecast (official)
Prediction V2
Prediction Eris
Nimbus beta
Experimental model fusing soil moisture, river flow, groundwater and catchment
character. The shaded band is its 10–90% range, widened so that about 80% of recent outcomes fall inside it.
Under evaluation — not yet promoted, so treat as a second opinion.
River Flow
90 days
Daily mean discharge (m³/s) with the daily min–max band, from the EA Hydrology API. Flow is the volume of water passing the gauge — often a more direct flood signal than level.
Flow Data: Daily mean flow (m³/s) to 8 Oct (2 days behind — the EA publishes each day's mean a day or two after it ends; unchecked, provisional)via EA Hydrology
Storm overflows whose water reaches this gauge on the mapped river network, nearest first by distance along the river. The status is each water company's monitor: it says whether an overflow is discharging, not how much or what it contains.
6 storm overflows are traced upstream of this gauge, the nearest 1.2 km away along the river. 0 report discharging now, 6 report not discharging.
Wessex Water · into Chalfield Brook(S) · 5.3 km away in a straight line · no mapped watercourse close enough to be sure
12 spills · 165 hours in 2025
Not discharging now · last
11 other overflows within 6 km are downstream of this gauge or on another branch of the river network, so they are not listed.
These are the water companies' monitor statuses; a spill does not by itself explain a change in the gauge level. River connections and distances are traced on OS Open Rivers (edition 2026-04), which leaves out many small channels. Explore the sewage map →
In a typical year this gauge reaches its typical high of 0.77 m
on about 26 days.
This year so far: 34 days.
202634 days, 4 of them high · 4 highso far
202530 days, 5 of them high · 5 high
202459 days, 12 of them high · 12 high
202353 days, 9 of them high · 9 high
20224 days
202116 days, 3 of them high · 3 high
202031 days, 7 of them high · 7 high
201925 days, 1 of them high · 1 high
201812 days, 1 of them high · 1 high
20175 days
Counted from each day's highest reading. Days with missing or implausible readings are left out.
The darker part is days above 1.48 m, the level this gauge tops only a few days a year.
Flood history near this gauge
Official Environment Agency warnings issued since 2012 for the 2 flood
areas linked to this gauge (nearest 8.5 km away).
Warnings apply to a whole flood area, not necessarily this exact spot. Years before 2006 aren't covered by the EA's historic record.
See also the Ashley flood history.
Flood areas linked to this gauge
Flood warnings and alerts are issued for whole areas. These are the 2 areas linked to this gauge, nearest first.
🌊 Groundwater-fedSlow and steady — fed largely by groundwater, so levels change gradually, not in sudden spikes.
Your catchment is all the land that drains rainfall into the river above this gauge. Its character — how
steep, wet, wooded, urban or chalky that land is — decides how fast rain here turns into a rising river. A steep, bare or clay
catchment is “flashy” (rises and falls quickly, floods easily); a flat, chalk or well-wooded one is
slow and steady. The tiles below put numbers to that; the flow-duration curve reads left-to-right
from the river’s typical high flows (Q5) down to its low flows (Q95) — a steep curve means a flashy river.
The physical character of the land that drains to this gauge, and how it shapes its flood response — from the National River Flow Archive (UKCEH).
Baseflow Index
0.73
groundwater-fed — slow & steady
Avg Annual Rainfall
922 mm/yr
1991–2020 · +6% since 1941–70
Urban Extent
1.4%
largely rural
Median Annual Flood
10.70 m³/s
QMED — typical yearly peak flow
Highest Daily Mean Flow
14.20 m³/s
25 Nov 2012 · daily mean, not the instantaneous peak
Flow-Duration Curve
Daily flow (m³/s) exceeded each % of the time — a steep curve is flashy, a flat one is steady. Q5 high · Q50 median · Q95 low.
Land Cover (2023)
Woodland 11%Grassland 48%Arable 37%Urban 4%
Grassland 53% → 48% since 1990
Flow affected by: effluent returns.
Photos
Gauging-station photographs from the National River Flow Archive (UKCEH).
Flat V weir primarily installed as a low flow station in 1981.
More detail
The catchment
The catchment area upstream of the station is mainly rural, with limited urban areas at Battiford, Box and Colerne. The area is underlain by strata of the middle Jurassic period, with Great Oolite limestone as the upper strata over most of the catchment. Erosion has exposed Midford Sands of the Upper Lias in some areas. Slowly permeable calcareous soils dominate along the river valleys. No major catchment changes.
The station
Primarily installed as a low flow station, opened in 1981 approximately 4km west of Corsham. Flat V weir 8m wide for low flow, then rated section for higher flows. Wing walls at 2m contain most floods.
How it measures flow
The channel bed consists of large stones. Highest observed flow at bankfull (2.11m), as which level flows become obstructed by a footbridge at the station. Meanders downstream. Single rating developed in 1996, based on theoretical weir rating and gaugings, applied retrospectively to the beginning of the record, modelling underway for the top end. Bend down stream causes inflection in rating.
Flow regime
Minor surface water abstractions in catchment. Gate movement upstream.
The flow record
Full period of record peak flow data reviewed and released in September 2020 (WINFAP Files v9).
How this gauging station is built and how long it has measured (NRFA / UKCEH).
Gauge type
Flat-V weir
Operating since
1971
Station datum
28.1 mAOD
Flow record
1982–2024 · 42 yrs · 100% complete
Peak-flow record
since 1981
Hydrometric area
53
Measured by
Environment Agency
Nearby Groundwater
Soil Moisture
Possible storm-overflow correlation
Frequently asked questions
Is the By Brook at Middlehill flooding today?
The current level is 0.15m, which is below the typical range. Flooding is very unlikely at this level.
Is the river level rising or falling at Middlehill?
Based on the most recent readings, the level is currently steady. The chart above shows the last 12 hours of measurements by default (up to 7 days), updated roughly every 15 minutes.
What is a normal level for the By Brook at Middlehill?
The typical range at this station is 0.19m to 0.77m, based on Environment Agency historical data. Levels above 0.77m are higher than usually seen and may indicate a flood risk.
How often is this river level data updated?
Readings are supplied by the Environment Agency gauge. FloodRadar checks for updates roughly every 15 minutes; the timestamp above shows how recent the latest available reading is.
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📮 Flood risk by postcode near this gauge
Postcodes within 5 km with properties in the Environment Agency’s rivers-and-sea flood-risk bands:
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29 Oct 2003 Upstream view to gauging station
29 Oct 2003 View across weir and right bank
29 Oct 2003 Downstream from gauging station
29 Oct 2003 Downstream from gauging station
