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⤴Unusual rise — FloodRadar+Top 1% rise rate for this gauge.
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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.
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EA/SEPA/NRW data and are best-efforts. Terms
Current Level
0.337 mASD
▬ Steady
24h Max
0.350 mASD
24h Min
0.321 mASD
Typical Range
0.28 - 2.00
mASD
Highest Recorded
3.30 mASD
EA official record
2.71 in our data (since Jun 1968)
Current level is 10% 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 6 Oct (2 days behind — the EA publishes each day's mean a day or two after it ends; unchecked, provisional)via EA Hydrology
None of the storm overflows FloodRadar holds is traced upstream of this gauge on the mapped river network. That is not the same as none: the map leaves out many small streams and culverts, so an overflow it cannot place may still drain here, and not every company publishes every overflow. Those nearby are listed below.
Nearby, connection not known
Within 6 km in a straight line, but the river map cannot say whether their water passes this gauge.
Wessex Water · into Tributary Of Semington Brook · 4.3 km away in a straight line · its water cannot be followed on the map
8 spills · 110 hours in 2025
Not discharging now · last
2 more within 6 km whose connection is not known.
12 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 →
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 Semington flood history.
Flood areas linked to this gauge
Flood warnings and alerts are issued for whole areas. These are the 5 areas linked to this gauge, nearest first.
🌊 Mixed responseA balance of quick runoff and slower groundwater baseflow.
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
0.56
mixed response
Avg Annual Rainfall
775 mm/yr
1991–2020 · +3% since 1941–70
Urban Extent
3.0%
largely rural
Median Annual Flood
17.23 m³/s
QMED — typical yearly peak flow
Highest Daily Mean Flow
24.00 m³/s
4 Jan 2014 · 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.
Formalised trapezoidal section installed in 1970 to replace previous velocity-area station. Bed-mounted hydro-acoustic gauge installed in 2006.
More detail
The catchment
Catchment flat and low-lying, mainly clay with steeper Chalk eastern boundaries. Kimmeridge and Gault Clay producing fairly sharp response to rainfall. Land use is predominantly rural. No major catchment changes.
The station
Station located 3km upstream of the confluence with the River Avon in operation since 1947. Formalised trapezoidal section with a 6m wide non-standard weir and a cableway. Replaced downstream velocity-area station in 1970 (superseded due to low banks and backwater from the Avon at high flows). Bed-mounted hydro-acoustic gauge installed 09/2006.
How it measures flow
Flow measurement is imprecise at medium to high flows. One rating applied across period of record. Station rated to 19.83 cumecs. There are significant errors in the rating curve at high flows due to backwater effects from the River Avon. ADCP installed but not matching peak stage timings due to velocities.
Flow regime
Flows influenced by some groundwater pumping & surface water abstractions. Mill operation and hydro-power upstream. Runoff increased by effluent returns.
The flow record
Flood records for period prior to 04/1970 (before installation of formalised trapezoidal section) are poor. Pre-2006 peak flows rejected because spot flows suggest high flows were underestimated prior to installation of the acoustics. Full period of record peak flow data reviewed and released in October 2018 (WINFAP Files v7) and in August 2024 (WINFAP Files v13).
How this gauging station is built and how long it has measured (NRFA / UKCEH).
Gauge type
Gauging structure
Operating since
1953
Station datum
33.1 mAOD
Flow record
1953–2024 · 71 yrs · 100% complete
Peak-flow record
since 1953
Hydrometric area
53
Measured by
Environment Agency
Nearby Groundwater
Soil Moisture
Possible storm-overflow correlation
Frequently asked questions
Is the Semington Brook at Semington flooding today?
The current level is 0.34m, which is within the typical range of 0.28 to 2.00m. Flooding is unlikely at this level.
Is the river level rising or falling at Semington?
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 Semington Brook at Semington?
The typical range at this station is 0.28m to 2.00m, based on Environment Agency historical data. Levels above 2.00m 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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27 Jul 2011 Semington Structure viewed from Downstrream
23 Mar 2011 Semington GS structure viewed from upstream
