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⤴Unusual rise — FloodRadar+Top 1% rise rate for this gauge.
Height for "Above a height"
Drag the line on the chart, or type a value:mASD
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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
0.281 mASD
▬ Steady
24h Max
0.294 mASD
24h Min
0.267 mASD
Typical Range
0.17 - 1.55
mASD
Highest Recorded
2.45 mASD
EA official record
2.45 in our data (since Jan 1971)
Current level is 11% 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
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.
1 storm overflow is traced upstream of this gauge, the nearest 5.3 km away along the river. 0 report discharging now, 1 reports not discharging.
Southern Water · into Tributary Of The Hilden Brook · 5.9 km away in a straight line · no mapped watercourse close enough to be sure
44 spills · 521 hours in 2025
No live feed for this overflow
9 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 Hadlow flood history.
Flood areas linked to this gauge
Flood warnings and alerts are issued for whole areas. These are the 4 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
0.63
mixed response
Avg Annual Rainfall
755 mm/yr
1991–2020 · +3% since 1941–70
Urban Extent
3.6%
partly urbanised
Highest Daily Mean Flow
9.41 m³/s
1 Aug 1991 · 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.
Electromagnetic gauge installed July 2002, located in a formalised flume structure. Flow record often incomplete. Capable of flashy response. In July 2024 the EM was retired and replaced with a Cross Correlation gauge within EM section.
More detail
The catchment
A largely baseflow dominated regime, the River Bourne rises on Gault Clay below the scarp of the North Downs, forming a tributary to the River Medway. The river flows south cutting through Ragstone Ridge, an outcrop of Lower Greensand, before entering the Vale of Kent. It is fed by springs from the Lower Greensand but runoff is predominantly generated from the Weald Clays of the Vale of Kent. Area of the catchment naturally impervious and pervious (half-and-half), including Upper, Middle & Lower Chalk, Folkestone Beds, Atherfield Clay, Gault Clay, Sandgate Beds, Hythe Beds, Weald Clay. A mainly rural catchment, excluding Borough Green which occupies <1% of the total catchment area. Remainder is grazing and woodland with a substantial acreage devoted to orchards.
The station
Electromagnetic gauge installed July 2002, located in a formalised flume structure, situated on a 0.2 km straight reach of the River Bourne approx 100m d/s of the A26 bridge at Hadlow. At the end of the measurement reach the river passes under a farm bridge. Originally a trapezoidal (long throated) critical depth flume, with stated capacity 8.5m3/s, though drowned at high flows - variable modular limit and constant dredging needed downstream. Removed from peak flows dataset in February 2018 (WINFAP Files v6).
How it measures flow
Electromagnetic flume has significantly bigger cross-section (and thus flow capacity) than previous trapezoidal (long throated) flume. Long throated flume rating based on hydraulic calculations. Rated to bankfull and hydraulic modelling beyond. No high-flow or out-of-bank gaugings to confirm rating. Cross correlation gauge appears to perform better than EM for low-medium flows when compared to flow gaugings. However, overwide section is causing erratic velocities through measuring section at higher flows. Currently flows above 2.5m3/s (1mASD) have the most uncertainty. Continous work to improve the gauges performance is ongoing.
Flow regime
Capable of flashy response; rapid runoff from the Weald Clay. Some artificial regulation from a mill half a mile u/s, this effect causes differences of up to 3 cumecs. Significant spray irrigation. Runoff increased by effluent returns. Very substantial baseflow contribution but capable of flashy response. Some artificial regulation from mill upstream. Significant spray irrigation. Public water supply abstractions from groundwater.
The flow record
Flow estimates for both the original flume and EM gauge are poor, with a step change between the two records. 1968 peak flow estimated at 57 cumecs on basis of wrack marks.
Timing, not cause. Gauges can move together simply because the same rain fell on both.
Frequently asked questions
Is the Bourne Tributary Medway at Hadlow flooding today?
The current level is 0.28m, which is within the typical range of 0.17 to 1.55m. Flooding is unlikely at this level.
Is the river level rising or falling at Hadlow?
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 Bourne Tributary Medway at Hadlow?
The typical range at this station is 0.17m to 1.55m, based on Environment Agency historical data. Levels above 1.55m 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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18 Sep 2024 Cross correlation gauge - Looking upstream
18 Sep 2024 Cross correlation gauge - Looking downstream
4 Apr 2022 Looking downstream of station
4 Apr 2022 Looking upstream of station
View of weir looking upstream