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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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Not an emergency service — if in danger call 999. Alerts rely on
EA/SEPA/NRW data and are best-efforts. Terms
Current Level
0.071 mASD
▼ Easing
24h Max
0.115 mASD
24h Min
0.068 mASD
Typical Range
0.13 - 0.26
mASD
Highest Recorded
1.40 mASD
EA official record
0.65 in our data (since Oct 1979)
Current level is 5% 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.
ARLESEY GS (E22346) — flow at this site
7 days
A separate gauge 8 m from this one at the same site, shown here for context.
Its readings are its own and are never merged with this page's.
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.
6 storm overflows are traced upstream of this gauge, the nearest 8.5 km away along the river. 0 report discharging now, 6 report not discharging.
Anglian Water · into Trib Of Tingewick Brook · 2.6 km away in a straight line · its recorded watercourse is not the one mapped beside it
3 spills · 12 hours in 2025
Not discharging now · last
5 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 0.26 m
on about 17 days.
This year so far: 11 days.
202611 days, 3 of them high · 3 highso far
202531 days, 12 of them high · 12 high
202453 days, 30 of them high · 30 high
202314 days, 4 of them high · 4 high
20225 days
202118 days, 10 of them high · 10 high
202011 days, 5 of them high · 5 high
20197 days, 2 of them high · 2 high
20188 days, 2 of them high · 2 high
20173 days, 1 of them high · 1 high
Counted from each day's highest reading. Days with missing or implausible readings are left out.
The darker part is days above 0.36 m, the level this gauge tops only a few days a year.
Flood history near this gauge
Official Environment Agency warnings issued since 2016 for the 6 flood
areas linked to this gauge (nearest 3.4 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 Arlesey flood history.
Flood areas linked to this gauge
Flood warnings and alerts are issued for whole areas. These are the 6 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
0.77
groundwater-fed — slow & steady
Avg Annual Rainfall
635 mm/yr
1991–2020 · +3% since 1941–70
Urban Extent
7.0%
partly urbanised
Highest Daily Mean Flow
23.82 m³/s
23 Sep 2024 · 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.
Crump profile gauging a predominantly Chalk catchment with arable farming and urban development, flows affected by weir drowning and artificial influences in the catchment.
More detail
The catchment
Predominantly Chalk catchment, with significant superficial deposits (Boulder Clay, sands and gravels). Predominantly arable farming but with significant urban development (Hitchin).
The station
Crump profile weir, 7m broad. Removed from peak flows dataset in September 2023 (WINFAP Files v12).
How it measures flow
Highest recorded flow was contained by weir banks. Subject to drowning at peak flows, but flows are not corrected. Out of bank rare and floodplain limb not verified. Few gaugings to confirm rating which is uncertain. Station subject to drowning with no non-modular correction.
Flow regime
Significant gw abstractions for PWS. Industrial/agricultural abstractions also occur. Augmentation by effluent affects diurnal flow pattern.
The flow record
Flows in August 2010 affected by drowning. Full period of record peak flow data reviewed and released in September 2019 (WINFAP Files v8).
How this gauging station is built and how long it has measured (NRFA / UKCEH).
Gauge type
Crump weir
Operating since
1973
Station datum
35.7 mAOD
Flow record
1973–2024 · 51 yrs · 100% complete
Hydrometric area
33
Measured by
Environment Agency
Nearby Groundwater
Soil Moisture
Possible storm-overflow correlation
Frequently asked questions
Is the River Hiz at Arlesey flooding today?
The current level is 0.07m, which is below the typical range. Flooding is very unlikely at this level.
Is the river level rising or falling at Arlesey?
Based on the most recent readings, the level is currently falling slightly. The chart above shows the last 12 hours of measurements by default (up to 7 days), updated roughly every 15 minutes.
Why is the level slowly falling?
When little or no rain has fallen for a while, a river level gradually drops as the water stored in the ground and soil drains away with nothing to replace it. This is called baseflow recession and is normal in dry spells. Only about 4.2mm of rain has fallen nearby in the last 7 days, so the flow is being sustained mainly by groundwater. A gentle decline like this is expected and is not a sign of a problem — downstream gauges often recede a little faster than headwaters further upstream, and levels recover once rain returns.
What is a normal level for the River Hiz at Arlesey?
The typical range at this station is 0.13m to 0.26m, based on Environment Agency historical data. Levels above 0.26m 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.
Embed this gauge on your website
Free live river-level widget — ideal for parish councils, angling clubs and local sites. Updates automatically.
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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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