← Back
0.05

Whitwell

Mimram
Mimram catchment • Whitwell • Hertfordshire • ID: 4730TH • Level
(1h ago) • 4 readings/hr • 167 views

Set water level alerts

Get notified about Whitwell — tick as many as you like, they all share the notify settings below.

Drag the line on the chart, or type a value: mASD
Quick pick:

Each one is saved as its own alert — pause or remove them individually any time.

Not an emergency service — if in danger call 999. Alerts rely on EA/SEPA/NRW data and are best-efforts. Terms

Current Level
0.053 mASD
▬ Steady
24h Max
0.055 mASD
24h Min
0.053 mASD
Typical Range
0.02 - 0.50
mASD
Highest Recorded
0.28 mASD
12 Feb 2001
Since Jan 1982
Current level is 19% of this
🚽 Sewage overflows nearby

Recent Water Levels

🌍 floodradar.co.uk
1 day

Recent Readings

Steady over 6h
08 Oct 01:30 ▬ steady 0.053 mASD
08 Oct 01:15 ▬ steady 0.053 mASD
08 Oct 01:00 ▬ steady 0.053 mASD
08 Oct 00:45 ▼ -0.2 cm 0.053 mASD
08 Oct 00:30 ▲ +0.2 cm 0.055 mASD
08 Oct 00:15 ▬ steady 0.053 mASD
08 Oct 00:00 ▬ steady 0.053 mASD
07 Oct 23:45 ▼ -0.2 cm 0.053 mASD
07 Oct 23:30 ▲ +0.2 cm 0.055 mASD
07 Oct 22:30 ▼ -0.2 cm 0.053 mASD
07 Oct 22:15 ▬ steady 0.055 mASD
07 Oct 22:00 ▲ +0.2 cm 0.055 mASD
07 Oct 21:45 ▼ -0.2 cm 0.053 mASD
07 Oct 21:30 ▬ steady 0.055 mASD
07 Oct 21:15 ▬ steady 0.055 mASD
07 Oct 21:00 ▬ steady 0.055 mASD
07 Oct 20:45 ▬ steady 0.055 mASD
07 Oct 20:30 ▲ +0.2 cm 0.055 mASD
07 Oct 20:15 ▬ steady 0.053 mASD
07 Oct 20:00 0.053 mASD

Station Details

  • Monitoring Station: Whitwell
  • Watercourse: River Mimram
  • Nearest Town: Whitwell
  • County: Hertfordshire
  • Coordinates: 51°52'37"N 0°16'53"W (51.876889, -0.281280)
  • Open in: Google Maps · Apple Maps (opens your maps app)
  • Date Opened: 1 Jan 1981
  • Status: Active
  • Station Type: River level station
Technical details: references, datum, range, flow archive
  • Station Reference: 4730TH
  • RLOI id: 7334 (the EA's check-for-flooding station id)
  • EA Gauge ID: 4730TH-level-stage-i-15_min-mASD
  • Parameter: Level
  • Unit: mASD
  • Typical data delay: ~22 min (measured reading→publication lag)
  • Tidal: No
  • Lock / structure: No
  • Catchment Area: Mimram
  • Typical Range: 0.021 – 0.500 mASD
  • Drainage Area: 39 km² upstream of this gauge
  • 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
  • EA Cross-check: 0.05 mASD (EA at 8 Oct 01:45)
  • Flow Archive: National River Flow Archive ↗

Geographic coordinates may reflect the access point for the gauge, and not the precise location in the watercourse that it is taking readings from.

Nearby Stations

Gauges connected to this river, and others nearby. A distance “by river” follows the river on the map; any other is in a straight line.

Connected downstream

💧 Storm overflows upstream of this gauge

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.

💧
Thames Water · into River Mimram · 890 m away in a straight line · its water cannot be followed on the map
13 spills · 96 hours in 2025
Not discharging now · last
💧
Thames Water · into N/A · 4.8 km away in a straight line · its watercourse is not on the river map
31 spills · 225 hours in 2025
Not discharging now · last

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 →

Contains OS data © Crown copyright and database rights 2026.

Rainfall & Weather

Loading rainfall and weather data...

How often this river runs high

This gauge rarely reaches its typical high of 0.50 m: 0 days since 2017. This year so far: 0 days.

2026 0 days so far
2025 0 days
2024 0 days
2023 0 days
2022 0 days
2021 0 days
2020 0 days
2019 0 days
2018 0 days
2017 0 days

Counted from each day's highest reading. Days with missing or implausible readings are left out.

Flood history near this gauge

Official Environment Agency warnings issued since 2009 for the 8 flood areas linked to this gauge (nearest 2.4 km away).

4flood warnings 25flood alerts

Most recent flood warning: 27 Sep 2024 — Ash Brook, Ippollitts Brook and River Purwell at Hitchin, Ashbrook, Little Wymondley and Graveley

Year by year
YearWarningsAlerts
2025 0 1
2024 2 8
2022 0 2
2021 1 3
2020 0 2
2016 0 1
2015 1 0
2014 0 4
2013 0 1
2012 0 1
2010 0 1
2009 0 1

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 Whitwell flood history.

Flood areas linked to this gauge

Flood warnings and alerts are issued for whole areas. These are the 8 areas linked to this gauge, nearest first.

Catchment Character

🌊 Groundwater-fed Slow 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
0.86
groundwater-fed — slow & steady
Avg Annual Rainfall
665 mm/yr
1991–2020 · +3% since 1941–70
Urban Extent
0.8%
largely rural
Highest Daily Mean Flow
0.467 m³/s
13 Oct 1993 · daily mean, not the instantaneous peak
Flow-Duration Curve
mean 0.0840.1890.0780.0145% (high)% of days exceeded95% (low)
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 9%Grassland 23%Arable 65%Urban 2%
Arable 72% → 65% since 1990

Flow affected by: groundwater abstraction.

Photos

Gauging-station photographs from the National River Flow Archive (UKCEH).

Photos © NRFA / UKCEH & the measuring authority — shown at web resolution. Full gallery on the NRFA ↗

About this gauge

The station is located in the upper Mimram catchment.

More detail

The catchment

A predominantly pervious (Chalk), rural catchment. Hydrological catchment divide is uncertain.

The station

Crump weir, 1.0m crest (rather insensitive) within wider section.

How it measures flow

All flows are contained and are modular.

Flow regime

Generally stable flow regime, sustained from Chalk springs. Low flows are occasionally augmented by pumping from local tube wells but overall runoff is significantly reduced by gw abstraction. U/s cress-beds can influence low flow pattern.

The flow record

Dry for over three months in late 1997.

Descriptions from the National River Flow Archive (UKCEH). NRFA station record ↗

Gauge Details

How this gauging station is built and how long it has measured (NRFA / UKCEH).

Gauge type
Crump weir
Operating since
1970
Station datum
88.1 mAOD
Flow record
1970–2024 · 54 yrs · 100% complete
Hydrometric area
38
Measured by
Environment Agency

Frequently asked questions

Is the River Mimram at Whitwell flooding today?

The current level is 0.05m, which is within the typical range of 0.02 to 0.50m. Flooding is unlikely at this level.

Is the river level rising or falling at Whitwell?

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 River Mimram at Whitwell?

The typical range at this station is 0.02m to 0.50m, based on Environment Agency historical data. Levels above 0.50m 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.

Preview

📮 Flood risk by postcode near this gauge

Postcodes within 5 km with properties in the Environment Agency’s rivers-and-sea flood-risk bands:

Check any UK postcode’s flood risk →

🏠 Buying or renting around here? Get the Property Flood-Risk Report for any English postcode — official risk band, recorded floods, warning history, river behaviour and nearby storm overflows. £19 one-off. Learn more →