Arun and Western Streams catchment
• Princes Marsh • Hampshire • ID: E10368 • Level
(23m ago) • 1 reading/hr • 154 views
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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 mASD/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"
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Current Level
0.055 mASD
▬ Steady
24h Max
0.059 mASD
24h Min
0.053 mASD
Typical Range
0.08 - 0.90
mASD
Highest Recorded
1.96 mASD
EA official record
1.88 in our data (since May 1981)
Current level is 3% of this
🚽Sewage overflows nearby
Recent Water Levels
🌍 floodradar.co.uk
1 day
Prediction V2
Prediction Eris
Nimbus beta
Experimental model fusing soil moisture, river flow, groundwater and catchment
character. Shown with its calibrated 10–90% confidence band. 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.
Long Term
🌍 floodradar.co.uk
—
Consecutive rainy days0 → 10+
Days Above Normal
This year vs 5-year monthly range
Recent Readings
Steady over 6h
23 Aug 22:45▼ -0.1 cm0.055 mASD
23 Aug 21:30▬ steady0.056 mASD
23 Aug 21:15▲ +0.1 cm0.056 mASD
23 Aug 21:00▬ steady0.055 mASD
23 Aug 20:45▬ steady0.055 mASD
23 Aug 20:30▼ -0.1 cm0.055 mASD
23 Aug 20:15▬ steady0.056 mASD
23 Aug 20:00▬ steady0.056 mASD
23 Aug 19:45▬ steady0.056 mASD
23 Aug 19:30▲ +0.1 cm0.056 mASD
23 Aug 19:15▬ steady0.055 mASD
23 Aug 19:00▲ +0.1 cm0.055 mASD
23 Aug 18:45▬ steady0.054 mASD
23 Aug 18:30▬ steady0.054 mASD
23 Aug 18:15▬ steady0.054 mASD
23 Aug 18:00▬ steady0.054 mASD
23 Aug 17:45▬ steady0.054 mASD
23 Aug 17:30▼ -0.1 cm0.054 mASD
23 Aug 17:15▬ steady0.055 mASD
23 Aug 17:000.055 mASD
Rainfall & Weather
Loading rainfall and weather data...
Flood history near this gauge
Official Environment Agency warnings issued since 2013 for the 6 flood
areas linked to this gauge (nearest 1.2 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 Princes Marsh flood history.
Geographic coordinates may reflect the access point for the gauge, and not the precise location in the watercourse that it is taking readings from.
Catchment Character
🌊 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
0.66
groundwater-fed — slow & steady
Avg Annual Rainfall
1,003 mm/yr
1991–2020 · +8% since 1941–70
Urban Extent
3.1%
partly urbanised
Highest Recorded Flow
21.00 m³/s
23 Dec 2013
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 weir draining a predominantly Chalk catchment in the headwaters. Regime is responsive but dominated by baseflow.
More detail
The catchment
Geology is mixed, Chalk predominates in the headwaters. Upper Greensand, Gault Clay, Folkestone Beds, Sandgate Beds & Hythe Beds also present. Half of the catchment naturally impervious, half pervious. Land use predominantly rural with large woodland tracts and significant urban development in the lower catchment.
The station
Crump profile weir, crest 5m broad. Removed from peak flows dataset in September 2019 (WINFAP Files v8).
How it measures flow
Large capacity structure, but modular limit is ~0.7m. Problem of drowning illustrated by spot flow data, 2003 rating review suggests due to road bridge 0.27 km downstream. This is thought to act as the hydraulic control at high flows. Downstream silt deposition during floods can occasionally cause temporary drowning also, however is soon removed by re-suspension under normal flows. Crest tapping present but not currently used. Bridge across centre of weir, not good for gaugings but good for maintenance. Hysteresis problems experienced at the site. Downstream head recorder installed, used to correct data for backwater effects. One peak flow rating applied across period of record. Rating derived from hydraulic modelling, mid-range gaugings suggest that the rating is seriously overestimating flows, but also some gaugings underestimate flows.
Flow regime
Significant baseflow but responsive regime. Abstractions and discharges have a minor impact on flows - small net loss. Runoff is increased by effluent returns; station is adjacent to sewage works at Petersfield UDC.
How this gauging station is built and how long it has measured (NRFA / UKCEH).
Gauge type
Crump weir
Operating since
1972
Station datum
56.4 mAOD
Flow record
1972–2024 · 52 yrs · 100% complete
Hydrometric area
41
Measured by
Environment Agency
Nearby Groundwater
Soil Moisture
Possible storm-overflow correlation
🚽 Storm overflows on this river
Frequently asked questions
Is the River Rother at Princes Marsh flooding today?
The current level is 0.06m, which is below the typical range. Flooding is very unlikely at this level.
Is the river level rising or falling at Princes Marsh?
Based on the most recent readings, the level is currently steady. The chart above shows the last 7 days of measurements, updated roughly every 15 minutes.
What is a normal level for the River Rother at Princes Marsh?
The typical range at this station is 0.08m to 0.90m, based on Environment Agency historical data. Levels above 0.90m are higher than usually seen and may indicate a flood risk.
How often is this river level data updated?
Readings are taken by the Environment Agency gauge roughly every 15 minutes and FloodRadar refreshes its data continuously, so the level shown is normally less than an hour old.
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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:
