Arun and Western Streams catchment
• Graylingwell • West Sussex • ID: E10893 • Level
(36m ago) • 4 readings/hr • 157 views
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Current Level
0.005 mASD
▬ Steady
24h Max
0.020 mASD
24h Min
-0.026 mASD
Typical Range
0.00 - 0.61
mASD
Highest Recorded
0.92 mASD
EA official record
A 1.38 reading (6 Jan 2026) sits in our unverified raw history and is not treated as the record
Current level is 1% 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. 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.
Long Term
🌍 floodradar.co.uk
—
Consecutive rainy days0 → 10+
Days Above Normal
This year vs 5-year monthly range
Recent Readings
Rising · +3 cm over 6h
10 Sep 13:30▬ steady0.005 mASD
10 Sep 13:15▬ steady0.005 mASD
10 Sep 13:00▲ +0.1 cm0.005 mASD
10 Sep 12:45▬ steady0.004 mASD
10 Sep 12:30▲ +0.1 cm0.004 mASD
10 Sep 12:15▲ +0.1 cm0.003 mASD
10 Sep 12:00▲ +0.2 cm0.002 mASD
10 Sep 11:45▲ +0.2 cm0.000 mASD
10 Sep 11:15▲ +0.1 cm-0.002 mASD
10 Sep 11:00▲ +0.1 cm-0.003 mASD
10 Sep 10:45▲ +0.2 cm-0.004 mASD
10 Sep 10:30▲ +0.4 cm-0.006 mASD
10 Sep 10:00▲ +0.2 cm-0.010 mASD
10 Sep 09:45▲ +0.2 cm-0.012 mASD
10 Sep 09:30▲ +0.2 cm-0.014 mASD
10 Sep 09:15▲ +0.4 cm-0.016 mASD
10 Sep 08:45▲ +0.3 cm-0.020 mASD
10 Sep 08:30▲ +0.3 cm-0.023 mASD
10 Sep 08:00▬ steady-0.026 mASD
10 Sep 07:45-0.026 mASD
Rainfall & Weather
Loading rainfall and weather data...
Flood history near this gauge
Official Environment Agency warnings issued since 2012 for the 19 flood
areas linked to this gauge (nearest 1.5 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 Graylingwell flood history.
Flow Data: Daily mean flow (m³/s) to 8 Sep (2 days behind — the EA publishes each day's mean a day or two after it ends; unchecked, provisional)via EA Hydrology
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
0.94
groundwater-fed — slow & steady
Avg Annual Rainfall
1,054 mm/yr
1991–2020 · +9% since 1941–70
Urban Extent
0.8%
largely rural
Median Annual Flood
1.74 m³/s
QMED — typical yearly peak flow
Highest Daily Mean Flow
7.78 m³/s
14 Dec 2000 · 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.
Land Cover (2023)
Woodland 36%Grassland 30%Arable 32%Urban 2%
Grassland 21% → 30% since 1990
Flow affected by: groundwater abstraction.
Photos
Gauging-station photographs from the National River Flow Archive (UKCEH).
Flat-V weir gauging an ephemeral stream in a permeable catchment. Baseflow-dominated regime affected by significant groundwater abstraction.
More detail
The catchment
The Lavant is an ephemeral stream within a permeable catchment, with an upper steep chalk catchment on the South Downs above Westhampnett and a flat, gravel plain lower catchment. Land use is agricultural with significant woodland in the upper catchment; the lower catchment is far more developed, especially close to Graylingwell and Chichester. Church Farm Pit, a water filled worked out gravel pit, is a good indicator of groundwater levels in the lower catchment. The oldest known continuous groundwater level record exists at Chilgrove House, within the catchment. This record, dating back to 1836, gives early warning of flood flows for Chichester.
The station
Flat-V weir (crest width 5.0 m, cross-slope 1:10, maximum head 1m, capacity 6 cumecs). The River Lavant has a long history of flooding, the last major events occurring in 1960, 1994-5 and 2000.
How it measures flow
Bypassing during extreme events (e.g. Jan 1994 and Nov 2000 when peaks were ~8 cumecs - based on current-meter gaugings). November 2000 event was gauged at 7.925 m3/s; bypassing of the gauge occurred at this time with further groundwater issuing from banks into the stream downstream of the gauge. Severe weed growth especially during summer can cause structure to drown out if not cleared. Structure suffers from velocity problems (underestimation of flow) at higher flows but this has been gauged. Gauge board had levelling problems in the past, this was amended following the rating review, May 2003. Major channel works carried out for Flood Alleviation scheme after 1994 flood; review in 2003 suggested rating should change in 1994 to accommodate channel clearance work. Two ratings applied across period of record, the most recent is valid from August-1994. Hydraulic modelling was used to derive upper limbs of the current rating.
Flow regime
A winterbourne stream with baseflow-dominated regime but spring outflows can increase dramatically following exceptional rainfall. Runoff is substantially reduced by groundwater abstraction. Flood alleviation scheme for Chichester had been completed sufficiently by 1992-93 for water to be taken from the Lavant downstream of the weir, through culverts to Church Farm Pit, through Forebridge Rife and discharged to Pagham Harbour through Pagham Rife. The oldest known continuous groundwater level record exists at Chilgrove House, within the catchment. This record, dating back to 1836, gives early warning of flood flows for Chichester. The area to the east and south of Chichester has undergone large scale gravel extraction over the past 50 years, leaving many worked out pits either filled in and developed, or water filled. This has possibly enhanced groundwater levels as the bulk flow is now confined to narrow corridors between former workings.
The flow record
Extended periods with zero flow as the stream is spring fed, which can give very low AMAX flows and no POT data are presented. Some years no flow altogether (e.g. WY1995/1996 and WY1996/1997). During summer 1963, low and medium flows were gauged by current meter on portable rods at weekly intervals until the Lavant dried up; gauging was continued on the downstream side of the Marsh Lane Bridge. Complete flow record from the 1970s. Full period of record peak flow data reviewed and released in September 2023 (WINFAP Files v12).
How this gauging station is built and how long it has measured (NRFA / UKCEH).
Gauge type
Flat-V weir
Operating since
1970
Station datum
20.7 mAOD
Flow record
1970–2024 · 54 yrs · 100% complete
Peak-flow record
since 1970
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 Lavant at Graylingwell flooding today?
The current level is 0.01m, which is within the typical range of 0.00 to 0.61m. Flooding is unlikely at this level.
Is the river level rising or falling at Graylingwell?
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 Lavant at Graylingwell?
The typical range at this station is 0.00m to 0.61m, based on Environment Agency historical data. Levels above 0.61m 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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Weir and hut looking upstream from left bank
Looking across weir from left bank
Looking across weir from right bank
Weir and hut looking upstream from right bank