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Estuary detail

Below is an interactive map and a table of parameters derived through various sources – Nature Conservancy Council (Davidson et al, 1991), EMPHASYS (2000c), Dyer (2002) in Futurecoast, Townend (2005), ABPmer (2024) and ABPmer (2025). The data is indicative of recently determined bulk properties suitable for broadscale intercomparison of estuaries.

Alternatively take a look in the viewer.

Estuaries Database Viewer View in Estuaries Database Viewer
Estuary ID
JNCC ID 35 
Name of estuary Mersey Estuary 
Alternative name  
Grid reference SJ415805  
WFD water body ID GB531206908100 
WFD water body name Mersey 
MAGIC URL link MAGIC link 1 
Latitude 53.318181 
Longitude -2.8796134 
JNCC classification Coastal Plain  
Updated classification Ria   read more on estuary classification..
Tidal classification Macrotidal  
Spring tidal range (m) 8.3  
Mean High Water Springs (mODN) 4.47 
Mean Low Water Springs (mODN) -3.83 
Mean Tide Level (mODN) 0.32 
Mean river flow (m3/s) 12.56 
Low river flow (m3/s) 3.99  
High river flow (m3/s) 30.8 
Name of furthest downstream flow gauge Westy Flow  
DEFRA Hydrology Gauge Data Explorer URL link DEFRA Hydrology Gauge link    
Area of basin (Ha) 8914  
Intertidal area (Ha) 5607  
Shoreline length (km) 102.9  
Channel length (km) 45.6  
Mouth width (m) 1525  
Valley width (m) 1525  
Volume at mean tide level (m3) 331000000  
Surface area at mean tide level (m2) 61500000  
CSA at mean tide level (m2) 26057  
Volume at low water (m3) 157000000  
Surface area at low water (m2) 25300000  
CSA at low water (m2) 16805 
Volume at high water (m3) 623000000 
Surface area at high water (m2) 76500000 
CSA at high water (m2) 35918 
Volume of tidal prism (m3) 466000000 
Dronkers' gamma (nondim) 0.57 
Storage volume over intertidal (m3) 256000000 
Channel volume to MTL (m3) 367000000 
Ratio of storage volume to channel volume (nondim) 0.7 
Hydraulic depth at MTL (m) 5.4 
DEFRA Catchment Data Explorer URL link DEFRA Catchment link   
Estuary template download link View

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Last Modified on: 20 June 2025
Printed from the Estuary Guide on 17/07/2025 23:19:47