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.
View in Estuaries Database Viewer|
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| Estuary ID | 6 |
|---|---|
| JNCC ID | 7 |
| Name of estuary | Severn Estuary |
| Alternative name | This estuary spans more than one WFD waterbody (Severn Lower boundary was taken from WFD cycle 2 and merged with Severn Middle and Severn Upper from WFD cycle 3) |
| Grid reference | ST405805 |
| WFD water body ID | GB530905415401,GB530905415402,GB530905415403 |
| WFD water body name | Severn Lower, Severn Middle, Severn Upper |
| MAGIC URL link | MAGIC link 1 MAGIC link 2 MAGIC link 3 |
| Latitude | 51.55480271 |
| Longitude | -2.72499302 |
| JNCC classification | Coastal Plain |
| Updated classification | Funnel read more on estuary classification.. |
| Tidal classification | Exceptionally large |
| Spring tidal range (m) | 10.5 |
| Mean High Water Springs (mODN) | 5.6 |
| Mean Low Water Springs (mODN) | -4.9 |
| Mean Tide Level (mODN) | 0.17 |
| Mean river flow (m3/s) | 77.8 |
| Low river flow (m3/s) | 17.04 |
| High river flow (m3/s) | 227.7 |
| Name of furthest downstream flow gauge | Haw Bridge |
| DEFRA Hydrology Gauge Data Explorer URL link | DEFRA Hydrology Gauge link |
| Area of basin (Ha) | 55684 |
| Intertidal area (Ha) | 16890 |
| Shoreline length (km) | 353 |
| Channel length (km) | 111.2 |
| Mouth width (m) | 13000 |
| Valley width (m) | 13000 |
| Volume at mean tide level (m3) | 5070000000 |
| Surface area at mean tide level (m2) | 515000000 |
| CSA at mean tide level (m2) | 206336 |
| Volume at low water (m3) | 2630000000 |
| Surface area at low water (m2) | 408000000 |
| CSA at low water (m2) | 136286 |
| Volume at high water (m3) | 7900000000 |
| Surface area at high water (m2) | 528000000 |
| CSA at high water (m2) | 280998 |
| Volume of tidal prism (m3) | 5270000000 |
| Dronkers' gamma (nondim) | 4.15 |
| Storage volume over intertidal (m3) | 984000000 |
| Channel volume to MTL (m3) | 6920000000 |
| Ratio of storage volume to channel volume (nondim) | 0.14 |
| Hydraulic depth at MTL (m) | 9.8 |
| DEFRA Catchment Data Explorer URL link | DEFRA Catchment link |
| Estuary template download link | |