54028 - Vyrnwy at Llanymynech
| Grid Reference: | 33 (SJ) 252 195 | 
|
| Operator: | EA |
| Local number: | 2028 |
|
Catchment Area: | 778.0 km2 |
| Level of
Station: | 62.0 mOD |
| Max. Altitude: | 624.0 mOD |
|
Mean flow: | 21.38 m3s-1 |
| 95% exceedance (Q95): | 2.322 m
3s-1 |
| 10% exceedance
(Q10): | 49.79 m3s-1 |
|
61-90 Av. Ann. Rainfall: | 1345 mm |
Sample Hydrograph of Gauged Daily Flows
Flow Duration Curve for Gauged
Daily Flows
Station Description
Velocity-area station, 35m wide, in a
substantially straight reach with natural shoal control. Rating relatively
stable. Out-of-bank flows gauged from a cableway extension over the floodplain.
Three major PWS abstractions in the catchment have a substantial effect on the
flow regime, notably the supply exported to Liverpool from Lake Vyrnwy.
Catchment Description
Geology: predominantly
Silurian and Ordovician sandstones and mudstones overlain by Boulder Clay and
sands and gravels in the main tributaries. Steep headwater streams and
broad-bottomed valleys. Land use is moorland, forestry and grazing.Factors Affecting Runoff
- Reservoir(s) in
catchment affect runoff.
- Regulation from surface water and/or ground water.
- Runoff reduced by public water supply abstraction.
- Runoff reduced by
industrial/agricultural abstraction.
River
Flow and Catchment Rainfall on the National River Flow Archive
| Gauged Daily Flows (gdf): | 1970 to 2008 |
|
Monthly Catchment Rainfall (rnf): | 1969 to 2008 |
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| Datatype | 1960s | 1970s |
1980s | 1990s | 2000s |
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For many stations monthly peak flows are
also archived. When daily flow data are not available monthly mean flows may be
held on the National River Flow Archive. See Data
Holdings for further information.
NRFA Home Page
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Regional Maps
Data Holdings