39002 - Thames at Days Weir

Grid Reference:	41 (SU) 568 935
Operator:	EA
Local number:	1900
Catchment Area:	3444.7 km²
Level of Station:	45.8 mOD
Max. Altitude:	330.0 mOD
Mean flow:	28.60 m³s^-1
95% exceedance (Q95):	3.28 m³s^-1
10% exceedance (Q10):	69.2 m³s^-1
61-90 Av. Ann. Rainfall:	690 mm

Sample Hydrograph of Gauged Daily Flows

Flow Duration Curve for Gauged Daily Flows

Station Description

Adjustable thin-plate weir (5.48m wide) plus 15 radial gates, replaced a barrage of radial and buck gates in 1969. Rating formulae based upon gaugings - tailwater calibration applies for flows > 70 cumecs; above 100 cumecs overspill occurs. River levels affected by lock movements and gates. D/s confluence with the Thame may also cause backwater effects. Peak flows under review. Hydraulic modelling indicates that the exceptional March 1947 flood may be overestimated. Daily naturalised flows available for POR (equal to gauged flows up to 1973) - allow for Didcot Power Station losses only.

Catchment Description

Mixed geology (Oolitic Limestone headwaters, Oxford Clay below). Predominantly rural with development concentrated along the valley; Swindon is the largest town.

Factors Affecting Runoff

Runoff reduced by public water supply abstraction.
Runoff increased by effluent returns.
Runoff reduced by industrial/agricultural abstraction.

River Flow and Catchment Rainfall on the National River Flow Archive

Gauged Daily Flows (gdf):	1938 to 2008
Naturalised Daily Flows (ndf):	1938 to 2002
Naturalised Monthly Flows (nmf):	1938 to 2002
Monthly Catchment Rainfall (rnf):	1938 to 2008

Datatype	1930s										1940s										1950s										1960s										1970s										1980s										1990s										2000s

gdf
ndf
nmf
rnf

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.

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