River Thames Flow Speed: Average 1.5 mph, But Highly Variable

The River Thames flows at an average 1.5 mph (2.4 km/h), but speed fluctuates constantly.

Key Drivers

• Discharge: Rainfall, groundwater, tributaries.
• Channel slope: Steeper = faster (upper reaches).
• Roughness: Weeds, debris, bedforms.
• Wind: Upstream/downstream push.
• Tides: Critical factor. The Thames is tidal to Teddington Lock (90 km inland). Flow reverses twice daily; peak ebb/flood speeds exceed 2–3 mph.

Tidal Dynamics

At London Bridge, spring tide range ~7 m. Flood tide (incoming) often stronger than ebb due to funneling estuary. Slack water lasts ~30 min.

Navigation, ecology, and flood risk all hinge on this tidal-fluvial interplay.