What country, countries, county, counties does the River Thames flow through?
The river basin is conventionally divided into four areas: the tidal, lower, middle and upper Thames. The Upper Thames flows from Thames Head (its source) to its confluence with the River Windrush at Newbridge, falling 46 metres over a distance of 64.7 km [4]. The Middle Thames runs through the first major cities along the river — Oxford (population 120,000), and into Reading [5]. The first major discharge of effluent directly to the Thames occurs in this stretch of the river — below Oxford. The lower Thames runs from the confluence of the River Kennet in Reading to Teddington weir — the official upper tidal limit of the Thames [6]. In this stretch of the river, the flow of the Thames is supplemented both by springs and seepages rising from the chalk aquifer, and from tributary flow; run-off from clay is important near the Teddington weir. At Teddington, the freshwater flow in winter may exceed 30,000 Ml/day; but this flow decreases significantly in summer, and has been known to dry up
