Oxford's major floods are a result, not of water falling onto the immediate area,
but of water which has fallen as far away as the Cotswolds coming down the valley
of the River Thames. Severe flooding occurs in the plain to the west of Oxford. There
is a marked geological narrowing of the Thames valley immediately south of Oxford
city, around the old Abingdon Road red-brick bridge over the railway at Redbridge
in South Oxford /Kennington. The natural narrowing has been made far worse by the
building of the railway, roads and buildings, and by landfill. In some cases these
seem to have been done with little or no regard for the possible effects on flooding,
and lack of proper maintenance over many years has made things even worse. Further
up, the Botley Road is a particular problem. It is a causeway across the floodplain
from the City to Botley and Cumnor beyond. There is not enough capacity to carry
water under it, or immediately to the south of it, so it acts as a dam. This leads
to flooding.
The Oxford Flood Risk Management Strategy is a major project by the EA, designed
to provide high level flood protection for Oxford. But it needs a lot of money to
be implemented in full.