This video from 2007 shows just how bad it was:
The problem at Earl Street, Duke Street and Bullstake Close is severe, complicated and not easy to solve. The initial threat is from groundwater, i.e. the rising water table caused by water pooling in the low-lying land, building up behind obstructions to the south. These obstructions, or pinchpoints, were identified at an early stage by OFA and have been the subject of numerous discussions with the EA.
Several days later, water building up to the north of the Botley Road, having by this stage inundated Bullstake Close, reaches a depth whereby it is no longer contained by the Botley Road. It breaches the road and continues its journey south down Earl Street, increasing water levels in the street by up to eighteen inches. Between these two events, groundwater in Earl Street and Duke Street will have been topped up through the surface water drains connecting those to the north of Botley Road and those to the south. The situation in Earl Street at this point is exacerbated by the fact that the water’s exit from the bottom of the street is blocked by the housing development formerly known as Oriel Mews, built, as it is, at a considerably higher level than Earl Street and the site it replaced.
Experience has shown that the pump, installed by the City Council following the floods in 2003, can cope with the groundwater, but is incapable of dealing with the secondary inundation of the surface water and is overwhelmed at this stage. Additional pumps brought in by the EA ease the situation but are unable to deal with the volume. The only other way for the water to go is along the alleyway between Earl Street and Duke Street, aided initially by the reprofiling of the footpath at the end of Earl Street to allow water to escape at a lower level. Pooling at the bottom of Duke Street is increased by this influx, countered by a culvert between Duke Street drains and a new outlet in the access route to King George’s Meadow, installed by the County Council after the 2007 floods.
Changes to the built environment, including alterations to the Botley Road, the new housing and impervious parking surfaces adjoining the retail development around these two streets and Bullstake Close have all contributed to the current situation and OFA continues to discuss these issues with the relevant agencies.