Data on flow rates is what's needed
The Environment Agency already monitors river levels at each lock plus a few other locations. In most places in Oxford the local water level tracks very closely with this, following within an hour or two because the water flows quite easily through the gravel layers that underlie the flood plain.
Details of water levels have been available on the 'net for a couple of years; a commendable effort, even though the graphical data is perhaps not in the most convenient form and reliability may leave a little to be desired
What would be really useful is if the Environment Agency were also to make available sluice settings and the estimated flow rates both through and around locks. With this and with data for recent raindfall and near-term forecasts in the appropriate catchment areas it would be possible to predict likely levels quite accurately. Already an 'educated guess' for the next day or two can be made simply by looking at the upstream river levels and their changes.
Unfortunately the Environment agency seems to hold onto details of data such as actual flow rates as if this were a national secret in wartime. Perhaps as well as having a few Mr Mannerings in their midst, with vital roles is the so-called bronze, silver and gold control centres which are set up to handle the crisis and control civilian populations during floods, they are also concerned that people may be a bit upset when management decisions are made which have the effect of flooding one area rather than another.