Amina Birdi, Y13, Cotham School, reports on Dr. West’s hydrology lecture

This talk explored why two neighbouring river basins, the Ock and the Lambourn in south/central England, behave so differently despite appearing almost identical at first glance. While the Ock is a “flashy” river, meaning that it is prone to variable flow and flooding, the Lambourn has a much more consistent rate of discharge. Dr. West explained how different characteristics of drainage basins including precipitation, land use and vegetation cover affect discharge, and how each can be measured, and showed that there is little variation in these three factors between both rivers. Another particularly interesting factor was topography; it would be expected that the more hilly Ock catchment would be more “flashy” than the flatter Lambourn, but in reality it is the other way around. This suggested a different deciding factor: geology. The Ock basin contains much less permeable rock than the Lambourn, which decreases the rate of infiltration and increases runoff, meaning that water drains into the main river channel much quicker, and heavy precipitation will cause a rapid increase in discharge.