Hydraulic conditions,oxygenation, temperatures and sediment relationships of bedwork watermeadows

This study investigates the interactions of water, oxygen, temperature, suspended sediment and topsoil texture of bedwork watermeadows. These ancient grassland irrigation systems survive on the floodplain around Salisbury, England but recent interest in their conservation and rehabilitation is not matched by detailed understanding of their operation. The dominant ‘bedwork’ form, by which water runs along the top of ridges and down ‘panes’, enables water to move swiftly through the sward and drain to avoid stagnation. This investigation demonstrates that condition of surface flow and rates of infiltration encourage the solution of atmospheric oxygen in the water, offsetting potentially anaerobic conditions in the root zone. Temperature conditions imparted by the flow were measured and found to be conducive to the early growth of grass. Whereas the sediment budget was found to be conservative under a steady‐state hydraulic regime, there is substantial ingress of suspended sediment at the start of an irrigation event and the sward traps coarse to medium‐sized silt particle fractions and influences topsoil texture. It is concluded that a study of watermeadow operation permits insights into the operation of floodplain processes in general. Copyright © 2003 John Wiley & Sons, Ltd.