Flooding with constraints: water meadow irrigation impacts on temperature, oxygen, phosphorus and sediment in water returned to a river

Abstract

AbstractWater meadows are pasture irrigation systems found across Europe. They potentially mitigate local flooding where a thin sheet of water is allowed across an engineered floodplain surface. In southern England, functioning ‘bedwork’ systems require investigation for their impact on water returned to a river in terms of temperature, dissolved oxygen, sediment trapping and the transport of phosphorus. Temperature change in water returned to the river is found to be minimal, and it remains well oxygenated. Water meadow systems reduce %silt in deposited sediment by an average of 14% and reduce mobile phosphorus by around one third. Soils show a decline in plant‐available phosphorus by one half. Evaluation of the impact on rivers is important because water meadows are typically managed under agri‐environmental schemes, and there is realisation of their historically demonstrated potential for floodwater retention.