The hydrological sustainability of constructed wetlands for wastewater treatment

It is argued that there is a need for a hydrological assessment to be undertaken at the design stage of wetlands, which are to be constructed for wastewater treatment, in order to ensure their long-term sustainability. A simple water budget provides a suitable tool for this purpose. The product of an appropriate crop coefficient (Kc), and the reference crop evapotranspiration (ETo) determined from meteorological data, is deemed a suitable procedure for determining the evapotranspiration component of the water budget. The UK and the Czech Republic are taken as case studies, representative of maritime and mid-continent climates, to illustrate a procedure for identifying regions where created wetlands are potentially at most risk from water deficits.