Evaluating the use of diurnal groundwater fluctuations for estimating evapotranspiration in wetland environments: case studies in southeast England and northeast Germany

Abstract

Wetlands are characterised by frequent saturated conditions, dense vegetation growth and thus high evapotranspiration (ET) rates. Understanding wetland processes and water re-source implications of wetland management and restoration requires estimates of evapotran-spiration rates. The analysis of diurnal groundwater fluctuations (DGF) for estimating ET has been established for nearly 80 years, yet the method is not yet well-utilised in practice due to inherent limitations. This paper assesses contemporary updates to the method to define a consistent tool and applies this to two contrasting riparian zones, in southeast England and northeast Germany. The method’s accuracy is compared to reference ET evaluation meth-ods and its utility for wetland hydrological management is assessed. Finally, practical guid-ance on how to apply the tool is provided