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

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.