An Analytical Framework to Investigate Groundwater‐Atmosphere Interactions Influenced by Soil Properties.

The interaction between climate and groundwater forms a complex, coupled system that affects land‐atmosphere feedback processes and thus local climatic parameters. We propose an analytical framework that integrates local groundwater information and soil hydrophysical characteristics to identify regions with bidirectional (two‐way) coupling where groundwater is influenced by climatic factors (e.g., precipitation) and may affect local climate (e.g., through surface fluxes). The framework capitalizes on the concept of the evaporation characteristic length to quantify the hydraulic connection of groundwater to the soil surface. To evaluate the framework, we calculate the maximum depth of hydraulic connection (Dmax) between groundwater and the soil surface in Hamburg, Germany. For regions with Dmax exceeding the groundwater depth (d), a bidirectional mode of coupling is defined, while Dmax < d implies a unidirectional coupling mode. Our results indicate that climate driven evaporation changes potentially alter the coupling between groundwater and climate depending on soil texture. Moreover, soil hydraulic properties and shallow groundwater tables could play a crucial role in shifting land‐atmosphere feedback processes by influencing the coupling mode. This research provides insights into the groundwater‐climate interactions under various climatic conditions and soil textures which could contribute to sustainable land‐use management practices, particularly in regions characterized by bidirectional coupling. Plain Language Summary: This study explores the hydraulic connection between climate and groundwater. We developed an analytical framework that combines local groundwater levels and soil hydrophysical characteristics to identify areas with potential two‐way climate‐groundwater interaction. In areas with bidirectional mode of coupling not only the groundwater is influenced by the climate (e.g., through precipitation), but also it may affect climatic parameters by influencing soil moisture and evapotranspiration. We employed the framework to calculate the maximum depth of hydraulic connection (Dmax) linking groundwater and climate in Hamburg, Germany. Results identify bidirectional coupling zones, where climate and groundwater can mutually influence each other. We found that changes in soil properties, evaporation dynamics, and groundwater levels affect the climate‐groundwater coupling thus shedding light on the impact of (shallow) groundwaters on land‐athmosphere feedback processes. Key Points: A physically based framework was proposed to quantify effects of soil hydraulic properties on groundwater and climate interactionsSaturated hydraulic conductivity and groundwater levels are crucial for assessing the coupling modes in the study area (Hamburg, Germany)Combined effects of climatic parameters, soil properties and shallow groundwater influence the mode of coupling in Hamburg, Germany [ABSTRACT FROM AUTHOR]