Assessing Managed Aquifer Recharge Processes under Three Physical Model Concepts

Physical models such as surface infiltration experiments in the lab and field are an approach to understand processes in the unsaturated soil zone. In the case of mapping processes influencing the operation of real-world managed aquifer recharge schemes they are helpful tools to determine interactions between processes in the unsaturated soil zone, and site-specific as well as operational parameters. However, the multitude of assumptions and scale-related limitations of downscale investigations often lead to over- or underestimations, rendering their results useless when translated to field-like conditions. Various real-world managed aquifer recharge operational scenarios were simulated in three physical models, a 1D-lab column, a rectangular shaped stainless steel 3D-lab infiltration tank and a rectangular shaped 3D-field unit, to understand the impact of the experimental set-up on the assessment of processes and to identify the experimental set-up which is most-suitable to describe these processes. Results indicate that water flow velocity, water saturation and oxygen consumption are often overestimated in 1D-column experiments due to sidewall effects and no existing lateral flow. For precise analysis of infiltration processes in general as well as during operation of managed aquifer recharge, 3D experiments are recommended due to their more realistic representation of flow processes.