Influence of aquifer heterogeneity on karst hydraulics and catchment delineation employing distributive modeling approaches

Abstract

Due to their heterogeneous nature, karst aquifers pose a major challenge for hydrogeological investigations. Important procedures like the delineation of catchment areas for springs are hindered by the unknown locations and hydraulic properties of highly conductive karstic zones. <br><br> In this work numerical modeling was employed as a tool in delineating catchment areas of several springs within a karst area in southwestern Germany. For this purpose, different distributive modeling approaches were implemented in the Finite Element simulation software Comsol Multiphysics^®. The investigation focuses on the question to which degree the effect of karstification has to be taken into account for accurately simulating the hydraulic head distribution and the observed spring discharges. <br><br> The results reveal that the representation of heterogeneities has a large influence on the delineation of the catchment areas. Not only the location of highly conductive elements but also their geometries play a major role for the resulting hydraulic head distribution and thus for catchment area delineation. The size distribution of the karst conduits derived from the numerical models agrees with knowledge from karst genesis. It was thus shown that numerical modeling is a useful tool for catchment delineation in karst aquifers based on results from different field observations

Transport and Attenuation of Particles of Different Density and Surface Charge: A Karst Aquifer Field Study

“…31 Previous investigations have included not only tracer experiments but also investigations into particle size distributions 32 and the origin, transport, and attenuation of organic micropollutants; 29,30,32−35 numeric modeling has successfully been used to simulate the groundwater flow, residence times, and solute transport for the aquifer. 36,37 A number of tracer tests based on injections at different sinkholes within the catchment area have shown a linear relationship between spring discharge and average flow velocity for discharge rates of between 0.1 and 0.8 m 3 s −1 , which indicates phreatic conditions. 31,34,38−40 The injection point for this particular tracer study was a dry sinkhole about 3000 m northwest of the spring (Figure 1).…”

Combining Experimental Methods and Modeling to Quantify the Complex Recharge Behavior of Karst Aquifers

“…lead to uncertainty in the conceptualization and parameterization and hence in the processes representation and application of model approaches (Jukic & Denić‐Jukić, ; Le Moine et al, ). The lack of available data imposes constraints particularly on spatially distributed models, which required higher resolution of input data (e.g., groundwater potential distribution and spatial distribution of the karstified horizons) for acceptable simulation and prediction results (Oehlmann et al, ; Saller et al, ). In contrast, lumped models have shown adaptability and strength in simulating the hydrogeological behavior under different contexts and scales (Hartmann et al, ), since data requirements for model inputs are less rigorous.…”

Impact of model complexity and multi-scale data integration on the estimation of hydrogeological parameters in a dual-porosity aquifer

“…One challenge is the intrinsic heterogeneity of geological media and the consequential variability of the hydrogeological properties, which can be of several orders of magnitude within the same aquifer system (e.g. Bohling et al, 2016;Fogg et al, 1998;Oehlmann et al, 2013;Williams et al, 2006). Moreover, because of the multiscale nature of geological media (Neuman and Di Federico, 2003), estimated effective values strongly depend on the volume of the aquifer investigated -also known as the support scale or support volume -and hence on the measurement method.…”