Abstract
Effective management of karst aquifers necessitates accurate characterization of flow and transport. However, modeling these highly heterogeneous systems is challenging due to the complex partitioning of recharge between bedrock and the embedded conduit network. The properties of conduit networks impact flow and transport, but there has not been a systematic, quantitative study of how conduit network structure and geometry impact spring hydrographs in naturalistic field conditions. In this field-inspired modeling study, we attempt to identify key geometric and structural properties of conduit networks that control flow in karst aquifers and use these insights to constrain our understanding of a nitrate and chloride-impacted karst aquifer in Southeastern Minnesota. We systematically vary network structure for a field-inspired conduit network and model spring flow with the model openKARST coupled with a linear reservoir model. We identify network complexity and slope as two key factors that impact the spring hydrograph by delaying peak arrival. However, no significant peak dispersion or attenuation was observed in any of the networks, evidenced by the lack of difference in recession coefficients between network structures. This introductory study demonstrates the quantifiable impact of conduit network structure on spring hydrograph behavior and provides some contexts in which spring flow is predominantly controlled by infiltration and matrix processes, resulting in minimal influence of the conduit network structure.
Rights Information
This work is licensed under a Creative Commons Attribution-Noncommercial-No Derivative Works 3.0 License.
DOI
https://doi.org/10.5038/9781967518012.1025
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A Field-Inspired Investigation of Conduit Network Impacts on Spring Flow in Karst Aquifers
Effective management of karst aquifers necessitates accurate characterization of flow and transport. However, modeling these highly heterogeneous systems is challenging due to the complex partitioning of recharge between bedrock and the embedded conduit network. The properties of conduit networks impact flow and transport, but there has not been a systematic, quantitative study of how conduit network structure and geometry impact spring hydrographs in naturalistic field conditions. In this field-inspired modeling study, we attempt to identify key geometric and structural properties of conduit networks that control flow in karst aquifers and use these insights to constrain our understanding of a nitrate and chloride-impacted karst aquifer in Southeastern Minnesota. We systematically vary network structure for a field-inspired conduit network and model spring flow with the model openKARST coupled with a linear reservoir model. We identify network complexity and slope as two key factors that impact the spring hydrograph by delaying peak arrival. However, no significant peak dispersion or attenuation was observed in any of the networks, evidenced by the lack of difference in recession coefficients between network structures. This introductory study demonstrates the quantifiable impact of conduit network structure on spring hydrograph behavior and provides some contexts in which spring flow is predominantly controlled by infiltration and matrix processes, resulting in minimal influence of the conduit network structure.