Abstract
Abstract. In karst systems, near-surface dissolution of carbonate rock results in a high spatial and temporal variability of groundwater recharge. To adequately represent the dominating recharge processes in hydrological models is still a challenge, especially in data scarce regions. In this study, we developed a recharge model that is based on a conceptual model of the epikarst. It represents epikarst heterogeneity as a set of system property distributions to produce not only a single recharge time series, but a variety of time series representing the spatial recharge variability. We tested the new model with a unique set of spatially distributed flow and tracer observations in a karstic cave at Mt. Carmel, Israel. We transformed the spatial variability into statistical variables and apply an iterative calibration strategy in which more and more data was added to the calibration. Thereby, we could show that the model is only able to produce realistic results when the information about the spatial variability of the observations was included into the model calibration. We could also show that tracer information improves the model performance if data about the spatial variability is not included.
Highlights
For a sustainable groundwater management, detailed quantitative knowledge about groundwater recharge is required (Vries and Simmers, 2002)
At calibration step 1 the modeled Qexp and Qseas closely compared with the observations, which was expressed by high NSQ,exp and N SQ,seas values
In this study we hypothesize that the spatial variability of epikarst recharge is due to the variability of system properties, which can be represented by simple distribution functions
Summary
For a sustainable groundwater management, detailed quantitative knowledge about groundwater recharge is required (Vries and Simmers, 2002). The epikarst, which develops due to higher dissolution activity of the carbonate rock near the surface (Williams, 1983), controls recharge dynamics. Field research (Aquilina et al, 2006; Williams, 1983, 2008) as well as modeling approaches (Kiraly et al, 1995; Perrin et al, 2003) revealed that the epikarst acts as a temporary storage and distribution system for infiltrating water into karst systems. Karst aquifer recharge can be estimated by different approaches. Information about past recharge conditions can be obtained using environmental tracers like chlorofluorocarbons (CFSs), 3H/3He relationships Estimates about future recharge conditions are only possible with numerical modeling approaches (Scanlon et al, 2002)
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