Publication Details

Category Text Publication
Reference Category Journals
DOI 10.5194/hess-23-171-2019
Licence creative commons licence
Title (Primary) Influence of input and parameter uncertainty on the prediction of catchment-scale groundwater travel time distributions
Author Jing, M.; Heße, F.; Kumar, R.; Kolditz, O. ORCID logo ; Kalbacher, T.; Attinger, S.
Journal Hydrology and Earth System Sciences
Year 2019
Volume 23
Issue 1
Page From 171
Page To 190
Language englisch
Abstract Groundwater travel time distributions (TTDs) provide a robust description of the subsurface mixing behavior and hydrological response of a subsurface system. Lagrangian particle tracking is often used to derive the groundwater TTDs. The reliability of this approach is subjected to the uncertainty of external forcings, internal hydraulic properties, and the interplay between them. Here, we evaluate the uncertainty of catchment groundwater TTDs in an agricultural catchment using a 3-D groundwater model with an overall focus on revealing the relationship between external forcing, internal hydraulic properties, and TTD predictions. Eight recharge realizations are sampled from a high-resolution dataset of land surface fluxes and states. Calibration-constrained hydraulic conductivity fields (Ks fields) are stochastically generated using the null-space Monte Carlo (NSMC) method for each recharge realization. The random walk particle tracking (RWPT) method is used to track the pathways of particles and compute travel times. Moreover, an analytical model under the random sampling (RS) assumption is fit against the numerical solutions, serving as a reference for the mixing behavior of the model domain. The StorAge Selection (SAS) function is used to interpret the results in terms of quantifying the systematic preference for discharging young/old water. The simulation results reveal the primary effect of recharge on the predicted mean travel time (MTT). The different realizations of calibration-constrained Ks fields moderately magnify or attenuate the predicted MTTs. The analytical model does not properly replicate the numerical solution, and it underestimates the mean travel time. Simulated SAS functions indicate an overall preference for young water for all realizations. The spatial pattern of recharge controls the shape and breadth of simulated TTDs and SAS functions by changing the spatial distribution of particles' pathways. In conclusion, overlooking the spatial nonuniformity and uncertainty of input (forcing) will result in biased travel time predictions. We also highlight the worth of reliable observations in reducing predictive uncertainty and the good interpretability of SAS functions in terms of understanding catchment transport processes.
Persistent UFZ Identifier
Jing, M., Heße, F., Kumar, R., Kolditz, O., Kalbacher, T., Attinger, S. (2019):
Influence of input and parameter uncertainty on the prediction of catchment-scale groundwater travel time distributions
Hydrol. Earth Syst. Sci. 23 (1), 171 - 190