Transient Groundwater Travel Time Distributions and Age-Ranked Storage-Discharge Relationships of Three Lowland Catchments

V. P. Kaandorp*, P. G.B. de Louw, Y. van der Velde, H. P. Broers

*Corresponding author for this work

Research output: Contribution to JournalArticleAcademicpeer-review

Abstract

The contribution of groundwater to streams is controlled by temporally and spatially variable groundwater flow paths with distinctive travel times. The aggregated average travel time distribution (TTD) of all these flow paths functions as a catchment characteristic. Currently, research on TTDs is expanding towards dynamic TTDs and building on this, we present dynamic backward TTDs and residence time distributions using forward particle tracking on a high-resolution spatially distributed groundwater flow model (25*25 m). We show that the dynamic backward TTDs of three Dutch catchments are determined by the interplay between the activation of shallow short flow paths and the intensification of fluxes through all flow paths when groundwater levels rise. In addition, the preference for young water in our lowland catchments appears strongly controlled by drainage density. Variations in catchment mixing with time and between catchments were analyzed using dynamic StorAge Selection (SAS) functions. This showed the effect of differences in geology and topography on the shape of the SAS functions. Additionally, the variability of SAS functions in time was shown to depend on the extent to which new flow paths can be activated. Time-varying SAS functions are required for computation of dynamic TTDs, and this research showed realistic values for the variability in the SAS functions of lowland catchments. The step towards dynamic TTDs is crucial for understanding the temporal and spatial behavior of streams, their chemical composition, and their ecological value.

Original languageEnglish
Pages (from-to)4519-4536
Number of pages18
JournalWater Resources Research
Volume54
Issue number7
Early online date20 Jun 2018
DOIs
Publication statusPublished - Jul 2018

Funding

We thank three anonymous reviewers and Alexander Buzacott for their comments that greatly improved the manuscript. This work is part of the MARS project (Managing Aquatic ecosystems and water Resources under multiple Stress) funded under the 7th EU Framework Programme, Theme 6 (Environment including Climate Change), contract 603378 (http://www. mars-project.eu). Presented (modeling) data are available online at https://doi. org/10.6084/m9.figshare.5729364.v2.

FundersFunder number
7th EU Framework Programme
Seventh Framework Programme603378

    Keywords

    • Catchment hydrology
    • forward particle tracking
    • groundwater dynamics
    • SAS-functions
    • travel time distributions
    • young water fractions

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