Chloride circulation in a lowland catchment and the formulation of transport by travel time distributions

Paolo Benettin, Ype Van Der Velde, Sjoerd E.A.T.M. Van Der Zee, Andrea Rinaldo, Gianluca Botter

Research output: Contribution to journalArticleResearchpeer-review

71 Citations (Scopus)


Travel times are fundamental catchment descriptors that blend key information about storage, geochemistry, flow pathways and sources of water into a coherent mathematical framework. Here we analyze travel time distributions (TTDs) (and related attributes) estimated on the basis of the extensive hydrochemical information available for the Hupsel Brook lowland catchment in the Netherlands. The relevance of the work is perceived to lie in the general importance of characterizing nonstationary TTDs to capture catchment transport properties, here chloride flux concentrations at the basin outlet. The relative roles of evapotranspiration, water storage dynamics, hydrologic pathways and mass sources/sinks are discussed. Different hydrochemical models are tested and ranked, providing compelling examples of the improved process understanding achieved through coupled calibration of flow and transport processes. The ability of the model to reproduce measured flux concentrations is shown to lie mostly in the description of nonstationarities of TTDs at multiple time scales, including short-term fluctuations induced by soil moisture dynamics in the root zone and long-term seasonal dynamics. Our results prove reliable and suggest, for instance, that drastically reducing fertilization loads for one or more years would not result in significant permanent decreases in average solute concentrations in the Hupsel runoff because of the long memory shown by the system. Through comparison of field and theoretical evidence, our results highlight, unambiguously, the basic transport mechanisms operating in the catchment at hand, with a view to general applications.

Original languageEnglish
Pages (from-to)4619-4632
Number of pages14
JournalWater Resources Research
Issue number8
Publication statusPublished - 2013
Externally publishedYes


  • chloride
  • transport
  • travel time distributions

Cite this