Preferential flow as a potential mechanism for fire-induced increase in streamflow

C.R. Stoof, E.C. Slingerland, W. Mol, J. van den Berg, P.J. Vermeulen, A.J.D. Ferreira, C.J. Ritsema, J.Y. Parlange, T.S. Steenhuis

Research output: Contribution to journalArticleAcademicpeer-review

14 Citations (Scopus)

Abstract

After vegetation fires, discharge of streams and rivers is often higher than before. This is usually attributed to decreased canopy interception and evapotranspiration caused by vegetation removal, and to increased overland flow resulting from increased soil water repellency. In this paper we examine whether fire-induced changes in preferential flow can reinforce this postfire streamflow response. We studied five recently burned soils and adjacent unburned soils in Portugal and found that by reducing topsoil moisture and increasing soil moisture variability, fire increased the propensity for preferential flow. This was confirmed by 2-D soil moisture and repellency profiles that showed preferential paths in burned soil that were more distinct, wetter, and slightly narrower than in unburned soil. Since water infiltrating along preferential flow paths bypasses the dry soil matrix, we suggest that narrow flow paths promote deep infiltration– which effect size varies with soil depth, (effective) rainfall, and overland flow. We pose that the resulting increase in infiltration increases drainage and interflow because the excess water cannot stay in the soil, and incorporate fire-induced or -enhanced preferential flow into a conceptual model of flow routing that explains the commonly observed increase in stream flow postfire.
Original languageEnglish
Pages (from-to)1840-1845
JournalWater Resources Research
Volume50
Issue number2
DOIs
Publication statusPublished - 2014

Keywords

  • soil-water repellency
  • portuguese shrubland
  • wildfire
  • persistence

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