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68 Water Movement in Hydrophobic Soils

Part 6. Soils

  1. Dr Stefan H Doerr1,
  2. Professor Coen J Ritsema2

Published Online: 15 APR 2006

DOI: 10.1002/0470848944.hsa072

Encyclopedia of Hydrological Sciences

Encyclopedia of Hydrological Sciences

How to Cite

Doerr, S. H. and Ritsema, C. J. 2006. Water Movement in Hydrophobic Soils. Encyclopedia of Hydrological Sciences. 6:68.

Author Information

  1. 1

    University of Wales, Geography Department, Swansea, UK

  2. 2

    Soil Science Center, Wageningen, The Netherlands

Publication History

  1. Published Online: 15 APR 2006

Abstract

Hydrophobicity (water repellency) can reduce the affinity for soils to water such that infiltration or wetting may be delayed for periods ranging from as little as a few seconds to in excess of weeks. Soil hydrophobicity is thought to be caused primarily by a coating of long-chained hydrophobic organic molecules on individual soil particles. These substances may be released from a range of plants, decaying organic matter, soil fauna, and microorganisms either naturally or during burning. Hydrophobicity tends to be spatially and temporally highly variable, which makes its effects difficult to observe and predict. It is often most prominent after prolonged dry spells and usually disappears after prolonged contact with water. Owing to the cultivation of certain frequently introduced plant species and the increase in wildfires in some regions, hydrophobicity has developed in previously unaffected areas. Amongst its effects are inhibited plant growth, increased overland flow and soil erosion, uneven spatial and vertical wetting patterns, reduced evaporation, and enhanced risk of groundwater contamination associated with enhanced preferential flow. Recent modeling approaches have been successful in predicting the effects of hydrophobicity on soil water movement at plot or small-field scales, however, approaches to predict in detail its hydrological effects at larger scales are yet to be developed.

Keywords:

  • soil;
  • hydrophobicity;
  • water repellence;
  • water repellency;
  • infiltration;
  • preferential flow;
  • surface tension;
  • water movement;
  • modeling