Articles | Volume 7, issue 3
Geosci. Model Dev., 7, 711–723, 2014
Geosci. Model Dev., 7, 711–723, 2014

Development and technical paper 06 May 2014

Development and technical paper | 06 May 2014

High-resolution hydraulic parameter maps for surface soils in tropical South America

T. R. Marthews1, C. A. Quesada2, D. R. Galbraith3, Y. Malhi1, C. E. Mullins4, M. G. Hodnett5, and I. Dharssi6 T. R. Marthews et al.
  • 1Environmental Change Institute, School of Geography and the Environment, University of Oxford, Oxford OX1 3QY, UK
  • 2Instituto Nacional de Pesquisas da Amazônia, 69060-001 Manaus, Brazil
  • 3School of Geography, University of Leeds, Leeds LS2 9JT, UK
  • 444 Leadervale Rd., Edinburgh EH16 6PA, UK
  • 5Higher Park, Pennymoor, Tiverton, Devon EX16 8LL, UK
  • 6Bureau of Meteorology, Melbourne 3001, Australia

Abstract. Modern land surface model simulations capture soil profile water movement through the use of soil hydraulics sub-models, but good hydraulic parameterisations are often lacking, especially in the tropics. We present much-improved gridded data sets of hydraulic parameters for surface soil for the critical area of tropical South America, describing soil profile water movement across the region to 30 cm depth. Optimal hydraulic parameter values are given for the Brooks and Corey, Campbell, van Genuchten–Mualem and van Genuchten–Burdine soil hydraulic models, which are widely used hydraulic sub-models in land surface models. This has been possible through interpolating soil measurements from several sources through the SOTERLAC soil and terrain data base and using the most recent pedotransfer functions (PTFs) derived for South American soils. All soil parameter data layers are provided at 15 arcsec resolution and available for download, this being 20x higher resolution than the best comparable parameter maps available to date. Specific examples are given of the use of PTFs and the importance highlighted of using PTFs that have been locally parameterised and that are not just based on soil texture. We discuss current developments in soil hydraulic modelling and how high-resolution parameter maps such as these can improve the simulation of vegetation development and productivity in land surface models.