IWRA World Water Congress 2008 Montpellier France
1. Water availability, use and management
Author(s): Julie Sansoulet
Yves-Marie Cabidoche
Philippe Cattan
Stéphane Ruy
Jirka Simunek
Keyword(s): Water fluxes, spatial distribution, stemflow, lysimeters, tensiometers, modelling,
Article: PDFAbstractWater
fluxes in the subsurface of forested and agricultural ecosystems are spatially widely variable because of several
interconnected phenomena. On the one hand, subsurface environments are often highly heterogeneous. On the other
hand, infiltration water is often distributed unevenly due to above-ground interception and redistribution of rainfall by
the plant canopy. These phenomena have important hydro-ecological consequences because they significantly affect
groundwater recharge and nutrient leaching. Field experiments involving subsurface lysimeters and tensiometers were
carried out to quantify the spatial distribution of fluxes in an andisol under a banana plant. Wick lysimeters were
installed at a depth of 70 cm at several locations with respect to the banana stem to measure spatial distribution of
subsurface water fluxes. Collected experimental data were simulated using the HYDRUS software package that
numerically solves the Richards equation describing three-dimensional variably-saturated water flow in the
subsurface. Spatially distributed drainage fluxes were well reproduced with the numerical model. Due to the impact
of stemflow, drainage volumes under the banana stem were up to six times higher than in the row downstream from
the stem, as well as between rows, as these areas were sheltered from direct rainfall by the banana leaves and
received only throughfall.