Water-table modelling to estimate irrigation losses: application to the Lower Durance, France

The consumption of water by irrigation in agriculture is very large and thus the effects of the management of irrigation systems on aquifers are very important. The basis of this preliminary study into the reduction of this consumption is to improve our understanding of the losses resulting from water transport and deep seepage inside the irrigated areas of cultivation (parcels) at the regional level (100 km) by studying water-table variations with reference to anthropogenic contributions. The use of a hydrodynamic model that incorporates adjustment of the quantity of irrigation water by a reduction coefficient enables actual water-table behaviour to be simulated. Losses can thus be deduced from the quantity of irrigation water flowing into the irrigation system and from hydrometeorological parameters.

Application of the technique in the Lower Durance (France) indicates that, in this region, 53% of the water remains in the irrigation network and 19% is lost by deep seepage, leaving only 28% of the water supplied for use by plants.