WATER-TABLE MODELING TO ESTIMATE IRRIGATION LOSSES - APPLICATION TO THE LOWER DURANCE, FRANCE

The consumption of water by irrigation in agriculture is very large an d thus the effects of the management of irrigation systems on aquifers are very important. The basis of this preliminary study into the redu ction of this consumption is to improve our understanding of the losse s resulting from water transport and deep seepage inside the irrigated areas of cultivation (parcels) at the regional level (100 km) by stud ying water-table variations with reference to anthropogenic contributi ons, The use of a hydrodynamic model that incorporates adjustment of t he quantity of irrigation water by a reduction coefficient enables act ual water-table behaviour to be simulated. Losses can thus be deduced from the quantity of irrigation water flowing into the irrigation syst em and from hydrometereological parameters. Application of the techniq ue in the Lower Durance (France) indicates that, in this region, 53% o f 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.