However, no data are published about such industrial water uses. About 450 million m3/y is directly abstracted from rivers and streams (i.e. not via reservoirs). Use of underground waters for irrigation is limited (about 3 per cent of the total). These figures are not, however, based on actual monitoring of volumes abstracted for irrigation purposes. Due to erosion and alluvium, their real water retention capacity' has been reduced to approximately 290 million m3.