摘要：L’aridité de la région du Cuyo, avec ses 150 à 300 mm de précipitations annuelles, sur le piémont des Andes, n’a pas empêché l’installation humaine, puisque la Province de Mendoza compte 1,7 million d’habitants (Recensement INDEC, 2010), dont 97 % sont concentrés dans des oasis, essentiellement dans l’agglomération de Mendoza (1,5 million d’habitants), ou dans d’autres villes comme Tunuyán, San Martín ou San Rafaël. Quatre rivières (du nord au sud : Mendoza, Tunuyán, Diamante et Atuel) irriguent trois oasis 1 (l’oasis Nord, 2500 km² ; l’oasis Centre, également appelée Valle de Uco, 800 km² ; et l’oasis Sud, 1600 km²) et alimentent en eau les centres urbains. L’écoulement dans les oasis Nord et Sud est régulé artificiellement par les barrages situés en leur amont. Au contraire, l’oasis centrale ne dispose pas encore de tel barrage et de régulation de l’écoulement, les fermiers utilisent l’eau souterraine mais un nouveau barrage est prévu par les gestionnaires du bassin versant du Tunuyan supérieur pour réguler en amont l’écoulement dans la Valle del Uco.
其他摘要：In the Argentinian Dry Andes, although the melting of glaciers is seen as a threat for the long-term water availability needed by the piedmont crops, the annual snowmelt is the main source of superficial water and aquifer recharge. In this study, we analyse the link between the seasonal and interannual variations in the discharge measured upstream of the first dams on four rivers (Mendoza, Tunuyán, Diamante, Atuel) of the Argentinian Cuyo region (in the Federal Province of Mendoza) and those of the snow bed extent as mapped by optical remote sensing (MODIS MOD10A2 product) on a weekly basis in the 2001-2014 period, at the scale of each watershed.For the four snow-glacier regime rivers, seasonal variations in the discharge appear directly related to those of the snow bed surface area in each watershed, as shown previously (Masiokas et al., 2006). We observed that the high-water period (September-April) discharge is directly related to the snow extent at the beginning of the snowmelt period, i.e. in September and October, as revealed by a correlation of about 0.8. Moreover, the decreasing trend in the winter snow bed extent from 2001 to 2014 clearly explains the observed decreasing trend in the annual water discharge.Agriculture and human activities in these oases mostly depend on river discharge, which from our results clearly depends on the snow extent. Our research indicates that it is possible to use remote sensing to forecast the average discharge in the September-April period (high-water season) from MOD10A2 images with an average uncertainty of 15%. As MOD10A2 data are freely available ten days after acquisition, it is possible to anticipate in early October the risk of water shortages in the coming summer.
