Modelling present and future glacier discharges of Río Santa Cruz in the Southern Patagonian Andes

ZORZUT, VALENTINA.; RIVERA, J.; PITTE, P.; VIALE, M.; VILLALBA, RICARDO; RUIZ, L.; MASIOKAS, MARIANO; TOUM, EZEQUIEL

Montreal

Congreso; 27th IUGG General Assembly; 2019

IUGG

Río Santa Cruz has the largest flow of the Argentinean rivers in the SouthernPatagonian Andes. The river extends for more than 380 km from the SouthernPatagonian Ice Field to the Atlantic Ocean, crossing all along the Patagoniansteppe. Most of the flow originates in the upper basin of the river from theabundant orographic precipitation throughout the year and the melting of theglacial ice that covers 17% (~2900 km2) of the upper basin. Given the importantcontribution of glaciers to river discharge and their potential contraction inrelation to global warming, it is extremely valuable to assess the possiblechanges in river discharge in the coming decades. We investigate the dynamicsof the river in the upper basin under present and future conditions using aglacio-hydroclimatological numerical model. The model computes all majorcomponents of glacier mass balance (snow accumulation, ice and snow meltand frontal ablation) and reproduces the present-climate monthly values ofdischarge at the Charles Fuhr gage station with a precision of ± 22% of annualmean discharge. Projections for the period 2070-2080 under the moderateemission scenario A1B predicts a 10% increase in annual discharge (within theerror range of the model) in response to an increase in melt water from glaciersand more abundant winter precipitation than in current climate. The modelsimulates an increase in meltwater from glaciers through the 21st centuryassociated with almost 50% shrinkage of glacier?s area in the basin.