INTERCONNECTIVITY OF HYDROMETEOROLOGY AND HYDROGEOMORPHOLOGY IN THE CENTRAL ANDES

The Andes Mountains are a particularly salient feature of the SA landscape where hydrometeorology and hydrogeomorphology are intertwined. The mountains block the flow of moist air moving from east to west across the SA continent, resulting in a significant rain shadow on the western coast and a wet climate on the eastern slopes of the Andes. Using high resolution (90m) DEMs for the area represented by 60°-80°W and 5°-20°S obtained from USGS HydroSHEDS and 13-year climatology of TRMM precipitation features (1998-2011) from the University of Utah TRMM data-base, we analyze the precipitation patterns over the topography of the study area. Our analysis yields three particular features: 1) a diurnal cycle where precipitation moves from low to high elevations during the day and from high to low elevations at night; 2) a clustering of nocturnal rainfall along river valleys and slopes; and 3) a clear signature of seasonality in the distribution of precipitation. This clustering is linked to locations in the landscape where there is evidence of multiple landslides, which explain the large sediment load in receiving rivers. This study documents a strong relationship between regional hypsometry from headwater catchments to basins of order 7 and the space-time precipitation patterns in the Central Andes beyond tectonics.