Pertinent spatio-temporal scale of observation to understand suspended sediment yield control factors in the Andean region: the case of the Santa River (Peru)

摘要

Hydro-sedimentology development is a great challenge in Peru due to limiteddata as well as sparse and confidential information. This study aimed toquantify and to understand the suspended sediment yield from the west-centralAndes Mountains and to identify the main erosion-control factors and theirrelevance. The Tablachaca River (3132 km2) and the Santa River(6815 km2), located in two adjacent Andes catchments, showed similarstatistical daily rainfall and discharge variability but large differences inspecific suspended-sediment yield (SSY). In order to investigate the mainerosion factors, daily water discharge and suspended sediment concentration(SSC) datasets of the Santa and Tablachaca rivers were analysed.Mining activity in specific lithologies was identified as the major factorthat controls the high SSY of the Tablachaca (2204 t km2 yr−1),which is four times greater than the Santa's SSY. These results show that theanalysis of control factors of regional SSY at the Andes scale should be donecarefully. Indeed, spatial data at kilometric scale and also daily waterdischarge and SSC time series are needed to define the main erosion factorsalong the entire Andean range.