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The incision of rivers into bedrock is considered as one of the most important processesdriving long-term landscape evolution. River incision is non-linearly dependent on riverdischarge, because river discharge must exceed a certain threshold to be able to transportbedload sediment and expose the riverbed to erosion. Fluvial erosion efficiency is, therefore,strongly controlled by the frequency and magnitude of flood events. In this study wehypothesise that catchment attributes, such as regolith thickness, lithology and vegetationcover, modulate the discharge response after a precipitation event, which has implications forthe fluvial erosion efficiency. We present preliminary results from a study, in which we exploit daily discharge recordsfrom 322 river gauging stations on a large climatic gradient in Chile (18˚ S-55˚ S). Thestudied rivers have catchment areas of 15 km2 to 24200 km2, which differ in topography,lithology, regolith thickness, vegetation cover and snow and glacier cover. First, we studieddischarge variability (i.e. magnitude-frequency distribution of flood events) andthe occurrence of different discharge regimes as result of seasonal variations, byobtaining the best fit of a weighted sum of two inverse gamma functions to the data(Scherler et al., 2017). Each of the distributions is interpreted to correspond to oneflow regime. When the weighted sum of two inverse gamma functions performedbetter than one, and each flow regime lasted at least 3 months, we interpret thedifferent flow regimes to reflect seasonal variation in a catchment. Results reveal largevariations in discharge variability along the climate gradient and strong seasonalvariations around 30˚ S-40˚ S which is mainly driven by climatic forcing and snowmelt. We are currently studying discharge variability by obtaining the flood flashinessparameter, the variability index and hydrologic response time from fitting the streamflowrecession model to the daily discharge records (Deal et al., 2018 after Botter et al., 2007). Wewill focus on the differences between seasons and El Niño, La Niña and normalyears and will compare all parameters with calculated topography and datasets ofclimate, vegetation density, regolith thickness, lithology and snow and glacier cover todisentangle their controls on flood flashiness, variability index and hydrologic responsetime. References: Botter, G., Porporato, A., Rodriguez-Iturbe, I. and Rinaldo, A.: Basin-scale soil moisturedynamics and the probabilistic characterization of carrier hydrologic flows: Slow,leaching-prone components of the hydrologic response, Water Resour. Res., 43(2),1–14. Deal, E., Botter, G. and Braun, J.: Understanding the role of rainfall and hydrology indetermining fluvial erosion efficiency, J. Geophys. Res. Earth Surf., 2018. Scherler, D., DiBiase, R. A., Fisher, G. B. and Avouac, J. P.: Testing monsoonal controlson bedrock river incision in the Himalaya and Eastern Tibet with a stochastic-thresholdstream power model, J. Geophys. Res. Earth Surf., 122(7), 1389–1429, 2017. [ABSTRACT FROM AUTHOR]