Climate change is considered as one of the main factors controlling sediment fluxes in mountain belts. However, the effect of El Niño, which represents the primary cause of inter-annual climate variability in the South Pacific, on river erosion and sediment transport in the Western Andes remains unclear. Using an unpublished dataset of Suspended Sediment Yield (SSY) in Peru (1968–2012), we show that the annual SSY increases by 3–60 times during Extreme El Niño Events (EENE) compared to normal years. During EENE, 82% to 97% of the annual SSY occurs from January to April. We explain this effect by a sharp increase in river water discharge due to high precipitation rates and transport capacity during EENE. Indeed, sediments accumulate in the mountain and piedmont areas during dry normal years, and are then rapidly mobilized during EENE years. The effect of EENE on SSY depends on the topography, as it is maximum for catchments located in the North of Peru (3–7°S), exhibiting a concave up hypsometric curve, and minimum for catchments in the South (7–18°S), with a concave down hypsometric curve. These findings highlight how the sediment transport of different topographies can respond in very different ways to large climate variability.

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Abstract. Hydro-sedimentology development is a great challenge in Peru due to limited data as well as sparse and confidential information. This study aimed to quantify and to understand the suspended sediment yield from the westcentral Andes Mountains and to identify the main erosioncontrol factors and their relevance. The Tablachaca River (3132 km 2 ) and the Santa River (6815 km 2 ), located in two adjacent Andes catchments, showed similar statistical daily rainfall and discharge variability but large differences in specific suspended-sediment yield (SSY). In order to investigate the main erosion 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 factor that controls the high SSY of the Tablachaca (2204 t km 2 yr −1 ), which is four times greater than the Santa's SSY. These results show that the analysis of control factors of regional SSY at the Andes scale should be done carefully. Indeed, spatial data at kilometric scale and also daily water discharge and SSC time series are needed to define the main erosion factors along the entire Andean range.

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Mountain glaciers are crucial sources of fresh water, contributing directly and indirectly to water, energy and food supplies for hundreds of millions of people. Assessing the impact of diminishing glacial meltwater contributions to the security of this resource is critical as we seek to manage and adapt to changing freshwater dynamics in a warming world. Both water quantity and quality influence water (in)security, so understanding the fluxes of water, sediment and contaminants through glacial and proglacial systems is required for holistic assessment of meltwater contribution to downstream resource security. In this paper we consider the socio-environmental role of and pressures on glacier-fed waters, discuss key research priorities for the assessment of both the quantity and quality of meltwater and reflect on the importance of situating our understanding within a transdisciplinary and inclusive research landscape.

Hydro-sedimentology development is a great challenge in Peru due to limited data as well as sparse and confidential information. Consequently, little is known at present about the relationship between the El Niño Southern Oscillation (ENSO), precipitation, runoff, land use and the sediment transport dynamics. The aim of this paper is to bridge this gap in order to quantify and understand the signal of magnitude and frequency of the sediment fluxes from the central western Andes; also, to identify the main erosion control factor and its relevance. <br><br> The Tablachaca River (3132 km²) and the Santa River (6815 km²), two mountainous Andean catchments that are geographically close to each other, both showed similar statistical daily rainfall and discharge variability but high contrast in sediment yield (SY). In order to investigate which factors are of importance, the continuous water discharge and hourly suspended sediment concentrations (SSC) of the Santa River were studied. Firstly, the specific sediment yield (SSY) at the continental Andes range scale for the Pacific side is one of the highest amounts (2204 t km² yr⁻¹). Secondly, no relationship between the water discharge (<i>Q</i>) and El Niño/La Niñ a events is found over a 54 yr time period. However, the Santa Basin is highly sensitive during mega Niños (1982–1983 and 1997–1998). Lastly, dispersed micro-mining and mining activity in specific lithologies are identified as the major factors that control the high SSY. These remarks make the Peruvian coast key areas for future research on Andean sediment rates