Horizon 1 1 17 ACL : Articles dans des revues avec comité de lecture répertoriées par l'AERES Journal of Hydrology : Regional Studies 100924 [16 ] Precipitation variability Diurnal and seasonal cycles Equatorial Andes EQUATEUR ANDES AMAZONE BASSIN GUAYLLABAMBA BASSIN NAPO BASSIN 2021 fdi:010083318 ENG Journal of Hydrology : Regional Studies ISI:000712249000002 10.1016/j.ejrh.2021.100924 https://www.documentation.ird.fr/hor/fdi:010083318 https://horizon.documentation.ird.fr/exl-doc/pleins_textes/2021-12/010083318.pdf 38 Horizon (IRD) Study region: The upper part of the Guayllabamba and Napo basins (78.2 degrees W, 0.3 degrees S; 18,500 km(2)) in the equatorial Andes, which are vulnerable to stress on the ecosystem services. Study focus: This paper analyses the diurnal cycle of precipitation over a transect from the Andes to the Amazon. The diurnal cycle is estimated as the diurnal distribution of precipitation for 2014-2019 using records from 80 stations. Cluster analysis performed on the diurnal cycle estimates depicts the spatial association between the diurnal and seasonal cycles of precipitation. New hydrological insights: A northwest-southeast spatial variation in the diurnal and seasonal cycles is identified with four groups of stations. In the western part, the seasonal cycles of Groups 1 and 2 are bimodal with precipitation maxima in the March-April and October-November seasons and a short drier season in July-August. In the eastern part, Group 3 also presents bimodality, but a weaker seasonal cycle. Conversely, Group 4 is unimodal with a peak in June. Distinct diurnal cycles are observed in both drier and wetter seasons of Groups 1-3; no marked diurnal cycle is observed in Group 4. Groups 3 and 4 are the most spatially heterogeneous, with an exceptional horizontal variation of 330 mm/yr/km. The analysis of these variations provides insight into the atmospheric dynamics driving precipitation in this zone, and may help to better optimize the water supply system. 062 UR252 Équateur