Elevation dependent effects of precipitation on river discharge at different spatio-temporal scales

The link between climate extremes and river floods is complex and greatly affected by regional characteristics. River discharges are highly dependent on elevation and size of catchment in mountainous regions. This study explores the effects of orography on the precipitation-discharge relationship in the Greater Alpine Region (GAR). We make use of  daily discharge data and several reanalysis and observation datasets. The region is stratified into low (LE), and high (HE) elevation categories to assess variations in discharge responses. The correlation of discharges with precipitation at HE shows stronger relationship during the autumn season (September-November), while LE exhibits a stronger association in summer (June-August). Coarser resolution (>0.25^o) datasets show degradation of the association of precipitation with river discharge at both elevation categories,  although with a larger sensitivity of HE  to decreasing spatial resolution (i.e. 0.10^o to 1^o degree) as compared to the LE category. Significant sensitivity to spatio-temporal scales is found also in the intensity and duration of the climate extremes (ETCCDI indices) and their relationship with discharges in the GAR. This study emphasizes the advantages of high-resolution, multi-scale approaches to understand the intensity and duration of climate extremes and their impacts on river discharges. An improved framework integrating climate and orographic indices is essential to identify the complex relationships governing flood extremes in the GAR. The improved framework will contribute to the development of diagnostic tools and enhance the skill of future flood extreme projections by climate models.