FIGURE 1. Izas catchment and the location of the automatic weather stations (yellow triangle) and gauging stations (blue square) and piezometers (red circles). Red line outlines the drainage area of the gauging station. Pink areas in the small map indicates the surface covered by the time lapse camera.
Snow covers most of the catchment for long periods, with the onset of snow cover being generally observed along November and melting starting in April or early May. Snow cover depletion is normally completed by the end of May or early June, even if snow patches occasionally last until late June. Snow depth shows a large interannual variability and also strong spatial variability, the later mostly driven by a combination of wind transport and the influence of elevation and topography on shortwave radiation (Revuelto et al., 2014). More than half of the annual precipitation (2000 mm yr-1) falls as snow (Anderton et al., 2004). The catchment benefits from a transitional climate from Atlantic to Mediterranean, where winter and spring are the most humid seasons while summer is the driest, when precipitation is mostly the result of convective thunderstorms (del Barrio et al., 1997). Annual mean temperature is +3ºC, with mean daily temperature below 0ºC for an average of 130 days per year (Revuelto et al., 2017).