2. STUDY AREA
The Izas Research Experimental Catchment (42º44´N, 0º25´W) is located in the headwaters of the Gállego River in the central Spanish Pyrenees (Figure 1). The catchment has an area of 0.33 km2 with altitudes ranging from 2075 m a.s.l. (gauging station) to 2325 m a.s.l. Landcover is dominated by subalpine meadows with some rocky outcrops. Slopes are gentle all over the catchment (mean slope ≈ 16º) (López-Moreno et al., 2013). Grasslands are mostly composed byFestuca eskia, Nardus estricta, Trifolium alpinum, Plantago alpine and Carex sempervirens (Revuelto et al., 2017). Soils are generally well developed presenting an approximate depth of 1 meter, with some areas accumulating deeper soils where some ephemeral springs are active during spring and early summer. Saturated soils during the melting period produce numerous solifluidal forms such as active lobes and terracets (García-Ruiz et al., 2021).