Long‐Term Changes in Runoff Generation Mechanisms for Two Proglacial Areas in the Swiss Alps II: Subsurface Flow

Lateral subsurface stormflow (SSF) is the most important runoff generation mechanism for hillslopes in temperate climates. It influenced by pedological, biological, and topographic factors that change during landscape evolution, but so far little known about how SSF changes over long-time scales. Therefore, we conducted sprinkling experiments on a silicate carbonate moraine chronosequence Swiss Alps. Each consisted of four moraines ranging between couple decades ∼13,500 years age. On each moraine, installed three plots measured shallow trench. We added tracers (δ2H NaCl) to water identify mixing flow pathways subsurface. The coarse drainable sediments young provoked more frequent larger responses than old moraines. There was no older at calcareous study area, occurred natural rainfall events. pre-event fractions were higher due increase silt, clay, soil organic matter content, subsequent amount stored soil. results this suggest vegetation development affect characteristics help—together with overland (companion paper; Maier & van Meerveld, 2021, https://doi.org/10.1029/2021WR030221)—to improve hydrological models our understanding near-surface processes first millennia evolution Alpine areas.