Incipient subsurface heterogeneity and its effect on overland flow generation – insight from a modeling study of the first experiment at the Biosphere 2 Landscape Evolution Observatory

摘要: Evolution of landscape heterogeneity is controlled by coupled Earth system dynamics, and the resulting pro- cess complexity a major hurdle to cross towards unified theory catchment hydrology. The Biosphere 2 Landscape Observatory (LEO), 334.5 m artificial hillslope built with homogeneous soil, may have evolved into hetero- geneous soil during first experiment driven an intense rainfall event. produced predominantly seep- age face water outflow, but also generated overland flow, causing superficial erosion formation small chan- nel. In this paper, we explore hypothesis incipient het- erogeneity development in LEO its effect on flow generation comparing modeling results from three-dimensional physically based hydrological model measurements total mass change seepage flow. Our null that hydraulically homoge- neous, while alternative developed downstream transport fine sediments saturated subsurface heterogeneous case modeled assigning hydraulic conductivity at (Ksat,sf) different rest (Ksat). A range values for Ksat, Ksat,sf, porosity, pore size distribution used account uncertainties estimating these parameters, more than 20 000 simulations. It found best runs under produce smaller errors those hypothesis, yield higher probability performance runs. These support hy- pothesis localized which facilitated This model- ing study suggests important role sediment processes evolution generation, highlighting need sys- tem integrates across disciplinary processes.