A Model for Water Flow in Patterned Glacial Till Incorporating Coupled Multi-Scale Heterogeneity Effects

English Abstract:

Representing subgrid-scale heterogeneity is becoming increasingly more feasible in land surface modeling and large scale hydrological modeling with the advance of computational power. However, in complex environments, such as the internally drained prairie basins, with highly variable snowpack and soil properties, our understanding of spatiotemporal storage dynamics and flow paths is still incomplete. An extensive and comprehensive field monitoring program was implemented to assess the field-scale water balance within a heterogeneous prairie pasture site. A 2-D hydrological model, including a novel representation of the patterned glacial till and associated surface properties, was developed. Instead of assuming homogeneous precipitation and soil properties over grids, the key soil parameters for two representative profiles were identified by inverse modeling using a simple 1-D hydrological model and field measurements of soil temperature, water content and water level. Then the parameters for spatial variability of those two profiles and boundary conditions were determined by near-surface soil water content surveys. The modeling results will be discussed in conjunction with the observed features.