Potential of a Gravity‐Driven Film Flow Model to Predict Infiltration in a Catchment for Diverse Soil and Land Cover Combinations

Demand, D. ORCIDiD
Weiler, M. ORCIDiD

DOI: https://doi.org/10.1029/2019WR026988
Persistent URL: http://resolver.sub.uni-goettingen.de/purl?gldocs-11858/9578
Demand, D.; Weiler, M., 2021: Potential of a Gravity‐Driven Film Flow Model to Predict Infiltration in a Catchment for Diverse Soil and Land Cover Combinations. In: Water Resources Research, 57, 5, DOI: https://doi.org/10.1029/2019WR026988. 
 
Weiler, M.; 1 University of Freiburg Institute of Earth and Environmental Sciences, Hydrology Freiburg Germany

Abstract

Applying physically based models that include preferential flow (PF) is still very challenging at the catchment scale. A gravity‐driven film flow approach could be a promising concept for modeling PF as it only requires a small number of parameters. We tested if this approach can be used for different soils and land covers within a 247 km2 catchment and if we can find generalizable relationships of the film flow parameters to site or rainfall properties. We used a unique data set from a soil moisture sensor network with 135 instrumented soil profiles in three different geologies (slate, marl, and sandstone) and two land covers (forest and grassland) and fitted the film flow model to around 1,700 infiltration events. The results demonstrate that the physical relationship of film flow was capable to predict wetting front velocity (v) and flow parameters from rainfall input (qs) alone. This relationship was pronounced in grassland sites but weaker for forest sites, probably due to heterogeneity of the rainfall input underneath the canopy. Incorporating the water content into the v‐qs relationship did not improve the quality, but showed that for the film flow the rainfall input and hence gravity is in fact the dominant driver and not capillarity. Furthermore, abstraction of water into the soil matrix during film flow is an important process to be included into the framework with reasonable agreements for marl and sandstone using a multiple linear regression. Film flow and corresponding functional parameter relationships for other regions could improve catchment wide PF modeling in the future.


Key Points:

Gravity‐driven film flow has a large potential to describe preferential flow during natural infiltration events at a diversity of sites.

Parameters can be determined from the rainfall input, which has a stronger effect on the flow velocity than initial soil water content.

Abstraction of water from film flow in macropores into the soil matrix is a process that has to be included in more detail.