We numerically study how the interactions between surface, subsurface,
and rainfall create complex runoff behavior in a headwater-dominated
high elevation, mountainous catchment in East River Watershed, Colorado,
USA. In order to understand the effect of surface--subsurface
interactions on the hydrological response, we compare model variations
with different soil permeability. We compute hydrographs, hydrological
indices, and spatio-temporal distributions of hydrological variables.
The indices and distributions are then linked to the hydrograph at the
outlet of the domain. Our results show that changing surface--subsurface
interactions trigger different flow regimes, connectivity dynamics, and
runoff generation mechanisms inside the catchment, and hence, affect the
distributed hydrological response. Increased surface--subsurface
interaction leads to a higher degree of connectivity in the catchment.
Temporal dynamics of both distributed and aggregated hydrological
response did not change significantly, which may be because the
structural connectivity of the catchment remained untouched. Our results
indicate that in higher order catchments, the effect of changes in
distributed hydrological response may not always be observable through
aggregated hydrological signatures.