TY  - JOUR
AU  - Schalge, Bernd
AU  - Haefliger, Vincent
AU  - Kollet, Stefan
AU  - Simmer, Clemens
TI  - Improvement of surface run‐off in the hydrological model ParFlow by a scale‐consistent river parameterization
JO  - Hydrological processes
VL  - 33
IS  - 14
SN  - 1099-1085
CY  - New York, NY
PB  - Wiley
M1  - FZJ-2019-04141
SP  - 2006-2019
PY  - 2019
AB  - We propose an improvement of the overland‐flow parameterization in a distributed hydrological model, which uses a constant horizontal grid resolution and employs the kinematic wave approximation for both hillslope and river channel flow. The standard parameterization lacks any channel flow characteristics for rivers, which results in reduced river flow velocities for streams narrower than the horizontal grid resolution. Moreover, the surface areas, through which these wider model rivers may exchange water with the subsurface, are larger than the real river channels potentially leading to unrealistic vertical flows. We propose an approximation of the subscale channel flow by scaling Manning's roughness in the kinematic wave formulation via a relationship between river width and grid cell size, following a simplified version of the Barré de Saint‐Venant equations (Manning–Strickler equations). The too large exchange areas between model rivers and the subsurface are compensated by a grid resolution‐dependent scaling of the infiltration/exfiltration rate across river beds. We test both scaling approaches in the integrated hydrological model ParFlow. An empirical relation is used for estimating the true river width from the mean annual discharge. Our simulations show that the scaling of the roughness coefficient and the hydraulic conductivity effectively corrects overland flow velocities calculated on the coarse grid leading to a better representation of flood waves in the river channels.
LB  - PUB:(DE-HGF)16
UR  - <Go to ISI:>//WOS:000477751000006
DO  - DOI:10.1002/hyp.13448
UR  - https://juser.fz-juelich.de/record/864345
ER  -