Abstract. The river routing scheme (RRS) in the Organising Carbon and Hydrology in Dynamic Ecosystems (ORCHIDEE)
land surface model is a valuable tool for closing the water cycle in a
coupled environment and for validating the model performance. This study
presents a revision of the RRS of the ORCHIDEE model that aims to benefit
from the high-resolution topography provided by the Hydrological data and
maps based on SHuttle Elevation Derivatives at multiple Scales (HydroSHEDS),
which is processed to a resolution of approximately 1 km. Adapting a new
algorithm to construct river networks, the new RRS in ORCHIDEE allows for the
preservation of as much of the hydrological information from HydroSHEDS as
the user requires. The evaluation focuses on 12 rivers of contrasting size
and climate which contribute freshwater to the Mediterranean Sea. First, the
numerical aspect of the new RRS is investigated, in order to identify the
practical configuration offering the best trade-off between computational
cost and simulation quality for ensuing validations. Second, the performance
of the new scheme is evaluated against observations at both monthly and daily
timescales. The new RRS satisfactorily captures the seasonal variability of
river discharge, although important biases stem from the water budget
simulated by the ORCHIDEE model. The results highlight that realistic
streamflow simulations require accurate precipitation forcing data and a
precise river catchment description over a wide range of scales, as permitted
by the new RRS. Detailed analyses at the daily timescale show the promising
performance of this high-resolution RRS with respect to replicating river
flow variation at various frequencies. Furthermore, this RRS may also
eventually be well adapted for further developments in the ORCHIDEE land
surface model to assess anthropogenic impacts on river processes (e.g.
damming for irrigation operation).
Comparison of observed and DEM-driven field-to-river routing of flow from eroding fields in an arable lowland catchment
