wiki:DevelopmentActivities/ORCHIDEE-CNP/hydrology

Version 1 (modified by dgoll, 7 years ago) (diff)

--

Soil hydrology

The default configuration leads to severe water stress of vegetation in particular on clay soils. All the following has to be added to the PARAM/run.def

soil depth

The default depth of soils in ORCHIDEE is 2m. You should increase the soil depth to more than 2m in case the actual soils are deeper. I suggest to use maximum 4m depth, as deeper soil can make problem while are unlikely to improve further the simulated GPP and heat fluxes. PARAM/run.def:

# increase soil depth to 4m:
DEPTH_MAX_H=4.0

soil resistance to evaporation

I strongly advise to activate the soil resistance to evaporation when the upper layers dry out. Without this resistance vegetation on clay soils experience severe water stress during the dry season. The effect of soil resistance on sandy soils is rather small. PARAM/run.def:

DO_RSOIL=y

re-infiltration of runoff

I suggest to keep the default value. However, if you are not happy with the evaporation to precipitation ratio (Budyko ratio) you can tune it by increasing or decreasing the re-infiltration of runoff. The higher the re-infiltration ratio is the higher the Budyko ratio gets.

# Increase slope if you want a higher E/P ratio; decrease it if you want a lower E/P ratio; default=0.5
SLOPE=0.5