The ISBA Standard or Baseline (Original) 2-layer Hydrological Model Configuration verses the Updated 3-layer scheme


The mass (water) pathways and reservoirs/stores. Note that the snow scheme of Douville et al. 1995a is considered the baseline snow model herein. ISBA-2L refers to the original hydrological scheme, and ISBA-3L refers to the new scheme. Refer to the baseline or standard model schematic for the corresponding diagam of the surface energy budget and heat transfer/turbulent exchange with the atmosphere.



ISBA-2L

   Water sources due to the various components of the precipitation are in blue, evapotranspiration sources/sinks are in green, and canopy drip, snowmelt runoff, surface runoff, drainage and soil water fluxes are in red.


ISBA-3L
std ebudget schematic std hydrology schematic
Prognostic variables are in blue.
Pr Total Precipitation (kg m-2 s-1)
Pn Snowfall (liquid equiv.) (kg m-2 s-1)
Ps Precipitation reaching soil (kg m-2 s-1)
Pv Precipitation intercepted by vegetation (kg m-2 s-1)
Pg Infiltration (kg m-2 s-1)
Qr Surface runoff (kg m-2 s-1)
D1 Surface/deep soil soil water diffusion (kg m-2 s-1)
K2 Gravitational drainage (kg m-2 s-1)
En Sublimation (kg m-2 s-1)
Eg Bare-soil evaporation (kg m-2 s-1)
Er Evaporation from interception (kg m-2 s-1)
Etr Transpiration (kg m-2 s-1)
Wr Canopy water store (kg m-2)
Wn Snow pack SWE (Snow Water Equiv.) (kg m-2)
wg Surface soil water reservoir (m3 m-3)
w2 Bulk soil water reservoir (m3 m-3)
ds Surface reservoir soil depth (m)
d2 Total soil depth (m)
Symbols are as defined at left, except for:
D2 Root-zone/baseflow soil water diffusion (kg m-2 s-1)
K2 Root zone gravitational drainage (kg m-2 s-1)
K3 Gravitational drainage (kg m-2 s-1)
w2 Root-zone soil water reservoir (m3 m-3)
w3 Baseflow/sub-root-zone soil water reservoir (m3 m-3)
d2 Root zone soil depth (m)
d3 Total soil depth (m)