The Variable Infiltration Capacity (VIC) model (Liang et al., 1994) is a grid-based macro-scale hydrological model that hat solves both the surface energy balance and water balance equations. The model represents sub-grid variability in vegetation and elevation, partitioning each grid cell into multiple land cover (vegetation) and elevation classes. The soil column is commonly divided into three soil layers (Figure 1). Evapotranspiration is calculated based on Penman-Monteith equation (Monteith, 1965; Penman, 1948). Surface runoff in the upper soil layer is calculated based on the variable infiltration curve (Zhao et al., 1980), and release of baseflow from the lowest soil layer is simulated according to the non-linear Arno recession curve (Todini, 1996). Surface runoff and baseflow are routed along the stream network to the basin outlet with an offline routing model that uses the unit hydrograph principle within the grid cells and linearized St. Venant’s equations to simulate river flow through the stream channel (Lohmann et al., 1998).
VIC is flexible in use of meteorological forcing variables, spatial resolution and temporal time steps and which the model can be applied. In the Water Systems and Global Change (WSG) group VIC has been widely used for change impact and scenario studies at global (e.g. Haddeland et al., 2014; van Vliet et al., 2013; van Vliet et al., 2016), European (e.g. Greuell et al., 2015) or large-river basin levels, as well as for seasonal forecasting work (e.g. Greuell et al., 2016). The WSG-group also previously contributed with VIC to global hydrological model intercomparison studies (Haddeland, 2011; Prudhomme et al., 2014) of WaterMIP and ISIMIP.
VIC model development is led by the Computational Hydrology group in the Department of Civil and Environmental Engineering at the University of Washington. In collaboration with this group at University of Washington, the WSG-group of Wageningen University contributes to the development of VIC5.1.
At present, the hydrological output data of VIC is directly used into the RBM stream temperature model, salinity and oxygen models and GloWPa water quality models. Current efforts at the Water Systems and Global Change group focus on using this data for other large-scale water quality models as well.