Urban water balance in Vancouver: impacts of changes in land cover

The water balance of urban terrain in Vancouver, BCis estimated. Three preexisting models for components of the balance are combined and developed. These are a water balance model, an evaporation-interception model and an urban energy balance model (including revised radiation submodels). This combination permits calculation of the water and energy balances over time scales ranging from less than one hour to years.

Here the combined model is used to assess the impact of changes in urban land cover and forcing conditions (meteorology) while keeping the input data requirements relatively simple. Performance of the model is tested against field measurements of heat and water fluxes in Vancouver, BC conducted on three occasions over a twenty seven year study period (in 1982, 1988 and during the Environmental Prediction in Canadian Cities (EPiCC) project in 2007-09). Over that period there have been significant changes in land cover, due to pressures on land availability and changes in the socioeconomic status of residents. The study assesses whether such changes have significant effects on the energy and water balance partitioning.