An Empirical Monthly Soil Moisture Model for Central British Columbia

A simple soil water balance computer model was developed for central British Columbia. The model uses monthly weather summaries as input, but was calibrated using daily soil moisture model output from four sites. The critical component in the monthly model was the empirical equation for the ratio of actual to potential evapotranspiration during each month. Only the growing season, April to September, was considered. The monthly model was suitable for generating long-term seasonal crop water use estimates for the central British Columbia sub-region from climate normals. It also showed potential for analyzing year-to-year crop water use in that sub-region. The technique may prove appropriate in other semi-arid and arid regions of the world.