Regional simulation of fall and spring soil moisture in Alberta

The recurrence of agricultural drought on the prairies has increased the demand for soil moisture information by farmers, regional planners and supporting sectors of agriculture. In response, estimation of regional soil moisture by soil survey is conducted despite its being resource intensive and having limited resolution in time and space. Models that estimate soil moisture on a regional scale would contribute to the evaluation of regional water deficits and overcome problems related to conducting field surveys. This study uses a modified version of the versatile soil moisture budget to estimate available soil moisture within the root zone on a regional scale. The spatial pattern of modelled soil moisture in the fall was similar to that mapped by soil survey. Of the 145 grid points compared, agreement between modelled and field survey was 60% or higher in 5 out of 8 yr. However, too few years of data were available for a reliable assessment of model performance in the spring. The simulated soil moisture was sensitive, and directly related to the value used for available water capacity (AWC). Accurate values of AWC are necessary for accurate simulation of regional soil moisture.