Estimated seasonal and annual water surplus in ontario
1999
Parkin, G.W. | Wagner-Riddle, C. | Fallow, D.J. | Brown, D.M.
The variability in seasonal and annual surplus water in four regions of Ontario is discussed in this paper. Surplus water is that water resulting from precipitation that runs off the land surface or drains through the soil profile to the groundwater table. A one-dimensional, deterministic model that simulated water flow in soil, including plant uptake, evapotranspiration, and freeze/thaw conditions was used to estimate the water surplus. This model, referred to as the Simultaneous Heat and Water (SHAW) model, was applied to daily climate data for all seasons of the year from December 1, 1960 to November 30, 1990 at four climate recording sites, one representing each region. The seasons were: winter (December, January, February and March); spring (April and May); summer (June, July and August); and fall (September, October and November). A corn crop and typical local soil profile conditions, with the hydraulic properties for the local soil, were used as inputs for the model.There were significant differences in average annual and seasonal water surpluses among the four regions. The variability from year to year was significant. Most of the annual surplus water occurred in the winter and spring seasons, and in some years the surplus exceeded the precipitation in the spring season, the latter due to the winter snowfall lasting into the spring season before melting. Average annual deep drainage exceeded runoff at the three southern Ontario sites and runoff exceeded deep drainage at the northern Ontario site. Much more deep drainage than runoff occurred in the summer and fall seasons, perhaps due to the relatively flat slope used in the model runs. Soil type had only a small influence in determining the surplus amounts compared to climate/precipitation effects.
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