SR9083 - Identification of Critical Regions for Water Quality Monitoring with Respect to Risk of Seasonal and Annual Water Surplus

Researcher:

Dr. Claudia Wagner-Riddle, Land Resource Science, University of Guelph

Objectives:

1. To assemble the required historical weather data for two climate regions in Ontario.
   

2. To apply a suitable computer simulation model to the climate data to estimate seasonal and yearly water surplus components for the 2 climate regions.
   

3. To compute the variability of the water surplus components for each season of the year for each region.
   

4. To determine the magnitude of differences in the variability of water surplus among regions for each of the seasons.
   

5. To specify if these differences are significant for groundwater contamination or for runoff into water channels.

Expected Benefits:

If there are significant differences in the risk of occurrence of extreme surplus water events among climate regions in Ontario, this information would provide a "caution" for municipal water managers, Conservation Authorities and farmers.

Summary of Research Results:

The variability in seasonal and annual surplus water in seven regions of Ontario is estimated and analyzed. Surplus water is that water resulting from precipitation that runs off the land surface or drains through the soil profile eventually reaching the ground water table. A computer model that simulated water flow in soil, including plant uptake, evapo-transpiration, and freeze/thaw conditions was used to estimate the water surpluses. The model was applied to daily climate data from January 1, 1954 to December 31, 2001 for recording sites in seven climate regions: Harrow, Guelph, Mount Forest, Smithfield, Ottawa, Kapuskasing and Emo. A corn crop and the typical soil profile conditions for each region were used as inputs for the computer model.

There were significant differences in average annual and seasonal water surpluses among the seven 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 would be due to winter snowfall lasting into the spring season before melting. Deep drainage exceeded runoff at four of the seven sites. Of the three sites where runoff exceeded deep drainage for the typical soil profile, the difference was most pronounced at Kapuskasing, because of the disproportionate snowmelt in the spring season. Deep drainage was relatively small at Emo and Harrow.

The most critical regions for monitoring water surplus, in terms of estimated excessive deep drainage and the associated potential for groundwater contamination occur in the snow belt region east of Lake Huron and in areas where sandy soils predominate as shown for Smithfield.