Lateral Flow Connecting Canadian Agricultural Lands to Surface Water Resources.

Lateral flow (LF) is a key pathways connecting sub-surface contaminant transport from lands to surface water bodies. The objective of this study was to develop a methodology for predicting the likelihood of LF occurrence in agricultural soils across Canada at a scale of 1:1 000 000. LF algorithm considers the presence of trees, and the influence of slope, soil depth, restricting layers, and volume of infiltrating water into the soil profile.
LF is more likely to occur in British Columbia and in the Eastern provinces such as Quebec, New Brunswick, Nova Scotia and some locations in Ontario. Locations of high potential for LF connect to large surface water bodies such as the St-Lawrence River, the Golf of St-Lawrence, the Bay of Fundy, and, but to a lower risk, the Great Lakes. LF in British Columbia is associated to shallow soils over compacted till in a sloppy areas with important presence of trees. The southern part of the St. Lawrence River watershed shows the highest risk of LF in Canada with its large rivers flowing toward it. LF in this region is due to important volume of water infiltration, compacted till and shallow soils.
The LF algorithm and LF distribution maps can be used as simple tools for supporting the identification of land surfaces where management should consider subsurface contaminant transport processes and to warn potential water pollution from inland agricultural contaminants.