Evaluation of the Impact of Controlled Tile Drainage on Surface Water Quality in the South Nation River Watershed

Abstract

In Ontario, many agriculture-dominated watersheds like The South Nation River watershed are experiencing ecosystem deterioration mainly resulting from agricultural activities. A promising best management practice, controlled tile drainage (CTD), maintains water and nutrients through controllable facilities and releases them in an intermittent manner, when available storage in the drains is exceeded. This thesis is to evaluate how much water quality improvement can be expected if CTD adopted at watershed scale on the basis of experimental data from the WEBs project. A watershed model AnnAGNPS was applied, calibrated and validated on the watershed. Simulation results indicate that CTD can significantly improve surface water quality by reducing nitrogen losses from agricultural areas. This research creatively uses the AnnAGNPS model to simulate CTD, and it also provides a reliable link the model to observations from experimental CTD fields. So far, there is no related research found from the literature.