Modeling Agricultural Tile Drainage Water Outflow Under Cool Climate Conditions.

Climatically, Newfoundland is the most maritime of the Atlantic provinces, and this is evident in all seasons, but especially in spring and summer, which are quite cool by Canadian standards. Although, precipitation is well distributed throughout the year, it is heaviest in fall, with November being the wettest month. An abundance of precipitation and cool temperatures are responsible for the large amounts of moisture available for vegetation in the province.  Since annual precipitation (1000 to 1600 mm) greatly exceeds potential evapotranspiration, improved drainage of Newfoundland soils is obvious to remove excess soil water from intensively cultivated fields. In this paper, we focus on improving the performance and applicability of water outflow modeling approach by using DRAINMOD. We evaluate the proposed approach on data obtained from St. John’s Research and Development Centre Experimental site, located in St. John’s, NL. The site falls within the Atlantic uplands of Newfoundland, an area of rolling landscapes. Site slopes range from 2-20% with most slopes being 5-9%. DRAINMOD, which is used widely to simulate tile drainage flows under cool climate conditions. To assess the effectiveness of DRAINMOD, this study specifically examined its performance in a cold climate. The findings indicate that DRAINMOD predicts monthly subsurface tile drainage outflow well under specific geographical and climatic conditions.