THE EFFECTS OF TILE DRAIN INPUT ON A GAINING STREAM: USING A THERMAL TRACER

Tile drains take excess water out of agricultural fields and channel it directly to the nearest surface water body decoupling the system from the natural flow paths. Although widely used, the impact of tile drains is not completely understood on the local and regional level. One way to measure the effects of these tiled waters is to look at the thermal energy of the stream compared that of the stream with the addition of tile water. Stream’s thermal signature experiences large fluctuations seasonally in the temperate climate along with small diurnal changes. Groundwater temperature does not show these small scale changes and the seasonal changes are often muted and lagged in comparison to meteoric water. This project looks to quantify any hydrologic change to the stream caused by the additional flow from a tile drain. Thermal signatures of the stream, streambed, tile and groundwater at the interface were measured using data loggers in 15 minute intervals. Interactions along the streambed was collected throughout an 80 meter stretch of the streambed and within the hyporheic zone. These relationships are thus quantified and correlated using an ANOVA and paired t-tests. The tile has shown a more constant temperature over data collection from January to July of 2015 with a lack of statistically significant diurnal effects. However, seasonal cycles are evident from the tile data. The results have shown the tile flow to be an additional component to correlate the hydrologic effects of the tile on the stream. The tile flow was consistent from January to May before a larger flux throughout the early summer. Data suggests the tile has a minimal thermal effect on the stream during baseflow, thus this tile is not a source of concern volumetrically on the stream.