Hydrologic assessment of blind inlet performance in a drained closed depression

Rainfall and discharge (10-minute interval) from (b) ADE and (c) ADW sites between 2006 and 2017. Shaded areas indicate periods of time when the tile riser was operating in the field (nonshaded areas show when the blind inlet was operating).

Monthly frequency of discharge (i.e., number of events with observed flow/total number of events) for ADE and ADW sites. Frequency of discharge did not significantly vary between periods when the fields were managed with the tile riser and periods when the fields were managed with the blind inlet.

Blind inlet infiltration rate. Infiltration rate at ADE and ADW sites was measured in 2012 (7 years after blind inlet installation) and 2018 (12.8 years after blind inlet installation). In 2012, infiltration rates were also measured from four recently installed blind inlets (1.5 years after installation; constructed using same design and materials as ADE and ADW). Numbers in parentheses show maximum flow rate through the blind inlet given a surface area of 18 m².

Relationships between ADE and ADW sites for event hydrograph characteristics when both fields were managed with blind inlets (black), when ADE was managed with a tile riser and ADW was managed with a blind inlet (red), and when ADW was managed with a tile riser and ADE was managed with a blind inlet (blue). Left panels show scatterplots of data, while right panels show linear regression lines. Regression lines denoted with an asterisk are significant at p < 0.05; ANCOVA results are presented in table 1.