Effects of Low-grade weir on hydraulic patterns of agricultural run-off in the Mississippi Delta

Author(s): Brison, A.; Poganski, B.; Kröger, R.

Agricultural best management practices, in the form of low-grade weirs, have demonstrated the ability to mitigate nutrient and sediment loads to downstream aquatic systems. In a recent study, investigations of impacts of artificial low-grade weirs implemented in drainage ditches reported increased hydraulic residence times, an essential component to enhance nutrient reduction. However, research on the success of weirs is currently limited to controlled experiments rather than naturally occurring storm event conditions. This research investigated the effect of low-grade weirs on hydraulic residence time in several agricultural drainage ditches in the Mississippi Delta. Effects of low-grade weirs was assessed by comparing means of storm events and precipitation totals of varying magnitude within drainage ditches between pre- and post- weir implementation. Preliminary results suggest significantly shorter time to peak values between storm events pre- and post-weir implementation (K=11.522; p<0.05; Kruskal-Wallis) and longer time to base (K=18.566; p<0.05). No significant difference was found between pre-and post- weir time to maximum peak height (K=9.334; p>0.05; Kruskal-Wallis). Further research should account for variable physical dimensions, drainage area of each drainage ditch, and the number and spatial arrangement of weirs implemented to understand how weirs impact hydraulic patterns of drainage.

Go back


Past Conference Archive