A ditch research facility incorporating a paired design was constructed at the SWROC in 2002.
Combined surface and subsurface runoff make-up flows through the facility. A 656 foot reach of
existing drainage channel was converted into a pair of experimental ditch channels. The two
ditch channels enable researchers to evaluate various performance characteristics of the
channels. While smaller than typical drainage channels, the experimental ditch channels were
designed with geometries similar to that of drainage channels in the region.
Under low-flow conditions, ditches exhibit similar chemical and microbiological functions as
wetlands and can be used to promote ecosystem services such as nutrient removal. In addition
to nutrient reduction, managed ditches have the potential to temporarily detain runoff and/or tile
flow, consequently reducing peak flows and potentially mitigating flooding.
Minimally invasive management to enhance water storage and nutrient removal capabilities of
suitable drainage ditches includes the installation of a stationary, low-grade weir in a ditch
channel. This management option includes a diverse set of considerations including channel
width, depth, slope, tile outlet depth, and drainage area. Pre-storm and post-storm drawdown
time are important for management and may vary by geography or system. Drawdown time
would represent the time necessary for water levels behind a low-grade weir to be drawn down
from 100% storage capacity to 25-50% storage capacity of the ditch. Managed ditches would
be assumed to be half full during periods without precipitation or runoff. During an event,
excess water discharges over a low-grade weir would be necessary to prevent water from
backing up into a field drainage system as well as preventing ditch vegetation from becoming
degraded resulting in the managed ditch losing water and nutrient cycling functionality.