2-Stage Ditch System
Adams Township
A demonstration Two-Stage Ditch System is being constructed in Adams Township in
Mower County.
A Two-Stage Ditch System utilizes the stream flow process to create a stable ditch, which requires less maintenance. It also creates fewer disturbances to the biology of the stream and may even reduce nutrient pollution to the ditch.
Natural stable stream concepts normally consist of a main channel with bends and meanders, a certain width and depth, a slope so that the water flows and a floodplain connection or outlet. Factors influencing the stream’s shape and size include, geology, topography, velocity of the flow, sediment transport and the particle size of the bed material, such as sand, gravel or boulders. These variables will produce a stream channel that has a dynamic equilibrium. That means that over time, the channel features are maintained and the system neither builds up nor degrades.
However, rapid land use changes, due to human activities, often cause instability to the stream system. Straightening and channelizing these streams can also be detrimental, because they change the dimension, pattern and profile of the stream.
As can be seen from the illustration of a Two-Stage Ditch System, there is a small main channel with vegetated “benches”. These benches are heavily vegetated with a dense grass which helps to stabilize the sides of the ditch. The channel of the ditch will often conform to a meandering path, which will reduce the velocity of the water. This type of design will also give the ditch more capacity, reducing flooding issues in most circumstances.
|
|
Before Construction Construction Begins
With the construction of a Two-Stage System in Mower County, we anticipate that we will see a reduction in maintenance of the open ditch system and a reduction in nitrate discharges. The low maintenance will save the landowners a lot of money over the years and if we can reduce the nitrate discharge even 10 – 20%, this will be very important to agriculture in the Midwest.
