Drainage Stream bank stabilization
Stream banks are likely to erode if Vegetation has been removed, Bank slopes are steeper than 3:1
, Outside curves are not protected or Runoff increases in the drainage area.
Removal of vegetation should be avoided if at all possible. Bank slopes can be cut back and replanted if severe erosion is occurring. Outside channel curves might need protection with large rock, imbedded root wads, logs or other material if banks are collapsing. Note that work in and around a stream will likely require one or more permits. In addition, the law regulates the flooding impacts of building in the floodplain and stream (see Appendices for details). Increased runoff in the drainage area, caused by new roads, parking lots, roofs, etc. can be addressed by promoting infiltration at every available opportunity. Direct roof gutters, parking lot discharges, and other run off onto grassy swales and vegetated or landscaped areas, rather than into ditches or creeks.
Unstable or bare stream banks can be stabilized with willow or hardwood cuttings harvested from vegetated areas near the site. Live stakes are 1- to 3-foot long cuttings from live hardwood trees or shrubs. Stakes are harvested during the dormant season (November–February) and driven into the stream bank, right-side up. They will develop roots and grow if sufficient moisture is available and they are not heavily damaged during installation. Willow, maple, poplar, cottonwood, dogwood, sycamore, oak and other hardwoods can be used. Plant half of the stake or cutting below the ground surface. Push into the ground where soils are soft; make a pilot hole with wooden or metal stake if soil is very hard. Make sure the bottom end—nearest to the roots—is put into the ground! Stakes or cuttings can be harvested and rooted in cool damp sand mixed with moist compost prior to planting if desired. Cover roots with at least 1 to 2 inches of soil when planting. Keep soil moist during dry season, until plants are well established. Wattles are also effective in stabilizing stream banks. Wattles are bundles of live cuttings approximately 4 to 6 inches in diameter and 6 feet long. They are placed across the slope at 3- to 5-foot intervals, in long rows. Wattles are laid in shallow trenches, staked down, and covered with 2 to 3 inches of soil. Shoots and roots will sprout along the entire length of the wattle, creating a continuous erosion barrier and stablising the bank.
Related posts:
- Stabilising Drainage Ditches
If you have a drainage channel or ditch which is suffering from poor maintenance there are a number of steps you can take to stabilise it. Man-made drainage ditches with gently sloping bottoms can be stabilised with thick grass seeding and erosion control blankets. Natural drainage channels and creeks or streams cannot be cleared, re-routed, or otherwise altered. Moderately sloping ditches will likely require turf reinforcement mats and perhaps some rip rap if soils are silty. Steeply sloping ditches need heavier armoring with concrete, riprap, gabion baskets, retaining walls, or other approved products. Ditches with silty soils are the most erodible and clay is the least erodible. Steeper ditches and those with highly erodible soils need more protection. Drainage ditch bank slopes must not exceed 2:1. If tractor mowers or other equipment will cross channels in the future, bank slopes must be 3:1 or flatter. The outlet must be installed, seeded, stabilised, and protected before the ditch receives incoming flows. Seed ditches and install silt checks before excavating, filling, or…...