OutdoorNebraska

Floating The Good Life • Nebraska Game and Parks Commission 35 T H E L A U N C H The launch area of the access is the transition from dry land to water. It is where the continuous influences from water flows and wave action occur and where accidents by users transferring from firm ground to watercraft most often occurs. Launch location design must study the behaviors of the water body, the stability of the embankment and channel, and how it may shift over time. While lakes are not subjected to the same behaviors as flowing river waters, influences such as wave erosion need to be considered. Armoring the Launch Most of Nebraska's rivers consist of sandy or soil riverbeds, which can produce scour holes – the greatest concern for sustaining a stable launch. Riverbed scouring occurs when surface water and channel flow converge with enough energy to remove sands and soils, leaving an eroded hole. Riverbeds susceptible to scours along launch locations can quickly compromise the integrity of the constructed amenity, leading to failure. Design to withstand potential scouring should be conducted by a professional consulting engineer with experience in addressing river flows. An engineer will determine the level of protection required, from simple placement of stone rip-rap to more involved solutions of sheet piling (see Shoreline Landings section that follows) headwalls. While there may be a significant cost to build measures to withstand scour and other river influences, it is a necessary expense. The measures ensure a functioning launch – the amenity that is the primary purpose for constructing the water access in the first place. See Figure 9 for an illustration on stabilizing the riverbank from erosion. Figure 9: Riverbank Stabilization Preserving and protecting the embankment is equally important to the design of the day use area. As rivers flow downstream, their forces are dynamic, continuously influencing and shaping the riverbanks. Incorporating stabilization techniques into the riverbank design will protect it from erosive natural forces and will extend the life and function of designed river access areas. The example shown is a CRIB WALL, which protects the area from the toe, or bottom, of the embankment to the bottom of the river. The crib wall is designed by an engineer and uses both natural materials and manufactured products to create a stabilization structure. All proposed river stabilization strategies must be approved through the permitting process with the U.S. Army Corps of Engineers governing development along all waterways. BURIED TREES AND ROCK are stacked to hold river embankment and provide additional benefits for fish feeding and habitat. EXISTING RIVERBANK prior to stabilization is steeper than enhanced riverbank. GEOTEXTILE FABRICS hold soil and form stable layers within the stacked embankment. ROOT SYSTEMS of tree, shrub and grassland species stabilize slopes from erosion. RIVERBANK STABILIZATION

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