Figure 1. Willow revetment construction. |
Much of the stabilization and revegetation was in the form of willow revetments (figure 1). The structure of the wall stabilizes the bank until the roots of the growing willows incorporate into the soils. Willow revetments are inexpensive to build and the raw material is readily available. Individually, willow cuttings will take root and provide a quick and cheap method of revegetation (figure 2). We also discovered that ninebark and dogwood will grow from cuttings. Native blackberries and rushes were transplanted. We used a few container plants. To get a sense of what plants are natural and will do well, just look around. But even hearty native species require watering and care their first couple of years. Browsing by deer or livestock can quickly set back efforts. |
Fish require cool, good quality water, year-round pools in which to mature, clean gravel beds for spawning, cover from predators, and a food supply. By stabilizing the stream bank through revegetation and by more carefully monitoring our grazing practices we reduced the amount of sediment entering the creek; created a more favorable environment for insects (food); developed shade canopy; provided woody debris and roots for cover; and helped protect our land from the adverse effects of flooding. What we needed, the fish needed. Win-win squared. |
Figure 2. Willow sprig planting. Sprigs 2 1/2 to 3 ft. in length, 3/4 in. diameter, trim all branches. |
The energy of flood flows dissipates over the flood plain. The sediment deposited fertilizes pastures. Vegetation stabilizes the stream bank and maintains a high water table. Floods are largely contained by the channel which must erode to accommodate the force. The water table lowers. Figure 3. The effect of downcutting and widening of a stream channel on flood flows, the water table, and vegetation. |
A stable, vegetated riparian corridor maintains a higher water table and thus supports more vegetation than an eroding creek that downcuts and widens. A deeper and wider channel would temporarily provide more capacity for storm flows but by its very nature it also lowers the water table, supporting less vegetation, and leaving the land more susceptible to erosion (fig, 3).
Vegetation along a creek does contribute a little bit to flooding by restricting the flow of water. But, if we agree that creeks will always flood, the stabilization of creek banks provided by plants easily offsets any disadvantage. Vegetation along the creek also protects against erosion where minor drainages enter. Sufficient vegetation limits the erosive force of receding flood waters pouring off the flood plain and back into the channel. |
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