Laserfiche WebLink
<br />the Rancho Mirage and Palm Desert fans to the concrete lined <br />canals built on the aprons near Albuquerque. TYPlcal <br />channels have trapezoidal cross-sections and lnvert slopes <br />equal to the fan surface slope. Hence, velocities in the <br />channel during floods can be extremely high (20 feet per <br />second or more). Channelization plans include deepening and <br />straiQhtening of natural watercourses, lining of natural <br />channels with grass. riprap or concrete, and construction of <br />new canals. Channels are sometimes combined with an <br />upstream debris basin or detention dam. The upstream <br />facility reduces peak water and sediment discharge. <br />preventing excessive scour and/or sediment deposition and <br />allowing a smaller channel. <br /> <br />~ structures <br /> <br />Reinforced walls or armored, steep slopes can be used to <br />dissipate flow energy in either ~hannels or landscape areas. <br />These drop structures can be constructed across the slope of <br />the fan between buildings to prevent cutting of localized <br />gulleys and to stabilize ground slopes in residential areas. <br />Concrete drop structures placed in channels help prevent the <br />very high velocities and intense scour found normally in <br />steeply sloped channels. <br /> <br />Debris Fences <br /> <br />These structures are used only where debris flows are common <br />and are designed such that water and sediment flow through <br />the fence. while large rocks and debris are trapped. They <br />typically consist of vertical steel I-beams mounted in a <br />Massive concrete foundation and projecting 6-8 feet above <br />ground level. The vertical beams may be 1-2 feet apart, so <br />that only the larger (most destructive) boulders and debris <br />are stopped. <br /> <br />66 <br />