In addition to being a tasty
drink, a mudslide is also a natural disaster common in steep areas during heavy
rain. A combination between a
flash flood and a rockslide, a mudslide occurs when heavy rain saturates a slope and sends a mass of mud sliding down onto areas below. When human-made structures are in the path of this massive flow of mud, they are usually destroyed or seriously damaged.
Roads below the mudslide are rendered impassible by tons of debris, and roads above the mudslide may be swept down the hill by evacuating soil. Mudslides can also blast into already-flooded
rivers and
creeks, backing up water and causing a cataclysmic dambreak a few minutes later.
Although mudslides can happen in most steep areas during heavy rain, they are most common in areas that have been disturbed and stripped of their native plant cover. The most common causes of this are fires or human activity. The latter is a particular problem, notably in the Malibu area of southern California. In a quest for the perfect ocean view, many people have built houses and roads on quite precipitous hillsides. In addition, to prevent massive fires, most people clear the vegetation away from their house. This does a good job of reducing fire damage to houses, but greatly increases mudslide danger.
Although mudslides can be very destructive, they can also be largely avoided. The easiest way to avoid being affected by a mudslide is to not build near a steep slope. If this is not possible, it is important to keep the hillside as undisturbed as possible. Avoid cutting into the hill for roads or house pads, this greatly destabilizes the whole hillside above. Keep native plants on the hill. (do not plant iceplant, many people think it stabilizes banks but it will end up in a pile of mud at the bottom of the hill.) To minimize fire risk, you can plant fire-resistant plants such as oak, holly-leaf cherry, and currant, and keep these plants thinned and free of dead wood. Good drainage is also vital. Many mudslides are caused by water draining down from a road or drainage ditch above. Make sure water does not drain from other disturbed areas onto the hillside. It is also possible to divert sheet flow from above, although this must be done without disturbing the hill's natural grade. And give water somewhere to go.. plan for a downpour, and when it happens, sit inside and enjoy the natural drainage of water off your property... don't end up filling up muddy sandbags in the rain.