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<br /> <br />14 <br /> <br />MudFlowj <br />Debris Flow <br /> <br />A MUD FLOw i 5 a mass of water and f i ne-gra i ned earth <br />materials that flows down a stream, ravine, canyon, arroyo or <br />gu I ch. I f more than ha I f of the so lids in the mass are <br />larger than sand grains--rocks, stones, bouJders-- the event <br />15 ca I I ed a JEBR I S FLOw. <br /> <br />Characteristics <br /> <br />Debris and mud flows are a combination of fast moving water <br />and a great volume of sediment and debris that surges down <br />slope with tremendous force. The consistency is like th3t of <br />pancake batter. They are sim! lar to flash floods and can <br />occur suddenly without time for adequate warning. When the <br />drainage channel eventually becomes less steep, the liquid <br />mass spreads out and slows down to form a part of a debris <br />fan or a mud flow deposit. .In the steep channel Itself, <br />erosion is the dominant process as the flow picks up more <br />sol id material. A drainage may have several mud flows a <br />year, or none for several years or decades. They are common <br />events in the steep terrain of Colorado and vary widely in <br />size and destructiveness. Cloudbursts provide the usual <br />source of water for a mudflow in Colorado. <br /> <br />Consequences <br /> <br />i""ud/debris flows ruin substantial improvements with the force <br />of the flow itself and the burying or erosion of them by mud <br />and debris. The heavy mass pushes in walls, re'lloves <br />bu i 1 dings from found at ions, fill sin basements and <br />excavations and sweeps away c3rs, trucks, heavy equipment and <br />other substantial objects. Boulders and trees swept along <br />by the muddy mass demol ish bu i I dings, flatten fences and <br />uti 1 ity poles. In mountain areas, portions of valleys have <br />been eroded to a depth of several feet by the flow process. <br /> <br />Aggravating Circumstances <br /> <br />The I ikel ihood of mud flows and mud flow damage Is increased <br />by actions which increase the amount of watGr or soils <br />