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<br />Slide C15. Watershed development, Laguna Beach, California <br /> <br />This shows a developed hillside in southern California. Watershed development can <br />increase the frequency and height of floods. Paved surfaces prevent the soil from <br />absorbing rainfall, thus increasing runoff. The runoff is collected in storm drains and <br />storm channels and sped to streams and rivers, contributing to flood flows. Sometimes, <br />existing storm drains are too small to handle the runoff from new development causing <br />backups and local flooding. <br /> <br />Slide C16. Structures in the floodway, Guerneville, California <br /> <br />Some buildings and facilities are particularly prone to flood damage because of their <br />locations, construction, or function. Buildings located in the floodway, such as these <br />houses on the Russian River in northern California, are flooded frequently. Structures <br />like these in the floodplain, particularly in the floodway, can also raise the height of <br />floodwaters by reducing the carrying capacity of the flood way. They can also redirect <br />floodwaters to areas that might otherwise be out of danger. <br /> <br />Slide C17. Pre-FIRM building <br /> <br />"Older" buildings like this one, called pre-FIRM buildings, are those constructed before <br />the community entered the National Flood Insurance Program usually sometime in the <br />1970's. As a condition for entering the program, the city had to adopt floodplain <br />regulations requiring new residential buildings in the 100-year floodplain to be elevated <br />to or above the level of the 100-year flood. New commercial buildings must be either <br />elevated or floodproofed. Buildings constructed before the city adopted such <br />regulations are usually more vulnerable to flood damage. <br /> <br />Slide CIS. Elevated houses in floodplain <br /> <br />This shows buildings in the floodplain. The two houses at the bottom of the slide are <br />constructed on fill and the gray house across the road from them is elevated. Access to <br />the elevated houses is lost, but people in the houses and their contents appear secure. <br />Elevated buildings like these are obviously less vulnerable to flooding than non- <br />elevated structures. <br /> <br />Slide C19. Damaged mobile home in Estes Park, Colorado <br /> <br />Mobile homes are particularly vulnerable to flood damage. The force of the water can <br />knock them off their supports or foundations and toss them about like toys. This <br />mobile home in Estes Park, Colorado was destroyed by a flash flood in 1982. <br /> <br />Script-Task C, page 4 <br />