CFM 1B - Floodplain Development Questions and Answers Graded A+

CFM 1B - Floodplain Development Questions and Answers Graded A+ How many households are there in floodplains in the US? 8-10 million Two problems that result from floodplain development 1) Development alters the floodplain and the dynamics of flooding. 2) Buildings and infrastructure are damaged by periodic flooding. Five main causes of flood damage 1) Hydrodynamic forces 2) Debris impact 3) Hydrostatic forces 4) Soaking 5) Sediment and contaminants Hydrodynamic force The force of moving water, including the impact of debris and high velocities. Three ways hydrodynamic forces can damage a building's walls. 1) Frontal impact (striking the surface) 2) Drag effect (water runs along the sides) 3) Eddies or negative pressure (suction as water passes downstream side) High-velocity flood Waters moving faster than 5 feet per second How much moving water needed for a car to float 2 feet Hydrostatic forces The pressure put on a structure by the weight of standing water. The deeper the water, the more it weighs and the greater the hydrostatic pressure. Lateral pressure The amount of pressure imposed sideways by standing water. Deeper water exerts more lateral pressure than shallower water. Amount of standing water needed to collapse the walls of a typical frame house. Three feet What does watershed development do to flooding? The increase in impervious surface results in increased runoff and higher flood levels. What is one of the problems with constructing seawalls to protect buildings from flooding or erosion? It can accelerate erosion on properties at the end of the wall. What are some of the safety and health hazards that accompany floods? (8) 1) Disruption of public utilities 2) Electrocution 3) Contamination of water supplies 4) Fire 5) Animal carcasses, garbage, and ponds that can become breeding grounds for germs and mosquitoes 6) Mold, mildew,, and bacteria that grow in damp, flooded areas 7) Contaminated air from dirty heating ducts 8) Stress and mental health problems. Prior to the 1960s, what was the primary way to reduce flood losses? Structural flood control projects What is the Unified National Program for Floodplain Management's definition of "floodplain management?" "A decision-making process that aims to achieve the wise use of the nation's floodplains." What are the two primary goals of floodplain management? 1) To reduce the loss of life, disruption, and damage caused by floods. 2) To preserve and restore the natural resources and functions of floodplains. What areas are conducive to flash flooding? (3) 1) Hilly areas with steep slopes and narrow valleys 2) Urban areas with large amounts of impervious surfaces and storm sewers 3) Areas downstream of dams or subject to ice jams Is erosion only a threat in coastal areas? No. Riverine erosion can move stream channels and undercut structures. What is ponding? Where stormwater runoff collects in depressions and cannot drain out. Are plants and animals the only beneficiaries of the "natural and beneficial functions" of floodplains? No. People benefit from floodplains through the food they provide, the recreational opportunities they afford, and the scientific knowledge gained in studying them. Floodplains also recharge groundwater supplies and their filtering actions help improve water quality. What does filling in a floodplain do? Filling reduces the floodplain's ability to store excess water, sending more water downstream and causing floods to rise to higher levels. Hydrodynamic forces are caused by _________ water and hydrostatic forces are caused by ________ water. Moving, standing List materials or household items that are particularly susceptible to flood damage by soaking. (8) 1) Wood 2) Gypsum wallboard 3) Furniture and upholstery 4) Carpeting 5) Mattresses 6) Books 7) Electrical appliances 8) Gasoline engines What are examples of non-structural flood protection measures? (7) 1) Regulations to prohibit development in high-hazard areas 2) Building codes requiring flood-resistant construction for new buildings in floodprone areas. 3) Acquisition and relocation of buildings in high hazard areas. 4) Modifying or retrofitting existing buildings 5) Installing flood warning systems. 6) Controlling stormwater runoff. 7) Providing self-help advice to property owners. What are the Unified National Program for Floodplain Management's four main floodplain management strategies? 1) Modify human susceptibility to flood damage. 2) Modify the impact of flooding. 3) Modify flooding itself. 4) Preserve and restore natural resources.