Floodplain Management Requirements Questions and Answers

Floodplain Management Requirements Questions and Answers Name five reasons people live near water transportation, water supply, water power, fertile soils, aesthetic and recreation hydrologic cycle Circulation of water throughout the environment Flood The hydrologic cycle getting out of balance Three categories of flood Riverine flooding Coastal flooding Shallow flooding Watershed Area that drains into a lake, steam, or other body of water Two other names for watershed basin and catchment area Channels Features on the ground that carry water through and out of a watershed Examples of channels Rivers, creeks, streams, ditches Riverine flooding Flooding that occurs along a channel Flash flood A sudden, violent flood that occurs within a few hours, or even minutes, of a storm. Most common type of flooding in the United States Overbank flooding Overbank flooding downstream channels receive more rain or snowmelt from their watershed than normal, or a channel is blocked by an ice jam or debris. For either reseason, excess water overloads the channels and flows out onto the floodplain. Velocity Speed of moving water How is the velocity of water measured feet per second Do floods last longer in small or large rivers Large What features of an urban area worsen flash floods impervious surfaces, gutter runoff, storm sewer runoff, dam failure What is the highest cause of flood related deaths in the United States Flash Floods Thalweg the deep part of a channel where most flow occurs Meander Curve in a channel Which part of meanders are most subject to erosion outside What causes the most coastal flooding Hurricanes and severe storms Storm serge Persistent high wind and changes in air pressure pushing water toward the shore Accrete Growth of the shoreline Tsunami A giant wave usually caused by an earthquake beneath the ocean floor. Shallow Flooding flooding that occurs in flat areas where a lack of channels means water cannot drain away easily Sheet flow Floodwater spreading out over a large area in a somewhat uniform depth Ponding Floodwater and runoff collects in depressions and cannot drain out What are the two types of closed basin lakes Lakes with no outlets and lakes with inadequate outlets Alluvial Fan A wide, sloping deposit of sediment formed where a stream leaves a mountain range Movable stream beds high-velocity flood runs through an area with sand or loose soil causing stream channel to be lowered, filled in, or relocated What causes a dam to break Foundation failure, poor design or construction, flooding that exceeds the dam's spillway capacity Floes Movement of ice chunks Mudflow Quickly moving downhill flow of soil and rock fragments containing a large amount of water How much of the nation's total land area is floodplain 7% How many households are in the nation's floodplain 8-10 million What is the biggest impact that human's have on riverine flooding constructing bridges and culverts with small openings When rain falls in a natural setting, what percent of it will infiltrate the ground 90% How many people die on average per year from floods 150 What are the 5 main causes of flood damage Hydrodynamic forces, debris impact, hydrostatic forces, soaking, and sediments & contaminants what creates a Hydrodynamic force Moving water What 3 ways does hydrodynamic forces damage a building's walls Frontal impact, drag effect (water runs along the sides of structure), and eddies (water passes the down stream side) What speed does water need to travel at to be considered high velocity 5 feet per second How much moving water does it take to float a car 2 feet What is hydrostatic pressure the weight of standing water What is the second most frequent cause of flood deaths Electrocution When did the federal government get involved in floodplain management 1800s Why did the federal government get involved in floodplain management They had an interest in maintaining the navigability of rivers to facilitate interstate commerce Until the 1960's, what projects were seen as the primary way to reduce flood loses Structural flood control What year was the National Flood Insurance Program created 1968 What are examples of non structural flood protection measures Regs to prohibit development, flood resistant construction building codes, modifying existing buildings, installing flood warning systems, controlling stormwater runoff, and providing self-help to property owners What did the Unified National Program set forth Conceptual framework for coordinating the floodplain management efforts of federal, state, and local agencies Floodplain management strategies- modify human susceptibility to flood damage- give an example of this strategy Regulating floodplain use by zoning codes, acquiring land in floodplain, restoring natural features What did the Flood Disaster Protection Act of 1973 do Prohibited most types of Federal assistance for acquisition or construction of buildings in the floodplain of non-participating communities and required buildings in flood hazard areas to have flood insurance to get federal financial assistance Since what year has the NFIP been self supporting 1986 Who is the NFIP a mutual agreement between Federal Government and local communities What do communities have to do in order to get flood insurance for properties Regulate development in the mapped floodplain