FEMA 480 Exam Questions With Complete Solutions

FEMA 480 Exam Questions With Complete Solutions /. Floodplain - Answer-An area at risk of flooding from a storm /.Three types of flooding - Answer-Riverine, Coastal, and Shallow /.Watershed - Answer-A watershed is the area that water drains into a lake, channel, or other body of water /.What other terms can describe a watershed? - Answer-A basin, or a catchment area /.Channel - Answer-Places where a stream, or river, flows through /.Riverine Flooding - Answer-Riverine flooding is flooding around a channel when it overbanks /.How does elevation impact water velocity? - Answer-On a flat surface it will pool. On a steep, mountainous surface, it will run fast. /.Flash Flooding - Answer-A quick flood that develops in a short time period in areas with a large basin and a small channel /.Overbank Flooding - Answer-Its when a flood breaks its banks /.Velocity - Answer-The speed at which water flows determined by the geography. It is measured in feet per second, or cubic feet per second. /.How quickly do floods occur? - Answer-It depends on the slope. On a flat surface, it may take days as water flows slowly. On a steep elevation, it may happen in a matter of minutes. /.How long do floods last? - Answer-With flash floods, they may come and go quickly. Some floods can stay for days in flat areas, or areas with a small channel leading out of them. This is particularly the case in areas with shallow flooding. /.What is the most dangerous type of flooding? - Answer-Flash flooding. /.What is Riverine Erosion, and what does it look like? - Answer-Erosion caused by the movement of a stream, it often comes in the form of meanders, forming sandbanks where water is moving slowly, and eroding where it is moving quickly /.Thalweg - Answer-The lowest part of a channel /.Sandbank - Answer-Where sand is deposited by slow moving water. /.Meander - Answer-A bend in the channel /.Oxbow Lake - Answer-A meander that has been cut off from the stream due to a combination of erosion and deposition. They are temporary and will evaporate or infiltrate over time. /.Where is property best located on a channel or a meander? - Answer-At the slowest part of the stream, near the sandbank. /.Coastal Flooding - Answer-Flooding at the coast typically caused by hurricanes, Nor'easters or other large storms. /.What is another name for coastal flooding? - Answer-Storm Surge /.What factors into coastal erosion? - Answer-The speed of the wind and water, the size of the grains of sand, the density of the soil, and the water level. /.What does accretion mean? - Answer-The counter part to receding, it is the adding of soil to a beach. /.What structures impact coastal flooding? - Answer-Channels, levees, dykes, and the placement of sandbags. /.Tsunami - Answer-A large wave triggered by underwater volcanic activity or earthquakes. Occasionally caused by large amounts of earth falling into the water. /.Where are Tsunamis most common? - Answer-The pacific, though they have been known to impact the Caribbean. /.What do Tsunamis look like as they travel? - Answer-In the open ocean, they are small, only a few feet high. However, as they get closer to the shore, they rise as the distance between the ocean floor and the surface decreases. /.Lake Flooding - Answer-Flooding of a lake, the larger the lake, the more like an ocean it behaves. The great lakes are the best known phenomenon of this. /.Shallow Flooding - Answer-Flooding of an area with a small or no natural outflow. They spread evenly and flatly. They occur when rain outpaces natural infiltration speeds. /.Sheet flow - Answer-Sheet flow occurs when there is no, or inadequate, draining of an area and can no longer soak into the ground. Water spreads downhill in a large sheet. /.Ponding - Answer-Water cannot outflow at all, and can only be removed via pumps, evaporation, or soaking. It essentially makes a small pond. /.What are some methods of urban drainage? - Answer-Channels, ditches, levees, or sandbags. Sewer or storm water management systems also play a major role, but are often less efficient than natural channels. /.Why are areas with levees more susceptible to flooding? - Answer-Because they are often lower than sea level, or if the levee breaches, they often are the place water wants to drain into rather than out of. /.What are the five types of special flood hazards in the united states? - Answer-Closed basin lakes, uncertain flow paths, dam breaks, ice jam floods, and mudslides. /.Closed Basin Lake - Answer-A lake with no, or an elevated, channel outlet. They are dangerous because flooding can take a long time to get removed, and while they are often flat, they can impact homes and septic systems. Waves can damage properties. /.Uncertain Flow Paths - Answer-Every flood causes a channel change, this is most common out west and in alluvial fans. /.What is an alluvial fan? - Answer-A large fan of sediment with loose soil that can change channels rapidly. They are dangerous as people who were across the city from a channel can now find themselves getting flash floods in their area. /.What are the three hazards associated with alluvial fans? - Answer-Velocity and debris carried by flow, sediment deposited by water, and rapid shifting of channels during a flood /.Moveable stream bed - Answer-High velocity of water meets loose soil, where the stream bed can change rapidly. Often seen in the coast or out west in the mountains. /.What are the three processes of erosion that cause moveable stream beds? - Answer-Degradation, aggregation, and migration /.Dam Breaks - Answer-Dam breaks are floods caused when a dam breaks, sending large amounts of water down stream with little to no warning. Often occurs within hours of the first sign of danger. /.Three methods of dam failure? - Answer-Foundation failure due to seepage, settling, or an earthquake, poor design or materials, and flooding overtop the dams spillways. /.Ice Jam Flood - Answer-A flood of large amounts of ice caused by warming water or rain sending large chunks of ice down stream. /.What issues compound ice jam floods? - Answer-When ice gets jammed on an obstacle, causing flooding upstream on clear days as water backs up, or debris pushed by large chunks of ice downstream as the ice breaks from the obstruction. /.Mudflow - Answer-When the surface is inundated with water and flows like a liquid. /.What is more dangerous, a mudflow or a clear water flood? - Answer-A mudflow due to the debris pushed along with them? /.What is the NFIP definition of a mudflow? - Answer-A condition where there is a river, flow or inundation of liquid mud down a hillside usually as a result of a dual condition of loss of brush cover, and the subsequent accumulation of water on the ground preceded by a period of unusually heavy or sustained rain /.Does the NFIP cover mudflows under their insurance? - Answer-Well yes, but actually no. What most people to be considered mud slides do not meet the definition laid out by the NFIP. It must be due to complete inundation with water, and not just a destabilization due to water. /.Natural and beneficial floodplain functions - Answer-People like them. They filter out toxins and pollution naturally. They handle stormwater better than most man made constructions. They are way cheaper to maintain. /.Three types of natural resources in flood plains - Answer-Water, living, and societal resources /.Water resources of a floodplain - Answer-They filter stormwater and pollution. They managed floods, reduce velocity, and severity of floods. They curb sedimentation and improve water quality. They recharge ground water and aquifers. /.Biological resources of floodplains - Answer-Support high rate of plant growth, increase natural biodiversity, they are a harbor for endangered species. They are a prime breeding ground for fish, and ducks (waterfowl) love them. /.Societal resources of floodplains - Answer-People like them. They are a great recreation resource when properly managed, and they are nice to live near. They are great for growing natural and cultivated plants, and they filter water. They are generally considered a huge quality of life amenity to live near. /.What are two problems with floodplain development? - Answer-It alters the floodplain and water dynamics, and buildings and infrastructure along the floodplain are periodically damaged by floods. /.What are the ways we develop Riverine floodplains? - Answer-We build channels, bridges, and culverts to add transportation over or through them. We drain water into them through man-made channels, and we obstruct or divert them with dams or levees. /.What is regrading or filling? What does it cause? - Answer-Adding soil back to a floodplain to provide a new place to build. This sends more water down stream, causing increased flooding. /.What happens the more you develop a watershed? - Answer-You increase the flow of water due to a lack of ability to infiltrate into the ground. More development means worse flooding. /.What happens downstream when urbanization happens upstream? - Answer-The velocity and frequency of flooding increases as more water is sent downstream. /.Coastal flooding is made worse by the removal of what? - Answer-Dunes, sand banks, and other barriers to wind and water. /.What are the structures we use to prevent coastal flooding, and what happens because of them? - Answer-We build jetties, levees, storm breaks, and channel. This increases the damage where these structures end to protect the properties behind them. /.How much damage do floods do every year, and how many people live in flood plains? - Answer-8-10 million live in floodplains, and they kill 150 people every year, and do 6 billion dollars in damage. /.What are the five main causes of flood damage? - Answer-Hydrodynamic forces Debris impact Hydrostatic forces Soaking Sediment and contaminants /.What are hydrodynamic forces? - Answer-They are the result of moving water, and they damage structures in three ways. /.What are the three ways structures are damaged by hydrodynamic forces? - Answer-Frontal Strikes, drag effect on the sides of a building, or eddy's in the space behind a building where water flows around them /.What is a high velocity flood? - Answer-A flood moving over five feet per second. /.What is the relationship between depth and velocity in a flood? - Answer-Depth and velocity compound the damage of a flood. The higher depth, the lower the velocity of a flood to do damage, and vice versa. /.How much water is needed for cars to start being washed away? - Answer-Two feet.