Name: Joshua FernandezLearning Unit 7: Flood Review QuestionsThis assignment is designed to assess your understanding of Unit 6 and includes some of the Questions for Review at the end of Chapters 10, 15 and 14 from your text plus a few additionalquestions. Each question can be answered in one to two sentences. Please limit yourself to a maximum of three sentences. Access the assignment, complete it with ANSWERS IN A DIFFERENT COLOR FONT as a separate file, and send it back for evaluation and grading through the assignment tab by or before the due date. 1. Of all of the common natural hazards, which causes more than 80 percent of all deaths?- Flooding of streams, due to precipitation2. What aspects of weather cause a flood? (Be specific: not merely “more water.”)- Area over which the rain falls, duration of the rain, intensity3. How is a drainage basin defined?- A cup of land bounded by areas oh high relief, precipitation that falls within the cup of land flows to the stream as runoff or infiltration and base flow4. Why does stream level rise within a few hours of a heavy rain, even though you see no water running off the slopes?- rises, causing more rapid flow from groundwater into stream downslope5. How would you calculate the discharge of a stream?- Q = A*v = cross sectional area of the stream channel (width x depth) x velocity measured in m3 or ft3 per second6. What is the definition of a flood? (Be specific: not merely more water)- Large discharge compared to normal for that channel7. How do the characteristics of upstream and downstream floods differ?- Upstream: flash floods, short intense rainfall, rapid runoff, quick rising water, locally, short lag, unpredictable, increased discharge velocity- Downstream: large amounts of rainfall over extended time, shallow, wide, long lag, predictable, disposition of sediment, 8. Why are upstream floods referred to as flash floods? What effect can flooding (an increase in discharge) have on stream flow in an upstream channel?- Caused by intense rainfall, steep runoff means rapid flowing in narrow channels, flood waters rise quickly, increase discharge=increase velocity9. What changes imposed on a stream would likely lead to higher level floods with the same rainfall pattern?- Increase urbanization, overgrazing10.With urbanization of the drainage area, what changes can be expected in the height or extent of the 100-year floodplain?- Floods would tend to peak earlier after a rainstorm, and have higher peak discharge 11.What information is represented by a hydrograph?- The relationship between precipitation and the effect it has on stream discharge 12.How would a hydrograph for a stream change if major urban growth were to occur?- Would be higher and narrower13.People should not build homes on floodplains because of the danger of flooding. What are better uses for floodplains?- It could be used for agriculture, parks, play fields, and golf fields14.If floodplains are such poor places to live, why are so many towns located on floodplains?- For transport, fertile soil, water15.What do we mean when we refer to a flood as the “10 year flood”.- Given level/magnitude of flooding that is likely to reoccur every 10 years16.What is the simple formula for calculating the recurrence interval (T) for a certain size floodon a stream in 1999 if there are sixty-nine years of record? Give a numerical example basedon the largest flood.- T= (n+1)/m17.If the 70-year floodplain was flooded in 1999, and there is a slightly larger flood 4 years later in 2003, what if any, change is there in the recurrence interval for the 1999 flood? Be numerically specific.- 37 year flood18.If a 100-year floodplain was flooded in 2003, in how many years should we expect the next 100-year flood?- could be anytime19.Why is the specified 100-year floodplain size or 100-year flood height not a very reliable indicator for future large floods?- Because it is based on sample floods that are much too short20.What are the limitations for building on a designated floodplain?- The limitations would be that the building cannot pass the 100 year flood level by one foot21.What are natural levees and where do they form?- Ridges of sediment deposited along the sides of stream channel; they form during floodsas water spills out of its channel22.Aside from protecting the adjacent stream bank, what effects do levees have on a stream?- Floodwater is confined between levees, causing the flood to flow deeper and faster, flooding of upstream/downstream levees increase23.What processes can lead to the failure of a river levee?- Erosion of levee, slumping of banks, water overtopping levee24.What constitutes channelization and what is it intended to do?- Is the deepening, straightening, widening, cleaning of streams and it increases the amount of discharge the stream can accommodate25.What is avulsion?- When the stream leaves its original/regular channel and flows into/creates a new
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