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Flood Magnitude VLE


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Flood Magnitude

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Flood Magnitude VLE

  1. 1. Flood Prediction and Flood Return periods Year 12 geography GCE
  2. 2. Flood Prediction? Hydrologists try to forecast the likelihood of future flood events using past records. The further back the records of the floods go, the more accurate the prediction. Records of river discharge are ranked over the longest period available, from the highest peak discharge to the lowest peak discharge. The following formula is then used to calculate the recurrence intervals
  3. 3. When the recurrence interval is plotted against discharge as a scatter graph on semi –logarithmic graph, it is possible to use the line of best fit to predict when the next flood of a particular magnitude might occur. This is called the flood return period.
  4. 4. Look at the graph below. What would the flood return period be for a discharge 10,000 and 5,000 cumecs?
  5. 5. Using the formula, calculate flood return period for the discharge recorded in 1997 and 1955 for the East Fork of the Carson River. The recording period was 200 years.