Physical Geognaphy Laboratory Manua 4.50 4.00 3.50 3.00 2.50 2.00 1.50 1.00 1000
ID: 295251 • Letter: P
Question
Physical Geognaphy Laboratory Manua 4.50 4.00 3.50 3.00 2.50 2.00 1.50 1.00 1000 10 Peak Discharge (cms) Figure 43-1: Rating curve for Cache Creek, Califomia, 1980-2015. (U.S. Geological Survey streamflow data) The next step is to calculate the recurrence interval or return period of floods along Cache Creek. The recurrence interval is an estimate of the number of years between times a peak stream discharge is reached or exceeded. For example, a "5-year" flood refers to the highest gage height likely to be reached once every 5 years, and a 100-year" flood is the highest gage height likely to be reached once every 100 years. However, because these estimates are based term averages, it is possible to have more than one 10-year flood in a decade, and for several ades to pass without such a flood. Further, because on long- dec- accurate long-term streamflow data are lacking estimates of 100-year floods and 500-year floods may be somewhat misleading streamflow data to calculate the recurrence interval (RI) of a flood, we first rank the peak flood discharge of the stream for each year. For example, in the data set shown in Figure 43-2, To use second with flow with 370 cubic meters per second, while 1986 was 302 cms. The rank of each year's peak discharge has been determined for you. We then use the following formula to calculate the recurrence interval: n+ 1 In the formula "n" is the number of years in the data record (36 years in this case), and "m" is the rank of a given flood on the list of annual floods. For example, the recurrence interval for the 10h ranked flood (which took place in the year 2004) is (36 +1) +10 3.7 years. This means that 296 Copyright O 2017 Peanon Education, Inc.Explanation / Answer
3
a)- 40cm - 2m ( from graph 43.1)
b)- 250cm- 3.70m( from graph 43.1)
4
a)- 2m - 40cm ( from graph 43.1)
b)- 3.5m- 210cm( from graph 43.1)
For solving question 7 there is need of graph 43.2 which is not clearly visible