Solve question 11.15

11.14 The peak-flow data on an annual basis from Cedar River near Austin, MN, are listed in the following table. Plot the flood-frequency curve on lognormal probability paper. Determine the (a) magnitude of a flood having a return period of 100 years (probability of 1%), and (b) probability of a flow of 100 cfs. Peak- Peak- Peak- Peak- flow flow flow flow Year cfs Year cfs Year ofs Year cfs 1965 7750 1978 979 1991 3880 2003 8690 1966 5440 1979 4940 1992 2110 2004 3410 1967 3580 1980 4260 1993 8270 2005 2190 1968 5260 1981 9400 1994 5740 2006 4440 1969 4000 1982 9530 1995 4140 2007 4070 1970 8800 1983 2330 1996 3910 2008 1400 1971 7070 1984 990 1997 1300 2009 3290 1972 7520 1985 9400 1998 12400 2010 7580 1973 6990 1986 3740 1999 4720 2011 4640 1974 5570 1987 3250 2000 3250 2012 3190 1975 2710 1988 2920 2001 4810 2013 10800 1976 2190 1989 3830 2002 3060 2014 2500 1977 2250 1990 1430 11.15 On the flood sequence of Problem 11.14, perform a frequency analysis by the theoretical method adopting the lognormal distribution./