3- Estimates of the mean monthly precipitation P , evaporation E (or evapotranspiration), and net runoff Q for the Upper Mississippi River basin are ,shown in the table below. Compute

the change in land surface DS (in mm) for each month.а. b. Assume that the land surface storage S at the start of January is 0 mm (Note:This is not the absolute storage, but an assumed reference). Compute the storage S (in mm) at the end of each month. c. In what month is the storage S at its maximum during the year? In what month is the storage at its minimum? What is the change in storage DS (in mm) from the maximum to the minimum? d. Plot the precipitation P, the evaporation E, the net runoff Q, and the land surface storage S versus month (on a single graph). [Take a look at the results to get a feel for changes in water availability over the year.] e. Compute the monthly runoff coefficient (net runoff as a fraction of precipitation) (in %). Plot the runoff coefficient versus month. [Take a look at the results -do the variations make physical sense?].