Lab Project No. 4 – Hydrograph Analysisimage1.png1. (90pts) The following storm occurs over the watershed:Time (hr) 0.5 1.0 1.5 2.0 2.Accumulative rainfall depth (inch) 0.5 1.2 2.0 3.0 3.2The following unit hydrographs are given for subareas A and B.Time(hr)Subarea A, 2-hr unit hydrograph, (cfs/in)Subarea B, 0.5-hr unit hydrograph, (cfs/in)Time(hr)Subarea A, 2-hr unit hydrograph(cfs/in)SubareaB,0.5hrunithydrograph(cfs/in)0004.52203100.53205.01702501.0160705.51201601.53101906.080902.04403106.560502.55304007.04023.04704507.53003.53804208.02004.03003608.500(a.) Using the (–index values, determine the excess rainfall over each subarea for the storm for each half-hour period (10).(b.) Compute the halfhour unit hydrograph for subarea A from the 2-hr unit hydrograph by using the S-hydrograph method (20). On the same graph, show the S-hydrograph, and the half- hour and 2-hr unit hydrographs (5). A table in your discussion should summarize the peak flow rate, time to peak, and time base of both the half- hour and 2-hr unit hydrographs for subarea A (5).(c.) For the storm above, calculate the direct runoff hydrographs and the streamflow hydrographs for both subareas (30). On the same graph, show both hydrographs for both subareas (5). A table in your discussion should summarize the peak flow rate, time to peak, and time base for the direct runoff and streamflow hydrographs (5).(d) Calculate the drainage area (in both acres and mi2) for each of the subarea (10).2. (10pts) Format and quality of your report.