1). the Drainage Area Is Shown As a Thick Closed Spline (Green Color) in the Drawing

Question 1: Question 2:

1). The drainage area is shown as a thick closed spline (green color) in the drawing.

2). The area of the drainage is about 164,000 feet2, which is 3.76 acres. The length of the drainage path from the remotest point in the drainage area to the outlet point is about 617 feet.

3). For the path in the forest area, the slope of watercourse is (454.3-451.7)/192 = 0.013. According to the table of Average Velocities for Overland Flow, we can get a velocity of 0.26 ft/sec. For the path in the open lawn, the slope of the watercourse is (451.7-448.6)/425 = 0.007. According to the table of Average Velocities for Overland Flow, we can get the velocity of 0.7 ft/sec. So the time of concentration is: 192/0.26+425/0.7 = 1345 second = 0.37 hour.

4). According table for Rainfall Intensity Curves, with a return period of 5 years (in NJ) and duration of 0.37 hour, the rainfall intensity is about 3.3 inch/hour.

5). Estimate the runoff coefficient for the site. We use weighted average method because we have two type of surfaces. According to the table of Values of Runoff Coefficients, we choose 0.2 for forested areas and 0.25 for lawn. So the weighted average should be: (0.2*192+0.25*425)/(192+425) = 0.23

6). Estimate the peak runoff. The peak runoff is: Q = CiA= 0.23*3.3*3.76 = 2.85 cfs.

Question 3:

Reducing the amount of impervious area on site  reduce size of paved areas (for example, using narrower lane widths)  use permeable materials where-ever possible for walkways, driveways and parking lots (examples: UCONN Stadium, West Farms Mall)  maintain as much of the natural landscape and drainage as is possible (for example, by clustering development on one part of the site and leave the rest of the site in its natural state)

Use the landscape and filter, infiltrate and attenuate runoff  use gutters to direct runoff away from impervious areas to permeable areas where it can seep into the ground  use green strips to collect water from impermeable areas (minimize directing water into storm drainage system)  use sediment traps to collect water and slow runoff from site  use 'green roofs'