Environmental Engineering FOURTH EDITION

Nonpoint Source Water Pollution

Slope length, meters

239

20.0

10.0

8.0

6.0

4.0

3 3.0

L-

Q 2.0

g 1.0

Q 0.8

d

n

c .-^0

!-

0.6

0.4

0.3

0.2

0.1

10 20 40 60 100 200 400 600 1000 2000

Slope length, feet

Note: The dashed lines are estimates for slope dirnenslons beyond the range of lengths

and steepness for which data are available.

Figure 11-3. Topographic factor (LS) for areas east of the Mississippi River.

Then from Eq. (1 1. l), the annual soil for the cropland would be

Amua = 200 x 0.37 x 1.08 x 0.49 x 0.25 x 0.60

A,,,a = 5.87 tons/acre-year,

and the average daily soil loss would be

5.86 tons/acre-year

365dayslyear

A&lY = 0.016 tons/acre4ay.

Adaily =

Calculating for watershed loading,

AwaW~edddy average = 180 XES X 0.016 tOnS/aCreday

Awatershed daily average = 2-9 tons/day.