Row

Erosion factor

Score

Description

1

Surface geology (0 to 10)

4.4

25% of the basin with very high erosion

10% of the basin with high erosion

23% of the basin with low erosion

42% of the basin with very low erosion

(0.25 × 10 + 0.10 × 8 + 0.23 + 0.42 × 1) = 4.4

2

Soil (0 to 10)

5

Moderate texture with boulders

3

Weather (0 to 10)

8.4

X = 0.2P2

The amount of rainfall within 6hrs with a two-year-return-cycle P2 = 42 (mm)

X = 0.2 × 42 = 8.4

4

Run off (0 to 10)

3.2

X = 0.006R + 10Qp

The height of the annual run off R = 247 (mm)

The special discharge of flood with a two-year-return-cycle Qp = 0.167 (m3/sec/km2)

X = 0.006 × 247 + 10 × 0.167 = 3.2

5

Unpaved areas (0 to 20)

13.5

X = 0.33S

S = 41 the moderate slope of the basin(mm)

X = 0.33 × 41 + 13.5

6

Plant coverage (−10 to +10)

7

X = 0.2pb

pb = 35 the percentage of stiff lands without coverage

X = 0.2 × 35 = 7

7

Lands usage (−10 to +10)

5

X = 20 − 0.2b

B = 75 the percentage of the plant coverage

X = 20 − 0.2 × 75 = 5

8

High land erosion (0 to 25)

10

The presence of different types of erosion about 25% of the lands-moderate erosion

9

River erosion and sediment transportation (0 to 25)

8

Flow with moderate continuity and depth with moderate river side or bed erosion