Soil and Water Conservation Works - Afforestation, Reforestation and Forest Restoration in Arid and Semi-arid Tropics - page 91

Trench Section
45 x 45 cm

Bund Used For Sowing

Ground Profile

10 to 20 m

Schematic Layout of Contour Trenches

5 cm from edge

Bund

45 cm

45 cm

a

Section of a Contour Trench

Direction of Ground Slope/Runoff

20 to 50 m
Schematic Layout of of V-ditches

1.20 m

0.30 m

b Section of a V-ditch

Characteristics of Standard Sections of Contour Trench and V-ditch
Recommended
Spacing (m)

Trench
No.

Section Sectional When Recommended

(m)
0.30 x 0.30
0.35 x 0.35
0.45 x 0.45

Area m 2

CT-1
CT-2
CT-3

0.09
0.12
0.20
0.18
0.09

5-10
7-15
10-20
25-50
10-25

Where soil depth is limited.
Where soil depth is limited.
Standard section.
Standard section.
Where soil depth is limited.

VD-1
VD-2

0.30 x 1.20
0.20 x 0.90

Fig. 5.2 Details of contour trench and V-ditch