Log check dams
Log check dams made of logs and posts are placed across the gully. They can also be built of planks, heavy boards, slabs, poles or old railroad ties. The main objectives of log check dams are to hold fine and coarse material carried by flowing water in the gully, and to stabilize gully heads.
They are used to stabilize incipient, small and branch gullies generally not longer than 100 m. and with catchment areas of less than two hectares.
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The maximum height of the dam is 1.5 m from the ground level. Both its downstream and upstream face inclination are 25 percent backwards. Its spillway form is rectangular. In general, the length and depth of its spillway are one to two meters and 0.5 to 0.6 m (Fig. 15).
Other specifications for log check dams
-Posts are set in two rows across the gully to a depth of about one-half of the post length and at least one m apart. The length of the posts used is 1.5 to 2.0 m and their top end diameter is more than eight cm.
-Logs or other kinds of material (planks, slabs, poles, etc) are set between the two rows of post so that the spillway is formed at the middle of the gully.
-The ends of the logs should enter at least 50 cm into each side of the gully.
-The tops of the posts should be tied with binding wire as indicated in Fig. 15.
-The wings on each side of the spillway should be protected against flash water by wing walls. The angle between the wing wall and wing should be 30 to 45 degrees. The height of the wing wall must be equal to the depth of the spillway. Dry-rock wing walls can be built instead of log wing walls if stones are available.
-The space between the wing and wing wall should be filled to spillway with soil excavated to build the foundation of the dam.