Drainage Line Treatment
Bank stabilisation activity is generally taken to stabilise the banks of drains/ nallah in the watershed, so that they are not eroded further. Following measures are adopted depending upon the availability of local material and site condition.
- Earthen Bund fortified with vegetation and safe disposal structure
- Planting of vegetation on the banks of nallah
- Stone pitching at vulnerable points
- Earthen/ Brushwood/ Gabion spurs fortified with vegetation.
VEGETATIVE CHECK DAM
These check dams are usually preferred in rills/ gullies having smaller catchment area to arrest sufficient soil and water necessary for the proper growth of vegetative cover. Mainly grass and shrubs like Agave, Ipomea , Ratanjot, Vetiver etc are planted across the drainage line.
BRUSH WOOD CHECK DAM
They are suitable for gullies with small drainage areas and are constructed with locally available wooden stakes and brushes/ branches of trees Vegetative check dams should also be established in the upstream side of these check dams so that it may become functional before the life of brushwood check dam is over.These structures are relatively cheaper.
LOOSE STONE CHECK DAM
These structures are constructed in small and medium size gullies using locally available stones/ boulders as dry masonry. A waste weir is also provided to discharge the peakrunoff safely from the catchment.
Gabion or woven wire check dams are used in gullies of moderate slope and small drainage areas. An important advantage of a gabion structure is its flexibility as it shapes according to the stream bed without loosing its stability.
These are constructed in medium to large size gullies by making earthen embankment in the nallah bed across the drainage line duly supported by locally available vegetation/ grass. They are provided where separate surplusing arrangement for water is available at site.
DUG OUT POND (NADI)
It is a water harvesting structure constructed in middle to large drainage lines across the flow to store surplus runoff . The pond is constructed near the point of use where maximum water can be stored requiring minimum amount of earth work. The earthen bund is fortified with vegetation and wasteweir.