Terracing is the mechanical practice used on slopping agricultural land to reduce the length and /or the degree of slope. There are following types of terraces:
- Level terrace or contour Bunding: It involves construction of bund passing through the points having same elevation (contour). The bund may have closed or open ends.the nmain objectives is to impound the surface run-off and hold it until it infiltrates,closed end bunds are built in low rainfall areas with high permeability and open end bund is used for soil with moderate permeability.whatever be the the case,contour bunding is not suitable for slopes steeper than 6%
- Channel Terrace or Graded Bunding: In heavy rainfall areas, a;; the water cannotr be impounded to percolate into soil. As such slight gradient is provided in channel above the bund to safely divert water to one sode of field. Then the water is discharged safely from grassed waterway. There are following types:
- Mangum Terrace: The bank up from both sides-uphill and downhill.
- Nichols Terrace: Bank is built by moving solely from the upper side.
- Broad Based Terrace: It has wide low bank and a shallow channel with gently sloping sides.
- Normal-based Terrace: It has steep-sided banks. These types of terraces are suitable for slopes not more than 8% slope.
- Bench terraces: A steep slope is converted into a series of steps, with horizontally or nearly horizontal ledges, and vertical or almost vertical walls between the ledges. In very stable soils, the walls may be held by vegetation, and in others some structural walls are necessary, as brick, stone or timber. Bench terraces are of threer types:
- Level Bench Terraces: It is used for uniform impounding of water in paddy fields etc.
- Inwardly slopping Bench Terraces: They are suitable for steep slopes. They keep runoff towards the hillside rather than on foil slopes.
- Outwardly Slopping Bench Terraces: They are used to reduce the existing steep slope to mild slope. All types of bench terraces are suitable for slope upto 15%