In designing each reach of a canal or branch, type cross sections should be drawn out for several different depths of digging, _e.g._, one for very shallow digging, _i.e._, where the bed is little, if at all, above the ground level, one for deep digging where the ground is higher than the water level, and one for the “balancing depth,” where the area of the channel excavation is equal to the earth required for the banks. In calculating the earthwork the sectional area of the digging or of the embankment is taken, whichever is the greater. The proper width and height of bank for any channel depends partly on the maximum depth of water in the channel, and partly on the discharge. Given a depth of water of say 8 feet, a breach will obviously be more disastrous with a great volume of water than with a small volume. The following statement gives some figures suitable to the rather light and friable soils of Northern India, but the question is largely one of judgment. Generally a low and rather wide bank is preferable to a higher and narrower one. If a road, with or without the small raised bank next the canal, is required, special widths can, of course, be arranged for. A 14-foot bank is required for a driving road. ------------+--------------+---------------+--------------- Top Width of|Height of Bank| Greatest | Greatest Bank. | above F. S. | Admissible | Admissible | | Discharge. |Depth of Water. ------------+--------------+---------------+--------------- Feet. | Feet. |C. ft. per sec.| Feet. 20 | 2 | 12,000 | 12 18 | 2 | 8,000 | 12 16 | 2 | 5,000 | 11 14 | 2 | 3,000 | 10 16 | 1·5 | 2,000 | 9 14 | 1·5 | 1,500 | 9 12 | 1·5 | 1,200 | 8 10 | 1·5 | 1,000 | 7 9 | 1·5 | 700 | 6 8 | 1·5 | 500 | 5·5 7 | 1·5 | 400 | 5 6 | 1 | 300 | 4·5 5 | 1 | 200 | 4 4 | 1 | 100 | 3·5 3 | 1 | 50 | 3 ------------+--------------+---------------+---------------