STANDARDS OF CANAL CROSS-SECTION
- Usual dimensions of canal cross-section elements have been given here and there inappropriate articles.
- The standards as suggest by CWPC are given as follows.
- A trapezoidal section is recommended for the canal.
- The longitudinal slope of the canal is determined depending upon the average slope.
- The natural ground along the proposed alignment.
- This is the maximum average slope that can be provided on the canal.
2. Side Slopes.
- These are dependent on the local soil characteristics and are designed to withstand.
- The following conditions during the operation of the canal.
(a) The sudden drawdown condition for inner slopes.
(b) The canal running full with banks saturated due to rainfall.
- Canal in the filling will generally have side slopes of 1.5: 1.
- For canals in cutting, the side slope should be between 1: 1 and 1.5: 1 depending upon the type of soil.
3. Free Board.
- Freeboard in a canal is governed by consideration of the canal size and location, rainwater inflow, water surface.
- Fluctuations caused by regulators, wind action, soil characteristics, hydraulic gradients.
- Service road requirements, and availability of excavated material.
- A minimum freeboard of 0.5 m for discharge less than 10 cumecs and 0.75 m for discharge greater than 10 cumecs is recommend.
- The freeboard shall be measured from the FSL to the level of the top of the bank.
- The height of the dowel portion should not be used for freeboard purposes.
4. Bank Top Width.
The minimum values recommended for top width of the bank are as follows.