construction and refurbishment of earthen irrigation channel banks

Government schemes generally have a long design life (80-100 years) with a highcapital cost but low annual maintenance costs.10.1.2.2 Shape of channel cross-sectionA good design cross-section will provide:• satisfactory bank width• adequate waterway width and depth• appropriate batter grades. Refer to Section 12.17.4.1 Inner Slopes.• the required bank design life• ease of construction• adequate protection from vermin and environmental degradation• take account of the structural stability of the bank-building material• allow all operations and maintenance activities to be carried out efficientlyAny deficiency in the above can cause premature deterioration of the bank and soprevent the channel bank from attaining its required life.Access TrackProtective Cover21Figure 10.1 Typical irrigation channel cross-sectionTypical irrigation channelPhoto 10-1New Irrigation Channel10.1.2.3 Depth, width and capacity of channel waterwayDesign depth, width and design capacity all effect the flow pattern of water downthe channel. Inadequate design can result in undercutting of banks and/or siltdeposition in the bed the of channel. These may result in further erosion ofbanks.10.1.2.4 Bank height above natural surfaceHigh banks are more prone to erosion than low banks. The greater the head ofwater on the bank, the greater the tendency for increased leaks and seepage. Alsoas there is a large exposed back of bank there is more likely to be damage due toshrinkage cracking if the bank is not protected.High banksPhoto 10-2Channel Bank over three metres highConstruction and Refurbishment of Earthen Channel Banks August 2002 - Edition 1.0 10-5