A direct irrigation scheme which makes use of a weir or a barrage, as well as a storage irrigation scheme which makes use of a storage dam or a storage reservoir, necessitates the construction of a network of canal. The entire system of main canals, branch canals, distributaries and minors is to be designed properly for a certain realistic value of peak discharge that must pass through them, so as to provide sufficient irrigation water to the commanded areas. These canals have to be aligned and excavated either in alluvial soil or non-alluvial soil; depending upon which they are called alluvial canals or non-alluvial canals.