Performance Evaluation of Sodium Bentonite Material for Seepage Control in Irrigation Channels

Abstract

Irrigation canals in Pakistan suffer tremendous water seepage losses due to unlined section of the canal. As most of canals are unlined, large amount of water is wasted in terms of seepage especially in link canal. When link canals pass through coarser areas, e.g. C-J link canal in Thal, a large portion of water is lost in the form of seepage. The present study aimed to investigate performance of sodium bentonite mixture blanket placed in the canal bed for seepage control and to find the sort of mixture combination that could be used under specified canal conditions for seepage control. Experimental study proved that sodium bentonite admixture layer can successively serve as seepage barrier as its swelling fills the pores or voids between the sand particles and effectively control the seepage through soil. Best mixing percentage of sodium bentonite with sand is 5% by weight for effective and practicable canal seepage control. The efficiency of seepage controlled by sand bentonite mixture is 100% under lab condition and 92% to 96% under field condition. The best results can be obtained by applying soil bentonite mixture depth of 25 to 30 cm. For dry mixing the soil material should be dry with moisture content of 15% or less.