الفهرس 
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Abstract
The present thesis is a study of the methods of the design of thickness of lining since existing methods have proved to be inadequate it is known that one third of the available water for irrigation is lost by evaporation and seepage during its convergence in open irrigation systems the theory of beams and slabs on elastic foundation gives an adequate method for designing the concrete lining thickness the method of the design includes. Both friction between the lining and the non-uniform soil reaction underneath the lining empirical formulae are presented. For the lining thickness for the two cases of the coefficient of friction between the concrete and the soil design graphs are also presented to obtain the best economical section.