The method of characteristics is used to obtain a solution for a dam-break flood on a sloping channel that is initially dry. It is shown that an exact solution of the St. Vcnant equations does not exist for this problem when traditional representations are used for the bed resistance term, and the solution given herein is obtained by neglecting bed resistance. The calculated solution is compared with experimental results, and it is concluded that the inviscid solution may, in some circumstances, give a more accurate approximation than experimental values obtained from small-scale experiments.