SEEPAGE LOSSES FROM A CANAL CONVEYING A VARYING DISCHARGE

Abstract

Due to increasing demands of water day by day either for agriculture or for an industry it is imperative to conserve water by reducing loss of water during transmission from source to place of utility. It has been observed that about 1/3 of the water drawn from an irrigation source is lost as transmission losses before it reaches the agricultural land. The transmission losses are comprised of leakage, waste, evaporation, transpiration, and seepage. The losses due to seepage are by far the most significant. There are various factors like soil texture, water turbidity, depth of water in the canal, velocity, temperature, position of water table and drainage condition, etc. which affect the seepage rate. The effects of many of these factors are difficult to determine and their relative importance has not yet been definitely known. Before any measure for controlling seepage from canals are taken up it is necessary to locate where such losses do occur and estimate how much quantity is being lost as seepage. For estimating this seepage loss there are several analytical and practical methods in vogue. For infinite depth of permeable medium with very deep water table, Vedernikov has given solution to the steady state seepage from trapezoidal and triangular canals. Vedernikov has used conformal mapping and hodograph method and has determined seepage from a canal. According to him, seepage per unit length of the canal is given by the formula: q= k(B + Ah)...