Studying of manning's roughness coefficient and seepage losses in earth farm ditch
1986
Tanit Japar
Where n is Manning's roughness coefficient, V equals velocity of flow in meters per second and R is the hydraulic Radius in meters. From this investigation, the value of n with various kinds of aquatic plant was found to vary from 0.0186 to 0.0507 and taken an average value of 0.0347. The first experiment was conducted in February, 1984, when the ditches were recently repaired and the water table was 1.5 meters below the top of bund. It the seepage loss would be more when the inflow rate at the inlet and/or effective length of ditch increased. The relationship might be written as : QP = 0.02150 Q 0.41489 L 0.81634. Where Qp is the seepage loss in liters per second, Q is the inflow rate at the upstream end of ditch in liters per second and L is the effective length of ditch in meters. The 2nd, 3rd and 4th experiments were respectively conducted in March, April and May, 1984. The water table was as high as the water surface in the field. Each experiment gave similar result; consequently the representative relation was established as : QP = 0.03894 Q 0.77120 L 0.55716.
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