The results of new experiments on bed load transport on steep longitud
inal slopes are presented. The experiments were carried out in a large
tilling duct with a fine sand (d(50) = 208 mu m) covering the range o
f slope angles beta of +/- angle of repose for the sand phi(s) (32 deg
rees), Measurements included bed shear-stress, flow discharge, and the
sediment pickup rate on slopes. The results suggest that existing the
ories for bed load transport on slopes are not adequate for all bed sl
opes and the new data are used to formulate a semiempirical relation t
hat satisfactorily predicts the transport rate on horizontal as well a
s mild and steep slopes. The following ate two important findings: (1)
Correcting the threshold term (for slope) in the Meyer-Peter and Mull
er formula adequately describes the transport rate on positive slopes
(elevation increasing in direction of flow) and on small negative slop
es. On steeper negative slopes an extra correction term is required, a
lthough the value of beta/phi(s) at which this term becomes necessary
is a function of shear stress; and (2) the influence of slope vanishes
at high shear stresses.