It has generally been assumed that diffusive sediment transport on soil-man
tled hillslopes is linearly dependent on hillslope gradient. Fieldwork was
done near Santa Barbara, California, to develop a sediment transport equati
on for bioturbation by the pocket gopher (Thomomys bottae) and to determine
whether it supports linear diffusion. The route taken by the sediment is d
ivided into two parts, a subsurface path followed by a surface path. The fi
rst is the transport of soil through the burrow to the burrow opening. The
second is the discharge of sediment from the burrow opening onto the hillsl
ope surface. The total volumetric sediment flux, as a function of hillslope
gradient, is found to be: q(s) (cm(3) cm(-1) a(-1)) = 176(dz/dx)(3) - 189(
dz/dx)(2) + 68(dz/dx) + 34(dz/dx)(0.4). This result does not support the us
e of linear diffusion for hillslopes where gopher bioturbation is the domin
ant mode of sediment transport. A one-dimensional hillslope evolution progr
am was used to evolve hillslope profiles according to non-linear and linear
diffusion and to compare them to a typical hillslope. The non-linear case
more closely resembles the actual profile with a convex cap at the divide l
eading into a straight midslope section. Copyright (C) 2000 John Wiley & So
ns, Ltd.