Abstract
Mathematical models for defining cross-section of self-formed straight sand-silt rivers are presented, in which sediments are actively transported everywhere as bed load and suspended load. A balance of lateral bed load and lateral diffusive transport of suspended sediment is imposed. to maintain a stable channel cross-section. Singular perturbation technique is employed to solve the sediment balance equation, from which a relation for stable depth is derived. A resistance formula for dune-covered bed is used to obtain stable width. It is revealed theoretically that the channel-center depth relative to sediment size is approximately proportional to S-0.82 for natural sand-silt rivers. The analysis is found to agree reasonably well with laboratory and field data.
