Topography Curvature Effects in Thin‐Layer Models for Gravity‐Driven Flows Without Bed Erosion

Depth-averaged thin-layer models are commonly used to model rapid gravity-driven flows such as debris or avalanches. However, the formal derivation of equations for general topographies is not straightforward. The curvature topography results in a force that maintains velocity tangent topography. Another term appears bottom friction with frictional rheologies. In this work, we present main lines mathematical these terms proportional square velocity. With SHALTOP numerical model, quantify their influence on flow dynamics and deposits over synthetic real topographies. This done by comparing simulations which exact, disregarded approximated. Coulomb rheology, slopes θ = 10 coefficients below μ tan (5°), neglecting increases simulated travel times up 10% 30%, respectively. When neglected, distance may be increased several hundred meters topographies, whatever coefficients. We observe similar effects channel slope 25° 15°, 50% increase kinetic energy. Finally, approximations can break noninvariance decelerate flow. Voellmy discrepancies less significant. Curvature thus have significant impact calibration overflows prediction, both being critical hazard assessment.