Storm Drain Design: Diffusive Flood Routing for PCs

DEMOS is an interactive model for the analysis and design of dendritic sewer networks. It routes hydrographs and pollutographs through conduits and detention basins on the basis of the one‐dimensional advection‐diffusion equation. The equations are solved numerically by exploiting the numerical diffusion inherent in the finite difference approximation to a simple advection equation. The model parameters may then be related to the hydromorphologic characteristics of the system. Steady or looped rating curves may be used to convert between flows and depths. The conduit geometry may be circular or trapezoidal. The model accomplishes pipe design by selecting pipe sizes that ensure open channel flow at all times, while accounting for transient, nonuniform flow conditions and storage in the conduit. For flow simulation, surcharging is identified, and a simple flow volume storage procedure is undertaken. The model includes several features that allow for easy implementation on a variety of systems, including microcomputers. Use of the microcomputer version of DEMOS, a public domain FORTRAN code, is demonstrated in an example that involves the simulation and design of a branched sewer network.