An Integrated Hydrodynamic Approach to River Sewer and

An Integrated Hydrodynamic Approach to River, Sewer and Overland Flow Modelling presented by Andrew Walker Innovyze Ltd

Modeling is now a pre-requisite to understanding the impact of Urban Development Government Directives dictate that Utilities and Cities now strictly control and closely manage their drainage networks.

The ability to simultaneously represent all flow paths is a necessity for integrated studies Requirement : To model “all sources” of flooding. Solution : Fully Integrated Catchment Analysis.

Fully integrated 1 D and 2 D simulation of above- and below-ground drainage networks in one powerful package To succeed, the software needs to combine these advanced modelling requirements in a single application with one Simulation engine.

The 1 D Engine Requirements § § § § Free surface and pressurized flows Flows not following predetermined directions Backwater effects Small depth situations Dry initial conditions Looped networks Pipes, culverts and non-prismatic channels Ancillary structures, including bridges

The 1 D Engine Solution § Solves the full dynamic equations of gradually varied flow (St. Venant equations) § A four-point implicit finite difference scheme § Non-linear Newton-Raphson iteration and an adaptive time-stepping algorithm § Convergence to within a relative tolerance of 1% before proceeding to the next timestep § Solution method is unconditionally stable, so there is no limit on the magnitude of the timestep to ensure stability

The 2 D Engine Requirements § § Suitable for surface flood flows Fits around complex urban geometry Efficient run-times Simple to couple with existing 1 D models

The 2 D Engine Solution § Finite volume § Conservation of mass and momentum § Unstructured triangular mesh § Gudunov scheme – Riemann solver § Semi-implicit, dual time-stepping Runge-Kutta (predictor-corrector) § Shock capturing

The 2 D Mesh Generation • Floodplain in rural area Ø Simple structured mesh 2 D Hydraulics • Complex geometry in urban area Ø Detailed unstructured mesh

2 D Linkages with 1 D Model

2 D Linkages with 1 D Model

2 D Engine Results

Calculate overland flow path and likely property inundation 2 D Engine Results

River Flooding and Bridge Inundation 2 D Engine Results • River reaches • Bridges • Radial sluices • Flood mapping

The ability to simultaneously represent all flow paths is a necessity for integrated studies

Case Study - Calculate cause of property flooding – stormwater or river flooding? 1 D and 2 D Integrated Results

An Integrated Hydrodynamic Approach to River, Sewer and Overland Flow Modelling

An Integrated Hydrodynamic Approach to River, Sewer and Overland Flow Modelling presented by Andrew Walker Innovyze Ltd