41.4 Routing - nptel - Indian Institute of Technology Madras

Hydraulics Prof. B.S. Thandaveswara
41.4.3.3 Information Required for Routing the Dam Break Flow
(1) The model and scheme that is to be adopted.
(2) Lateral Flow - whether distributed or lumped inflow and outflow and its
characteristics with respect to time. The lateral flows include
(i) Contribution of rainfall on the free surface
(ii) Overland flow
(iii) Infiltration
(iv) Evaporation
(v) Seepage
(3) Cross sectional details
(a) Prismatics or (b) Non-uniform properties of natural rivers.
Following methods are used for representing the cross sections
Replacing of actual river by unform channel for total length such as Trapezoidal section.
Indian Institute of Technology Madras
• Repacing of actual river by series of prismatic channel.
• Representing cross sections by Polygonal sections.
• Replacing of surveyed sections by Polynomials.
• Interpolation of cross sections.
• Stochastic generation of cross sections.
(4) RESISTANCE PROPERTIES:
Any resistance law such as Chezy's, Manning's, Darcy- Weisbach's may be used. The
relevant coefficients need to be defined as a function of length (or section) and its
variational function with respect to depth should be known.
(5) Details of channel network in Flood plains
41.4.3.4 : Numerical Methods for Solving the Governing Equations
Any of the following numerical methods may be used for solving the governing Saint-
venant equations in conservation form. Many schemes such as Total Variation
Diminishing (TVD), Essentially Non-Oscillating (ENO) have been proposed in recent
years for correct numerical solution of the governing equations.