Can someone please direct me to a tutorial where I can learn more about how to model flooding using data from gauging stations along rivers using QGIS?
If you use GRASS GIS as backend in QGIS (via QGIS-GRASS toolbox or Sextante plugin), you can use a range of hydrological tools. See http://grass.osgeo.org/wiki/Hydrological_Sciences for options.
The GRASS recommendation from @markusN is a good one. Another option, although it's not integrated into QGIS, is the Gerris Flow Solver. GFS is a tremendously powerful hydraulic and hydrological modeling tool. From the site:
Gerris is a Free Software program for the solution of the partial differential equations describing fluid flow. The source code is available free of charge under the Free Software GPL license.
Gerris was created by Stéphane Popinet and is supported by NIWA (National Institute of Water and Atmospheric research) and Institut Jean le Rond d'Alembert.
A brief summary of its main features:
- Solves the time-dependent incompressible variable-density Euler, Stokes or Navier-Stokes equations
- Solves the linear and non-linear shallow-water equations
- Adaptive mesh refinement: the resolution is adapted dynamically to the features of the flow
- Entirely automatic mesh generation in complex geometries
- Second-order in space and time
- Unlimited number of advected/diffused passive tracers
- Flexible specification of additional source terms
- Portable parallel support using the MPI library, dynamic load-balancing, parallel offline visualisation
- Volume of Fluid advection scheme for interfacial flows
- Accurate surface tension model
- Multiphase electrohydrodynamics
There is also a very detailed tutorial on the Karamea river, in New Zealand. If you follow that example you will learn a lot about the software, flood visualization, and hydraulic modeling.
Have a look at Crayfish for QGIS
"Crayfish is a plugin (extension) developed by Lutra Consulting for the free and open source GIS platform Quantum GIS (QGIS).
The Crayfish plugin aspires to be a complete set of pre and post-processing tools for hydraulic modellers using TUFLOW, ISIS 2D and other modelling packages."
Personally, I have no experience with it.
Sort of depends where you are (which country) on what software and methods are usually used or are standardised on - some councils, state governments and governments have required methods. Also what sort of area are you looking at modelling ? Urban, rural ???
eg for Australia have a read of the www.arr.org.au site. They are in the process of releasing updated guidelines and some state governments are in the process of releasing their required methods. drafts chapters of their new releases www.arr.org.au/downloads-and-software/chapters/
QGIS and SAGA are very useful
WBN have released a tuflow plugin for QGIS back in april (2014)
They also have a tutorial for using qgis to prepare models for tuflow http://www.tuflow.com/GIS%20Platforms.aspx?QGIS_and_SAGA http://wiki.tuflow.com/index.php?title=Main_Page
Drains for urban pipe and drain flow (required by some councils) also for flows into pipe and drains for tuflow www.watercom.com.au/download.html
Can download hecas for free
In the US be very careful about units as some states use metric and some US imperial for their data.