Hi Andre,
For sure, you should use the QGIS plug-in.
It will be much easier if you're french reader as the wiki is only written in french.
Anyway, follow the procedure step by step :
- extremities and branchs... easy to do but need to be acchieved with care as your linear referencing will be based on it
- importation of topograhic information, creation of Cross-section and building of it combining data extracted from DEM and topo... maybe the more difficult stage as you need to understand the "ergonomy" of the plugin and the "role" of different layers
- singularities
- don't let yourself be disturbed by the plugin "philosophy" influenced by the original developer and the user community (I'm a member)... french river flood forecast services (vigicrue).
For that reason, the plugin has many feature to work in event mode... and consequently, the plugin is not straightforward in a more classical use.
- If you want to do mapping, you can export and use cartoZI
http://wikhydro.developpement-durable.gouv.fr/index.php/CartoZI#Mise_.C3.A0_disposition
It would be great to see new users adopting (at least trying) Mascaret and the plugin.
Alexis