Hello! Do you know how much does it costs for re-sectioning and re-alignment of rivers separately?
sorry this answer took a while, I am moving house.
Costs of restoring a river bed or changing it depends on the its size, the topography of the area and the type of bed-rock. If the work is in a city the costs are much higher too, about double.
I guess that realignment costs 3x as much as resectioning.
You can use the Munich Isar Project as an example and as a base to estimate other project costs by interpolating the values of water-flow volume, length and geology. Munich's regeneration (renaturalisation) of the river Isar, which was a straight concrete channel, to a natural level of flow cost €350 million for a 1500 meter length http://www.youtube.com/watch?v=JAmpgEieg9o
You may find other projects to compare. Here are some links to river restoration projects: http://goo.gl/n7GqHU