Looking for interpolation tool to produce river bathymetry (topography) from sections

Have you had a look at GRASS Wiki "Marine Science" yet? It discusses Bathymetry processing and the necessary steps.

At this point I have to correct myself.

The solution I was looking for, is a tool incorporating a set of procedures, 2 linear interpolation methods, etc. rather than a single interpolation method/tool.

I did not find any tool able to do the task properly, other then Dr Venkatesh Merwade's tool.

I had to downgrade my ArcGIS for Desktop version in order to use it. The tool is still not bug-free, but it does the job.

I found an open source (python, R, QGIS, and PostGIS) workflow by Michele Tobias, based on Dr Venkatesh Merwade's 2005 paper here: http://www.slideshare.net/MicheleTobias/open-source-workflow-for-surface-interpolation-with-curvilinear-anisotropy

There is a Github project with documentation trying to turn this into a (very useful) Qgis plugin: https://github.com/MicheleTobias/CurvilinearAnisotropy