Programing for operational hydrology
The Python language ( http://www.python.es ) is very interesting for hydrology.
It is free, free and open source.
Most of the developments described in these pages have been programmed with this language.
There are many utilities that can be programmed with this language and the community offers a large number of solutions. See:
PyPI - the Python Package Index, https://pypi.python.org/pypi
The Python Wiki, https://wiki.python.org/
Thus, for example, it is worth mentioning:
LibreOffice ( https://es.libreoffice.org/ )
Libraries (open source):
There are many open source libraries that can be used in development.
SciPy.- Scientific Computing
With the above tools it is possible to implement hydrological models, and it is possible to find some complete developments in this language, or utilities to connect with others, in the case of Hec applications (see EDAPHI -MHH application)