This work is part of the GEOtop project and its new implementations (see also here). The intention is to use the new numerical method implemented by Casulli and Zanolli (2010, 2011) of the extended Richards equation (see also the video here). The new method promise to be faster than the older one, more stable, and implemented for unstructured grids, while at present, GEOtop 2.0 uses a structured grid. Hopefully, the new development will be made in OMS3.
Casulli, V., & Zanolli, P (2010). A nested newton-type algorithm for finite colume methods solving Richards' equation in mixed form. SIAM J. SCI. Comput., 32(4), 2225–2273.
Casulli, V., & Zanolli, P. (2012). Iterative solutions of mildly non linear systems, Journal of Computational and Applied Mathematics, 236(16), 3937–3947. http://doi.org/10.1016/j.cam.2012.02.042
Dall'Amico, M., Endrizzi, S., Gruber, S., & Rigon, R. (2011). A robust and energy-conserving model of freezing variably-saturated soil. The Cryosphere, 469–484. http://doi.org/10.5194/tc-5-469-2011