Quoted from: https://github.com/PSUmodeling/MM-PIHM
The Multi-Modular Penn State Integrated Hydrologic Model (MM-PIHM) is a physically based watershed model with multiple optional modules. MM-PIHM is the sweetest PIHM, ever!
The current release contains the source code for PIHM, Flux-PIHM, Flux-PIHM-BGC, and RT-Flux-PIHM.
PIHM is a spatially-distributed, physically based hydrologic model. Flux-PIHM adds a land surface model (adapted from the Noah land surface model) to PIHM for the simulation of land surface processes. Flux-PIHM-BGC couples Flux-PIHM with a terrestrial ecosystem model (adapted from Biome-BGC) that enables the simulation of carbon and nitrogen cycles. RT-Flux-PIHM couples Flux-PIHM with a multicomponent subsurface reactive transport module. A deep groundwater module can be turned on for PIHM, Flux-PIHM, and RT-Flux-PIHM.
MM-PIHM is open source software licensed under the MIT License. All bug reports and feature requests should be submitted using the Issues page.