Summary:

Difference between CLM5.0 and CLM4.5:

1. Routing Methods:
   - CLM4.5 uses RTM, a linear reservoir method, for river routing.
   - CLM5.0 adds MOSART, a more physically-based kinematic wave method, as an option for river routing.

2. Runoff Treatment:
   - RTM in CLM4.5 routes runoff regardless of its sign, allowing for negative streamflow.
   - MOSART in CLM5.0 only routes non-negative runoff, ensuring positive streamflow, which is important for modeling riverine heat and biogeochemical fluxes.

3. Input Parameters:
   - RTM in CLM4.5 requires only one layer of a spatially varying variable of channel velocity.
   - MOSART in CLM5.0 requires 13 parameters, all available globally at a 0.5° resolution.

4. Outputs:
   - RTM only produces streamflow simulation.
   - MOSART additionally simulates time-varying channel velocities, channel water depth, and channel surface water variations.