Summary of the Article:

## Water Content in Snow Layers

### Conservation Equation for Water Mass

The conservation equation for the mass of water in snow layers is:

(2.8.15) ∂wliq,i/∂t = (qliq,i-1 - qliq,i) + (Δwliq,i)p/Δt

Where:
- qliq,i-1 is the flow of liquid water into layer i from the layer above
- qliq,i is the flow of water out of layer i to the layer below
- (Δwliq,i)p/Δt is the change in liquid water due to phase change (melting rate)

### Liquid Water Inflow to Top Snow Layer

For the top snow layer only, the liquid water inflow is:

(2.8.16) qliq,i-1 = fsno (qgrnd,liq + (qsdew - qseva))

Where:
- qgrnd,liq is the rate of liquid precipitation reaching the snow
- qsdew is the liquid dew
- qseva is the evaporation of liquid water

### Updating Liquid Water Content in Bottom Layer

After calculating surface fluxes and snow/soil temperatures, the liquid water content in the bottom layer (snl+1) is updated as:

(2.8.17) wliq,snl+1^(n+1) = wliq,snl+1^n + fsno (qgrnd,liq + qsdew - qseva) Δt

### Water Flow Between Layers

When the liquid water in a snow layer exceeds the layer's holding capacity, the excess water is added to the underlying layer, limited by the effective porosity of the layer. The water flow between layers, qliq,i, is initially calculated as:

(2.8.18) qliq,i = (ρliq [θliq,i - Sr (1-θice,i)] fsno Δzi) / Δt ≥ 0

Where:
- θice,i is the volumetric ice content
- θliq,i is the volumetric liquid water content
- Sr = 0.033 is the irreducible water saturation

The flow is limited by the water holding capacity of the underlying layer:

(2.8.21) qliq,i ≤ (ρliq [1-θice,i+1 - θliq,i+1] Δzi+1) / Δt

### Updating Liquid Water Content

The liquid water content, wliq,i, is updated as:

(2.8.22) wliq,i^(n+1) = wliq,i^n + (qi-1 - qi) Δt

The total flow of liquid water reaching the soil surface is qliq,0, which is used in the calculation of surface runoff and infiltration.