Results (post-processing)

Mass balance

The page lists the water and solute balance at the print times, as Mass Balance Information in HYDRUS-1D (file Balance.out, here BALANCE.csv).

Columns

Column	Meaning
time	print time
water volume	water in the profile per unit area [L]
WatBalT	absolute error of the water balance [L]
WatBalR	relative error of the water balance [%]
mass k	mass of solute k in the profile [M/L²]
CncBalT k, CncBalR k	absolute and relative error of the solute balance

The absolute error is the difference between the change of the water volume since the start and the cumulative boundary fluxes and sink terms:

ε_a^w = V_t − V₀ + ∫₀^t T_a dt − ∫₀^t (q₀ − q_N) dt

with the volumes V of the profile, the actual transpiration T_a and the fluxes q₀, q_N across the bottom and the surface Šimůnek et al. (2009). The relative error relates it to the larger of the absolute change of the volume and the cumulative fluxes:

ε_r^w = 100 |ε_a^w| / max(Σ|ΔV_i|, ∫ |T_a| dt + ∫ |q₀| dt + ∫ |q_N| dt)

A well-posed problem usually has a relative error below about 1 %. Larger errors call for a smaller maximum time step, tighter iteration criteria or a finer mesh near the surface or at material interfaces (discretization).

Sub-regions

At the last print time the table lists every sub-region (set on the page Soil profile): its length, water volume, inflow (rate of change of the volume), mean pressure head and the mass and mean concentration of each solute.

Literature cited in this topic

Šimůnek, J., M. Šejna, H. Saito, M. Sakai, and M. Th. van Genuchten (2009). The HYDRUS-1D Software Package for Simulating the One-Dimensional Movement of Water, Heat, and Multiple Solutes in Variably-Saturated Media, Version 4.08. HYDRUS Software Series 3, Department of Environmental Sciences, University of California Riverside, Riverside, CA, USA, 330 pp. https://www.pc-progress.com/en/Default.aspx?h1d-description

All sources: References.