Table 1 Comparison of variables and parameters between the two PINN models.

From: Solving the Richards infiltration equation by coupling physics-informed neural networks with Hydrus-1D

Category

Symbol

Meaning

Type

Classical PINN

Hybrid PINN

State Variable

\(\:\theta\:(z,t)\)

Water Content

Model output

Objective Function of the Network Prediction

Input Variable

\(\:z/t\)

Depth/Time

Model Input

Range [0, Z]/Range [0, t]

\(\:\theta\:(z,0)\)

Initial Water Content

Residual of Initial Conditions Incorporated into the Loss Function

\(\:\theta\:\left(0,t\right)\)

\(\:\:\theta\:({z}_{0},t)\)

Upper and Lower Boundary Conditions

Residual of Boundary Conditions Incorporated into the Loss Function

Hydrus-1D Data

\(\:{\theta\:}_{data}(z,t)\)

Water Content Field

Data-Driven Input

Not Incorporated

Incorporation

Soil Parameters

\(\:{\theta\:}_{s}\),/\(\:{\theta\:}_{r}\)

Saturated/Residual Water Content

Calibrated Parameters

See Table 2

\(\:{K}_{s}\)

Saturated Hydraulic Conductivity

\(\:\alpha\:/m/n\)

VG Model Parameters

  1. In this study, two PINN frameworks are considered:.
  2. (1) Classic PINN: This framework fully relies on physical equations without any measurement data;.