💧 IGW-NET · Quick Tutorial 12 of 31

Tutorial 12: Vertical Profile Modeling

Create vertical cross-section (profile) models to analyze flow in the vertical dimension. Useful for studying layered aquifer dynamics.

IGW-NET Tutorial 12 Prereq: MAGNET4WATER account 3 sections

This tutorial covers

  1. Approach 1 — Simple 2D Vertical Profile
  2. Approach 2 — 3D Slice Profile
  3. What's Next

1Approach 1 — Simple 2D Vertical Profile

Step 1 — Enter Synthetic Mode

Click Utilities Go to Synthetic 'Go to Synthetic Case Area' under Utilities to create a blank domain. In this model, the x-axis is horizontal distance and the y-axis is elevation. Synthetic canvas showing rectangular domain

Step 2 — Draw the Water Table

Click DrawLine SaveShape to draw a line feature representing the water table, sloping from right (higher elevation) to left (lower elevation), with a break-in-slope near the lower-left edge — simulating a hillslope with a discharge zone at the base. In the line attributes, choose 'Equal to Y (e.g., Water Table)' under prescribed head. This tells the solver that the head along this line equals the y-coordinate — i.e., the water table IS the line you drew.

Step 3 — Deactivate the Unsaturated Zone

Click ZonePoly SaveShape to add a zone feature covering the space above the water table line. Assign this zone as 'Inactive'. This removes the unsaturated zone from the computation — the solver only operates below the water table, where groundwater equations apply.

Step 4 — Add a High-K Basal Unit

Click ZoneRect to add a rectangular zone along the bottom of the model representing a deeper unit of higher hydraulic conductivity. Set Settings K = 70 m/day (the domain default is 22.8 m/day). This creates a two-layer system: a lower-K upper zone and a higher-K basal zone — mimicking a typical geological setting where coarser sediments underlie finer materials.

Step 5 — Simulate and Analyze

Submit for simulation. Then click Analysis Display Charts 'Display Charts' to view the mass balance of the basal unit and a 3D surface chart of the water table. The results reveal classic vertical circulation: downward flow beneath the recharge area (higher water table), horizontal flow through the aquifer, and upward flow at the discharge point (break in slope).

Simple 2D vertical profile model showing: A) synthetic domain setup, B) water table line sloping right to left with break-in-slope, inactive zone above water table, and high-K basal unit at bottom, C) simulation results with flow vectors showing downward recharge flow, horizontal transport, and upward discharge at the break-in-slope
Figure 1: Simple 2D vertical profile — (A) synthetic domain, (B) water table line with inactive zone above and high-K basal unit below, (C) simulation results showing classic vertical circulation: downward flow under the recharge area, horizontal flow through the aquifer, upward flow at the discharge point.
3D surface and mass balance visualization of the vertical profile model showing water table surface, flow distribution between upper and lower units, and mass balance bar chart
Figure 1-C: 3D surface chart and mass balance — visualizing the water table shape and quantifying flow exchange between the upper and lower hydraulic units.

2Approach 2 — 3D Slice Profile

Step 1 — Create a New Synthetic Model

Click Go to Synthetic 'Go to Synthetic Case Area' to start a fresh synthetic domain.

Step 2 — Add River/Stream Boundaries

Click ZoneRect SaveShape to add rectangular zones along the left and right edges of the domain representing rivers/streams. These provide the driving force for groundwater flow:

Left edge: Prescribed head = 0 m
Right edge: Prescribed head = -100 m

The 100 m head difference drives regional flow from left to right.

Step 3 — Add a Low-K Zone

Click ZoneRect to add a rectangular zone in the center of the domain representing a low-conductivity barrier or geological feature. Set Settings K = 70 m/day (domain K = 22.8 m/day). This creates a heterogeneous system where flow must navigate around or through the contrast zone.

Step 4 — Add a Second Layer

Click Add Layer 'Add Layer' to add a 2nd layer underneath Layer 1. Use default properties: K = 22.8 m/day, top elevation unchecked (auto-chained), thickness = 50 m. This creates a two-layer system that allows vertical flow between layers.

Step 5 — Simulate

Click Submit to submit for simulation. The solver computes 3D flow — the water table emerges as part of the solution (not prescribed as in Approach 1).

Step 6 — View Cross-Section as Vertical Profile

Click Display Charts Analysis 'Display Charts' under Analysis to view the cross-section charts. Each cross-section through the 3D model IS a vertical profile — showing head distribution, flow vectors, the computed water table, and how flow navigates between layers and around the heterogeneous zone.

3D slice profile model setup showing: A) synthetic domain with prescribed head boundaries on left (0m) and right (-100m), low-K zone in center, and second layer added below. Head contours and flow vectors visible in plan view.
Figure 2-A: 3D slice model setup — prescribed head boundaries on left (0 m) and right (-100 m) drive regional flow. A heterogeneous zone in the center and a second layer below create a system with both horizontal and vertical flow components.
Cross-section views of the 3D slice model showing vertical profiles through the two-layer system with head contours, flow vectors showing horizontal and vertical components, and the computed water table position. The heterogeneous zone deflects flow patterns visible in the vertical plane.
Figure 2-B: Cross-section slices as vertical profile models — the 3D solution viewed in the vertical plane reveals head distribution across both layers, flow vectors showing vertical circulation, and how the heterogeneous zone deflects and concentrates flow. The water table position emerges from the solution — it wasn't prescribed.

When to Use Each Approach

Approach 1 (known water table): Use when you have field data for the water table position, when studying flow beneath a specific topographic profile, when the water table shape is the given and you want to understand circulation patterns beneath it. Classic applications: Toth flow systems, seepage under dams, flow around sheet piles, classroom demonstrations of regional circulation.

Approach 2 (3D slice): Use when the water table is unknown and depends on the interaction between recharge, boundaries, and aquifer properties. The water table is computed, not prescribed. More realistic for real-world problems where you need both the horizontal and vertical flow structure. The cross-section is a "slice" through a full 3D solution.

The "Equal to Y" trick: In Approach 1, the key insight is that for a vertical profile model, the y-coordinate IS elevation. By assigning "prescribed head = y" along a line, you set the head equal to the elevation along that line — which is exactly the definition of a water table (pressure head = 0, total head = elevation). This elegant trick turns a standard 2D plan-view solver into a vertical profile solver without any code changes.

3What's Next

With profile modeling mastered, continue the learning path:

Tutorial 13: Importing Shapefiles — bring external GIS data (geological cross-sections, well logs) into your model
Tutorial 14: Post-Analysis Tool — load and inspect completed model results including cross-sections
Tutorial 15: Stochastic Flow Model — add random heterogeneity and see how it affects vertical circulation patterns