I have modelled a submerged tunnel in `Sofimshc`

in 3D.

The quad elements used are placed in the centreline of each slab and wall, as seen here:

Now I want to add water pressure to the topslab, which I have defined using free area loads like this.

```
AREA REF QGRP 'Top' Proj 'yy' WIDE 500[m] TYPE 'pzz' P1 0 X1 0 Y1 0 Z1 0 $$
P2 0 X2 1000 Y2 0 Z2 0 $$
P3 -100 X3 1000 Y3 0 Z3 -100 $$
P4 -100 X4 0 Y4 0 Z4 -100
```

Unfortunately, as slabs vary in thickness, this method will result in higher water pressure in the areas highlighted in red.

Is there a clever way around this?