I found it's really important to understant these headS. When analysing your hydro system, the heads are very often playing a big role. But what relationship between them?

total head = hydraulic head + velocity head

We often ignor velocity head in ESA, and makes total head = hydraulic head. hydraulic head = pressure head and elevation head.

When doing groundwater modelling, if use total head to calibrate your model, you would get total head drawdown. When using elevation head to calibrate your model, the head drawdown will equivalent to the elevation drawdown.

Please correct me if I am not right.