Some research enters a thriller almost invisibly. The ancient qanat is a good example: an ingenious piece of hydraulic engineering that can be explained in a sentence while carrying thousands of years of history behind it.
Water underground
Qanats are underground water-management systems developed to transport water over long distances through gently sloping subterranean channels. Vertical shafts provided access during construction and maintenance, while keeping much of the water protected from surface evaporation.
Systems of this general type became fundamental to settlement and agriculture in arid parts of the Middle East and spread far beyond their earliest centres of use.
A detail rather than a lecture
In The 13th Tablet, qanats appear because they belong naturally to the landscape and to the practical problems faced by the characters. The intention was deliberately not to stop the action for an archaeological explanation.
This became one of my basic rules for writing the thriller: do the research in depth, then allow only the small amount the reader actually needs to remain on the page.