As all good Monty Python fans know, water technologies feature large in the legacy of benefits left by Roman civilisation. But while aqueducts, sewers and baths retain an obvious presence in the landscape and in the archaeological record, the Romans’ largest and most important water achievement may have been “virtual”.
The Romans developed networks of trade and food supply that enabled them to escape local water constraints, in a way that is explained in a new study in the journal Hydrology and Earth System Sciences. Fertile regions such as southern Spain or Italy’s Po valley would grow lots of food and ship it back to Rome or to the drier outposts of the Empire.
Embedded within this is a what geographers call a virtual water trade – an indirect way of shifting this precious resource from wetter, less populated areas to those regions with more people or a less consistent climate.
The map below shows this in action. The amount of virtual water imports (a) and exports (b) in different parts of the Empire are illustrated by the size of the circles. The numbers express this in tonnes of grain. Rome is by far the largest water importer, followed by Alexandria and Memphis in Egypt, and Ephesus and Antioch in modern-day Turkey. Spain and Egypt were the biggest exporters.
All ships lead to Rome
