Basic irrigation systems were widespread in the ancient world because they were simple to maintain. Perennial irrigation was rarer, and required longer canal systems, a method of storage, and better maintenance to ensure that silt and salt build-up was kept in check. In Mesopotamia, the river system was able to supply water to the surrounding arable land in the dry season through a system of canals, closed off by dykes and sluice gates. Water was stored in reservoirs, either natural or man-made, and then lifted into the irrigation channels. While this was a labour-intensive task, the results of such toil were remarkable and hugely beneficial to harvests in the area.
