Geoarchaeological study of the Achaemenid dam of Sad-i Didegan (Fars, Iran)

Constructed during the Achaemenid period, the Sad-i Didegan dam represents a well-preserved example of a system of ancient water control and provides an interesting case study hinting at the regional character of such investments. The study of the site has allowed for a detailed description of the monument and as such provides a more profound comprehension of the measures devoted to water control and the economic importance for the wider Pasargadae countryside. The field survey of the dam’s surroundings reveals the dam to have been well planned within the natural, pre-dam configuration of the valley, with all major raw resources available at a local scale. Though the actual hydrological and landscape impact of the dam may well have been rather modest, the construction of the dam would have required a high labour input over a considerable construction period. Moreover, estimates of canal discharge and reservoir volume indicate the scale and capacity of the dam largely exceeded a strict local use. Combining both archaeological and geoarchaeological data, we are able to conclude that the site functioned within a more regional effort of catchment control, thus controlling discharge for the downstream arable surfaces. It would have done so in conjunction with other dams in the region such as the potentially linked site of Sad-i Shahidabad.