Palustrine carbonates are frequently found with active and dried karstic springs in the foothills of the mountains bordering the Persepolis Basin, southwest Iran. A combination of geological conditions favours their formation, including (i) the presence of karstic limestone aquifers in the limbs of anticlines cut through by fault systems; (ii) very gentle slopes from the spring resurgence point towards the centre of the alluvial plain, creating a flat waterlogged area; and (iii) a semiarid climate with marked precipitation seasonality or significant fluctuations in water discharge and wetland water table. We suggest the term “anastomosing wetlands” or “anastomosing palustrine environments” to denote the studied karstic spring–fed carbonate wetlands, because of similarities with anastomosing river systems in aerial view. The common presence of extended anastomosing wetland carbonates in the Persepolis Basin and adjacent basins in the central and southern Zagros suggests that they can play an important role in the geological records of collision-related basin-and-range settings dominated by karstic limestones. Karstic spring wetlands are a main source of fresh water hosting a rich biodiversity, which attracts human communities, whose impact is visible in the archaeological material imbedded in the wetland stratigraphy. Fresh water availability, through these spring wetlands, partly explains why the semiarid Persepolis region was selected by successive civilizations, from Elamites to Persians until early Islamic entities, to establish regional centres throughout the period from the third millennium B.C. to the first millennium A.D. Only a few of these ecosystems have survived the intensive human activities of recent decades.

Successful heritage management requires a robust comprehension of the threats facing archaeological sites, at both current and future timescales. Siraf, on the Persian Gulf of Iran, is a site of national and international importance whose history stretches back to the Sassanid period (224-652 AD). In the present context of global change (drought and relative sea-level rise) and anthropogenic impacts (coastal artificialization and reduced sediment supply), the city's waterfront archaeology is undergoing significant erosion. Nonetheless, at present, the processes leading to the loss of Siraf's in situ archaeological remains are still poorly understood, including the rates, timing and drivers of coastal erosion. Here we use Landsat images to monitor shoreline changes along the Siraf coastline between 1973 and 2016. We spatially quantify the causes and impacts of surface changes along 244 transects. The results demonstrate that coastal erosion is responsible for widespread and archaeologically significant damage, with 48% of the studied transects showing erosion during the period 1973-2016. We elucidate significant temporal variations in the data and, most notably, demonstrate that continued drought since the early 2000s has impacted upon sediment supply to coastal areas, severely accentuating erosion. For instance, between 2003 and 2016, 70% of transects recorded shoreline retreat with worrying implications for the waterfront archaeology of Siraf. These quantitative results provide invaluable spatial information regarding the causes and impacts of erosion upon Siraf's waterfront heritage, in addition to furnishing a template for the protection of the city's internationally important cultural heritage.