Evaluating ancient coastal wells as sea‐level indicators from the coast of Israel

Abstract

This paper re‐evaluates previous records and adds new data to the relative sea level (RSL; namely the sea level related to the level of the national terrestrial datum) reconstruction in Israel from the last 2400 years based on ancient coastal water wells. Different methods for obtaining the most accurate modern offset between coastal groundwater level and mean sea level are also tested, since this is a crucial component for using wells as reliable sea‐level indicators in the Mediterranean and beyond. Very few, if any, sea‐level studies outside of Israel use coastal wells as RSL indicators; refinements to the methods associated with this indicator type will facilitate their use in other regions. Coastal wells in the study are located within 200 m of the present‐day coastline. The functional age range for the wells is based on site stratigraphy, artifacts, historical records, and the coastal water well typology. These archaeological indicators rely on finding the vertical offset between present‐day coastal groundwater and sea level, and applying it to ancient times. The current study explores two methods to calculate accurate vertical offsets: a) modern averages of the upper aquifer groundwater elevation in the vicinity of ancient wells, which are calculated from 60 years of measurements by the Israeli Hydrological Service; and b) a hydrological model where groundwater elevation is a function of distance from the modern coastline. The model uses a simulation of the coastal aquifer with a two‐dimensional, vertical cross‐section. The modeled approach is found to be preferable. The results show that sea level in Roman times (1st century CE) was similar to present‐day, slightly higher in the Byzantine period (4th to 7th centuries CE), and lower in part of the Early Islamic period (9th to 10th centuries CE). For the later Fatimid/Ayyubid and Crusader periods (11th to 13th centuries CE), RSL reaches its lowest elevations (of about −0.5 m) as previously found. Following these low levels, sea level rose going into the 18th and 19th centuries CE.

Late Holocene sea level change along the coast of Fethiye Gulf in southwestern Turkey

“…However, Auriemma and Solinas () suggest that functional height depends on the typology of the archaeological structure. Harbor structures (e.g., quays, docks, and piers), fish tanks and water wells are more reliable indicators than buildings, pavements, and so forth which are not directly related to former sea level (Morhange & Marriner, ; Vacchi et al, ; Vunsh et al, ).…”

“…of the archaeological structure. Harbor structures (e.g., quays, docks, and piers), fish tanks and water wells are more reliable indicators than buildings, pavements, and so forth which are not directly related to former sea level(Morhange & Marriner, 2015;Vacchi et al, 2016;Vunsh et al, 2017).I focused upon quay remains for the calculation of relative sea level change because they are the most reliable sea level indicators among the submerged remains. A minimum original elevation of 0.6 m was assigned for quays, taking into account their sheltered location close to wave action, the capacity for the landing of small boats and small tidal range (Aucelli, Cinque, Mattei, & Pappone, 2016; Auriemma & Solinas, 2009).…”

Can we detect centennial sea-level variations over the last three thousand years in Israeli archaeological records?

“…1) on the Carmel coast. Other sea-level studies based on archaeology for the Late Holocene include coastal structures (Flemming, 1978;Raban and Galili, 1985), coastal water wells , and cisterns (Vunsh et al, 2018). Fish pools, flushing channels, and sewage systems have also been used as indicators (Sivan et al, 2001;Anzidei et al, 2011a;Toker et al, 2012).…”

“…Flemming et al, 1986;Pirazzoli, 1987;Sivan et al, 2001). Sea-level indicators include fishponds (Auriemma and Solinas, 2009;Evelpidou et al, 2012), harbour structures such as quays (Leatham and Hood, 1958), submerged prehistoric settlements (Galili et al, 1988) and coastal wells (Nir, 1997;Vunsh et al, 2018).…”

“…Archaeological indicators, however, do not directly estimate past RSL. Instead, the function of a measured architectural remain and its relationship to RSL at time of construction must be evaluated with variables that are specific to the type of archaeological remain, such as the draughts of the ships using a stone pier (Auriemma and Solinas, 2009) or the local water table where a coastal well was dug (Vunsh et al, 2018). The relationship between the archaeological remains and RSL is known as the functional height (Morhange and Marriner, 2015).…”