Received: 29 September 2015 Revised: 5 October 2016 Accepted: 7 October 2016 DOI: 10.1002/gea.21637 RESEARCH ARTICLE The underground water systems of Ma’abarta—Flavia Neapolis, Israel Amos Frumkin Cave Research Center, Institute of Earth Sci- ences, The Hebrew University of Jerusalem, Abstract Jerusalem, Israel The Roman city Flavia Neapolis (Hebrew—Shechem; Arabic—Nablus) and its predecessor Hel- Correspondence lenistic Ma’abarta, is a continuously active city, located close to Israel’s water divide. The city pros- Amos Frumkin, Cave Research Center, Institute pered due to water abundance from local springs, associated with its setting along the natural of Earth Sciences, The Hebrew University of Jerusalem, Jerusalem 91904, Israel. outlet of the karstic aquifer of Mt. Gerizim, the holy site of the Samaritans. Complicated tunnel Email: [email protected] systems were constructed for water distribution and consumption during the Hellenistic-Roman Scientific editing by Joe Schuldenrein and Jamie periods. The subterranean systems of the major springs within the city, Ras el ’Ein, ’Ein Qaryun, and Woodward ’Ein Dafna, as well as the main tunnel running along the city include rock-hewn tunnels for ground- water collection, and masonry-built tunnels for the distribution of spring water to the city by grav- itation, and for drainage. Architectural features and structures below the Roman city indicate that some tunnels had already been constructed during the preceding Hellenistic period. A potential cultic element of the urban hydrographic system can be inferred from the elaborate entrance structures of the large springs, Ras el ’Ein and ’Ein Qaryun, as well as from historic accounts. Doc- umentary references to the subterranean water system indicate that its existence may date as far back as 2000 years ago. KEYWORDS Roman, aqueducts, 31 B.C.E. earthquake, barrel vaults, springs, water tunnels 1 INTRODUCTION gle, low-elevation spring (Benami-Amiel, Grodek, & Frumkin, 2010). This restriction necessitated implementation of various strategies to The hydrogeology of Ma’abarta—Flavia Neapolis is unique among maximize water storage and distribution. Chief among these were southern Levantine cities, based on documentary accounts as well as runoff harvesting into cisterns and large reservoirs, as well as con- the archaeological record. The water systems discussed in this paper struction of long aqueducts and tunnels that mobilized and diverted provide evidence of these ancient systems, currently unexposed and water from remote springs (Amit & Gibson, 2014). Similar strategies completely concealed underground. These subterranean systems pre- were applied in Sebaste (Frumkin, 2002; Fig. 1b), a city without any serve structural evidence that is singular within the contexts of ancient springs within its boundaries. Low-elevation cities, such as Akko— artificial cavities (e.g., Parise et al., 2013). Ptolemais (Frankel, 2002), Caesarea (Porath, 2002), and Dor (Peleg, 2002; Fig. 1a), also lacked springs within their urban territories, but their low-altitude settings allowed for the diversion of large water sup- 1.2 Hydrogeology plies from regional sources and catchments. The aforementioned cities The southern Levant is located at the desert border, and features a became increasingly dependent on water supply from distant sources dry Mediterranean to arid climate. The ancient cities along the back- when their populations increased during the Hellenistic-Roman bone of Israel’s central mountain ridge such as Jerusalem (Fig. 1) periods. commonly experienced water shortages, as springs across this ele- Ma’abarta—Flavia Neapolis is a hydrogeological exception, as it con- vated terrain are rare and typically small (e.g., Frumkin, 1999; Mazar, tained large springs within the city and at locations less than 1 km 2002), typical of the situation on most karst areas (Parise & Sammarco, from the city limits. The city’s unique hydrogeological setting is par- 2015). As most cities had no large springs within their urban domains, tially a product of its location within a deep transverse valley that varied efforts were undertaken to overcome water shortages. For breaches the central synclinal divide ridge, between Mt. Gerizim to the example, Jerusalem’s extensive population during the Hellenistic- south and Mt. Ebal to the north (Fig. 2). The main recharge zone of Roman periods exceeded the city’s supply of water derived from a sin- the Ma’abarta—Neapolis springs is the elevated terrain of Mt. Gerizim. Geoarchaeology. 2018;33:127–140. wileyonlinelibrary.com/journal/gea c 2017 Wiley Periodicals, Inc. 127 128 FRUMKIN FIGURE 1 (a) Location map with main groundwater catchments of the region. (b) Geologic map of the research area (map area marked on a). The aquifer of Neapolis springs is within et = Eocene Timrat Formation cropping out on Mt. Gerizim, south of the city (courtesy Israel Geological Survey). Grid is 5 km. lck = lower Cretaceous; c1 = Albian—lower Cenomanian; c2 = middle Cenomanian; c3 = upper Cenomanian; t = Turonian; sp = Senonian-Paleocene; ca = Campanian; ea = lower Eocene; et = lower-middle Eocene; ebk = middle Eocene; nqc = Neogene-Quaternary; q = Quaternary. (c) Structural map (top Judea Group) of Neapolis region. Map area same as b (courtesy Israel Geophysical Institute). Thin lines are structural contours in meters relative to mean sea level. Thick lines are faults; teeth note downfaulted side. Note that Neapolis is located at the focal point of Mt. Gerizim dips. (d) Neapolis rainfall and temperature (Atlas of Israel) [Color figure can be viewed at wileyonlinelibrary.com] FRUMKIN 129 FIGURE 2 The topographic setting of Neapolis-Shechem, between Mt Ebal and Mt. Gerizim, oblique Google Earth view from the NE. The syncli- nal aquifer of Mt. Gerizim is shown schematically. The main springs flow at the northern (right) edge of Mt. Gerizim [Color figure can be viewed at wileyonlinelibrary.com] Structurally, this ridge is a syncline, demarcating the upstream edge a higher concentration of soil-solutes content (e.g., Frumkin & Stein, of the northeastern mountain subaquifer, which is the most important 2004). Eocene aquifer in Israel (Cook, Roth, & Mimran, 1970) (Figs. 1c and 2). The limestone is underlain by Paleocene marls of the Mt. Scopus Group which forms an impervious aquiclude (Cook et al., 1970). The 1.3 History and archaeology synclinal structure of the ridge plunges northward, such that ground- The Roman city Flavia Neapolis (henceforth: Neapolis) was founded water converges from Mt. Gerizim northward, toward Neapolis (Figs. by the Romans in 72–73 C.E., as indicated by the city coins (El-Fanni, 1c and 2). The ridge is steeply entrenched by the Shechem valley, and 2007). The location was on the site of the Hellenistic town “Ma’abarta” Ma’abarta—Neapolis emerged at the foot of the steep slopes of Mt. (Flavius, Wars, 4:8:1) or at “Mamortha” (Pliny the Elder, V:14, p. 427) Gerizim. close to the Biblical city Shechem (Wright, 1965). Neapolis is well- Rainfall infiltrates easily at the fracture-dissected and barren out- documented from archaeology, coins, and historical records, but its crops of the Eocene Timrat Formation limestone on the mountain predecessor Ma’abarta is only sparsely documented and still needs (Fig. 1b). The formation is well-bedded, promoting subhorizontal water to be studied (Magen, 2009). While the population of Ma’abarta is flow along bedding planes northward, along the dip of the syncline axis. unknown, Neapolis was a gentile city with a pagan temple during Mean annual rainfall at Gerizim—Neapolis area is 594 mm (Fig. 1d). Roman times. A Christian population grew in number and was subse- Warm temperatures induce annual potential evaporation of 1600 quently replaced by Moslems. Samaritan and Jewish minorities also mm (The New Atlas of Israel, 2011). Within this Mediterranean cli- played a role in the city’s history. mate zone, rainfall totals are concentrated between November to Several historic records mention briefly the abundant water April, while the summer is hot and dry. Only the larger rain storms sources of Neapolis. Al-Muqaddasi (1994, p. 146) described the city between December to March provide sufficient water to replenish around 985 C.E. as follows: “It lies in a valley shut in between two the aquifer (Sheffer et al., 2010). Ma’abarta—Flavia Neapolis spring mountains…The town is paved and clean, with a stream of running discharges reflect this annual pattern, wherein late winter-spring water through it.” The running water is mentioned also by other writ- flow substantially exceeds late summer-autumn discharge (Fig. 3). ers, such as Dimashki, and by Ibn Batutah (quoted in Le-Strange, 1965, Waters within the studied spring complexes are supersaturated with pp. 513–514). respect to calcite, and undersaturated with respect to dolomite The medieval geographer Yaqut al-Hamawi, writing around 1225 (Sabri, Merkel, & Tichomirowa, 2015). That trend is typical for the C.E., noted that “Nabulus has much water, for it lies adjacent to a moun- Eocene limestone aquifer. The main water solutes are derived from tain, where the soil is stony” (quoted in Le-Strange, 1965, p. 512). This the limestone bedrock, and a secondary source is soil derived. Sr description is consistent with the karstic nature of Mt. Gerizim with its isotopes indicate that Ras el ’Ein has the lowest concentration of many springs, which still supply water to modern Nablus. soil-derived solutes, ’Ein Qaryun is slightly more enriched in soil Geographers and travelers confirmed the abundance of flowing solutes, and ’Ein Dafna has the highest Sr isotopic values, indicating water in the city during the 19th century in art (e.g., Fig. 4), maps 130 FRUMKIN FIGURE 3 Discharge of the two major springs at Neapolis. (a) Mean monthly average of ’Ein Qaryun and Ras el ’Ein. (b) ’Ein Qaryun discharge 1967–2000 [Color figure can be viewed at wileyonlinelibrary.com] (e.g., Fig. 5), and textual reports: 15 springs within the city walls where it is pumped to elevated reservoirs, and consequently dis- were reported by Guérin (1874, vol.