Holocene sea-level rise and coastal aquifer interactions: Triggering mechanisms for environmental change and impacts on human settlement patterns at Dor, Israel

Abstract

Future sea-level rise is expected to affect coastal aquifers and environments and have significant impacts on coastal communities. Here, we describe the impact of early to late Holocene sea-level variations on the coastal environment and human settlements of the Carmel Coast, Israel. One of these ancient communities, Tel Dor, was settled initially during the Late Pottery Neolithic (ca. 7 ka) on a wetland surface and then abandoned for ca. 1.5 ka before resettlement occurred on the adjacent aeolianite ridge from the Middle Bronze Age to the Crusader period (4.3–0.9 cal Ka BP). For the first time, high resolution chrono-bio-chemo-stratigraphy of sediment cores collected landward of the current shoreline at Dor are presented capturing a record of poorly sorted sand mixed with marine shells, well sorted aeolian sand and silty clay deposits. The record represents a series of brackish-freshwater wetlands formed in the coastal area of Dor between ca. 15 to 7 ka in response to relative sea-level rise and resulting rise of the coastal aquifers. After 7 ka, due to rising sea level and a transgressing shoreline, sand largely derived from the Nile Delta, reached the coast including the coastal wetland. Landward from the current shoreline, the period between ca. 7 to 4 ka is represented by alternating sand-silt facies consisting of reworked marine shells and brackish-fresh water biota. These lithological cycles reflect fluctuations between coastal and wetland environments governed by the response of the coastal aquifer to sea-level rise. Rapid sea-level rise led to a rise in the groundwater table and inundation of the area around Tel Dor, while periods with slower rates of sea-level rise resulted in coastal sand deposition. The settlement gap at Dor between 7 and 5.6 ka possibly reflects the behavioral response of the coastal settlers to sea-level fluctuation, and sediment depositional variation instigating aquifer inundation coastal marsh development and mobilization of sand bodies. This study provides a record of beach profile build-up along the Mediterranean coast of Israel and serves as an example of how sea-level rise affect unconfined coastal aquifers and the formation of wetlands due to rising water tables in low elevation coasts. Coastal inundation is a long-term risk factor for densely populated low-lying coastal regions that require a proactive approach for solving cascading impacts of sea-level rise.