Impact of sea level rise on groundwater in ancient Olympos: Modeling from ∼500 BC to today

Abstract

In the ancient port city of Olympos, located in Antalya, Türkiye, groundwater rise due to long-term sea-level increase threatens significant archaeological structures. Historically, an ancient lake in the northern part of the city, once drained by channels, has transformed into a swamp due to sediment accumulation and channel dysfunctionality, resulting in raised groundwater levels. Consequently, structures like the Building with Mosaics (BM), a prominent archaeological structure from the Early Byzantine Period, have become partially submerged. To investigate this phenomenon, a detailed field study was conducted in May 2017, where meteorological data (precipitation and evapotranspiration), geological, hydrogeological, and high-precision topographic measurements were collected. Groundwater levels were monitored via observation wells, and a tracer test using Rhodamine WT was conducted to estimate hydraulic conductivity. These datasets were utilized to develop steady-state groundwater flow models for three periods (∼500 BC, ∼AD 1, and the present) using MODFLOW software. Results indicated groundwater level increases around BM from approximately 0.33 m (∼500 BC) to 1.62 m (∼AD 1) and 3.55 m (present day). Additionally, the ancient lake's area decreased significantly from 30,000 m² (∼AD 1) to 14,325 m² currently due to sedimentation. These findings underscore how sea-level rise and sedimentation influence groundwater dynamics, highlighting the necessity for targeted groundwater management strategies to safeguard archaeological heritage.