Revisiting historical sea level elevation in Israel from the British Mandate period through the present day (1922–2017)

Abstract

Long-term series of reliable sea level (SL) data are essential for understanding the trends and causes of SL changes, for furthering knowledge about the effects of current climate change and for predicting future SL evolution. This study aims to extend the SL time series of measurements along the Israeli Mediterranean coastline by revisiting historical benchmarks (BM) along the Israeli coast, first determined by the British Survey of Palestine (SOP) at 1922 and later by the Survey of Israel (SOI) in 1995. By identifying and remeasuring the historical BM from Gaza to Imera (1922) and in Jaffa (1936), this study reconstructs the historical mean sea level (MSL), anchoring it to the present national height network, and extending the SL time series of equipped measurements along the Israeli coastline. Accordingly, the study provides long-term SL trends for the Levantine Basin. The long-term SL time series reveals an increasing trend in the 1920s, which moderates during the 1930s, a decreasing trend from the 1960s to the 1990s, and a rapid increasing trend in the 1990s. As a result, it can be deduced that the historical datum can reflect the historical MSL of its period, extend the long-term SL data and by that indicate for environmental changes. Based on long-term SL data (1956–2016) it can be determined that the MSL of Israel is 0.082 m relative to the 1995 Israeli datum.