Rainfall distribution during Dead Sea lake-level rises and falls: Implications for Holocene climates and water resources during long-term droughts in the Middle East
by
Yehouda Enzel
Institute of Earth Sciences and Dept. of Geography Hebrew University of Jerusalem
Coauthors: Revital Ken-Tor (Hebrew University of Jerusalem), Haim Gvirtzman (Hebrew University of Jerusalem), Mordechai Stein (Hebrew University of Jerusalem), David Sharon (Hebrew University of Jerusalem)

The challenge facing any paleoclimate research based on data from paleolakes is the transformation of the geologic/limnologic data into hydrological changes (lake area, stages, etc.). Even more problematic is the transformation of the hydrological changes into quantitative climatic parameters such as precipitation. The difficulties arise from the quality of age dating, spatial and temporal coverage of the climatic data, and large errors in quantifying reservoirs and fluxes of hydrological system. For example, most measurements in and around the Dead Sea basin postdate the intensive diversion of water from the basin. Therefore, a simple relationship between Dead Sea levels and rainfall in its headwaters cannot be obtained directly.

We will present existing and recently constructed chronologies of Dead Sea levels over the last 3000 years and then quantify the level changes in terms of precipitation and water resources in the basin. We overcome the complexity of the hydrologic system of the Dead Sea and the lack of rainfall data that correspond to the Dead Sea levels to construct an analogue for lake level changes in terms of rainfall fluctuations of Jerusalem rainfall; the longest rainfall record in the region. Jerusalem rainfall fluctuations are representing well areas in Israel (north of Beer Sheba), northwestern Jordan, southwestern Syria, and south-central Lebanon. The historic lake curve of the Dead Sea and rainfall data since 1880s are utilized to calculate the mean and standard deviation of Jerusalem rainfall during rise (648 mm/year, sd = 122 mm), fall (445 mm/year, sd = 117 mm), and stable (553 mm/year, sd = 120 mm) lake levels of the Dead Sea prior to the artificial diversions. We suggest that these values can characterize Holocene rains during Dead Sea lake-level changes.

This indicates that the association between Jerusalem rainfall and the Dead Sea level variations, on the one hand, and the precipitation in these areas on the other hand, point at the magnitude of droughts in the entire region. The simple (and obvious) connection between Galilee rainfall and available water in the Sea of Galilee indicates that during these late Holocene Dead Sea level falls little or no available water existed in that major reservoir and the prevailing climatic conditions during these multi-year episodes were severe droughts.

Date received: March 13, 2001

Copyright © 2001 by the author(s). The author(s) of this document and the organizers of the conference have granted their consent to include this abstract in Atlas Conferences Inc. Document # cagc-10.