Hydro-meteorological variability in the Levant (200–1850 CE) reconstructed from historical documentary evidence

Understanding long-term hydro-climatic variability is essential for contextualising present and future water stress in semi-arid regions. In the Levant, instrumental observations are short and paleoclimate reconstructions remain spatially coarse, leaving large gaps in knowledge of past drought and flood dynamics. This study explores the potential of historical documentary evidence to reconstruct hydro-meteorological variability across the Levant between 200 and 1850 CE, with a detailed focus on Damascus, one of the best-documented cities in the region.

We compiled and harmonised 3,507 hydrometeorological records extracted from major historical databases and scholarly compilations based on Arabic, Greek, Syriac, and Latin sources. Events were standardised by type, timing, location, and intensity using a common classification scheme, enabling consistent temporal and spatial analyses. Event frequencies were aggregated at decadal resolution to assess documentation density, biases, and long-term variability across the region. While the resulting dataset spans more than 1,600 years and 50 locations, coverage is highly uneven, with a strong concentration in major urban centres after the thirteenth century. Damascus emerges as the only site with sufficiently continuous records to support quantitative analysis.

For Damascus, we analyse long-term precipitation and flood events between 1250 and 1520 CE, the period of highest documentary density. A semi-quantitative dryness index derived from historical descriptions was constructed and compared with the Palmer Drought Severity Index (PDSI) from the Old World Drought Atlas. Both datasets were aggregated into decadal bins, and drought frequencies were statistically evaluated. Results reveal pronounced multi-decadal hydro-climatic fluctuations, including persistent dry phases in the late fourteenth and early fifteenth centuries, punctuated by episodic but severe flood clusters. The documentary-based dryness index shows a moderate and statistically significant correlation with PDSI at the decadal scale, indicating broad coherence between independent historical and tree-ring-based reconstructions.

Seasonal analysis of historical records further highlights the vulnerability of Damascus to precipitation deficits during autumn and winter, the city’s primary rainy seasons. These findings demonstrate that, despite fragmentation and strong spatial biases, historical documents can provide robust, locally grounded indicators of past hydro-climatic variability when systematically harmonised and analysed.

The study also underscores key limitations, including uneven spatial coverage, source availability, and interpretive uncertainty, reinforcing the need for close collaboration between historians and climate scientists. Integrating documentary evidence with paleoclimate proxies offers a valuable pathway for improving reconstructions in data-sparse regions and for linking hydro-climatic variability to societal impacts in the long term.