Climate Change and Climate Disaster

An integrated analysis of observed changes in hydro-climatological variables of Iran

Document Type : Original Article

Authors

Peyman Mahmoudi
Abdolraoof Shahozei

Department of Physical Geography, University of Sistan and Baluchestan, Zahedan, Iran

10.30740/cccd.2025.737314
Abstract
This study presents an integrated analysis of trends in key hydro-climatic variables, i.e. minimum temperature, maximum temperature, precipitation, and potential evapotranspiration (ET₀), across annual and seasonal timescales, utilizing 30 years (1986-2015) of data from 62 meteorological stations in Iran. Using Sen’s slope estimator, results reveal a consistent warming trend across the country, notably a significant increase in winter temperatures, implying reduced snow-to-rain ratios and earlier snowmelt. At the national scale, the increasing trend in ET₀ ​coupled with decreasing precipitation paints a clear picture of Iran’s climate becoming drier. Spatial analysis identified Western and Northwestern Iran as “Hotspots of Change,” experiencing the most pronounced temperature increases and precipitation decreases, posing threats to regional water and food security. A notable finding was the observed decreasing trend in ET₀​ in some southern stations, attributed to the “Evaporation Paradox,” highlighting the importance of considering factors like wind speed and solar radiation. Collectively, this study provides robust evidence of escalating climatic stress on Iran’s water resources and underscores the necessity for adaptive, regionally-focused management strategies for vulnerable areas.

Keywords

Trend, Sen&rsquo
s slope estimator, Potential evapotranspiration, FAO-56 Penman-Monteith method, Thiessen polygon method
Subjects

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