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Combined parametric and non-parametric assessment of relative humidity trends in a semi-arid river basin

Document Type : Research Paper

Authors

  • Hedieh Ahmadpari 1

  • Vitaly Khaustov 1

  • Ata Amini 2

  1. 1 Department of Engineering Hydrology, Institute of Hydrology and Oceanology, Russian State Hydrometeorological University, Saint Petersburg, Russia
  2. 2 Assistant Prof. Kurdistan Agricultural and Natural Resources Research Center, AREO, Sanadaj, Iran
DOI icon https://doi.org/10.22034/ewe.2025.538388.2048

Abstract

Relative humidity is an essential climatic parameter with direct implications for environmental studies and water resource management. Despite its importance, long-term variability in relative humidity remains less explored in many semi-arid river basins. This study aimed to detect trends in relative humidity in the Darreh Dozdan River Basin, Iran, over the period 1998–2022. To achieve this, four complementary methods were applied at monthly and annual scales, including the Mann–Kendall trend test, Sen’s slope estimator, Pearson correlation, and linear regression.  The analysis revealed that only two months, January and May, exhibited statistically significant trends. January showed a consistent decline, with relative humidity decreasing by about 0.39% per year (Mann–Kendall Z = –2.06; Pearson r = –0.47; p = 0.02). In contrast, May displayed an increasing trend of approximately 0.51% per year (Z = 2.18; Pearson r = 0.40; p = 0.05). No other months indicated significant changes, and the annual trend analysis confirmed remarkable stability, with no detectable long-term increase or decrease in relative humidity during the 25 years. These findings suggest that while annual humidity has remained stable, seasonal shifts are emerging. Such insights are valuable for climate monitoring and for guiding adaptive water management strategies.

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References
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Environment and Water Engineering

Volume 11, Issue 4
March 2025

Pages 519 - 532

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  • Receive Date: 28 September 2025
  • Revise Date:
  • Accept Date:
  • Publish Date: 28 September 2025
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