Trend analysis of monthly rainfall data using the Innovative Polygon Trend Analysis (IPTA) in the Tafna Watershed (Northwestern Algeria)

Authors

  • Djillali Fettam Laboratory n° 25, Promotion of the Water Resources, Mines and Pedological. Legislation of the Environment and Technological Choices, Department of Hydraulics, Faculty of Science and Technology, University Centre of Maghnia, 13300 Tlemcen, Algeria https://orcid.org/0009-0000-6766-0642
  • Radia Gherissi Laboratory n° 25, Promotion of the Water Resources, Mines and Pedological. Legislation of the Environment and Technological Choices. Department of Hydraulics, Faculty of Science and Technology, University Centre of Maghnia, 13300 Tlemcen, Algeria https://orcid.org/0000-0002-1248-8483
  • Abdelkader Otmane Laboratory n° 25, Promotion of the Water Resources, Mines and Pedological. Legislation of the Environment and Technological Choices. Ibn Khaldoun Tiaret University, Faculty of Natural Sciences and Life, Karman, BP14000, Tiaret, Algeria https://orcid.org/0000-0002-0646-3327

DOI:

https://doi.org/10.36253/ijam-3110

Keywords:

Rainfall, Trend, Mann-Kendall test, IPTA, Tafna Watershed

Abstract

Trend analysis of hydroclimatic data is essential for assessing climate variability. Precipitation is an important parameter affected by climate change in the Mediterranean climate, particularly in sensitive regions like the Tafna watershed in Northwestern Algeria. This study used the Innovate Polygon Trend Analysis (IPTA) to study the change between two successive months. Additionally, the Mann-Kendall (MK) test was compared to the IPTA method in detecting trends. Total monthly rainfall data was collected from 14 stations in the Tafna watershed over 50 years from the hydrological year 1970-71 to 2019-20. The maximum trend length using the IPTA method was found in the transition May-June for most stations. The MK test does not indicate any significant trend (increase and decrease) in most of the months at all stations. In contrast, the IPTA method shows an increasing trend in October and January in all stations; August, September, November, and December show an increasing trend in most stations. A decreasing trend was found in February and March at all stations and in May at most stations. The results showed that the MK test detected a significant trend in 6.5% of the total months analyzed in this study, whereas the IPTA method identified a trend in 88.7% of the total months. The findings revealed that the IPTA method was more sensitive to detecting trends in precipitation data than the MK test, which suggests the IPTA method could be a valuable tool for assessing trends of precipitations in the Tafna watershed.

Downloads

Published

2025-06-11

How to Cite

Fettam, D., Gherissi, R., & Otmane, A. (2025). Trend analysis of monthly rainfall data using the Innovative Polygon Trend Analysis (IPTA) in the Tafna Watershed (Northwestern Algeria). Italian Journal of Agrometeorology. https://doi.org/10.36253/ijam-3110

Issue

Just Accepted Manuscripts

Section

CLIMATOLOGY

License

Copyright (c) 2025 Djillali Fettam, Radia Gherissi, Abdelkader Otmane

Creative Commons License

This work is licensed under a Creative Commons Attribution 4.0 International License.

Licence and copyright agreement for IJAM

(revised October 2020)

The following licence and copyright agreement is valid for any article published by IJAM.

Author’s certification

By submitting the manuscript, the authors certify the following:

  • They are authorized by their co-authors to enter into these arrangements.
  • The work described has not been published before (except in the form of an abstract or proceedings-type publication – including discussion papers – or as part of a published lecture or thesis); it is not under consideration for publication elsewhere; and its publication has been approved by all the author(s) and by the responsible authorities – tacitly or explicitly – of the institutes where the work was carried out.
  • They have secured the right to reproduce any material that has already been published or copyrighted elsewhere.
  • They agree to the following licence and copyright agreement:

Copyright

  • The copyright of any article is retained by the author(s). More information on the transfer of copyright can be found below.
  • Authors grant our journals a licence to publish the article and identify itself as the original publisher.
  • Authors grant any third party the right to use the article freely under the stipulation that the original authors are given credit and the appropriate citation details are mentioned.
  • The article is distributed under the Creative Commons Attribution 4.0 License. Unless otherwise stated, associated published material is distributed under the same licence.

Creative Commons Attribution 4.0 License

Anyone is free to share — to copy, distribute, and transmit the work to remix — to adapt the work under the following conditions:

  • Attribution — The original authors must be given credit.
  • For any reuse or distribution, it must be made clear to others what the licence terms of this work are.
  • Any of these conditions can be waived if the copyright holders give permission.
  • Nothing in this licence impairs or restricts the author’s moral rights. The full legal code of this licence.