Irrigation Sciences and Engineering

Irrigation Sciences and Engineering

Revealing climatic changes in reference evapotranspiration in Kermanshah province using the water requirement system

Document Type : Research Paper

Authors
Mehdi Jovzi 1
Niaz Ali Ebrahimi Pak 2
Seyed Narges Hosseini 3
1 Assistant Professor, Soil and Water Research Department, Kermanshah Agricultural and Natural Resources Research and Education Center, AREEO, Kermanshah, Iran.
2 Associated Professor, Irrigation Research Department, Soil and Water Research Institute, Agricultural Research, Education and Extension Organization (AREEO), Karaj, Iran.
3 Researcher, Irrigation Research Department, Soil and Water Research Institute, Agricultural Research and Education Organization (AREEO), Karaj, Iran
10.22055/jise.2024.45541.2107
Abstract
Reference evapotranspiration, as one of the important components of the hydrologic cycle, is an important factor in field irrigation planning, drought assessment and climate change (Li et al., 2017). Reference evapotranspiration represents the maximum amount of water transferred from the land surface to the atmosphere (Yang et al., 2020). Determining this parameter is the first step in estimating the water requirements of plants and irrigation water management (Yassen et al., 2020). Research on temporal and spatial changes of reference evapotranspiration is very important in order to understand climate change and its effects on hydrologic processes and water resources (Liu and Zhang, 2013). Knowledge of reference evapotranspiration change trends can help agricultural irrigation management and support decision makers involved in water resources management in the future (Yang et al., 2020). In many regions with a shortage of water resources, such as Kermanshah province, the study of reference evapotranspiration changes can help to understand the spatial distribution and temporal changes of water. The purpose of this research is to determine the temporal variations of reference evapotranspiration and the factors affecting it in 10 synoptic meteorological stations of Kermanshah province. The information obtained from this research can provide guidance for agricultural water requirements, irrigation planning and sustainable water resource management under climate change conditions.
Keywords
Climate change
Kermanshah
Penman Monteith
Pettitt's test
Revealing
Water requirements
Subjects

Methodology

The study area is Kermanshah province. This province is located in the geographical coordinates of 33° 41ʹ to 35° 17ʹN and 45° 25ʹ to 48° 6ʹE. The area of this province is 2.44 million hectares, which is about 1.5% of the total area of Iran. Its average height is 1200 meters above sea level. The meteorological data used include minimum and maximum temperature, average temperature, minimum and maximum relative humidity, wind speed, net radiation input to the surface, and daylight hours in the statistical period of 1999 to 2022. The water requirement system of plants which is the result of the Penman Monteith method of FAO was used to determine the reference evapotranspiration. This reference evapotranspiration estimation method is proposed in FAO publication No. 56 as the best method compared to other reference evapotranspiration estimation methods (Sumner and Jacobs, 2005). Pettitt's test of XLSTAT software was used to determine the possible changes in reference evapotranspiration and climatic factors affecting it. Pettitt's test was first presented by Pettitt (Pettitt, 1979). Pettitt's test is a non-parametric test that does not require any assumptions about the data distribution. This test is an adaptation of the Mann-Whitney test, which allows identifying the time in which the change occurs.

 

Results and Discussion

The results of Pettitt's test for reference evapotranspiration in the synoptic meteorological stations of Kermanshah province are shown in Table (1). In Table (1), when the p-value is < 0.05, Pettitt's test is significant at the 5% probability level and indicates the sudden changes of reference evapotranspiration in the investigated time series. The results of Table (1) showed that the changes of monthly and annual reference evapotranspiration time series were significant in 42 and 60% of the studied stations, respectively, at the 5% probability level and indicated the existence of a sudden change in these variables.

 

Table 1-The results of Pettitt's test for reference evapotranspiration in synoptic meteorological stations of Kermanshah province

 

The year and amount of reference evapotranspiration change in the synoptic meteorological stations of Kermanshah province are presented in Table (2). The results of Table (2) showed that the meteorological station of Gilan Gharb had sudden incremental changes in reference evapotranspiration in all months of the year. Eslamabad-e-Gharb, Kermanshah, Gilan Gharb, Javanrud and Hersin stations had sudden incremental changes in annual reference evapotranspiration. Gilan Gharb station had the highest amount of this change with 429 mm. In order to find the reason for the biggest increase in annual reference evapotranspiration at Gilan Gharb station, the time series of each of the parameters affecting the annual reference evapotranspiration was investigated by Pettitt's test. The results showed that although the maximum annual temperature had a sudden decrease, but with an increase in the average minimum annual temperature, wind speed, daylight hours and net radiation, and a decrease in the maximum relative humidity, the reference evapotranspiration increased in this station. The research results of Fu et al. (2022) in China showed that the increase in temperature and wind speed and the decrease in relative humidity had positive and large effects on the increase in evapotranspiration, which agrees with the results of the present study. Ravansar station had a sudden decrease in evapotranspiration of annual reference amounting to 183 mm. In order to find the reason for the reduction of annual reference evapotranspiration at Ravansar station, the time series of each of the parameters affecting the annual reference evapotranspiration was investigated by Pettitt's test. The results showed that although the average temperature, minimum temperature and maximum annual temperature had a sudden increase, but with the increase in the average maximum relative humidity and the decrease in wind speed and annual daylight hours, the annual reference evapotranspiration in this station decreased. In the study of Jhajharia et al. (2012) also pointed out the contradiction of increasing temperature while reducing evapotranspiration. The research results of Liu and Zhang (2013) showed that a significant reduction in wind speed dominates the change of reference evapotranspiration and neutralizes the effect of increasing air temperature that increases the reference evapotranspiration and leads to its reduction. This result agrees with the findings of the present study.

 

Table 2-The year and value of reference evapotranspiration change (mm) in synoptic meteorological stations of Kermanshah province

 

Conclusions

The results of this study show that, in general, from 2003 to 2015, sudden incremental changes in reference evapotranspiration and have occurred in most meteorological stations of Kermanshah province. Sudden incremental changes in reference evapotranspiration indicate an increase in the water requirement of plants. Therefore, water resources should be providing to the agricultural sector with a more appropriate planning, and the farmers, considering the amount of evapotranspiration, should act with better planning regarding the crop selection.

 

Acknowledgments

The authors of this article express their appreciation and gratitude to the officials of the Water Requirement System of Plants (NIAZAB), Soil and Water Research Institute (SWRI), and the I.R. of Iran Meteorological Organization (IRIMO) for their cooperation and providing the data needed for this study.

  • Ahmadi, A., Daccache, A., Snyder, R.L. and Suvočarev, K., 2022. Meteorological driving forces of reference evapotranspiration and their trends in California. Science of the Total Environment, 849, 157823. doi: 10.1016/j.scitotenv.2022.157823.

 

  • Akhvan, S., Mousabeygi, F. and Hashemi Garmdareh, S.E., 2019. Assessment of reference evapotranspiration (ETo) methods under data scarcity scenarios (case study: Kermanshah). Journal of Irrigation and Water Engineering, 9(1), 183–197. doi: 10.22125/iwe.2018.93443 (In Persian).

 

  • Allen, R.G., Pereira, L.S., Raes, D. and Smith, M., 1998. Crop Evapotranspiration: Guidelines for Computing Crop Water Requirements. FAO Irrigation and Drainage Paper 56, Rome, Italy.

 

  • de Martonne, E., 1926. L’indice d’aridité. Bulletin de l'Association de géographes français, 3 (9), pp. 3–5. doi: 10.3406/bagf.1926.6321.

 

  • de Oliveira, R.G., Valle Júnior, L.C.G., da Silva, J.B., Espíndola, D.A.L.F., Lopes, R.D., Nogueira, J.S., Curado, L.F.A., et al., 2021. Temporal trend changes in reference evapotranspiration contrasting different land uses in southern Amazon basin. Agricultural Water Management, 250, 106815. doi: 10.1016/j.agwat.2021.106815.

 

  • Di Nunno, F. and Granata, F., 2023. Future trends of reference evapotranspiration in Sicily based on CORDEX data and Machine Learning algorithms. Agricultural Water Management, 280, 108232. doi: 10.1016/j.agwat.2023.108232.

 

  • Dinpazhoh, Y. and Foroughi, M., 2018. Impact of Climate Change on Sudden Changes in Potential Evapotranspiration Time Series (Case Study: NW of Iran). Journal of Water and Soil, 32(3), 617–632. doi: 10.22067/jsw.v32i3.71351 (In Persian).

 

  • Dinpazhoh, Y., Jahanbakhsh Asl, S. and Foroughi, M., 2019. Sensitivity Analysis of Evapotranspiration to Change in Meteorological Parameters in North-West and West of Iran. Journal of Water and Soil Resources Conservation, 8(2), pp. 1–14. (In Persian).

 

  • Ebrahimi Haftcheshmeh, I. and Farhadi Bansouleh, B., 2021. Spatial variation of reference evapotranspiration in Kermanshah province. Journal of Agricultural Meteorology, 9(2), 61–66. doi: 10.22125/agmj.2021.262567.1106 (In Persian).

 

  • Eslamian, S., Khordadi, M. J. and Abedi-Koupai, J., 2011. Effects of variations in climatic parameters on evapotranspiration in the arid and semi-arid regions. Global and Planetary Change, 78 (3–4), pp. 188–194. doi: 10.1016/j.gloplacha.2011.07.001.

 

  • Fisher, J.B., Whittaker, R.J. and Malhi, Y., 2011. ET come home: potential evapotranspiration in geographical ecology. Global Ecology and Biogeography, 20(1), 1–18. doi: 10.1111/j.1466-8238.2010.00578.x.

 

  • Fu, J., Gong, Y., Zheng, W., Zou, J., Zhang, M., Zhang, Z., Qin, J., Liu, J., Quan, B., 2022. Spatial-temporal variations of terrestrial evapotranspiration across China from 2000 to 2019. Science of The Total Environment, 825, 153951. doi: 10.1016/j.scitotenv.2022.153951.

 

  • Ghamarnia, H., Mousabeygi, F., Amiri, S. and Amirkhani, D., 2015. Evaluation of a Few Evapotranspiration Models Using Lysimeteric Measurements in a Semi Arid Climate Region. International Journal of Plant & Soil Science, 5(2), 100–109. doi: 10.9734/IJPSS/2015/14320.

 

  • Ghasemi, A.R., 2015. Changes and trends in maximum, minimum and mean temperature series in Iran. Atmospheric Science Letters, 16(3), 366–372. doi: 10.1002/asl2.569.

 

  • Haghizadeh, A., Bayat, V. and Arshia, A., 2019. Estimation of The Evapotranspiration potential of Kermanshah synoptic stations Using Genetic Programming. Journal of Geographic Space, 19(67), 29–42. (In Persian).

 

  • Jhajharia, D., Dinpashoh, Y., Kahya, E., Singh, V.P. and Fakheri-Fard, A., 2012. Trends in reference evapotranspiration in the humid region of northeast India. Hydrological Processes, 26(3), 421–435. doi: 10.1002/hyp.8140.

 

  • Jovzi, M., Ebrahimi Pak, N.A. and Tafteh, A., 2023. Estimation of reference crop evapotranspiration by Hargreaves Samani and modified Hargreaves Samani methods and evaluating them using the water requirement system of plants in Kermanshah province. Hydrogeology, 8(1), 1–16. doi: 10.22034/hydro.2023.53196.1271 (In Persian).
  • Li, Y., Yao, N. and Chau, H.W., 2017. Influences of removing linear and nonlinear trends from climatic variables on temporal variations of annual reference crop evapotranspiration in Xinjiang, China. Science of the Total Environment, 592, 680–692. doi: 10.1016/j.scitotenv.2017.02.196.

 

  • Liang, L., Li, L. and Liu, Q., 2010. Temporal variation of reference evapotranspiration during 1961–2005 in the Taoer River basin of Northeast China. Agricultural and Forest Meteorology, 150(2), 298–306. doi: 10.1016/j.agrformet.2009.11.014.

 

  • Liu, X. and Zhang, D., 2013. Trend analysis of reference evapotranspiration in Northwest China: The roles of changing wind speed and surface air temperature. Hydrological Processes, 27(26), 3941–3948. doi: 10.1002/hyp.9527.

 

  • Maunder, W.J., 1995. Dictionary of Global Climate Change. 1st ed., Springer US, Boston, MA. doi: 10.1007/978-1-4615-6841-4.

 

  • Mirmousavi, H., Panahi, H., Akbari, H. and Akbarzadeh, Y., 2012. Calibration Methods to Estimate Reference Crop Evapotranspiration and Calculated Potential Water Requirements of Olive Plant in Kermanshah Province. Geography and Environmental Sustainability, 2(2), 45–64. (In Persian).

 

  • Peterson, T.C., Golubev, V.S. and Groisman, P.Y., 1995. Evaporation losing its strength. Nature, 377, 687–688. doi: 10.1038/377687b0.

 

  • Pettitt, A.N., 1979. A Non-Parametric Approach to the Change-Point Problem. Applied Statistics, 28(2), 126–135. doi: 10.2307/2346729.

 

  • Rahman, M.N., Azim, S.A., Jannat, F.A., Hasan Rony, M.R., Ahmad, B. and Sarkar, M.A.R., 2023. Quantification of rainfall, temperature, and reference evapotranspiration trend and their interrelationship in sub-climatic zones of Bangladesh. Heliyon, 9(9), p. e19559. doi: 10.1016/j.heliyon.2023.e19559.

 

  • Soil and Water Research Institute, 2023. Water Requirement System of Plants. available at: http://niwr.ir/Login.aspx..

 

  • Sumner, D.M. and Jacobs, J.M., 2005. Utility of Penman–Monteith, Priestley–Taylor, reference evapotranspiration, and pan evaporation methods to estimate pasture evapotranspiration. Journal of Hydrology, 308(1–4), 81–104. doi: 10.1016/j.jhydrol.2004.10.023.

 

  • Tabari, H., Marofi, S., Aeini, A., Talaee, P.H. and Mohammadi, K., 2011. Trend analysis of reference evapotranspiration in the western half of Iran. Agricultural and Forest Meteorology, 151(2), 128–136. doi: 10.1016/j.agrformet.2010.09.009.

 

  • Xu, L., Shi, Z., Wang, Y., Zhang, S., Chu, X., Yu, P., Xiong, W., et al., 2015. Spatiotemporal variation and driving forces of reference evapotranspiration in Jing River Basin, northwest China. Hydrological Processes, 29(23), 4846–4862. doi: 10.1002/hyp.10541.

 

  • Yang, L., Feng, Q., Adamowski, J.F., Yin, Z., Wen, X., Wu, M., Jia, B., et al., 2020. Spatio-temporal variation of reference evapotranspiration in northwest China based on CORDEX-EA. Atmospheric Research, 238, 104868. doi: 10.1016/j.atmosres.2020.104868.

 

  • Yassen, A.N., Nam, W. H. and Hong, E. M., 2020. Impact of climate change on reference evapotranspiration in Egypt. CATENA, 194, 104711. doi: 10.1016/j.catena.2020.104711.

 

  • Yin, Y., Wu, S. and Dai, E., 2010. Determining factors in potential evapotranspiration changes over China in the period 1971–2008. Chinese Science Bulletin, 55(29), 3329–3337. doi: 10.1007/s11434-010-3289-y.

 

  • Zare Abyaneh, H., Saghaei, S., Ershad-Fath, F. and Nozari, H., 2014. Modeling and Forecasting of Reference Crop Evapotranspiration Using Time Series, Case Study: Kermanshah Province. Journal of Agricultural Meteorology, 2(1), 45–56. (In Persian).
Irrigation Sciences and Engineering
Volume 48, Issue 1
Spring 2025
Pages 93-112

  • Receive Date 12 December 2023
  • Revise Date 24 April 2024
  • Accept Date 27 April 2024
  • Publish Date 21 March 2025