Irrigation Sciences and Engineering

Irrigation Sciences and Engineering

Evaluation of the accuracy of LarsWG models and precipitation forecasting in the Karkheh Basin

Document Type : Research Paper

Authors
Maryam Aryasadr 1
Dariush Rahimi 2
1 1- Ph.D. Graduate of Climatology, Department of Physical Geography, Faculty of Geographical Sciences and Planning, University of Isfahan, Isfahan, Iran
2 Professor, Department of Physical Geography, Faculty of Geographical Sciences and Planning, University of Isfahan, Isfahan, Iran
10.22055/jise.2025.48808.2153
Abstract
Recent droughts have significantly reduced river discharge and increased the vulnerability of water resources, making reliable precipitation projections under climate change essential for sustainable water resources management. However, climate simulations are inherently uncertain, and evaluating model performance is a prerequisite for producing reliable future projections. This study aimed to identify the most accurate climate models for simulating precipitation and to assess future precipitation changes in the Karkheh River Basin, Iran. Daily precipitation records from three representative weather stations located in the upstream (Kermanshah), middle (Khorramabad), and downstream (Bostan) sections of the basin were analyzed for the baseline period (1991–2021) using the LARS-WG8 weather generator and outputs from multiple CMIP6 global climate models. Model performance was evaluated using the correlation coefficient (r), Root Mean Square Error (RMSE), and Normalized Root Mean Square Error (NRMSE), and precipitation was projected for the period 2021–2100 under the SSP1-2.6, SSP2-4.5, and SSP5-8.5 scenarios. The results showed that ACCESS-ESM1 consistently achieved the highest performance across all stations, while CNRM-CM6-1, GFDL-ESM4, and MRI-ESM2-0 also demonstrated high predictive accuracy. Future projections indicate considerable spatial and temporal variability in precipitation, with generally increasing precipitation in parts of the central basin but declining trends in the upstream and downstream regions under most scenarios. The observed north-to-south precipitation gradient is expected to persist, while drought frequency and severity are projected to increase, particularly in the northwestern and southern parts of the basin. These findings provide valuable information for climate adaptation planning and sustainable water resources management in the Karkheh River Basin.
Keywords
Estimator Converter
Validation
Karkheh catchment
Global Warming
Subjects
  • Abbasian, M., Moghim, S. and Abrishamchi, A., 2019. Performance of the general circulation models in simulating temperature and precipitation over Iran. Theoretical and Applied Climatology, 135, pp.1465-1483. Doi: https://doi.org/10.1007/s00704-018-2456-y.

 

  • Abdolalizadeh, F., Mohammad Khorshiddoust, A., Jahanbakhsh, S., 2022. 'Assessment of the performance of CMIP6 model for analysis of temperature and precipitation in Urmia Lake basin', Climate Change Research, 3(11), pp. 17-30. Doi:30488/CCR.2022.361233.1093 (In Persian)

 

  • Ahmed, K., Sachindra, D.A., Shahid, S., Demirel, M.C. and Chung, E.S., 2019. Selection of multi-model ensemble of GCMs for the simulation of precipitation based on spatial assessment metrics. Hydrology and Earth System Sciences, 23, pp.4803-4824. Doi: https://doi.org/10.5194/hess-2018-585

 

  • Ajam Zadeh, A., Mollaeinia, M., 2016. 'Assessment of Impact of Climate Change on Firoozabad River Runoff with Downscaling of Atmospheric Circulation Models Output by SDSM and LARS-WG Softwares', Iran-Water Resources Research, 12(1), pp. 95-109. SID. Doi: https://sid.ir/paper/100449/fa (In Persian)

 

  • Almazroui, M., Islam, M. N., Alkhalaf, A. K., Saeed, F., Dambul, R., & Rahman, M. A. 2016. Simulation of temperature and precipitation climatology for the CORDEX-MENA/Arab domain using RegCM4. Arabian Journal of Geosciences, 9, 1-14. Doi: https://doi.org/10.1007/s12517-015-2045-7.

 

  • Ansari, S., Dehban, H., Zareian, M., Farokhnia, A., 2022. 'Investigation of temperature and precipitation changes in the Iran's basins in the next 20 years based on the output of CMIP6 model', Iranian Water Researches Journal, 16(1), pp. 11-24. Doi: https://doi.org/10.22034/iwrj.2022.11204 (In Persian).

 

  • Ashraf Vaghefi, S., Mousavi, S.J., Abbaspour, K.C., Srinivasan, R. and Yang, H., 2014. Analyses of the impact of climate change on water resources components, drought and wheat yield in semiarid regions: Karkheh River Basin in Iran. hydrological processes, 28(4), pp.2018-2032. https://doi.org/10.1002/hyp.9747.

 

  • Bucchignani, E., Mercogliano, P., Rianna, G., & Panitz, H. J. 2016. Analysis of ERA‐Interim‐driven COSMO‐CLM simulations over Middle East–North Africa domain at different spatial resolutions. International Journal of Climatology, 36(9), 3346-3369. Doi: https://doi.org/10.1002/joc.4559.

 

  • Eskani Kazzazi, G. H., 2017. 'Tghyyraqlym simulated effects on water on resources and disaster management of large Karun Basin (The case study: Ahwaz)', Geography (Regional Planning), 6(25), pp. 235-242. Doi: 1001.1.22286462.1395.7.1.35.1 (In Persian).

 

  • Gebisa, B.T., Dibaba, W.T. and Kabeta, A., 2023. Evaluation of historical CMIP6 model simulations and future climate change projections in the Baro River Basin. Journal of Water and Climate Change, 14(8), pp.2680-2705. Doi: https://doi.org/10.2166/wcc.2023.032.

 

  • Habibi, A., and Kolahi, B., 2022. Structural equation modeling and factor analysis, Academic Jihad. (In Persian).

 

  • Hasheminasab, S., Rahimi, D., Zakerinejad, R., & Kropáček, J., 2022. Assessment of climate change impact on surface water: A case study—Karoun river Basin Iran. Arabian Journal Of Geosciences, 15(9), 904. https://doi.org/10.1007/s12517-022-09969-5.

 

  • Hamed, M. M., Sobh, M. T., Ali, Z., Nashwan, M. S., & Shahid, S., 2024. Aridity shifts in the MENA region under the Paris Agreement climate change scenarios. Global and Planetary Change, 238, 104483. https://doi.org/10.1016/j.gloplacha.2024.104483.]

 

  • He, M., Chen, Y., Sun, H. and Liu, J., 2023. Projected Changes in Precipitation Based on the CMIP6 Optimal Multi-Model Ensemble in the Pearl River Basin, China. Remote Sensing, 15(18), p.4608. Doi: https://doi.org/10.3390/rs15184608.

 

  • IPCC, 2022, Change, I.P.O.C., 2001. Climate change 2007: Impacts, adaptation and vulnerability. Genebra, Suíça..

 

  • Jahangir, M. H., Asadi, A., Noroozi, E., Talei, M., 2020. 'Forecasting of Precipitation in Karkheh Catchment Area through LARS-WG Model', Journal of Ecohydrology, 7(4), pp. 981-992. Doi: 22059/IJE.2020.302480.1328 (In Persian).

 

  • Khorshiddoust, A. M., Banafsheh, M. R., Mirhashemi, H., & Kakolvand, Y., 2016. Studying the trend of changes in precipitation-discharge the Karkhe Rive Sub-Basin using non-parametric methods, case study: Kashkan Basin. Irrigation Sciences and Engineering, 38(4), 177-188. (In Persian).

 

  • Khosravi, M., Ismailnejad, M., and Nazaripour, H., 2010. Climate change and its impact on water resources in the Middle East. International Congress of Geographers of the Islamic World, -(4), pp. 0-0. SID. Doi: https://sid.ir/paper/484264/fa (In Persian).

 

 

  • Mesgari, E., Hosseini, S. A., Hemmesy, M. S., Houshyar, M., & Partoo, L. G., 2022. Assessment of CMIP6 models’ performances and projection of precipitation based on SSP scenarios over the MENAP region. Journal of Water and Climate Change, 13(10), 3607-3619. https://doi.org/10.2166/wcc.2022.195.

 

  • Mollaienia, M.R., Mousavi, Z.A. and Mohammadi, M., 2024. Flood modeling in the Qarasu River catchment using four-dimensional vine copulas. Journal of Climate Research, 1403(57), pp.101-118. DOI: 22034/jcr.2024.190468.

 

  • Mukheef, R. A., Hassan, W. H., & Alquzweeni, S. J. A. R., 2024. Projections of temperature and precipitation trends using CMhyd under CMIP6 scenarios: A case study of Iraq's Middle and West. Atmospheric Research, 306, 107470. https://doi.org/10.1016/j.atmosres.2024.107470.

 

  • Nguyen-Duy, T., Ngo-Duc, T. and Desmet, Q., 2023. Performance evaluation and ranking of CMIP6 global climate models over Vietnam. Journal of Water and Climate Change, 14(6), pp.1831-1846. https://doi.org/10.2166/wcc.2023.454.

 

  • Peng, S., Wang, C., Li, Z., Mihara, K., Kuramochi, K., Toma, Y. and Hatano, R., 2023. Climate change multi-model projections in CMIP6 scenarios in Central Hokkaido, Japan. Scientific Reports, 13(1), p.230. Doi: https://doi.org/10.1038/s41598-022-27357-7.

 

  • Rahimiani Iranshahi, H. , Moradi, H. R. and Jalili, K., 2022. Trend of precipitation and temperature changes at different time scales in the Karkheh Watershed. Water and Soil Management and Modelling, 2(2), 1-12. https://doi.org/10.22098/mmws.2022.9520.1048 (In Persian).

 

  • Roshani, A., and Mehdi, H., 2021. Forecasting the effects of climate change scenarios on temperature and precipitation based on CMIP6 models (case study: Sari station). Water and Irrigation Management, 11(4), pp. 781-795.‎ Doi: 22059/JWIM.2022.330603.920 (In Persian).

 

  • Saharwardi, M. S., Dasari, H. P., Hassan, W. U., Gandham, H., Pathak, R., Zampieri, M., ... & Hoteit, I. (2025). Projected increase in droughts over the Arabian Peninsula and associated uncertainties. Scientific Reports, 15(1), 1711. https://doi.org/10.1038/s41598-025-85863-w.

 

  • Salman, S. A., Hamed, M. M., Shahid, S., Ahmed, K., Sharafati, A., Asaduzzaman, M., ... & Dewan, A., 2022). Projecting spatiotemporal changes of precipitation and temperature in Iraq for different shared socioeconomic pathways with selected Coupled Model Intercomparison Project Phase 6. International Journal of Climatology.  http://dx.doi.org/10.1002/joc.7794.

 

  • Semenov, M.A., 2008. Simulation of extreme weather events by a stochastic weather generator. Climate Research, 35(3), pp.203-212. DOI: https://doi.org/10.3354/cr00731.

 

29-Semenov, M.A. and Stratonovitch, P., 2015. Adapting wheat ideotypes for climate change: accounting for uncertainties in CMIP5 climate projections. Climate Research, 65, pp.123-139. DOI: https://doi.org/10.3354/cr01297.

 

 

  • Shafiei, M., Bazrafshan, J. and Irannejad, P., 2018. Assessment of the role of rainfall in river flow drought retrieval in the Karkheh basin. Journal of Meteorology and Atmospheric Science, 1(1), pp.39-52. (In Persian).

 

  • Xie, F., Chandan, D., & Peltier, W. R., 2024. Dynamical Downscaling of the Mid-Holocene Climate Using a Coupled Atmosphere-Ocean Model Over the Mediterranean, North Africa and Middle East Regions. North Africa and Middle East Regions. Doi: http://dx.doi.org/10.2139/ssrn.4723699.

 

  • Yang, X., Sun, W., Wu, J., Che, J., Liu, M., Zhang, Q., Wang, Y., Huai, B., Wang, Y. and Wang, L., 2023. Evaluation and projection of precipitation in CMIP6 models over the Qilian Mountains, China. Remote Sensing, 15(17), p.4350. Doi: https://doi.org/10.3390/rs15174350.

 

  • Zareian M., 2022. Effects of Climate Change on Temperature and Precipitation in Yazd Province Based on Combined Output of CMIP6 Models. jwss 2022; 26 (2), pp. 91-105. ‎ Doi: 10.47176/jwss.26.2.31501 (In Persian).

 

  • Zohrabi N, Massah Bavani A, Goodarzi E, Heidarnejad M., 2016. Identify Trend in the Annual Temperature and Precipitation in Karkheh River Basin. Wetland Ecobiology, 8 (2) :5-22 URL: http://jweb.ahvaz.iau.ir/article-1-434-fa.html (In Persian).

 

36- Zhai, J., Mondal, S.K., Fischer, T., Wang, Y., Su, B., Huang, J., Tao, H., Wang, G., Ullah, W. and Uddin, M.J., 2020. Future drought characteristics through a multi-model ensemble from CMIP6 over South Asia. Atmospheric Research, 246, pp.105111. https://doi.org/10.1016/j.atmosres.2020.105111

Irrigation Sciences and Engineering
Volume 49, Issue 2
Summer 2026
Pages 51-72

  • Receive Date 18 January 2025
  • Revise Date 03 July 2025
  • Accept Date 30 June 2025
  • Publish Date 05 August 2026