Türkiye’de Referans Bitki Evapotranspirasyonunun Geleceğe Yönelik Değişim Öngörüleri

Abstract

İklim değişikliğinin, küresel ölçekte evapotranspirasyon dinamiklerini yoğunlaştırması beklenmekte olup bu durum, sürdürülebilir su yönetimi ve tarımsal üretkenlik açısından önemli zorluklar doğurmaktadır. Bu çalışmada, referans bitki evapotranspirasyonunun (ETo) Türkiye genelindeki mekânsal ve zamansal değişkenliği, HADGEM iklim modeli kullanılarak RCP4.5 ve RCP8.5 senaryoları altında, yakın (2023-2052) ve uzak gelecek (2069-2098) dönemleri için, referans döneme (1971-2000) göre değerlendirilmiştir. ETo hesaplamaları FAO Penman-Monteith denklemi ile yapılmış; zamansal süreklilik ve değişkenlik sırasıyla Spearman sıra korelasyonu ve değişim katsayısı kullanılarak incelenmiştir. Sonuçlar, Türkiye’nin büyük bölümünde ETo değerlerinde yaygın ve istatistiksel olarak anlamlı bir artış olduğunu ortaya koymuştur. En belirgin değişim, uzak gelecek dönemine ait RCP8.5 senaryosu altında gözlenmiştir. Ortalama ETo artış oranı, Isparta, Niğde ve Gaziantep gibi karasal ve güney illerinde %25’in üzerine çıkarken, nemli Karadeniz Bölgesi en az etkilenen bölge olmuş ve artış oranı %20’nin altında kalmıştır. Mevsimsel analizler, yaz mevsiminin en istikrarlı ancak en yoğun buharlaşma dönemini, kış mevsiminin ise en yüksek değişkenliğe sahip dönemi temsil ettiğini göstermiştir. Bu bulgular, artan sıcaklıklar ile değişen nem–ışınım etkileşimlerinin buharlaşma talebini ve sulama gereksinimlerini önemli ölçüde artıracağını ortaya koymaktadır. Dolayısıyla, bölgeye özgü uyum stratejileri ve entegrasyon temelli su yönetim politikaları, gelecekteki iklim koşulları altında tarımsal dayanıklılığın sağlanması açısından kritik öneme sahiptir.

Keywords

• İklim değişikliği
• HADGEM
• Penman-Monteith
• mekansal değişkenlik
• Spearman korelasyonu

Thanks

This study contains partial findings of the PhD dissertation of Ali Kaan Yetik. The authors are gratefully acknowledged to the Turkish State Meteorological Service for sharing meteorological data used for this study.

Projected Variations in Reference Crop Evapotranspiration Across Türkiye

Abstract

Climate change is expected to intensify evapotranspiration dynamics globally, posing significant challenges for sustainable water management and agricultural productivity. This study assessed the spatial and temporal variability of reference crop evapotranspiration (ETo) across Türkiye using the HADGEM climate model under RCP4.5 and RCP8.5 scenarios for the near (2023-2052) and far future (2069-2098) periods, relative to the reference baseline (1971-2000). ETo was estimated using the FAO Penman Monteith equation by ETo Calculator, while temporal persistence and variability were examined through the Spearman rank correlation and coefficient of variation, respectively. Results revealed a widespread and statistically significant increase in ETo across most regions, with the most pronounced changes occurring under the far-future RCP8.5 scenario. Average ETo increases exceeded 25% in continental and southern provinces such as Isparta, Niğde, and Gaziantep, while the humid Black Sea region remained the least affected, showing increases below 20%. Seasonal analyses identified summer as the most stable yet intense evaporative period, and winter as the season with the highest variability. These findings indicate that rising temperatures and altered humidity-radiation interactions will substantially increase evaporative demand and irrigation requirements. Consequently, region-specific adaptation strategies and integrated water management policies will be critical to ensure agricultural resilience under future climate conditions.

Keywords

• Climate change
• HADGEM
• Penman-Monteith
• spatial variability
• spearman correlation

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