Şanlıurfa'da iklimden kaynaklanan risklerin tarımsal meteorolojik açıdan analizi
Agricultural meteorological analysis of risks resulting from climate in Şanlıurafa
Yazar: BURAK IŞIK
Danışman: PROF. DR. LEVENT ŞAYLAN
İstanbul Teknik Üniversitesi / Lisansüstü Eğitim Enstitüsü / Meteoroloji Mühendisliği Ana Bilim Dalı / Atmosfer Bilimleri Bilim Dalı
Derece: Yüksek Lisans, 2024
Konu: Meteoroloji = Meteorology

Özet:
Günümüzün en önemli çevresel problemi olan iklim değişikliği ile mücadelede mevcut ve gelecekteki durumun belirlenmesi üzerine birçok farklı alanda çalışmalar sürdürülmektedir. İklim değişikliğinden en çok etkilenen alanlardan biri olan Güneydoğu Anadolu bölgesinde, özellikle yaz dönemlerinde küresel ortalamanın üzerinde sıcaklıklar yaşanmaktadır. Artan sıcaklıklar ile birlikte, ekstrem hava olaylarının şiddetinde ve sıklığında da değişimler meydana gelmektedir.
Bu çalışmada, Şanlıurfa il sınırları içerisinde yer alan Haran, Ceylanpınar ve Bozova ilçeleri ile il sınırında olan Sınır çalışma alanlarının iklim indisleri incelenmiştir. 1986-2020 dönemi için 5,5 km yatay çözünürlüğüne sahip olan "Copernicus European Regional ReAnalysis (CERRA)" verisi, 2026-2100 dönemleri için MPI-M-MPI-ESM-LR (Germany) ve IPSL-CM5A-MR (France) küresel iklim modelleri tarafından üretilen EUR-11 domaine ait 0,11° (~12,5 km) yatay çözünürlüğüne sahip EURO-CORDEX verileri iyimser RCP4.5 ve kötümser RCP8.5 senaryoları kullanılmıştır. Dünya Meteoroloji Örgütü'ne (WMO) bağlı İklim Değişikliği Belirleme ve İndis Uzman Grubu (ETCCDMI) tarafından belirlenen indis tanımları dikkate alınarak, geçmiş ve gelecek dönemler için iklimden kaynaklanan risk ve kuraklık analizleri yapılmıştır. 
Bu analizlerde, bölgenin önemli tarım ürünlerinden olan Harran için pamuk, Bozova için fıstık, Ceylanpınar ve Sınır için mısır bitkileri ele alınarak bitki gelişmesi için elverişli olan optimum sıcaklık aralığı değerlerinin iklim analizleri yapılmıştır. Yapılan analizlere göre hâlihazır dönem ortalama minimum ve maksimum sıcaklık değerleri Harran için 12,3°C ile 23,6°C, Bozova için 11°C ile 22,2°C, Ceylanpınar 12,7°C ile 24°C ve Sınır için ise 12,8°C ile 24,3°C'dir. Yıllık toplam yağış değerleri ise Harran için 377 mm, Bozova için 429 mm, Ceylanpınar için 436 mm ve Sınır için 348 mm'dir. 
2026-2100 yılları RCP4.5 ve RCP8.5 senaryolarına göre yıllık ortalama minimum sıcaklıklarda yaklaşık 1,5°C ile 3,5°C, maksimum sıcaklıklarda ise 2,5°C ile 5°C artış beklenmektedir. Yıllık toplam yağış değerlerinde ise, %10 ile %15 olmak üzere, yaklaşık 30 ile 60 mm azalma beklenmektedir. Gelecek dönemler için yapılan kuraklık analizlerinde ise kurak gün sayısının arttığı nemli gün sayısının azaldığı görülmüştür.
Yüksek sıcaklık değerlerine maruz kalan bitki sağlıklı yaşamını sürdürememekte ve ürünün verim değerleri düşmektedir. Bitki gelişme dönemi olan nisan – ekim ayları arası incelendiğinde sıcaklık değerleri ve sıcak hava dalga sayısı artmakta ve bitki optimum sıcaklık gün sayısı azaldığı görülmüştür. Gelecek dönemlerde bitkiler uzun süre yüksek sıcaklıklara maruz kalacağı öngörülmektedir. Bu durum bitkilerin fizyolojik süreçlerini etkileyerek ürün kalitesinde ve miktarlarında düşüşlere neden olacağı ve bitki gelişme döneminin değişeceği tahmin edilmektedir.
Bu çalışmanın sonucu, Güneydoğu Anadolu Bölgesi'nde, özellikle Şanlıurfa'da, tarım üzerindeki iklim değişikliği etkilerini anlamak açısından büyük önem taşımaktadır. Sıcaklıkların artması ve yağışların azalmasıyla birlikte, çiftçiler ve yöneticilerin bu etkileri hafifletmek için stratejiler geliştirmesi giderek önem kazanmaktadır. Bu stratejiler, daha dayanıklı ürün çeşitlerinin benimsenmesi, sulama verimliliğinin artırılması ve daha iyi toprak yönetimi uygulamalarını içerebilir. Ayrıca, değişen iklime uyum sağlamak ve bölgedeki tarımsal uygulamaların sürdürülebilirliğini sağlamak için sürekli izleme ve araştırma yapılması da kritik öneme sahiptir.

Abstract:
Efforts to address climate change, one of the most pressing environmental problems of our time, involve assessing the current situation across various fields. The Southeastern Anatolia region, one of the areas most affected by climate change, experiences above-average global temperatures, especially during the summer months. Along with rising temperatures, there are changes in the intensity and frequency of extreme weather events. Rising temperatures and decreasing total precipitation values have always been the most critical meteorological parameters for plant growth and productivity. Changes in climate have increased the significance of agricultural lands. For a country like Turkey, which has an arid and semi-arid climate, the further reduction of water resources due to climate change has begun to negatively impact agricultural activities. Considering the increasing consumption needs, it is crucial to conduct academic and strategic studies on plants to minimize the negative effects of climate change in the agricultural sector. Therefore, many researchers analyze the relationship between plant growth dynamics and temperature and precipitation parameters on both regional and global scales.
Studies have highlighted that temperature plays a critical role in the growth and development of plants, emphasizing that every organism has a base temperature below which plant development does not occur. Growing Degree Days (GDD) is used to predict the development of plants and insects throughout the growing season, as well as to forecast crop maturation and harvest dates. Models indicate that with the doubling of atmospheric CO2 levels and a global temperature increase of 1.5-4°C, winter temperatures in Turkey are expected to rise by 2°C, summer temperatures by 2-3°C, summer precipitation to decrease by 5-15%, and summer soil moisture to decrease by 15-25%. Researchers have also investigated the impacts of climate change on plants, finding that the ideal temperature for photosynthesis in cotton is between 26-28°C, with photosynthesis rates decreasing at temperatures above 30°C. To increase cotton yield, it has become important to identify and develop cotton genotypes with high-temperature tolerance. It has been found that the detrimental effects of temperature stress can be mitigated by developing plants with higher temperature tolerance. For maize, extreme temperature stress has been found to significantly reduce maize yield on a global scale. High temperatures, particularly during flowering and maturation periods, can be harmful to maize plants. Researchers have noted that temperature increases will most adversely affect maize yields in tropical and subtropical regions. 
In studies involving pistachio trees, it has been observed that while temperature increases during the summer positively affect plant growth, temperature increases during the winter months adversely affect fruit formation. It has been determined that pistachio trees require chilling during the winter months. Researchers using climate indices with climpact software have examined various meteorological indices such as Prcptot (annual total rainy days), CDD (consecutive dry days), CWD (consecutive wet days), R10mm (number of heavy rain days), R20mm (number of very heavy rain days), Rx1day (maximum one-day rainfall), and Rx5day (maximum five-day rainfall). These indices help us comprehensively understand the impact of precipitation patterns on agriculture.
This study examines the climate indices of Harran, Ceylanpınar, and Bozova districts, and the border areas within the Şanlıurfa province. For the period 1986-2020, the "Copernicus European Regional ReAnalysis (CERRA)" data with a horizontal resolution of 5,5 km was used. For the period 2026-2100, the EURO-CORDEX data produced by the global climate models MPI-M-MPI-ESM-LR (Germany) and IPSL-CM5A-MR (France) for the EUR-11 domain with a horizontal resolution of 0,11° (~12,5 km) was utilized, under the optimistic RCP4.5 and pessimistic RCP8.5 scenarios. Risk and drought analyses for past and future periods were conducted based on the indices defined by the Expert Team on Climate Change Detection and Indices (ETCCDMI) affiliated with the World Meteorological Organization (WMO). 
Monthly bias correction was performed for total precipitation, maximum temperature, and minimum temperature values. To assess the accuracy of these corrections, root mean square error (RMSE), Nash-Sutcliffe efficiency (NSE), Pearson correlation, and Spearman correlation values were calculated. In the study, monthly bias correction was conducted for total precipitation, maximum temperature, and minimum temperature values under RCP4.5 and RCP8.5 scenarios. The years 1986-2005 were used for calibration, and the years 2006-2020 were used for validation. To verify and compare the corrections, root mean square error (RMSE), Nash-Sutcliffe efficiency (NSE), Pearson correlation, and Spearman correlation values were calculated for both raw and corrected data. For raw data, NSE was approximately 0.7, and Pearson and Spearman correlations were around 0.9. After bias correction, NSE improved to approximately 0.9, and Pearson and Spearman correlations remained around 0.9. RMSE decreased from an average of 200 to 100 for precipitation and showed little change for temperature values. Based on these results, corrected climate projection data for the years 2026-2100 were obtained. Similar results were found in another study for Şanlıurfa, where climate projection values were analyzed with both raw and corrected data.
In these analyses, the crops considered include cotton for Harran, pistachio for Bozova, and corn for Ceylanpınar and the border areas, focusing on the minimum and optimum temperature values favorable for plant growth. According to the analyses, the current average minimum and maximum temperature values are 12,3°C and 23,6°C for Harran, 11°C and 22,2°C for Bozova, 12,7°C and 24°C for Ceylanpınar, and 12,8°C and 24,3°C for the border areas. The annual total precipitation values are 377 mm for Harran, 429 mm for Bozova, 436 mm for Ceylanpınar, and 348 mm for the border areas. For the years 2026-2100, the RCP4.5 and RCP8.5 scenarios project an increase in annual average minimum temperatures by approximately 1,5°C to 3,5°C, and maximum temperatures by 2,5°C to 5°C. Annual total precipitation values are expected to decrease by 10% to 15%, which corresponds to a reduction of approximately 30 to 60 mm. 
The current and future trends in the study areas indicate a decrease in frost days, cool days, cool nights, cold spells, and lengths of cold wave days, as well as annual total rainfall. Conversely, an increase is observed in summer days, tropical nights, heatwave frequency, hot days, hot nights, and periods of drought.
During the plant growth periods from April to October, the current average temperature exceeds the maximum temperature needed for cotton by 55 days and for corn by 10 days. In future periods, these days are expected to increase to 70-120 days for cotton and 20-80 days for corn. For pistachio trees, the number of cold requirement days from December to February is currently 60 days, decreasing to 20-50 days in future periods.
Degree days for cotton are currently between 2292 and 2360, increasing to 3520 in future periods. For corn, current degree days are 3644, expected to rise to between 3853 and 5276 in future periods.
The rising temperatures are likely to bring changes during the plant growth period from April to October. In future periods, March is projected to be the planting season and July-August the harvesting period. Increased temperatures negatively impact plant development, potentially reducing product quality and yield due to accelerated growth. In Şanlıurfa, Turkey's least rainy province, decreased rainfall and expected drought during the plant growth period are likely to increase irrigation activities in the region.
The results of this study are of great importance in understanding the effects of climate change on agriculture in the Southeastern Anatolia Region, particularly in Şanlıurfa. With rising temperatures and decreasing precipitation, it is becoming increasingly important for farmers and policymakers to develop strategies to mitigate these effects. These strategies might include adopting more resilient crop varieties, improving irrigation efficiency, and implementing better soil management practices. Additionally, continuous monitoring and research are critical for adapting to the changing climate and ensuring the sustainability of agricultural practices in the region.