Meteorolojik kuraklık analizi ve yeraltı suyu değişimleri üzerindeki etkileri, Marand Ovası (Iran) örneği

Öz

Meteorolojik kuraklık, spesifik bir kuraklık türü olarak, bir bölgede yağışın uzun vadeli ortalamalardan daha az olması durumunda ortaya çıkmaktadır. Yeraltı sularında gözlemlenen bu olayın tehlikeli etkilerinden biri, kuraklıklara tepki olarak su seviyesinin düşmesidir. Bu çalışmada, iklimsel ve yeraltı suyu verileri, aralarındaki muhtemel ilişkiyi anlamak için son yıllarda kuzeybatı İran’da Marand ovasında yer alan eğilimlerini analiz etmek için kullanılmıştır. Buna göre, ilk olarak yeraltı suyu seviyesi verileri analiz edilmiş ve zamansal eğilimleri çıkarılmıştır. Daha sonra bölgenin iklimsel durumunu anlamak için Ombrotermik diyagramı kullanılmıştır. Son olarak kuraklık indeksi (SPI) ile kuraklık analizleri yapılmıştır. Çalışmadan elde edilen sonuçlara göre, yeraltı suyu seviyesinin hem aylık hem de yıllık değişimlerinde azalış eğilimi tespit edilmiştir. Ayrıca, bölgede Mayıs ve Ekim ayları arasındaki periyodun kurak geçtiği ve bölgenin kısmen kuru bir iklime sahip olduğu da tespit edilmiştir. SPI değerleri bölgenin 2001 ve 2002 yıllarında ve genel olarak Temmuz ve Haziran ayları arasında oldukça kurak dönemler geçirdiğini göstermiştir. Yeraltı suyu seviyesi ve SPI değerlerinin ortak analizi, kuraklığın etkilerinin yeraltı suyu seviyesi değişikliklerinde belirgin olduğunu ortaya çıkarmıştır. Buna göre, bölgenin yeraltı suyu değişimlerinin çoğunlukla aylık kuraklıklarla ilişkili olduğu ve su seviyesinin beklenen şekilde ıslak ve kurak aylara tepki verdiği tespit edilmiştir. Ancak, aynı zamanda, çalışma alanının yeraltı suyu seviyesindeki yıllık değişikliklerinin, kuraklık dönemleriyle doğrudan ilişkili olmadığı ve bu olguda diğer faktörlerin de etkili olabileceği ortaya koymuştur.

Anahtar Kelimeler

• Yeraltısuyu değişimleri,CBS,Kuraklık,Marand ovası,İran

Analyses of meteorological drought and its impacts on groundwater fluctuations, a case study: Marand Plain (Iran)

Öz

Meteorological drought is one specific type of drought that occurs when precipitation is less than the long-term averages in a particular area. One of the hazardous impacts of this phenomenon observed on subsurface waters is the decline of water level in response to droughts. In this study, the climatic and groundwater data were used to analyze their trends in Marand plain, NW Iran, over the past decades to understand the likely relationship between them. To this, groundwater level data were first analyzed and its temporal trends were extracted. Then, the climatic condition of the region studied using the Ombrothermic diagram. Finally, drought analyses were conducted through drought index (SPI). Based on the results of the study, a descending trend was detected in both monthly and annual fluctuations of the groundwater level. It's also found that the region had a partially dry climate with a period of dry months between May and October. The SPI values showed extremely dry periods in 2001 and 2002 and months of July and June during the study period. The joint analysis of groundwater level and SPI values revealed that the impacts of drought were evident on groundwater level changes. Accordingly, the region's groundwater fluctuations found to be mostly under the control of monthly droughts where water level responds to wet and dry months in an expected manner. However, it's also found that the yearly changes in the groundwater level of the study area were not directly correlated to drought periods, suggesting that other factors might be effective in this phenomenon.

Anahtar Kelimeler

• Groundwater fluctuations,GIS,Drought,Marand plain,Iran

Kaynakça

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