Wilcoxon testi ve saçılma diyagramı kullanılarak hidrometeorolojik verilerin trend analizi
Trend analysis of hydrometeorological data using Wilcoxon test and scatter diagram
Yazar: HATİCE YAĞMUR KALKINÇ
Danışman: DOÇ. DR. YAVUZ SELİM GÜÇLÜ
İstanbul Teknik Üniversitesi / Lisansüstü Eğitim Enstitüsü / İnşaat Mühendisliği Ana Bilim Dalı / Hidrolik ve Su Kaynakları Mühendisliği Bilim Dalı
Derece: Yüksek Lisans, 2024
Konu: İnşaat Mühendisliği = Civil Engineering
Dizin: Hidrometeoroloji = Hydrometeorology ; Yeni eğilimler = New trends ; Yenilik = Innovation ; Zaman serileri = Time series

Özet:
Günümüzde, iklim değişikliğinin etkileriyle birlikte artan su kaynaklarına olan talep 
arasında denge sağlanması zorunlu hale gelmiştir. İklim değişikliği nedeniyle 
mevsimsel değişiklikler, sel ve kuraklık gibi aşırı hava olayları artmakta ve bu durum 
su kaynakları üzerindeki baskıyı artırmaktadır. Bu bağlamda, hidrometeorolojik 
verilerin trend analizi, su kaynaklarının sürdürülebilir yönetimi için hayati öneme 
sahiptir. Bu tez çalışması, yağış ölçümlerinin trend analizine odaklanarak detaylı bir 
inceleme yapmayı amaçlamaktadır.
Tez, geleneksel Mann-Kendall (MK) testi ve modern Yenilikçi Trend Analizi (YTA) 
yaklaşımı gibi yöntemlerin yanı sıra, Wilcoxon testi ve saçılma diyagramı 
kombinasyonunu içermektedir. Bu yöntemler, hidrometeorolojik verilerdeki trendleri 
daha hassas bir şekilde belirlemek ve karakterize etmek için kullanılmıştır. Ayrıca 
saçılma diyagramı ve Wilcoxon testinin birlikte kullanılması, hidrometeorolojik 
verilerin değişen eğilimlerini daha açık bir şekilde görselleştirmektedir.
Çalışma, Türkiye'nin Ege ve Akdeniz kıyı şeridinde yer alan Çeşme, Erdemli, 
Finike, Gazipaşa, Gökçeada, Köyceğiz, Manavgat ve Milas istasyonlarına ait 1989-
2020 yılları arasındaki 32 yıllık yağış verilerini incelemiştir. İncelenen sekiz
istasyonda genel olarak yıllık yağış miktarında bir artış eğilimi gözlemlenmiştir. 
Analizler, Meteoroloji Genel Müdürlüğü'nden alınan 30 dakika, 60 dakika ve 120 
dakika süreyle ölçülen maksimum yağış verilerini içermektedir.
Yapılmış olan analizlerde, 30 dk, 60 dk ve 120 dk'lık yağış verileri ve sekiz istasyon 
için (MK testi için 24, Wilcoxon için 24 ve YTA için 24) toplamda görsel ve sayısal 
olmak üzere 24'der sonuç elde edilmiştir. MK ve Wilcoxon testleri, istatistiksel 
olarak anlamlı azalan bir trende rastlanmadığını, ancak bazı istasyonlarda genellikle 
artan bir trendin olduğunu göstermiştir. 30, 60 ve 120 dakikalık verilerin 
analizlerinde benzer örüntüler ortaya çıktığı gözlemlenmiştir. Coğrafi olarak Ege ile 
Akdeniz birleşiminde bulunan istasyonlarda bariz bir trend artışı ortaya çıkarken, bu 
artışın Akdeniz'in iç istasyonlarında azaldığı net olarak belirlenmiştir.
Elde edilen sonuçlar, bölgesel ölçekte iklim değişikliğinin yağışlara etkilerini 
vurgulamaktadır. Bu bulgular, taşkın risk hesaplamalarında ve su yapılarının 
tasarımında kullanılabilir. Çalışma, Türkiye'nin belirli bölgelerindeki yağış 
trendlerini anlamak adına önemli bir adım oluşturmuş ve sürdürülebilir su kaynakları 
yönetimi için önemli ipuçları sunmaktadır. Bu bağlamda, hidrometeorolojik verilerin 
analizi, gelecekteki iklim değişikliklerine uyum sağlama stratejilerinin 
geliştirilmesinde kritik bir rol oynamaktadır.

Abstract:
In the present era, striking a balance between the effects of climate change and 
the increasing demand for water resources has become imperative. Seasonal 
variations due to climate change lead to extreme events such as floods and droughts, 
intensifying the pressure on water resources. In this context, trend analysis of hydro-meteorological data is crucial for sustainable water resource management. This thesis 
aims to conduct a detailed trend analysis of rainfall measurements, a type of hydro-meteorological data.
The thesis employs both traditional methods like the Mann-Kendall (MK) test and 
modern approaches like the YTA method, alongside the combination of the 
Wilcoxon test and scatter diagram. These methods will be used to determine and 
characterize trends in hydro-meteorological data more accurately. Additionally, the 
study encourages the use of scatter diagrams and the combined use of the Wilcoxon 
test to visualize changing trends in hydro-meteorological data more explicitly.
Focusing on a comparative and practical contribution to the field of trend analysis of 
hydro-meteorological data, the thesis examines 32 years of rainfall data (1989-2020) 
from eight stations located in the coastal areas of Cesme, Erdemli, Finike, Gazipasa, 
Gokceada, Koycegiz, Manavgat, and Milas in Turkey. The results generally indicate 
an increasing trend in annual rainfall in these regions, possibly linked to the onset of 
the impacts of climate change.
The analysis includes time series graphs, MK and Wilcoxon test results, and YTA 
trend analyses based on 30-minute, 60-minute, and 120-minute maximum rainfall 
data obtained from the Turkish State Meteorological Service for the years 1989-
2020. The results from MK and Wilcoxon tests organized geographically and by 
station, reveal consistent patterns in the analysis of 30-minute, 60-minute, and 120-
minute rainfall data. Notably, a clear upward trend is observed in stations located at 
the confluence of the Aegean and Mediterranean regions, while a decrease in 
increasing trend is noted in the inner stations of the Mediterranean.
Various analyses, including time series graphs, MK and Wilcoxon tests, and YTA 
trend analyses, have been conducted on 30-minute, 60-minute, and 120-minute 
maximum rainfall data. The results indicate consistent patterns, with an overall 
upward trend observed in most stations.
The maximum rainfall data for 30 minutes, 60 minutes, and 120 minutes from the 
Gökçeada station was analyzed through the MK test, Wilcoxon analysis, and YTA. 
For 30 minutes, ZMK was found to be 2.06, and ZW was 1.71; for 60 minutes, ZMK
was 2.79, and ZW was 2.48; for 120 minutes, ZMK was 2.56, and ZW was 2.12. In all 
three cases, positive trends were observed. The YTA results support an overall 
increasing trend.
The 30-minute maximum rainfall data for the Çeşme station reveals a ZMK value of 
2.08 based on MK test results, and the Wilcoxon analysis on the same dataset 
determines a ZW value of 1.34. For the 60-minute data, ZMK is found to be 2.42 with 
a positive trend in MK, and ZW is 1.65 with a positive trend in Wilcoxon. The 120-
minute data indicates a ZMK value of 2.32 with a positive trend in MK, and ZW is 
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1.45 with no significant trend in Wilcoxon. The overall increasing trend is evident in 
the YTA results for each case.
The 30-minute maximum rainfall data from the Milas observation station were 
evaluated using MK and Wilcoxon test results, determining a ZMK value of 4.18 and 
ZW value of 2.59. Similar analyses for 60-minute and 120-minute data sets also 
revealed positive trends with ZW values of 2.59 and 2.90, and ZMK values of 4.35 and 
4.33, respectively. These statistical results are supported by YTA results and 
depicted in corresponding scatter diagrams.
The MK test on 30-minute maximum rainfall data from the Köyceğiz station yielded 
a ZMK value of 1.59, while the Wilcoxon analysis based on the same data indicated a 
ZW value of 2.33, revealing a positive trend, confirmed by YTA results. Similar 
analyses for 60-minute and 120-minute data sets also revealed positive trends, with 
ZMK values of 1.56 and 1.59; ZW values of 2.17 and 1.86, respectively, supported by 
YTA results and evident in corresponding scatter diagrams.
Analyzing the 30-minute maximum rainfall data from the Finike station using the 
MK test revealed a ZMK value of 1.93, while the Wilcoxon analysis yielded a ZW
value of 1.47. Positive trends were evident in the MK test results, in contrast to the 
absence of a discernible trend in the Wilcoxon test results; nonetheless, the overall 
increasing trend was affirmed by YTA. For the 60-minute dataset, the MK test 
produced a ZMK value of 2.08, and the Wilcoxon analysis resulted in a ZW value of 
1.47, indicating a positive trend in MK results, while no discernible trends were 
observed in Wilcoxon test results, supported by YTA findings. In the case of the 
120-minute dataset, the MK test yielded a ZMK value of 1.54, and the Wilcoxon 
analysis resulted in a ZW value of 0.67. No discernible trends were identified in both 
MK and Wilcoxon test results, supported by YTA findings for the overall trend.
Manavgat station's 30-minute maximum rainfall data showed a ZMK value of 2.55 in 
the MK test and ZW value of 1.76 in the Wilcoxon analysis, indicating a positive 
trend; a consistent increasing trend was evident in YTA. Similarly, for the 60-minute 
dataset, ZMK was 2.21, ZW was 1.60, and a positive trend was observed in MK, with 
an overall increasing trend confirmed by YTA. The 120-minute data had ZMK of 1.95 
and ZW of 1.40, with a positive trend in MK, an increasing trend affirmed by YTA.
The 30-minute maximum rainfall data from Gazipaşa observation station showed 
ZMK as 0.60 in the MK test and ZW as 0.67 in the Wilcoxon analysis, indicating no 
discernible trend, a conclusion supported by YTA results. Similarly, for the 60-
minute data from Milas station, ZMK was 0.65, and ZW was 0.57 in MK and 
Wilcoxon analyses, respectively, with no observed trend in both analyses. The 120-
minute data from the same station had ZMK of 0.99 and ZW of 1.14 in MK and 
Wilcoxon analyses, respectively, with no discernible trend. The YTA results also 
confirmed the absence of a trend.
Erdemli station's 30-minute maximum rainfall data resulted in ZMK of -0.45 in the 
MK test and ZW of 0.00 in the Wilcoxon analysis, indicating no discernible trend in 
both tests, a conclusion supported by YTA results. The 60-minute data from the same 
station had ZMK of -0.23, ZW of 0.59, with no observed trend in MK and Wilcoxon 
tests, further confirmed by YTA results. The 120-minute data yielded ZMK of 0.24 
and ZW of 1.09, with no discernible trend in both MK and Wilcoxon tests, as 
evidenced by YTA results. The scatter diagram also supports the absence of a trend, 
consistent with the Wilcoxon test.
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Mann-Kendall (MK) and Wilcoxon test results did not reveal statistically significant 
decreasing trends, but generally indicated an increasing trend in some stations. This 
may signify changes in rainfall patterns due to the effects of climate change.
The trend analysis of rainfall data holds critical importance for future water resource 
management. While increased rainfall facilitates irrigation and meets drinking water 
needs, intense and short-duration rainfall poses risks such as floods. Therefore, water 
resource management must consider these risks. The study's results offer valuable 
insights into water resource management. While increased rainfall can positively 
impact sustainable water resource use, the potential risks of intense rainfall events 
must be considered. Flood risk assessments and the design of water structures can 
benefit from the trend analyses conducted in this study.
In conclusion, this research represents a significant step in understanding rainfall 
trends in specific regions of Turkey. Future research should expand to include more 
stations and diverse climate regions for a comprehensive perspective.