Sürdürülebilir Kalkınma Amaçları
Yayınlar
- MakaleYalnız künye2026The Trend of Monthly Mean Streamflow Values and Regimes in the Susurluk Basin (Türkiye) with Mountain and Semi-Arid Climates
Yıldız, Mehmet Berkant; Toğrul, Burçe; Kankal, Murat; Akçay, Fatma; Şan, Murat; Nacar, Sinan
This study diagnoses monthly trends in streamflow magnitude and regime for the Susurluk Basin (Türkiye), which spans semi-arid and mountainous sub-climates. Monthly records from 1990 to 2019 were analyzed at 14 stream gauges and nine precipitation stations. Trends are assessed with the Mann–Kendall (MK) test alongside recent graphical approaches, Improved Visualization for Innovative Trend Analyses (IV-ITA) to resolve value class-based (low/high) behavior, and Innovative Polygon Trend Analysis (IPTA) with the Star Concept to quantify intra-annual transitions. Before the trend analyses, the stations were tested to determine whether their values were homogeneous, and any inhomogeneous stations were excluded from the study. The consistency between the trends of nine precipitation stations and the streamflow data in the basin was analyzed. Across the basin, the average streamflow increased by approximately 40–60% between January and March at many measurement points. However, it then decreased by around 80% in April, albeit at a more moderate rate in December. This suggests significant rebalancing occurred during the December–April period, when most of the annual streamflow occurs. IV-ITA exhibits broadly similar trends for both low and high streamflow classes, with notable exceptions in January–February. Precipitation–streamflow trend directions are largely consistent in the high-flow season (December–April), supporting the notion that climatic control influences the detected shifts. To contextualize these signals, basin-wide land-use/land-cover shifts (1990–2018), notably urban growth, forest expansion, and cropland reconfiguration, provide process context, indicating that a larger fraction of rainfall is routed as fast surface runoff while infiltration and base streamflow recharge decline, alongside seasonally modified water demand. Collectively, the MK+IV-ITA+IPTA framework reveals class-specific and intra-annual dynamics that are obscured by monolithic tests alone and provides decision-relevant evidence for allocation, drought–flood risk, and operations in an intensively managed basin.
- MakaleYalnız künye2023Reply to discussion of “Innovative approaches to the trend assessment of streamflows in the Eastern Black Sea basin, Turkey”*
Akçay, Fatma; Kankal, Murat; Şan, Murat
In this reply we thank the authors for their comments on our article “Innovative approaches to trend assessment of streamflows in the Eastern Black Sea basin, Turkey.” They stated that the trend slope calculations in our study are incorrect. A response to the discussion on this topic offered.
- MakaleYalnız künye2023Trend analysis of precipitation using innovative approaches in northwestern Turkey
Körük, Ali Emre; Kankal, Murat; Yıldız, Mehmet Berkant; Akçay, Fatma; Şan, Murat; Nacar, Sinan
Precipitation is highly sensitive to climate change, and monitoring its trends over time is essential for understanding the effects of global warming on the Earth's water cycle. This study investigates the effects of climate change on monthly precipitation in the Susurluk Basin located in northwestern Turkey, using innovative trend analysis methods. Innovative Polygon Trend Analysis (IPTA) using star graphics and Improved Visualization for Innovative Trend Analysis (IV-ITA) techniques were used to analyze precipitation data from nine stations in the basin over 50 years (1970–2019), and the findings were compared to classical Mann-Kendall (MK) results. According to the trend analysis results, the MK method detected significant trends in only two months in the decreasing direction. In these decreasing trends observed at Simav and Keles stations in November, z values were calculated as −2.38 and −2.05, respectively. IPTA method detected increasing trends in 54 months and decreasing trends in 40 months; this means there is a change of more than 5% between two half series. The IV-ITA method indicated an increase of more than 40% in the low values for January, March, August, and September. In addition, there was an increasing trend of more than 40% in the high values observed in September at all stations. It was observed that mean precipitation heights increased from September to December and then decreased throughout the basin. It is predicted that decreases in precipitation during dry seasons may put intense pressure on agricultural water use and affect water quality. In addition, the increase in precipitation in spring months may increase flood events. It was determined that graphical innovative trend analysis methods are more effective in trend identification than MK, and these methods' results have much higher visual inspection and linguistic interpretation possibilities. Innovative methods allow for more flexible and in-depth analysis using different statistical parameters.
- MakaleYalnız künye2023Annual Trends of Precipitation and Temperature in the Northwestern Part of Turkey Using Innovative Approaches: A Holistic and Partial Study
Akçay, Fatma; Şan, Murat; Nacar, Sinan; Kankal, Murat
Trend analysis benefits collecting and analyzing reliable data in climate change studies. In this context, long-term temperature and precipitation data analysis, two variables sensitive to climate change, is essential. This study aims to holistically and partially determine the annual trends of precipitation and temperature time series for 1970–2019 at nine selected stations in the Susurluk Basin, Turkey. The innovative trend significance test (ITST), innovative crossing trend analysis (ICTA) method, and Mann-Kendall (MK) test were used to determine holistic trends. Also, partial trends were determined using successive average methodology (SAM). For the precipitation variable, while an increasing trend was determined for the ITST, there was mostly no trend for the other methods. While a strong increasing trend was detected for the temperature according to the ITST and MK methods, no trend was observed in any station according to the ICTA method. According to the SAM results, the maximum trend durations for the peak and trough change points were 4.9 (10.3) and 5.3 (8.4) years, respectively, for precipitation (temperature). The strong temperature trends in the basin will likely continue, requiring precautions against extreme events such as drought.
- MakaleAçık Erişim2022Innovative polygon trend analyses with star graph for rainfall and temperature data in agricultural regions of Turkey
Acar, Emine; Kankal, Murat; Akçay, Fatma; Şan, Murat
Agriculture is affected by climate change, such as extreme increases or decreases rainfall and temperature patterns. It is possible to research that effect by using trend analysis methodologies. This paper investigates trends of monthly total rainfall and mean temperature data of nine selected stations from agricultural regions of Turkey between 1969 and 2020. To the end, the classical Mann–Kendall, Innovative Trend Significance Test (ITST), and Innovative Polygon Trend Analysis (IPTA) with Star Graph methods providing the opportunity to examine seasonal behavior were used for trend analysis. The analysis reveals that about 96% of all monthly rainfall in the Mann-Kendall test has no trend. However, nearly all stations tend to decrease (increase) in November (September) in both innovative approaches. For temperature, it is seen that increasing trend or no trend dominated in general. There were increasing trends in the innovative approaches throughout the year except for April. Temperatures have increased significantly throughout the year in all regions over the last decades. With the help of IPTA, it was also concluded that the seasonal internal variability of rainfall over the entire time and in the last 30 years is quite complex and persists in all agricultural regions. The results show that irregular changes in rainfall and rising temperatures in all stations negatively affected crop yield and/or required more irrigation. In addition, according to the results obtained by comparing trend methods, innovative approaches are very insistent on determining of trend and provide additional information through a visual review of trend behaviors.
- MakaleAçık Erişim2022Innovative approaches to the trend assessment of streamflows in the Eastern Black Sea basin, Turkey
Akçay, Fatma; Kankal, Murat; Şan, Murat
The issue of detection of hydrometeorological trends remains relevant because of the importance of climate change in design, operation, and management studies related to water resources. This study examines the effects of changes in climate and land use on monthly flows (1962–2018) in the Eastern Black Sea basin, Turkey, using innovative trend analysis methods. In this context, innovative polygon trend analysis (IPTA) and innovative trend significance test (ITST) were used to detect the trends and compared with Mann-Kendall test. Only stations with homogeneous data that did not experience non-climatic changes are used in the analysis. IPTA and ITST approaches are much more sensitive than Mann-Kendall in detecting trends. Although the innovative methods are mostly compatible with each other (90%), IPTA presents additional information about trend transitions between successive parts of time series. Results indicate significant decreasing trends in summer months, likely due to diminishing precipitation and effective evaporation.
- MakaleYalnız künye2021Innovative and polygonal trend analyses applications for rainfall data in Vietnam
Şan, Murat; Akçay, Fatma; Linh, Nguyen Thi Thuy; Kankal, Murat; Pham, Quoc Bao
It is a known fact that the size, frequency, and spatial variability of hydrometeorological variables will irregularly increase under the impact of climate change. Among the hydrometeorological variables, rainfall is one of the most important. Trend analysis is one of the most effective methods of observing the effects of climate change on rainfall. Recently, new graphical methods have been proposed as an alternative to classical trend analysis methods. Innovative Polygon Trend Analysis (IPTA), which evolved from Innovative Trend Analysis (ITA), is currently one of the proposed methods and it does not contain any assumptions. The aim of this study is to compare IPTA, ITA with the Significance Test and Mann-Kendall (MK) methods. To achieve this, the monthly total rainfall trends of 15 stations in the Vu Gia-Thu Bon River Basin (VGTBRB) of Vietnam have been examined for the period 1979–2016. The analyses show that rainfall tends to increase (decrease) in March (June) at nearly all stations. IPTA and ITA with the Significance Test are more sensitive than MK in determining the trends. While trends were detected in approximately 90% of all months in IPTA and ITA with the Significance Test, this rate was only 23% in the MK test. Although the arithmetic mean graphs in the 1-year hydrometeorological cycle are considerably regular at almost all stations, their standard deviations are relatively irregular. The most critical month for trend transitions between consecutive months for all the stations is October, which has an average trend slope of −1.35 and a trend slope ranging from −3.98 to −0.21, which shows a decreasing trend.