Drought Features of the Akçay Lower Catchment Area (Antalya/Finike) and Identifying Potential Areas for Water Harvesting in the Basin
Neslihan Açıkgöz, Ebru AkköprüThis study focuses on drought and water harvesting issues. The standardized precipitation index (SPI) was used to determine the drought characteristics of the region. To identify potential areas for water harvesting, this study employed analytical hierarchy processes (AHP) from multicriteria decision-making methods and geographic information systems. The results of the drought analysis of SPI made with the data of the Finike Meteorology Station from 1973 to 2021 showed that the dry periods for the last 3 years have been more severe than the previous ones. The study determined six criteria based on the geographical and meteorological characteristics of the area: land use, river distance, geology, slope, precipitation, and temperature. The AHP was used to determine the weights of the criteria, and the results showed that precipitation was the most important criterion, followed by slope, river distance, geology, temperature, and land use. Weighted overlay analysis was performed on the criteria, and it was found that there was a suitable area with 23% strength for water harvesting.
Akçay Havzası Aşağı Çığırının (Antalya/Finike) Kuraklık Özelliği ve Su Hasadı Yapılabilecek Potansiyel Alanların Belirlenmesi
Neslihan Açıkgöz, Ebru AkköprüAkçay havzası aşağı çığırının (Finike/Antalya) kuraklık özelliği ve bu alanda su hasadı yapılabilecek potansiyel alanların belirlenmesi başlıklı bu çalışmada, kuraklık ve su hasadı konuları üzerinde durulmuştur. Bölgenin kuraklık özelliğini belirlerken kuraklık indeksleri arasında yaygın olarak kullanılan standartlaştırılmış yağış indeksi (SYİ) kullanılmıştır. Ardından su toplama sistemlerinden bahsedilmiştir. Çok Kriterli Karar Verme (ÇKKV) yöntemlerinden analitik hiyerarşi prosesleri (AHP) ve mekansal analizlerde kullanılan Coğrafi Bilgi Sistemleri (CBS), su hasadı yapılabilecek potansiyel alanların belirlenmesinde kullanılan yöntemlerdir. Finike Meteoroloji İstasyonu 1973-2021 yılları arası verileri ile yapılmış standartlaştırılmış yağış indisinin yıllık ortalama kuraklık analizi sonuçlarına göre son 3 yıldır kurak dönemlerin, daha önceki kurak dönemlere göre daha şiddetli olmasıdır. İnceleme alanının coğrafi ve meteorolojik özellikleri dikkate alınarak 6 kriter belirlenmiştir. Bunlar: Arazi kullanımı, nehir mesafesi durumu, jeoloji, eğim, yağış ve sıcaklıktır. Kriterlerin ağırlıkları AHP ile belirlenmiş ve en fazla önemin yağış olduğu, bunu sırasıyla eğim, nehir mesafesi, jeoloji, sıcaklık ve arazi kullanımının takip ettiği görülmüştür. Kriterlere ağırlıklı çakıştırma analizi yapılarak su hasadı için %23 kuvvetle uygun alan bulunduğu tespit edilmiştir.
Drought is a natural disaster that develops slowly but has a huge impact. The distribution of water resources and precipitation is uneven worldwide, and water is a cycle. Turkey is located in a semiarid/semihumid climatic region, and if a drought disaster occurs, different regions can be affected in various ways. Taking measures before a crisis occurs can delay or reduce the severity of disasters. Therefore, it is essential to harvest rainwater in suitable areas. Water harvesting techniques reduce the effects of water scarcity and drought by collecting rainwater in arid regions (Kuzucu, 2019: 577). The process of accumulating or storing rainwater falling on the surface in arid and semiarid areas with little or no precipitation is known as “water harvesting” (Oweis, et al., 2001: 3; Kuzucu 2013: 6). Water harvesting is a method that has been in use for 40–50 years in many arid regions worldwide. This method is particularly useful in deserts and dry areas with annual precipitation of 50–80 mm (Köksal, 2000; Kuzucu 2013: 3).
To ensure maximum efficiency in water harvesting projects, suitable areas are identified using multicriteria decision methods, remote sensing, and geographic information systems. By conserving water, it is possible to achieve positive effects such as reducing the severity of drought or delaying its onset.
Long-range meteorology bulletin, monthly, annual, and average data of precipitation and temperature parameters of Finike Meteorology Station, located in the lower part of the Akçay basin, were obtained from the GDM in 4 region.
A location map that denotes the study area’s boundaries and location along with topography, slope, hydrology, soil, and land use maps was obtained from General Directorate of Maps (GDM). A temperature distribution map was created using the Lapse rate formula in the ArcGIS 10.5 program, and precipitation distribution maps were created using Kriging analysis.
The standardized precipitation index (SPI) is the most used index to determine drought conditions in any region (Türkeş, 2012: 15). Using the method developed by Mckee et al., (1993), the SPI value is calculated by converting the precipitation value into a numerical value (Arslan et al., 2016: 190). This index can be calculated for different periods, such as 1, 3, 6, 9, 12, and 48 months. To accurately calculate SPI values, at least 30 years of data are necessary (Mckee et al., 1993; Arslan et al., 2016: 191). To ensure accuracy, 51 years of data (1970–2021) were used in this study, and the “SPI SL 6.exe” program was used for calculation.
The analytical hierarchy process (AHP) method is the most used method for eligibility analysis (Güler and Yomralıoğlu, 2017; Uyan, 2017; Gürkan et al., 2021; Ödeker and Bayar, 2021; Akıncı et al., 2015; Ertunç and Çay, 2020; Akıncı et al., 2012; Yalçın and Yüce, 2018). Herein, six criteria were first determined using the AHP method: slope, land use, geology, stream distance, rainfall, and temperature. To evaluate the importance of these criteria, 15 comparative matrices were created, and 10 experts were asked to complete a questionnaire using Saaty’s 1–9 scale. The geometric averages of the completed questionnaires were used to calculate consistency and weight ratios. The “Super Decisions” program was utilized to determine the weights of each criterion. These weights were then used in the reclassification process of the maps using the ArcGIS 10.5 program. The resulting “Reclassified” maps were overlapped with the “Weighted Overlay” analysis to identify suitable potential areas using spatial analysis.
This study utilized various methods and techniques. The standardized precipitation index was used to examine drought, and an annual average drought analysis was conducted for the basin. Suitability analysis methods were employed to identify potential areas for water harvesting. The analytical hierarchy process, a multicriteria decision-making method, played a crucial role in this study. This method helped determine the criteria and their weights, creating a vector of priorities. Criteria classification was done using the obtained weight values and geographic information systems, and a map showing suitable areas was generated using the weighted overlay method.
Based on data from the Finike Meteorology Station, the annual average drought analysis of the standardized precipitation index between 1973 and 2021 showed that the area was neither completely dry nor completely humid. However, the last three years had more severe dry periods compared to previous years.
Geographic information systems were used to determine potential areas for water harvesting and conduct spatial analysis. However, it is important to note that these systems require additional methods, such as analytical hierarchy, to support them. Herein, criteria were determined, expert opinions were used to determine their weights, classification was performed, and then weighted overlapping analysis was applied. This led to the identification of strong suitable areas, moderately suitable areas, low-level suitable areas, and unsuitable areas in the Akçay basin for water harvesting.
