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    Evaluation of Drought Using Meteorological Drought Indices, a Case Study: Alanya (Türkiye)
    (2024) Ghasemlounia, Redvan; Utlu, Mustafa
    Drought is one of the most important challenges that many countries, especially countries in the Middle East region, are struggling with. Based on this, the study and monitoring of hydrological and drought factors is an important issue that can have a significant impact on management decisions in the field of water resources, especially in crisis management. Therefore, investigating the drought parameters is very important to understand the drought situation of a region. In this study, Alanya region, which is located on the southern coast of Turkey, was selected as a case study for drought analysis. Four drought indices for the selected region including: China Z-Index (CZI), Standardized Precipitation Index (SPI), Modified China Z-Index (MCZI) and Z-Score Index (ZSI) have been investigated. All these indicators have been investigated and evaluated using time scales of 1, 6, 12 and 24 months, the coefficient of determination (R2) has been calculated for each drought index with a different time scale and their results have been compared. The findings of the research showed that SPI and CZI drought indices performed better than other selected drought indices in identifying and effectively tracking drought severity. In addition to the study of dry events, wet events were also investigated, which indicates the presence of consecutive floods in the last years of the studied period in the region. The results indicated similar very dry events for the selected indicators in the 6-month period. Also, the rainfall trend for the period of 2015-2022 was taken into consideration to examine the rainfall of the last eight years. The results show that precipitation has decreased in recent years and has a downward trend in most months of the period in question, and the possibility of flood events due to sudden showers in the region has increased due to the continuation of droughts experienced in the years before 2015. Investigating soil moisture and vegetation for the selected period in the study area is also important for the evaluation of the drought level. Evaluation of the available land (vegetation) cover maps of the years 1975, 1985, 2000, 2010, 2020 and 2022 show that the vegetation cover has weakened over the years, and it has been evaluated as an indicator that the danger of drought in the region has increased.
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    Flood prioritization of basins based on geomorphometric properties using principal component analysis, morphometric analysis and Redvan's priority methods: a case study of hars , it river basin
    (Elsevier, 2021) Ghasemlounia, Redvan; Utlu, Mustafa
    Flood events in the Hars, it River Basin, which is located in the Eastern Black Sea Region and actively experienced one of the most flood events in Turkey, were discussed based on drainage basin morphometry using three different methods. In this study, 26 sub-basins over 10 km2 are taken into account and flood dynamics of subbasins are evaluated depending on morphometric properties. The results obtained according to the morphometric parameters are evaluated based on statistical techniques, and the flood priority is determined. A total of 20 different indices were used in this study. The obtained morphometry results were evaluated according to the probability of occurrence of floods according to three different methods including morphometric priority, flood priority according to principal component analysis method and Redvan's priority ranking method. Each method is evaluated within itself and flood priorities of sub-basins have been determined. With respect to the 26 subbasins of the Hars, it River and according to the morphometric priority method and results obtained from this method, 8 sub-basins have low flood priority, 12 basins have medium flood priority, and 7 basins have high flood priority. By examining the results obtained from the PCA priority method, 11 sub-basins have low flood priority, 6 sub-basins have medium flood priority, while 9 basins have high flood priority. Finally, according to the Redvan's priority method and its classification, 11 sub-basins are located in the low priority class, 6 sub-basins have medium flood priority. According to this method, the number of sub-basins with high priority is 9. Priorities obtained using three different techniques were checked for accuracy with 6 different statistical parameters based on predicted and inventory datasets. Accordingly, the accuracy value for the RPRM and PCA methods are higher than the MA method. On the other hand, the RPRM method has the highest TN value, which is equal to 7 subbasins, which shows the correct prediction of sub-basins with the low flood risk. Based on the results, it was seen that the obtained values have a high consistency in basin morphometry. The RPRM, which is a new suggested technique in determining basin flood priority, shows that common basins give very similar results with the results obtained according to morphometry and PCA method. Sub-basins with common flood risk, due to outputs of used methods, were compared with recorded floods map of Turkey.
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    Flood Prioritization Watersheds of the Aras River, Based on Geomorphometric Properties: Case Study Iğdır Province
    (2021) Utlu, Mustafa; Ghasemlounıa, Redvan
    Drainage watershed morphometry plays a major role in terms of understanding flood dynamics. Flood potentials are explained considering the linear, areal, and relief morphometry features of the watersheds. In general, there are number of geomorphometric indices in the description of these features. The formal geometries, geomorphology, geology, and general climate characteristics, etc., which play a decisive role in the flood potential in the watershed, can be determined relatively with morphometric indices. In this study, 35 different river watersheds draining their waters to the Aras, located in the center of Iğdır Province, were examined. Geographic information systems (GIS) and statistical software were chosen to analyze and calculate indices for this research. Flood events occur in these 35 different river watersheds and this study evaluates river watersheds in terms of their flood potential using 14 different indices. In the evaluation of the results obtained, the values that have a high impact on the floods are ranked according to their priorities. These results were evaluated in terms of flood priorities using morphometric analysis and principal component analysis methods. Flood priorities of watersheds, obtained through two different methods, are classified as high, medium, or low priorities. The number of common watersheds, determined based on two different methods, is 8 in river watersheds with "high" priority, 11 in river watersheds with "medium" priority, and 7 in river watersheds with "low" priority. According to these results, it is seen that river watersheds with high priority flood potential correspond to the areas where flood events occurred.