The effect of climatic change on the physical and chemical properties of Sazlıdere Dam (Başakşehir-İstanbul) upstream and downstream waters

Water is the source of life for all living beings. Potable water resources are limited both globally and in our country. The storage and safe preservation of large amounts of water are done through dams. Due to the increase in civilization level and population, the importance of rivers has increased. Initially, the usage was dependent on the natural regime of the rivers, but this became insufficient over time. With the growing population and advancing technology, water began to be stored. On the other hand, especially with the industrial revolution, and reaching its peak in the 20th century, hydroelectric power plants were established almost everywhere in the world to meet the increasing energy needs. Thus, while water was being supplied for use, cheap energy was also obtained without causing environmental pollution.During the Ottoman period, up until the Republican period, some dams were built in Anatolia. These were generally intended to supply drinking water and were mostly concentrated around Istanbul. The thesis study area is located within the Sazlıdere Dam (Başakşehir-Istanbul) and is a dam built on Sazlıdere, 40 km long, with the purpose of supplying drinking water to Istanbul. Among all the dams in Istanbul with the same purpose, Sazlıdere Dam ranks sixth in terms of efficiency with 33.35 hm³/year, following Ömerli, Terkoz, Büyükçekmece, Darlık, and Alibeyköy dams. The study covers the seasonal changes of the upstream and downstream waters of the dam over the years. Research within the scope of this thesis was conducted in the form of field studies and office studies. In the preliminary office studies, works related to the subject conducted in and around the thesis area were examined, and then field studies were carried out. In the field studies, the geological units around the Dam Lake and the relationship between sample points were examined in detail. In the office studies, 20 years of temperature and precipitation data of Istanbul obtained from the Ministry of Climate Change, the General Directorate of Meteorology 1st Regional Directorate, and the raw physical and chemical analysis results data from the streams feeding Sazlıdere Dam obtained from the 14th Regional Directorate of State Hydraulic Works were statistically evaluated. For the correlation of the changes in the water quality's chemical and physical parameters with climatic data, the SPSS statistics program and Microsoft Excel were used. Monthly correlation analysis was performed for each year with the precipitation data obtained from measurement stations. The data were defined, some tests were conducted, and tables were produced using the SPSS analysis program. This analysis examined the impact of annual precipitation amounts on water parameters. Correlation analysis was conducted to determine if there is a relationship between the variables. Answers were found to the questions of how the chemistry of water changes when the amount of precipitation changes and how the amount of precipitation is affected when the chemistry of water changes. According to the obtained data, the upstream and downstream waters were evaluated according to the Water Pollution Control Regulation, and the impact of climatic change on water quality was determined by utilizing previous studies.