Özet:

Statement of the Problem: Nowadays, it is noteworty that global climate change and its associated with water source variability. For this reason, studies on surface water is of great importance for planning water resorces.Purpose of the Study: The aim of this study is the put out the current trend of Pupa, Hoyran and Gelendost rivers flowing into the Lake Eğridir which are located in province of Isparta, and determine the effect of the rainfall on the trend. Streamflow trend is important that gives impressions for future about nutritional condition of Lake Eğirdir which is the root of natural life and one of the water resourse in the region.Methods: For this purpose, Pupa, Hoyran and Gelendost gauging stations and Gençali, Senirkent and Eğirdir weather stations were anayazed. Non-parametric Mankendall MK trend test was used to determine decrease or increase in the mounthly and annual data sets, and also Sequenal Mann-kendall Coralation Statistic was utilized for define the start time of posibble trends. Seasonal Mann-Kendall test is apllied for show the seasonal changes except normality reason at the time series. Spearman’s coralation test and Kendall tau rank corelatian tests were choosen for represent precipitation effect on the streamflow.Finding and Results: The results show that there isn’t establish a significant trend in precipitation however there is significant downward trend in sellected streamflow in some month, although there isn no trend in annual mean streamflow. Assuming that these decrease trends are shown in all other discontinous steams which flow into the Lake Eğirdir, it can be said that lake’s ecosystem and biodiversity will be affected by decreasing streamflows.Suggestions: Decreasing trend of streamflows is important for planning and management, and should be taken into account for water resource management. If the using of water don’t be controled, ecosystem of Lake Eğirdir will be in jeopardy

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