Bu çalışmada, Türkiye'nin önemli su havzalarından biri olan Seyhan Havzası'nın yağış yapısının ve atmosferik sirkülasyon değişiminin akım üzerindeki etkisi analiz edilmiştir. Seyhan havzasında yer alan iki farklı akım gözlem istasyonundan elde edilen aylık ortalama akım değerlerinin ve iki farklı yağış gözlem istasyonundan elde edilen aylık ortalama yağış değerlerinin trend analizi yapılmış ve anlamlı trend varlığının belirlenmesi amaçlanmıştır. Trend varlığının belirlenmesinde, lineer olmayan Mann-Kendall ve Spearman'ın Rho testleri, trend eğimlerinin belirlenmesinde Sen'in trend eğim metodu ve trend başlangıç yıllarının belirlenmesinde ise Mann-Kendall sıra korelasyon testi kullanılmıştır. Çalışma sonucunda, ele alınan 17351 ve 17802 numaralı meteoroloji gözlem istasyonlarına ait aylık toplam yağış değerlerinde trend belirlenmemiş olup, 1801 ve 1822 numaralı akım gözlem istasyonlarının aylık ortalama verilerinin beş ayında azalan yönde trend varlığı görülmüştür

Trend analysis of hydrometeorological variables has great concern in the recent past because of the attention given to global climate change from the scientific community. Trend analysis can help in better understanding of the changing pattern of the prominentclimaticvariablesinariverbasin.Precipitation is a key component of the hydrologic cycle and changes in its pattern would directly influence the water resources of a region, as it affects streamflows, soil moisture and groundwaterreservesIn this study, the effects of rainfall structure and atmospheric circulation variability on streamflow in the Seyhan River Basin is analyzed. Monthly mean streamflowobtainedfromtwodifferentgaugingstation and monthly rainfall data observed at the precipitation station within the Seyhan River Basin which is an important basin in Turkey are used to determine the the trend analyses. In the determination of streamflow and rainfall trends, non-linear Mann-Kendall and Spearman's Rho tests are used. The linear slopes of trends are calculated by a technique proposedbySen.TheMann-Kendallrankcorrelation test is used to determine the years in which trends begin. From the present analyses it is found that among the studied stations there are decreasing trends in monthly streamflow data in 1801 and 1822 stations for five months, and there are no trend is found in monthly total precipitation data in 17351 and 17802 meteorological stations.

Population growth, urbanization, industrialization and widespread of irrigation creates a growing pressure on water resources.The maximum water consumption occurs in agricultural irrigation.There is a growing pressure on the more efficient use of water for irrigation.However, there is not a general agreement or method on how to ensure that.By participatory irrigation management, DSI started to transfer of operation of irrigation systems particularly to irrigation associations; the turnover rate has reached 96%. The main income of irrigation associations based on water charges. Pricing policies plays guiding and controlling role for water management. In this study are intended to identify in Harran Plain farmers' willingness to pay for irrigation is a first in this respect.Thereare22wateruserassociations(WUAs) in Harran plain. In the analysis Probit model, a kind of regression analysis was used in Limited Dependent package program. Sampling is done by simple random sampling method among the farmers who are located in Harran plain from every WUAs. It has been found to be very low cost of current water for irrigation. Farmers were payingthe water fee as 5.43% of net income per acre.If certain conditions are met, farmers have shown more willingness to pay with a rate of 71.69%, corresponds to the ratio 9.32% of the net income of farmers per acre. This study is first of its type in GAP-Harran plain and results will be guiding to decision makers in water management