Determination of Climate Changes on Air Temperature and Shahar-Chai River in the West of Urmia Lake Using Trend and Stationarity Analysis

Ahmadi, Farshad; Khalili, Keyvan; Behmanesh, Javad; Verdinazhad, Vahidreza

Determination of Climate Changes on Air Temperature and Shahar-Chai River in the West of Urmia Lake Using Trend and Stationarity Analysis

Document Type : Research Paper

Authors

Farshad Ahmadi ¹

Keyvan Khalili ²

Javad Behmanesh ²

Vahidreza Verdinazhad ²

¹ M. Sc. Student, Water Engineering Department, Faculty of Agriculture, Tabriz University, Iran .

² Assistant Professor, Water Engineering Department, Urmia University, Iran.

Abstract

Detecting trend and stationarity in hydrological time series may help us to understand the possible links between hydrological processes and global climate changes. The main purpose of this study is to find any possible relations between streamflow and temperature trend and climate changes. Trend analysis with Mann-Kendall and seasonal Kendall test showed that there is no trend in annual mean discharges but monthly flow series exhibit significant downward trend in specific months. Stationarity tested with five methods which are ADF test, Dickey-Fuller test with GLS detrending (DFGLS), KPSS test, Phillips and Perron test and Elliot, Rothenberg and Stock test. Most annual and monthly discharge series appear to be significantly stationary. All methods for 10 days and daily flow series cannot pass stationarity test even at 1% level. Nonstationarity on daily and 10days timescale might be the result of climate changes. The results imply that because of high dependence of rivers located in the west of UrmiaLake on snow melt water, and temperature, climate change is the main cause of downward trend of ShaharchiRiver and Urmia lake depletion.

Keywords

Stationary test

Terend analaysis

River

climate change

Urmia lake