Trend detection of the rainfall and air temperature data in the Zayandehrud basin

Abstract

Climate change is one of the most important challenges among scientists and researchers. This phenomenon has a complex dynamic and time depending and it needs to an integrated long time study. The goal of this study is determining trend of rainfall and temperature that can be useful for better water management in the study area. In this study trend detection of these variables was used in annual and seasonal time scales in the Zayandehrud Basin stations namely, Isfahan, Damane Feridan, Varzaneh, Hamgin, Pole Zamankhan andNajafabad during a 40 years period (1966 till 2005). Parametric tests including t-test and linear regression andNon parametric tests of Mann Kendall, Mann Whitney and Spearman's rho was used for trend detection in the time series of data. Results indicated that there are not any linear and nonlinear significant trends among rainfall time series both annual and seasonal scale in the Zayandehrud basin except spring rainfall of Varzaneh station and summer rainfall of Pole Zamankhan station. But there are linear (results of t-test and linear regression) and nonlinear significant trends (results of Mann Kendall, Mann Whitney and Spearman's rho tests) in the most time series of selected stations. These trends in air temperature are mainly positive and show increasing of air temperature in the Zayandehrud basin. Thus it is require to a comprehensive study of impact assessment in this basin especially its impacts on the water supply systems and agriculture section. © 2011 Asian Network for Scientific Information.