عنوان مقاله [English]
نویسندگان [English]چکیده [English]
Evaluation of river discharges trends is very important for water resources management and design of irrigation and drainage networks. In this research, annual, seasonal and monthly trends of Maroon river discharge were evaluated using the Mann-Kendall and Senâs slope estimator non-parametric tests and the regression analysis parametric test. For this purpose, river discharge data from five hydrometric stations including Idanak, Behbahan, Gorgor, Meshrageh and Shadegan were applied during 1987-2006. The results of this study showed that annual discharge values decreased at all stations in the last two decades. The data indicated that decreasing trends of annual river discharge at Behbahan, Meshrageh, Gorgor, Shadegan and Idanak stations were 80, 40, 21, 1.4 and 0.4 m3 per decade, respectively. The analysis of seasonal discharge results using the three tests demonstrated that spring and winter discharge values decreased in the study period, while increasing trends were observed in summer discharge values. The most differences between non-parametric and parametric tests were detected in autumn discharge values. The non-parametric tests showed positive trends in autumn discharge values, while these time series were characterized with negative trends using the parametric test. The analysis of monthly discharge results by the applied tests indicated that March, April, May and June discharge values declined at all of the stations. The results of such research can be applicable to prediction of future droughts, irrigation planning and water resources management.