Assessment of variations in river discharge and sediment at some stations of Gorgan-Roud River, Golestan Province, Iran

ABSTRACT: The main part of sediment in each river is formed of suspended load. In this investigation, to assess the relationship between sediment discharge and flow discharge in 14 hydrometer stations of Golestan Province, corresponding data of inventory years of 1971 to 2008 were received and analyzed. To do this, first the discharges and corresponding sediment data in different seasons were recognized and defined. To determine data trend, Mann-Kendall non parametric test was used. Considering that all of annual and seasonal series of observed discharge and sediment were not normal in all investigated stations, Mann-Kendall non parametric method was an appropriate method for determining time series in this study. Results of data trend evaluation showed that the trend of annual and seasonal discharge and sediment was descending in most of studied stations. Also, results showed that by dividing discharge and sediment data to sets and times, assessing the trend is of higher precision and sensitivity and better results could be obtained.