Document Type : Research Paper
Authors
Abstract
Differences in particle size through downstream is a proper tool to understand evolution steps and river channel morphological changes, including sediment transport, channel migration context, the risk of floods and human activities. The present study investigated sediment deposits in upper rangelands of Tehran- Qazvin highway located in Khur-Sefidarak Basin, Tehran Province. Two main channels with Gravelly- sand bed as the main drainage channels were studied. The aim of this study was to investigate changes in particle size based upon sedimentology and its correlation with textural parameters including sorting, skewness, and kurtosis and calculating the approximate volume of sediments behind dams. These parameters were analyzed by sampling 66 samples from upstream to the downstream side of the Khor-Sefidarak channels. All natural factors (secondary branches and sediment sources) and non-natural factors (such as small dams) were effective in tissue changes on this system and the results indicated the continuity of sediment along the channels due to regular gradient of channel bed. Sediment particles through these two channels had a medium sorting. Sorting decreased toward downstream, because of facing secondary branches and increment of shared formation number and totally increased diversity in sediments. Results of bed sediment volume showed that the amounts of bed load sediment through Khor and Sefidarak branches were 271.6 and 246.3 cubic meters per year, respectively.
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