بررسي خصوصيات رسوبشناختي جريان مختلط در حوزه آبخيز زيارت گرگان

A study on sedimentologic characteristics of debris flow in Ziarrat Basin,Gorgan

Most of the experts have a similar idea about debris flow and flash flood and usually make mistake in management, controlling, estimation of sediment Ioad and reconstruction of peak flow and precipitation data. After occurrence of a harmful flash flood in August 1999, samples of sediments have been taken randomly from the undisturbed cross section of river. Then granulometery and hydrometery tests have been done and four sedimentologic indices have been calculated and interpreted. From the study it concluded that the selected flow was a type of debris flows and classified as a high sediment flow. A severely decrease in cross section of flow has been seen from upstream to downstream, which indicates the action of debris flow in the river. To study the case of debris flow, the Atterberg Limits test has been conducted that the Liquidity Limit of samples was 50%. These types of sediments, by absorbing a low percentage of water, forms landslids and mud flows.