The Study of Sedimentological Characteristics of Debris Flows and its Comparison with Source Areas: A Case Study of Tool Baneh Watershed, Golestan Province

Debris flows are including of mass movement that usually happen in watersheds and play an important role in sedimentation in mountainous regions. In many cases، this phenomenon be confused with flooding. In this research، the debris flow was investigated that happened in Tool Baneh''s watershed southern Gorgan، Golestan province in summer 2010، after a heavy rainfall. In this regard، 40 samples that consist of depositions، recorded data، and lateral landslides were investigated and analyzed according to sedimentology indicators. Then، Krumbine and symmetry sedimentological indices and trask coefficient were also computed for each sample. The mean of Krumbine in the sediment samples and the mean of sorting index is 0. 81 and -0. 73، respectively. The negative symmetry index reflects more sorting on the fine particle of grading curve. All indices showed very poorly sorting of deposition of happened flow and its difference with flooding. Also average and lowest coefficient values of deposits trask were 6. 83 and 3. 57، respectively. Results of comparing sedimentological coefficients in origin and sedimentation from debris flow showed that there is no significant statistically differences between sedimentological indices in above two regions.