Hossein Kheirfam; Behzad Kheirfam; Yaaghoub Azhdan; Saleh Hossein
Abstract
Variability analysis of river sediment transport in different temporal and hydrological conditions is important in hydraulics and hydrological science and engineering. Otherwise, behavior analyzing of the riverian systems at the different temporal conditions is necessary in managerial decisions to control ...
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Variability analysis of river sediment transport in different temporal and hydrological conditions is important in hydraulics and hydrological science and engineering. Otherwise, behavior analyzing of the riverian systems at the different temporal conditions is necessary in managerial decisions to control and reduce sediment transport. However, knowledge about the type and amount of sediment in watersheds in various temporal and hydrological conditions is limited. Therefore, this study aimed to investigate the variability of bed and suspended load and bed to suspended load ratio. The 6-years period (1998-2003) data of bed and suspended load (g l-1) and discharge (m3 s-1) were collected from Yazdekan station of Qotour Chay River. The analyses also were carried out in Excel 2007 software. The results indicate that discharge increasing caused that the suspended load was increased and the bed to suspended load ratio was decreased at all seasons. As well, the lowest and highest bed and suspended load transport were occurred at the winter and spring, respectively. Amounts of minimum, maximum and median bed to suspended load ratio at spring, summer, autumn and winter were 5.02, 563.99 and 27.34%; and 0.075, 2034.91 and 135.80%; and 28.31, 659.15 and 184.94%; and 28.96, 457.61 and 169%, respectively. Also, during the study period the bed to suspended load ratio was varied about 0.7 up to 2034%. Therefore, using indirect methods to estimate sediment is not accurate because of complex behavior of sediment particularly bed load and bed to suspended load ratio with discharge. By and large, it is necessary that daily bed load measuring in sediment gauges.
Hossein Kheirfam; Seyed Hamidreza Sadeghi
Abstract
Measurment of river sediment transport in different temporal and hydrological conditions is important in hydraulics, hydrology and soil and water conservation science and engineering. Bed load is rarely measured because of difficulties and low efficiency of conventional samplers. The present study was ...
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Measurment of river sediment transport in different temporal and hydrological conditions is important in hydraulics, hydrology and soil and water conservation science and engineering. Bed load is rarely measured because of difficulties and low efficiency of conventional samplers. The present study was carried out in order to design a bed load sampler based on the conditions prevailing in the mountainous rivers flumes. The sampler with dimensions of 120 cm length, 60 cm height and 60 cm width was designed and subsequently fabricated. The accuracy of sampler was evaluated through comparing the bed loads estimations made by the designed equipment and those measured by collecting the whole discharged runoff to a 300 liters water tank installed at the outlet flume and with the help of statistical criteria. The t-test, relative erorr (RE) and relative bias (RBIAS) criteria were then used for statistical analyses. The results showed that the mean mesured bed load by water tank and designed sampler were 0.00635 and 0.0064 gl-1, respectively with no siqnificant differece (p<0.0763). In overall, the designed sampler had a high accuracy and efficiency in river bed load measurement with relative erorr and relative bias of about 8.5% and 0.107, respectively.