Analysis of selected microscopic approaches of sediment load transport.

Sahita Waikhom, Manali Shah, Dr. Sanjay M Yadav

Wednesday 1 july 2015

12:51 - 12:54h at Mississippi (level 1)

Themes: (T) Sediment management and morphodynamics, (ST) Sediment transport mechanisms and modelling, Poster pitches

Parallel session: Poster pitches: 8A. Sediment - Erosion

Sediment transport is the key factor in effective design of hydraulic structures and open channel water conveyance. Among the microscopic approaches, sediment transport formulae of Van Rijn (1984) and Swamee and Ojha (1991) are tested against Samaga et al flume data in the present study for bed load, Suspended load and total load transport for four sediment mixtures, having different sediment characteristics. Statistical parameters such as Mean Square Error (MSE), Root Mean Square Error (RMSE), Discrepancy Ratio (r) and Inequality Coefficient have been computed for evaluating the performance of selected formulas. Van Rijn bed load function over predicts the sediment transport rate for Mixture M-1, nearly equal for mixture M-2 and M-3 and under predicts for M-4 mixture. Swamee and Ojha bed load function under predicts the sediment transport rate for Mixture M-1 and M-2, nearly equal for M-3 and over predicts for M-4 mixture. Van Rijn suspended load function gives much larger values, with an error ranging from +300% to +2500%, for all four mixtures. Swamee and Ojha provide comparatively better results with error ranging from -70% to +230%.Total load computed, according to Van Rijn, overpredicts the results for all four mixtures. However, for Swamee and Ojha, it is overpredicted for mixture M-1 and nearly same for the rest of the three mixtures viz. M-2, M-3 & M-4. In order to further verify the validity of Van Rijn suspended bed load function, another data set (29 Field data) measured at two United State Geological Survey (USGS) gauging station along river Sacramento in California has been tested. Suspended load calculated by Van Rijn are within the acceptable limit of error for all four mixtures. Keywords: sediment transport, Bed load sediment transport, Suspended load sediment transport and total load sediment transport.