Total sediment transport in the lower reaches of river Þjórsá : results from the year 2004

Abstract

This report presents data on suspended and bedload sediment samples taken in the lower reaches of the Þjórsá river in 2004. Five sediment campaigns were carried out in 2004, in four of them both suspended and bedload samples were obtained. In addition, bedload transport was also estimated at Sandártunga in one campaign. The main objectives with the study are to obtain samples for better understanding of the total sediment transport in the area, to gain a better idea of the quality of different suspended sediment samples, and gather information for later comparison with older suspended sediment samples. Suspended sediment concentration varied substantially between sampling sites ant between campaigns. The suspended sediment was relatively coarser during winter than in summer/fall samples, and coarsest in samples taken from the old Urriðafoss cableway. Bedload transport at Krókur was highest between 50 and 70 m, with total transport lowest 1.4 kg/s, in August. Total bedload transport reached a maximum og 66.5 kg/s during one sampling set in a winter flood in March, but was lower by an order of magnitude at Sandártunga.