Premium
A field study on turbidity currents initiated from spring runoffs
Author(s) -
Chikita Kazuhisa
Publication year - 1989
Publication title -
water resources research
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.863
H-Index - 217
eISSN - 1944-7973
pISSN - 0043-1397
DOI - 10.1029/wr025i002p00257
Subject(s) - turbidity current , froude number , turbidity , overbank , hydrology (agriculture) , sediment , erosion , geology , spring (device) , surface runoff , environmental science , geotechnical engineering , flow (mathematics) , geomorphology , mechanics , fluvial , oceanography , sedimentary depositional environment , mechanical engineering , physics , structural basin , engineering , ecology , biology
The hydrodynamics of turbidity currents from spring runoffs of an influent river is examined by measuring velocity, water temperature, and concentration of suspended sediment in a reservoir. Crosssectional measurement of turbidity currents, made from a bridge, shows the effect of centrifugal force on the downstream movement. This is due to considerable meandering of the old river channel. The turbidity currents, initiated at high sediment concentration of 1,700 mg/L, were bifurcated into an underflow and some interflows in the downstream reach, because of the relatively dense bottom water of the reservoir. The “lower layer” of turbidity currents exhibits a log linear relationship between dimensionless velocity and height under a hydraulically smooth condition. The velocity distribution in the upper and lower layers could be explained by overall Richardson number. Two drag coefficients, related with shear stresses at bottom bed and interface, generally decrease with increasing densimetric Froude number, but are independent of Reynolds number. The conditions of sediment deposition and erosion by turbidity currents can be explained by using the “extended Shields diagram.”