Submitted to: Journal of Hydraulic Engineering
Publication Type: Peer reviewed journal
Publication Acceptance Date: 9/13/2007
Publication Date: 7/1/2008
Citation: Kuhnle, R.A., Jia, Y., Alonso, C.V. 2008. Measured and Simulated Flow Near a Submerged Spur Dike. Journal of Hydraulic Engineering, 134(7): 916-924, doi:10.1061/(ASCE)0733-9429 (2008)134:7(916-924), 2008. Interpretive Summary: Studies by researchers at the USDA Agricultural Research Service and other locations have established that in many agricultural watersheds the majority of the sediment that reaches the channels results from instability and the resulting erosion of the channel boundary. This sediment in many cases causes negative impacts to the habitat for fish and other aquatic organisms and also decreases the amount and productive use of agricultural and other lands. More effective techniques are needed to stabilize channel boundaries at a reasonable cost. A laboratory study was conducted using a model stream channel to accurately measure the 3-dimensional flow velocities in the vicinity of a model spur dike (a structure widely used to protect stream banks). The flow in the vicinity of spur dikes is very complicated and poorly known. The measured flow velocities were compared with the calculated velocities from a computer model (CCHE3D). The comparison between measured and calculated flow velocities was very good. This study represents an important step in the improvement of the design of effective structures for channel erosion control and enhancement of the aquatic habitat. Improved tools for structure design and analysis are needed by managers concerned with agricultural watersheds.
Technical Abstract: To improve knowledge of the flow and scour processes associated with spur dikses, 3-dimensional flow velocities were measured using an acoustic Doppler velocimeter at a closely spaced grid over a fixed flat bed with a submerged spur dike. Three-dimensional point velocities around a trapezoidal shaped submerged spur dike were measured at 2592 locations. General velocity distribution and detailed near field flow structures were revealed by the measurement. Important differences between the flow fields measured in this study and those measured for non-submerged vertical obstructions were observed in this study. Numerical simulation was performed using the free surface turbulent flow model, CCHE3D. The numerical simulation of the flow showed very good agreement between the computational results and the measurements. The numerical simulation results indicate the CCHE3D model can be used to accurately predict near-field flows around hydraulic structures.