Submitted to: International Symposium on Gully Erosion Under Global Change Proceedings
Publication Type: Proceedings
Publication Acceptance Date: 4/15/2004
Publication Date: 8/26/2004
Citation: Kuhnle, R.A., Yia, Y., Alonso, C.V. 2004. Flow near a model spur dike with a fixed scoured bed. In: Proceedings 3rd International Symposium on Gully Erosion, April 28-May 1, 2004, Oxford, Mississippi. 2004 CD-ROM (pp. 166-187). Interpretive Summary: 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 erosion of the channel boundary. In many cases the sediment may cause negative impacts to the habitat of fish and other aquatic organisms and may also decrease the amount and fertility of the soil on 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. This study was the second part of a sequence of studies on this problem. 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: Three-dimensional flow velocities were measured using an acoustic Doppler velocimeter at a closely spaced grid over a fixed scoured bed with a submerged spur dike. Three-dimensional flow velocities were measured at 3484 positions around the trapezoidal shaped submerged model spur dike over a fixed scoured bed. General velocity distributions and detailed near field flow structures were revealed by the measurement. Clear differences were revealed between flow over fixed flat and scoured beds. Strong lateral flows were the dominant cause of the observed local scour.