The effect of dikes on water surfaces in a mobile bed

River engineering;sediment transport;physical modeling;groynes;dikes;dike field;water surface elevations

Brauer, Edward ; Schmidt ; Arthur R.

关键词: River engineering;    sediment transport;    physical modeling;    groynes;    dikes;    dike field;    water surface elevations;   

Others  :  https://www.ideals.illinois.edu/bitstream/handle/2142/44762/Edward_Brauer.pdf?sequence=1&isAllowed=y

美国|英语

来源: The Illinois Digital Environment for Access to Learning and Scholarship

【 摘 要 】

Dikes, also referred to as groynes, have been used on rivers in both the U.S. and abroad to solve river engineering problems dating back to the nineteenth century. They are the prominent tool used to maintain navigation depths and prevent bank erosion on many major rivers in the world. A dike is defined as a structure constructed at an angle to the flow for the purpose of redirecting the flows to achieve a desired result. The elevation and shape of the structure can be manipulated to result in different flow and scour patterns.Although dikes used in the United States are constructed below the top of bank and designed to be effective only in low water, it is necessary to understand their effect on water surfaces, particularly for flood flows. To help answer questions that have arisen as to the effect of dikes on flood levels, this study considers effect of movable bed, which has been largely neglected in previous studies. Previous research on this topic has relied on field data, numerical modeling and physical modeling. A majority of the modeling has been a fixed bed condition and has not accounted for the bed scour resulting from the presence of dikes.This study tested the effect of submerged dikes and dike fields on water surfaces in a moveable bed sediment transport flume. The flows tested varied from mean flow (1/2 bankfull) to 200 year flood flows to determine the effect of increasing flow and submergence on water surface. The length and number of dikes in the dike fields were changed to determine what effect, if any, the number of dikes had on water surface. The results of the tests were used to determine if the presence of dikes can result in an increase in flood heights.The results of the tests in this thesis showed that the effect of dikes on water surfaces decreased as flow/submergence increased along the rating curve. There was no direct cumulative effect for up to the four structures tested in this study. Additionally, this study found that other variables exist in the model and in the prototype that have a greater effect on water surfaces than the presence of dikes.