SCOUR

[jadams]

Its been so long since I ran a scour analysis I have forgotten a few things. Once i have the flow distributions inputted and calculated and the appropriate D50 and D95 I run the Hydraulic design tool. The abutment scour is rather deep and will extend beyond the layer of soil represented by my D50. How can I account for the loss of that entire layer in the model so I can input the next soil layers D50 and rerun.

[jadams]

BTW if anyone is interested I determined that if you want to further model scour after a soil layer is theoretically removed, you must manually edit the sections to show the loss of the soil layer.

[Anonymous]

Also in many DOT manuals you should know that abutment scour is not to be entirely trusted with either the Froehlich or HIRE equation. The entire idea of abutment scour is an engineering judgement call and should be followed up by using HEC-23. Before I run scour in HEC-RAS i always use HEC-18 to calculate scour. It is good to have comparable results.

Also if scour is calculated below the depth at which the soil sample is taken at, a new D50 should be used corresponding to a depth at which scour was initially calculated at; then re run.

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