Rating Curve
Rating Curve
(OP)
Hello everyone,
I have attached a rating curve which i developed from HECRAS and Excel for a lateral structure (spillway) which drains into a culvert, the crest elevation of spillway is 333 meter and that of the roadway is 335 m.
I took a C value of 1.44 (SI) assuming the spillway as broad crested and C value of 2.18 (SI) assuming the spillway as Ogee crested.
I could not understand the shape of the curve however. Is it the effect of the culvert downstream? i.e. the effect of pressure/weir flow? If so how would i incorporate this in Excel?
I have attached a rating curve which i developed from HECRAS and Excel for a lateral structure (spillway) which drains into a culvert, the crest elevation of spillway is 333 meter and that of the roadway is 335 m.
I took a C value of 1.44 (SI) assuming the spillway as broad crested and C value of 2.18 (SI) assuming the spillway as Ogee crested.
I could not understand the shape of the curve however. Is it the effect of the culvert downstream? i.e. the effect of pressure/weir flow? If so how would i incorporate this in Excel?





RE: Rating Curve
See from page 8/24 in the document attached.
RE: Rating Curve
Excel sheet available, and should be validated in more detail.
C will be of :
1.71 when H/Hd = 0
2.19 when H/Hd = 1
2.44 when H/Hd = 2
RE: Rating Curve
but why is the shape of the curve different in excel and HEC?
at some point in HEC the C value seems to be less and the curve rises rapidly for less discharge, which is not the case for Excel.
RE: Rating Curve
RE: Rating Curve
RE: Rating Curve
There is no submergence effect coz the d/s water level is well below the crest(335m).
when i remove the culvert and did let the flow from the lateral structure to out of the system then the curve is just like that calculated from excel.:S
RE: Rating Curve