How to estimate the downstream flood level for residential stormwater design ?

[tngv752]

For OSD (Onsite stormwater detention) calculation, I am not sure how to estimate the downstream flood level for 1.5 year and 100 year flood level.

Thanks

 

[civilman72]

You need to provide more information to get any useful responses. Is the OSD discharging to a stream, or are you trying to determine tailwater elevations downstream of your outlet? Also, are you trying to estimate or calculate?

 

[tngv752]

The OSD will discharge water into the street gutter through a stormwater pit (stormwater pit with inlet pipe and orifice outlet). Downstream flood level will help me to obtain orifice and overflow weir level.

 

[rlondeen]

your TW would be determined by your downstream drainage facility at the rainfall frequency as dictated by your governing authority. In this case, IT SEEMS that it would be the WSE of your street gutter, but it is hard to tell with little information.