Hi all,
Wondering if it is ever appropriate to do a partial culvert assessment. We came upon a culvert that upstream appeared to be a dry stream bed. However, there was water inside the culvert, a pool at the outlet and water was draining out of the pool downstream. Would it be appropriate to attempt to take parameters in the upstream portion, even if it's dry (bankfull's)? Or should we only do the lower half which had water? We were able to gather data for all downstream parameters.
Or should this culvert be listed as "not surveyable"?
(Top photo is from downstream looking into culvert upstream. Bottom photo is from road looking upstream into dry stream bed.)
Thanks
Hello,
If the culvert sits on a stream, as I think this one appears to, then even if the stream bed is dry (whether dry at one or both of the sides of the crossing) it is appropriate to attempt to do a full crossing assessment, with the crossing type set to stream.
It is possible to identify bankfull widths even in a dry stream bed - the indicators remain the same (change in bank slope, vegetation/staining lines, top of deposits, etc.). So, if on the upstream side bankfull widths are identifiable, then a full assessment of the 'stream' type should be performed. Of course water depth measurements would be 0 at any location that was dry at the time of the assessment, and so it would be useful to note in the comments that the location (upstream/downstream/both) was dry to differentiate this from a data error. So, though it may seem somewhat strange, if you come to a crossing with a dry stream, but you can tell it is a stream due to the presence of bankfull widths, even though it might be ephemeral - meaning transitory in time, related to spring flows or intense rain events, then perform a full assessment.
This may seem counter intuitive, but almost all of the parameters that go into the GC and AOP and Hydraulic Capacity Scores can be collected in dry streambeds.
Hope this helps.
Tom