Abrupt drops in stream flows?

[jayL]

I was checking the gauge for valley today, and noticed a series of daily abrupt drops. They appear to be consistent, followed by long periods of constant flows.

Aside from the idea that they might only take frequent readings during rains, I'm not sure why this might be.

Any ideas?

 

[JasonS]

jayL,

I'm not sure but I check that gauge a lot and sometimes it will go for periods of up to 8 hours without being updated. Maybe this is what the graph is showing?

PS-I was down there on Saturday and got to talking with the lovely ladies of the National Park Service. They were out in the creek netting the invasive rusty crayfish. I asked them how they got in there, said it was most likely bait fisherman. Apparently they are in the skuke, but there's no way they could get over the damn without some help. What are the chances of Valley going all artificial? I'm not selfish enough to ask for FFO, OK I am but I'm also a realist.

 

[vcregular]

jayl. I think it is just a reflection of a lack of data points. Thus the graph rendering is not as 'smoothed' as you might find with more data gathering.

What is more scary with this stream is almost the complete lack of ramping down after a rain even. Water/run-off literally gets funneled into the stream, it spikes, and it the fully runs off. Worst thing for it is super-heated parking lot water from an afternoon thunderstorm. Fortunately, we did not have many of these events last year, and this year has been relatively cool. Overnight lo-wise. Rain fall has been lacking though imo.

 

[jayL]

In looking at the graph again, it looks like they might only be able to measure CFS to a whole number precision, which could also be a factor. In the lower range, the Y axis gets scaled much larger.

I am guessing it may be a combination of that and your observation, Jason/VC.

As to the rusty crayfish, the commission believes that the rusty crayfish is not spread by bait anglers to the extent that they would create regulations based on it: http://www.fish.state.pa.us/newsreleases/2005/rusty_cray.htm

If Mike is out there, I'd be curious to hear his input on this, as well as on Jason's idea.

Edit: thanks VC. I was surprised to see the stream at a below median level. I am guessing that the 10 days I was away were dry ones.

I was mainly curious about the drops because they appear to be inconsistent with the runoff periods. At the very least, it appears that they are taking more measurements in those periods.

 

[JasonS]

Most of the recent rain we have been getting has been short burst of heavy rains. I can't remember the last sustained rain we had. It was nice earlier this year when we had that two week period of rain just about everyday. Plenty of water in the stream and the fishing was on fire.

 

[Chaz]

A quick look at the data for Valley Creek shows that rainfall data indicate storms coinciding with each spike. I also look at Perkiomen Creek which is fiarly close and it had similar spikes.

 

[jayL]

Spyder20oz wrote:
Possibly unrelated but...Valley also has a large number of houses that siphon off of it for irrigation and those drops are recorded.

That was my initial concern. I figured that there was a minimal irrigation hit to a suburban spring fed stream, but I didn't know that it was widespread.

 

[Chaz]

Who's watering their lawn in SE PA this year? Come guys think about it. The data is right there on the USGS site.

 

[Chaz]

No problems on my end, but the spikes I see aren't caused by irrigation, and I didn't see that post. Like I saidthe data is right there, it is not open to interpretation.

 

[afishinado]

I agree with Chaz, the spikes coincide with the precipitation. As Jay later posted, the "abrupt" changes in flow without any precip. are actually due to the scale on the graph.

Attached are charts of flow and precip. Also attached is some good info describing the watershed and its challenges.

http://www.savevalleycreek.org/watershed.asp#

 

[Chaz]

My point is to answer JayL's question. I have no axe to grind, what's your point? Don't ask me if I can read. Don't ask me if I have trouble with comprehension. If you are looking for a p@#*ing match you won't get it from me. I'll just reach through the computer and choke you

 

[FishOn247]

Chaz, i know i am new here but all of your recent posts seem angry. Its fishing dude, chill out.