Recent Rain

[JeffK]

When one gets an extreme rainfall like 7" in a day impervious surface doesn't mean too much since no surface can absorb all that water. Where impervious surfaces really make a difference is in increasing the one to 2 year bank full floods. 2" to 3" rainfalls that might have been mostly absorbed in farmland can now cause flooding.

 

[sixfootfenwick]

I'd forget all the suggestions made in this thread and would focus on the map you presented.

 

[lycoflyfisher]

That seems rather surprising given the drainage area at the Sonestown gauge is 23.8 sq mi and because I thought (45 yrs ago) that much of the drainage above Sonestown was wooded or at least undeveloped. Was I wrong or has there been a change? (The survey also produced a number of wild browns and a wild tiger trout).

Still mostly forested. Lots of roads channelize tribs and the main creek above sonestown effectively reducing floodplain connectivity. This area got 7in of rain in a short period of time. Flooding will always happen in that scenario and cabins/ homes and roads in the floodplain will get damaged.

In these extreme rain events we also see massive amounts of water coming straight off the mountain sides in places where water is not typically flowing. This is often where small landslides occur onto roadways.

 

[sixfootfenwick]

More flooding on the way.....

 

[Jay_H]

I got out this evening before another downpour soaked south central PA. Past few times I’ve been out has just been very uneventful, but at least I’m getting out. If for just an hour…