[Odonata-l] drought areas in US

[Joshua Stuart Rose]

I was going to say something along the same lines as Steve. Perhaps  
the MS Dave smelled could be elevated to a Ph.D. by comparing the  
degree to which various watersheds have lots odonate species, to the  
degree to which those watersheds have increased in imperviousness  
(pavement, buildings, etc.). This should distinguish Dave's  
suggestion of changes in rainfall intensity vs. Steve's runoff idea.  
(I recall, at some point a few years ago, a discussion of releases  
from dams, and the disappearance of species downstream due to the  
similar effects, sudden rises and falls in river levels)

Joshua Stuart Rose, Ph.D.
Program Director
World Birding Center
Bentsen-Rio Grande Valley State Park
Mission TX
http://www.worldbirdingcenter.org/sites/mission/index.phtml
956-584-9156 extension 236
joshua.rose at tpwd.state.tx.us

On Jul 4, 2007, at 10:25 PM, Steve Collins wrote:

> Dave,
>
> You would find that many rivers and streams are more flashy now,  
> with contributing watersheds composed of more impervious surface  
> and other landuse changes condusive to increased runoff.  Many USGS  
> data sets indicate this, despite the advent of stormwater  
> management.  I don't know about the rainfall intensity itself,  
> however.
>
> Cheers,
> Steve Collins
> Towson, MD
>
> Dave McShaffrey wrote:
>> Drought is a problem for sure, but I think there is another  
>> subtler problem in the works for the odonates.  I can’t prove it,  
>> but it seems to me that when it rains now it really rains hard,  
>> and these spates are causing rivers to rise and fall quickly.  A  
>> river that rises quickly has the capability to wipe out a whole  
>> generation of emerging odonates along its banks.  I think for some  
>> of our river species the unpredictability of river levels may be  
>> just as important as drought.
>>
>>
>> I suppose if one had time one could use the USGS sites like this one:
>>
>>
>> http://waterdata.usgs.gov/oh/nwis/dv? 
>> cb_00065=on&cb_00060=on&begin_date=1998-10-01&end_date=2007-07-03&sit 
>> e_no=03115400&referred_module=sw
>> to see if things have really changes over time.  Of course, this  
>> particular site only has height data going back to 1998.  Still, a  
>> random sampling of sites with a longer period of record might turn  
>> something up.  I small a MS thesis in here somewhere…
>>
>>
>> Dave
>>
>>
>> Dave McShaffrey
>>
>> Marietta College
>>
>> (740) 376-4743
>>
>> www.marietta.edu/~mcshaffd