Perrenial stream??
RGU...@cblad.state.va.us
Any hint or idea would be of use. Thanks,
Ram
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Jo Schaper
wrote:
>Is there any criteria to know wheather a stream is perrenial or not?
>Any hint or idea would be of use. Thanks,
>
>Ram
Do you mean perennial? If so, water in the streambed at all
seasons of the year would be a dead giveaway. My dictionary
says that perennial means a) occuring at all seasons of the
year b) recurring on an annual basis without outside
intereference such as in flowers which come back ever year
without replanting.
By the first definition, any permanent stream would be
perennial. By the second, perennial would mean recurring
annually in the same place (such as an intermittent stream
which flows only in the spring, but unfailingly so.) A
truly intermittent stream based only on runoff would not be
considered perennial.
See how this info applies to your situation.
Jo Schaper
scha...@mail.idt.net
kmflynn
"Streamflow may be (1) perennial, in a channel which never dries up,
(2) inermittent, in a channel which at drier times of year may have
some reaches with flowing water interspersed with other reaches in
which the water flows below the surface, and (3) ephemeral, in a
channle which flows only after rainfall." (chapter 8)
Mark
is as follows:
Intermittent= A stream wherein the 7Q10 flow (a week-long low flow with a
1-year-in-10 recurrence interval) is 0.
Perennial = A stream wherein the 7Q10 flow is more than 0.
Which is not to say that there is room to quibble, otherwise we consultants
would always get along with the regulators and vice versa. Hope this helps.
RGU...@CBLAD.STATE.VA.US wrote in message
<71sb5o$52c$1...@nnrp1.dejanews.com>...
>Is there any criteria to know wheather a stream is perrenial or not?
>Any hint or idea would be of use. Thanks,
>
>Ram
>
ppia...@my-dejanews.com
Intermittent = sometimes base flow, sometimes dry
Ephemeral = only flow in response to surface runoff, no base flow.
In article <72g21m$hbc$1...@autumn.news.rcn.net>,
bkd
Compare the definitions of "perennial" and "intermittent" in the AGI
dictionary.
Regards
baby_...@hotmail.com
Any info would be greatly appreciated.
Thanks
Kim
Please e-mail me at mad...@hotmail.com
Jo Schaper
wrote:
>Does anyone know this or know of a website with this information?
>Any info would be greatly appreciated.
>Thanks
>Kim
>Please e-mail me at mad...@hotmail.com
Only if the color in the water is due to impurities which
somehow bind to the water, reducing its evaporation rate.
The color itself is irrelevant.
Jo Schaper
scha...@mail.idt.net
Mark Brigham
In article <72lj0g$fib$1...@nnrp1.dejanews.com>, baby_...@hotmail.com writes:
> Does anyone know this or know of a website with this information?
> Any info would be greatly appreciated.
> Thanks
> Kim
> Please e-mail me at mad...@hotmail.com
>
> http://www.dejanews.com/ Search, Read, Discuss, or Start Your Own
I recommend as a starting point the following text:
Wetzel, R.G., 1983, Limnology, 2nd ed., Saunders Pub., Chapters 2, 5, & 6.
I don't think it's on the web, but it should be in a good college or university
library. Good luck!
--
Mark E. Brigham, Environmental Engineer -- email: mbri...@usgs.gov
U. S. Geological Survey, 2280 Woodale Drive, Mounds View, MN 55112-0049
WWW: http://wwwmn.cr.usgs.gov/
Brian Davis
> Only if the color in the water is due to impurities which
> somehow bind to the water, reducing its evaporation rate.
> The color itself is irrelevant.
Not in a natural setting. A dark or cloudy body of water will probably
evaporate faster than a clear one. The high turbidity or absorbsion will
produce more solar heating in the surface layers, making the surface
warmer than for a clear or colorless body of water. The result, more
evaporation.
I've got lakes (5 m deep, area 1-2 acres) thatI've studied where solar
heating raises the water temperature as much as 7 deg-C. I would think
(although I have no direct observations) that turbidity or dark color
would influence evaporation slightly.
--
Brian Davis
Jo Schaper
This may be so in standing water. Most of the water I am
familiar with is flowing, (either streams or springs) and
temperature fluctuates more with velocity, temperature of
runoff, amount of time in the recharge system, climate and
the day/night cycle than with color. The water gets colder
at night not because it is "dark" but because there is no
sun to warm it. The apparent color of a spring (due to
depth) has very little effect on the temperature of the
water per se, except that the deeper the spring conduit, the
closer the water temp is to the mean annual temp, as opposed
to showing the effects of solar warming. Therefore, the
darker the water color, the colder it is likely to be, in
contradiction to what Brian has found in his lakes. But it
is not a relationship to the apparent color, at all, but
other co-occurring factors.
What I really meant to say, (and expressed badly) is
that such things as turbidity surely *do* affect evaporation
rates, but it has not been my experience that the color of
the water is not the deciding factor as much as the sediment
load or dissolved ions in the water--which could (and
probably do) absorb solar heat at different rates than water
itself.
Jo Schaper
Brian Davis
> ...such things as turbidity surely *do* affect evaporation
> rates, but it has not been my experience that the color of
> the water is not the deciding factor...
Yes, and I agree with you completely - the biggest factor in the
evaporation from the lakes I mentioned before was the prior days
temperature and solar heating, which dominated all else (I was actually
using the lakes as climate proxies, and so air temperature (or water/air
temperature difference) was critical).
> ...as much as the sediment load or dissolved ions in the water--which
> could (and probably do) absorb solar heat at different rates than
> water itself.
Agreed - I was just considering these as one type of "color". As you
point out, in general when the lakes were "drak" (cloudy), they were
also cold, and little evaporation was taking place. My point was that
*other factors aside*, dark water (or water that absorbs a larger
percentage of the incoming energy in its upper layers) should warm
faster, and evaporate faster.
I guess it really depends critically on why this question was asked.
Are we talking natural lakes, (how deep), or puddles, or streams and
springs? Why isn't anything ever easy on Usenet?
--
Brian Davis