This is Dan Barkin, deputy managing editor of the N&O. We're trying to get a sense of the impact of the drought, and we'd like to enlist local photographers. If your yard (like mine) looks like the Gobi Desert, we'd like you to post your photos with some info about what we're looking at. But it doesn't have to be yards. It could be other impacts of the dry spell.
It's so dry...
...I got a ticket for trying to whet my appetite. Hehe.
No, wait. Sorry, wrong phorum.
...from Orange County, North Carolina as of August 18, 2007.
Stay tuned...
As promised here is a short photodocumentary showing how the drought has impacted Orange County. Since I always have my camera in tow on weekends I came up with this series of photos below during the course of my travels throughout the day on August 18, 2007 while in Orange County, NC.
The water supplies are getting so low that water for the cows at Maple View Farm has to be brought in from the farm operated Maple View Farm Country Store nearby.
Photo taken August 18, 2007
Fortunately this corn field was planted early in March (even had received a dusting of snow too) and had reached maturity just as the drought had begun. A few years ago Maple View Farm sold their gas driers and have been field drying their corn crops for silage ever since. In a few weeks the combines will be sent in to be harvesting all this corn.
Photo taken August 18, 2007
Holsteins take refuge from the sun and heat under a shade tree along Dairyland Road at Maple View Farm
Photo taken August 18, 2007
Here around the one mile nature trail called 'The Poet's Walk' which circles around Ayr Mount at Hillsborough, in the lowlands the Eno River passes by between Ayr Mount and the Historic Occoneechee Speedway Trail site which is also listed in the National Registry of Historic Places.
In this photo as one can plainly see, the Eno River's flow has been reduced to that of no more than a small stream.
Photo taken August 18, 2007
Looking upstream towards where the other photo was taken along the Eno River at the Poet's Walk around Ayr Mount one can see the waters pooled up here are running very slowly.
Photo taken August 18, 2007
The picture shown here was taken on August 17, 2007, posted to the gallery on August 20, 2007. It shows a sample of the cracks in Lake Lynn bed at the far end of the lake away from the dam. The water level had already been getting lower for a couple of months, little islands have emerged and ducks and geese can walk and sit where they used to swim.
A small Cypress tree stands upon high barren ground above the shore line at the Upper Barton Creek portion along Falls Lake. This photo was taken across Six Forks Road and across the lake from the Upper Barton Creek boat ramp.
Photo taken August 19, 2007
Previously submerged tree stumps now rise above the water at the Upper Barton Creek portion of Falls Lake across Six Forks Road and the lake from the Upper Barton Creek boat ramp.
Photo taken August 19, 2007
An additional note of concern: Considering the amount of surface area which Falls Lake has from which water can evaporate I would hazard to guess that much more water is being evaporated from the lake itself than what little flow of water is still left running into it. (See the Eno River photo taken at the Poet's Walk at Ayr Mount in Hillsborough above for an example.)
Like ghosts from the past, stumps which have been submerged from the late 1970's are re-emerging from the waters of Falls Lake at Upper Barton Creek just west of Six Forks Road.
Photo taken October 6, 2007
I forgot the evaporation data for Falls Lake I heard on the news recently, but it was a huge amount. The following web site from the UN's Food and Agriculture Organisation gives some education on evaporation and transpiration (of plants). It shows an evaporation calculation of 4.9 mm of depth per square meter of water loss per day in a lake in summer time, assuming 80 % of solar radiation to the lake results in evaporation.
http://www.fao.org/docrep/X0490E/x0490e04.htm
So, if we round up 4.9 to 5 mm/sq m, or .005 m/sq m, that's .005 cubic meter, or 5 liters per sq meter, or 5 x 10000 per hectare (10000 sq m), that is 50 cubic meters per hectare. From Falls lake data, I estimate the low lake area today at about 10,000 acres. Given approximately 2.5 acres per hectare, lake area would be about 4000 hectares, total evaporation per day could then be 50 x 4000 = 200,000 cubic meters, or about 53,000,000 gallons!
Maybe I heard 47 Million gallons after all..., correct me if I am wrong.
(Update) By the way, Falls Lake data show the lake total area falls dramatically with the drop in lake elevation, which means the lake is quite shallow in many corners.
Bernard (update: sorry, this should have been entered as a reply to Java55 above)
I wonder what summer time temperature the UN's Food and Agriculture Organisation was using for a standard from which to do these calculations? That 20 degrees C (or blistering 68 degrees F in merry old England) is certainly not the 40.5 C (or 105 F) like we've had this past Tuesday! (and all those other really hot days these past few weeks).... so I imagine the evaporation rates from this super heated water may have been much greater during these past several weeks or so.
Thanks for the link and info! It does give us some idea of what's going on here.
It's got me to rethinking about the two liter soda bottles I standardly place into my recyle bin each week... maybe I should start refilling them with tap water instead to build up an emergency stockpile of water gradually over time just in case...
The UN FAO figures I pulled look like they are indeed based on water, not air, at 20 degrees C or 68 F, which is a key reference temperature for people living by the metric system. However I guess the solar radiation of 15 MJ/day was based on a clear summer day in temperate regions favorable to growing crops. I understand that Falls Lake higher temperature (missing in today's lake report but I guess around 30 C or 86 F) should lead to increased evaporation but high humidity should counter that, with low wind speed being neutral.
More specific Falls Lake information can be found in the daily and historic reports at the site you (Java55) pointed to in another topic:
http://www.saw.usace.army.mil/falls/index.htm
For instance, the lake elevation peaked most recently on April 17. 2007 at 254.69 ft, since going down the drain to end up at 247.25 ft yesterday, August 22, 2007, close to a 7.5 ft drop!
Then, just looking at the latest daily report (midnight to midnight on August 22, 2007), we can see the elevation started at 247. 27 ft, then peaked at 247. 37 ft at 3 am (I guess because of storms or lack of withdrawal), but it still ended up with a loss at 247.25 ft after 24 hours.
Further, 65.8 MGD (I guess Megagalons per day) of water supply were withdrawn in 24 hours, but lake storage at the end was short 175 ac-ft (acres-feet). Darn, where are the cubic meters! Let's translate that one... I usually go to this site for conversions:
http://www.onlineconversion.com/
That says 175 acre-feet correspond to 215,860 cubic meters which again translate to 57,024, 331 US gallons. So 65.8 Mgallons were withdrawn and the lake ended up 57 Mgallons short in 24 hours.
But..., if the 175 ac-ft storage decrease was due to elevation dropping from 247.27 ft to 247.25 ft (.02 ft) in 24 hours, storage lost since the 3 am peak at 247.37 ft is much higher, and that would reflect evaporation, infiltration and dam outflow...
(Update on 8/23/07 at 1 pm)
I realize that extrapolation from a .02 water level drop to one inch of drop may not be reliable, I'll check the reasoning on another day where the stated 24 h storage loss is greater because of a higher level drop.
However, another figure can be based on the level drop of .12 ft or 1.44 inch from peak time at 3 am to the following midnight, and the estimated 10,000 acres of lake area left at this time. That's 14,400 acre-inches of volume which translates to 391 021 719 gallons, or about 392 Mgallons.
So, out of 392 Mgallons lost since 3 am, 66 or less (count started at midnight) was withdrawn for consumption, maybe 50 Mgallons evaporated or infiltrated (see previous append), that leaves 276 Mgallons that went to the drain, or more likely represents the dam outflow to the Neuse River for sustaining wildlife and our neighbors downstream.
The bottom line seems to be that the lake level still dropped in 24 hours despite the inflow, and the dam outflow and lake evaporation combined volume was much larger than the volume of water withdrawn for consumption. So, will conservation in Raleigh make a big difference on slowing the lake level drop at those rates? Maybe it will put the brake a bit on it but not much.
(End of update)
Bernard
Not sure if it's drought or heat...
I'm not sure if it's been drought or the excessive heat last week but this past Sunday afternoon (August 12, 2007) while visiting Occoneechee Mountain State Natural Area near Hillsborough, after hiking down over the mountain and to the Eno River below I noticed that a lot of leaves were lost from the trees lining the river banks.
The Eno River at this time of year is usually free from floating leaves and being that most appear to be leaves from River Birch trees which grow along the river upstream from where this photo was taken, I am assuming that heat stress may have been more of a factor than lack of water in this particular case.