Monday, December 19, 2011

How to catch, store, and use rainwater

Plant a rain garden

When rain falls in Seattle, homeowner Lyn Dillman smiles: Water that used to run down the street now pools in a thickly planted infiltration basin at the garden’s edge, where it percolates into the groundwater below.

“It’s a win-win situation,” says landscape designer Malissa Gatton. “The garden helps reduce this household’s environmental footprint. Anybody could do it.”

If you have soil that drains well, a rain garden is a great option. Channel rainwater from the roof into a shallowly buried pipe that empties into an infiltration basin or swale at least 10 feet away from your house.

Grow water-tolerant plants such as shrub willows in the basin.

Design: Malissa Gatton ( or 888/ 472-7748)

Who owns the rain?

All Western states except Colorado and Utah give you the freedom to catch and use rainfall; some jurisdictions even require it. Here’s how different states see it.

Arizona The state offers an individual income-tax credit to cover 25 percent (up to $1,000) of the cost of rainwater-capture systems.

Colorado Your roof is considered a tributary to a stream somewhere, so unless you have water rights in that drainage, you can’t legally harvest rainwater. However, state legislators this year will consider a bill to permit the collection of water for irrigation.

New Mexico Santa Fe County requires cisterns for commercial buildings and for all new houses larger than 2,500 square feet; smaller dwellings must have rain barrels, berms, or swales to make use of rainfall.

Utah Rainwater is state property; homeowners can’t legally keep it. State Senator Scott Jenkins plans to introduce legislation this month that would allow homeowners to harvest rainwater.

Washington Existing law is ambiguous, so the state’s Department of Ecology doesn’t enforce laws that might regulate rainfall harvest.

Monday, November 14, 2011

Hungry mosquitoes fly farther than you think

Hungry mosquitoes fly farther than you think

Harry Boerema pointing to an antique map of the area surrounding his farm Thursday Oct. 6, 2011, lives on the edge of a drainage project, where Dutch authorities are dredging a huge meter-deep (3-foot) bowl in the northern rural landscape to head off flood waters and protect towns and villages from disaster.The project, begun in 2003, threatens to inflict hordes of mosquitoes on people bordering the 1,700 hectare (4,200-acre) water retention area, where heavy rainwater will collect and slowly be channeled to the North Sea. The frequent wet-dry cycles will be perfect breeding grounds.

How far does a mosquito fly? Harry Boerema wants to know.

Boerema lives near a drainage project, where Dutch authorities are dredging a huge meter-deep (3-foot) basin in the northern rural landscape to head off flood waters and protect towns and villages from disaster.

The project threatens to inflict hordes of mosquitoes on people living around the water retention area, so scientists set out to calculate how to keep the boundaries of the ditch far enough from human habitation to protect residents from pest infestation.

The question they needed to find out: How far does a common European human-biting mosquito fly?

What they found surprised them: A hungry female looking for a "host" will fly at least 150 meters (yards), three times farther than previously thought, said Piet Verdonschot, who conducted the research.

The 1,700 hectare (4,200-acre) basin, begun in 2003, is designed to collect heavy rainwater that will slowly be channeled to the North Sea. But frequent wet-dry cycles will be perfect breeding grounds for mosquitoes.

Buzzing pests are nothing new for Boerema, a retired professor of architectural history who has lived for 36 years in his quiet cottage set amid dairy farms.

"I don't mind them to a certain extent. But not in surplus," he says. "I'm a nature lover, and mosquitoes are part of nature _ although not the most likable ones."

Not everyone took the prospect of living on water's edge with such equanimity, and local complaints led authorities to commission the mosquito research, said project manager John Tukker.

At the outset, Verdonschot believed mosquitoes stay within about 50 meters (yards) of their breeding ground. The biggest nuisance for humans often originates in flower pots, buckets of collected rainwater or any kind of water left stagnant in the back garden or barnyard.

"The assumption in the literature is that people who suffer bites have bred their own specimens in their own gardens," he said.

Hundreds of mosquito species exist around the world _ 36 in the Netherlands alone _ but Verdonschot concentrated on the two species most common in the Dutch climate: the culex pipiens, which prefers birds to people but will still keep you awake at night during the summer, and the Culiseta annulata, larger, more aggressive insects active year-round. Neither normally carries dangerous diseases.

Verdonschot, an aquatic ecologist working for the private environmental research institute Alterra, hatched 40,000 mosquitoes in large tents in a grassy field. The tents were surrounded by concentric circles of traps set at 50 meters, 100 meters and 150 meters. Around the edges of the field were ditches with tall reeds and wild grasses on the banks.

The traps drew mosquitoes into smoke from dry ice then instantly froze them. At the end of each day researchers collected the corpses and counted them one-by-one, using tweezers under a microscope.

Verdonschot expected most mosquitoes to be caught in the closest traps. Instead, about 80 percent were found in the farthest, meaning most flew at least 150 meters from the tent where they were hatched.

Verdonschot then refined his experiment, placing evergreen shrubs within the inner circle of traps. The numbers caught in the closest ring of traps shot up by one-third. The bushes offered both shelter from predators and moisture evaporating from the leaves.

That discovery led Tukker, working in the north, to create small raised islands of vegetation in the middle of the retention area, which becomes a swamp after a heavy rain. Those islands deflect mosquitoes from nearby farms.

The experiments produced a few other surprises, too.

Mosquitoes are mostly quiet during the day, preferring to concentrate on the edge of a body of water. When females hunt for blood _ necessary for reproduction _ they move for about an hour at dusk or at dawn, staying close to the ground.

"They move differently than we thought, they move farther than we thought," Verdonschot said.

Verdonschot believes his team's research adds to scientific knowledge about mosquitoes. Tomes have been written about mosquito bites and the effects on human health, but little research has been done on their habits, he said.

Verdonschot's simple experiments this summer have value for others building catchment areas around Europe and for housing developers.

"The whole northwestern European climate is becoming more dynamic because of climate change, because of wetter summers. And all this urban infrastructure has to be protected from water excess," he said.

Boerema also has a mosquito trap in the hedge around his cottage, helping to keep track of the mosquito population during wet and dry periods. He is anxious to see the water storage project completed, recalling that he was ordered to evacuate his home during a 1998 flood.

"I think it will ease the danger," he said, even though he's likely to have more mosquitoes.

"We've always been bitten. I don't react very much, but my wife hates them _ but not to the extent that we find it unbearable to live here."

Tuesday, November 8, 2011

Tuesday, March 29, 2011

Ice Age Yukon and Alaskan Camels

t is a poorly known fact that camels (Family Camelidae) originated and underwent most of their evolution in North America. The earliest known Late Eocene (about 40 million years ago) camelids like Protylopus were rabbit-sized with four-toed feet and low-crowned teeth. The sheep-sized Poebrotherium of Oligocene time (37 to 24 million years ago) was common in open woodlands of what now is South Dakota, and had already "lost" the lateral toes. During the Miocene (24 to 5 million years ago), camels increased in size with lengthening necks and limbs, also developing and efficient pacing gait for traversing the expanding steppe and grassland habitat of the time. In the Early Pliocene some 5 million years ago, camels spread, eventually reaching South America and the Old World(via a Bering Isthmus). Some of these camels were gigantic, like Titanotylopus from Nebraska. The South American lineage gave rise to such species as llamas and their relatives all adapted to grazing on high-altitude steppes.

Camel Ironically, camels became extinct in their place of origin toward the close of the last glaciation. Although we know a good deal about camels and their origins, few people realize that they once lived in the Yukon and Alaska.

Camelid bones recovered in the Old Crow River Basin in northern Yukon are chiefly from large camels, much larger than either the modern twin-humped camel (Camelus bactrianus, which occurs naturally in small numbers in the Gobi Desert of central Asia) or the single-humped dromedary (Camelus dromedarius, used domestically from North Africa to India and now running wild in the Australian outback after introduction there). The fossils are closest in shape and size to a very large member of the true camel group (Camelini) like Titanotylopus mentioned earlier. That camel had long, massive limbs, a relatively small braincase, a convex region between between the eye sockets and well-developed third premolar teeth in both jaws. It was about 3.5 m tall, with long spines on the thoracic vertebrae indicting a large hump. Its snout was shorter than that of Camelops, the other smaller camel reported from Yukon and Alaskan Ice Age deposits. Evidently males were larger and had more robust skulls and canine teeth than females. Titanotylopus occupied western North America from about 5 to 1 million years ago. Could these Yukon Titanotylopus-like camels be relics of an earlier migration to Eurasia, having given rise to Giganotylopus (considered by some experts as identical to Titanotylopus) of the southern Ukraine(Odessa and Cherkassy) about 5 million years ago?

A number of bones of another smaller camel (Camelops hesternus, the western camel, distantly related to the modern llamas of South America) have been recovered on the banks of the Sixtymile River near the Yukon-Alaska border. Oddly, all Camelops bones are from the same locality, a placer-mining site of Chuck and Lynn McDougall. In the process of washing away masses of frozen silt("muck") covering the gold-bearing gravels, the miners sometimes encounter bones of Ice Age animals. This particular site has produced hundreds of fossils belonging to woolly mammoth, steppe bison, large and small horses, American mastodon, caribou, mountain sheep, helmeted and tundra muskoxen, caribou, moose, wapiti, wolf, wolverine, scimitar cat, American lion, ground squirrel (with ancient nests and droppings), bird and a virtually perfect carcass of a black-footed feret, fur and all! One of the Camelops bones from Sixtymile was radiocarbon dated to about 23,000 years ago, near the cold peak of the last glaciation. Climate was drier then, and cool steppe-like conditions with broad grassy tracts prevailed compared to the spruce forest that covers the area now, with tundra on the uplands.

Thirty-six western camel remains have been reported from mining sites near Fairbanks, Alaska (about two-thirds are from Cripple Creek and Gold Hill; others are from Engineer, Fairbanks and Ester creeks). Dates on a number of the bones range between 40,000 and 25,000 years ago when climate began cooling toward the peak of the last glaciation. So, perhaps western camels did not enter Yukon and Alaska from the south until the relatively warm mid-Wisconsinan interstadial(about 50,000 to 25,000 years ago), dying out there toward the peak of the last glaciation.

Western camels were confined to North America, having been most abundant in the western United States, southwestern Canada(Alberta and Saskatchewan) and central Mexico during the last part of the Ice Age(about 600,000 to 10,000 years ago). They probably reached unglaciated Yukon and Alaska by migrating northward via dry terrain on the eastern flanks of the Rocky Mountains during a relativley warm period. How did they survive the northern winters? Modern camels are able to grow thick pelts under cold conditions. I have seen Bactrian camels at ease, wandering over snow-covered land in mid-winter at a game farm in Alberta, and travellers have encountered them "plodding stolidly through north-Asiatic blizzards".

In life, the western camel probably looked like a large dromedary, however its limbs were about a fifth longer, its head was longer and narrower and the face was flexed downward to a greater extent. The shape of the snout(premaxilla) indicates that Camelops probably ate as much leaves, forbs(herbs other than grass) and fruits, as grass. The long neck and limbs allow it to reach high browse as well. Camelops seems to have been adapted to arid scrublands and grasslands, and Yukon and Alaskan finds suggest that it could tolerate cool, at times snow-covered steppe-like grasslands.

Western camel remains have been reported from at least 18 Paleo-Indian sites dating between about 12,600 and 10,000 years ago(when the species seems to have become extinct). A camel bone chopping tool was found at the Colby site, and there is evidence of butchering at the Casper and Carter/Kerr-McGee sites, also in Wyoming.

C.R. Harington, Canadian Museum of Nature
June, 1997


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