There are many people that think the "drought" is over. However, many more think it is only a "lull" and that it hasn't really turned around yet. There is no single definition for drought. When a drought begins and ends is difficult to determine. Rainfall data alone won't tell you if you are in a drought, how severe your drought may be, or how long you have been in drought. We can, however, identify various indicators of drought, such as rainfall, snowpack, streamflow, and more, and track these indicators to monitor drought. Researchers have developed a number of tools to help define the onset, severity, and end of droughts. Drought indices take thousands of bits of data on rainfall, snowpack, streamflow, etc., analyze the data over various time frames, and turn the data into a comprehensible big picture.
On SEPTEMBER 24, 2015 / 3:24 PM. the intake was unplugged to finish flooding an $817 million tunnel and complete a complicated and perilous "Third Straw" project to draw drinking water for Las Vegas from a shrinking Lake Mead. The plug that was pulled weighed 17,200 pounds. "It was a milestone. We're ready for operation," project chief Jim Nickerson, of Vegas Tunnel Constructors, said ahead of the final act in the six-year project. The new intake taps the lake at 860 feet above sea level. That's 190 feet below the tallest existing intake and 218 feet below the lake's surface level. The next step will be completion in 2020 of a third pumping station. That job began in October of 2015 and will cost another $650 million. The region had about 126,000 residents when it began drawing water from Lake Mead in 1971. It now has 2 million residents and draws 40 million tourists a year. Southern Nevada averages a little over 4 inches of rain a year, and the Southwest U.S. is also gripped by a record 20-year drought.
A drought index value is typically a single number, which is interpreted on a scale of abnormally wet, average, and abnormally dry. The declines there during the past 18 years, they say, also reflect the Colorado River's worsening "structural deficit." The 10 scientists, who make up the Colorado River Research Group, said even though the four Upper Basin states — Colorado, New Mexico, Utah and Wyoming — haven't been using all the water they're legally entitled to, Lake Powell has declined due to extra water releases into Mead. Those releases, they said, are "the only thing that has kept Lake Mead from dropping into shortage conditions." "I want people to know that what's going on at Lake Mead is very, very closely tied to what's going on Lake Powell," said Doug Kenney, the group's chair and a professor at the University of Colorado. "We're draining Lake Powell to prop it up." The scientists titled their report "It's Hard to Fill a Bathtub When the Drain is Wide Open." That is why the water levels for 2020 is roughly 10 feet higher than previous years.See the grafts in (Fig. 01) below.
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| (Fig. 01) |
Full capacity is 1,220 feet. And as we've written several times in the past couple of years, the 1,075-foot level is critical; if the lake level drops below that, it could trigger a water-shortage declaration, resulting in mandatory water reductions for Nevada, California, Arizona, and Mexico. Still, the lake has another 75 feet to drop to be in any danger of running out of water. Clearly, the lake has a long way to go to regain even a fraction of the 140 feet it's lost. But it's managing to stay above the shortage level and no shortage is currently projected.
The Southern Nevada Water Authority’s response to the "shrinking" of the lake was to dig the so-called “third straw,” which ensures Las Vegas of a water supply should the depth of Lake Mead fall below 1,000 feet. This was an enormous project involving a tunnel-boring machine chewing through solid rock underneath Lake Mead and an intake structure two and a half miles offshore. More than 1,000 concrete truck loads were transported to the intake site on 143 barge trips. About 300 people worked on the project. One worker, Thomas Albert Turner, 44, of Henderson, died on the job in June 2012. A $25 million drilling rig the length of two football fields was lowered in pieces 600 feet underground and reassembled to chew through bedrock while inching along a set of rails. The tunnel was tiled behind it with more than 2,400 14-inch-thick sections of curved concrete. The result is a clean, 20-foot-diameter tube big enough for a subway train. It slopes slightly from the bottom of a vertical shaft below Lake Mead's Saddle Island to a round vault cemented to the lake bottom and capped by what Nickerson called a hemispheric bulkhead.
On SEPTEMBER 24, 2015 / 3:24 PM. the intake was unplugged to finish flooding an $817 million tunnel and complete a complicated and perilous "Third Straw" project to draw drinking water for Las Vegas from a shrinking Lake Mead. The plug that was pulled weighed 17,200 pounds. "It was a milestone. We're ready for operation," project chief Jim Nickerson, of Vegas Tunnel Constructors, said ahead of the final act in the six-year project. The new intake taps the lake at 860 feet above sea level. That's 190 feet below the tallest existing intake and 218 feet below the lake's surface level. The next step will be completion in 2020 of a third pumping station. That job began in October of 2015 and will cost another $650 million. The region had about 126,000 residents when it began drawing water from Lake Mead in 1971. It now has 2 million residents and draws 40 million tourists a year. Southern Nevada averages a little over 4 inches of rain a year, and the Southwest U.S. is also gripped by a record 20-year drought.
