Recently in Drought Monitoring Category
Desalination of salt water and brackish water is becoming a critical issue as inland lakes and ponds suffer from droughts and water relocation projects.
Ecosystems suffer first. Terminus lakes could benefit from a new desalination system being developed at the University of Nevada, Reno.
Terminus lakes are located in closed-basin regions where there is no outflow for the water and a high evaporation rate, leaving a high concentration of minerals and salts.
This new, low cost way to desalinate water uses a specialized low-cost solar pond and patented membrane distillation system powered by renewable energy.
Hundreds of terminus lakes worldwide such as the Great Salt Lake, the Salton Sea in California, the Aral Sea and Nevada's Walker Lake are experiencing a decline in water levels and an increase in salinity from both human and natural processes," says Francisco Suarez, a doctoral student in hydrological sciences.
Suarez is developing an artificial salt-gradient stratification process that traps solar heat at the bottom of the solar pond and uses the collected energy to power the membrane distillation system recently patented by the University. The hot brine in the lower storage zone of the pond, which can reach temperatures greater than 195 degrees Fahrenheit, may be used directly for heating, thermal desalination, or for other low-temperature thermal applications.
The process has been highly successful in the lab in a small-scale experiment using a 400-gallon tank, where dissolved solids and precise fiber-optic temperature sensing are being used to track the process as it desalinates the water. The next step for Suarez and the research group is to build a pilot-project, demonstration-scale, low-temperature desalination system in an open environment.
This desalination system is designed to help sustain the ecosystems of these closed-basin regions.
Read more about this desalination system at the University of Nevada
Ecosystems suffer first. Terminus lakes could benefit from a new desalination system being developed at the University of Nevada, Reno.
Terminus lakes are located in closed-basin regions where there is no outflow for the water and a high evaporation rate, leaving a high concentration of minerals and salts.
This new, low cost way to desalinate water uses a specialized low-cost solar pond and patented membrane distillation system powered by renewable energy.
Hundreds of terminus lakes worldwide such as the Great Salt Lake, the Salton Sea in California, the Aral Sea and Nevada's Walker Lake are experiencing a decline in water levels and an increase in salinity from both human and natural processes," says Francisco Suarez, a doctoral student in hydrological sciences.
Suarez is developing an artificial salt-gradient stratification process that traps solar heat at the bottom of the solar pond and uses the collected energy to power the membrane distillation system recently patented by the University. The hot brine in the lower storage zone of the pond, which can reach temperatures greater than 195 degrees Fahrenheit, may be used directly for heating, thermal desalination, or for other low-temperature thermal applications.
The process has been highly successful in the lab in a small-scale experiment using a 400-gallon tank, where dissolved solids and precise fiber-optic temperature sensing are being used to track the process as it desalinates the water. The next step for Suarez and the research group is to build a pilot-project, demonstration-scale, low-temperature desalination system in an open environment.
This desalination system is designed to help sustain the ecosystems of these closed-basin regions.
Read more about this desalination system at the University of Nevada
Having been intimately involved in flooding and the devastating effects of urban flooding on my neighborhood in Tulsa, OK, I found the following followup information about the recent Atlanta floods heart-wrenching. And a reminder about how flooding is never predictable. the "100 Year flood" terminology that was used in the building and community planning sectors for decades is no longer adequate to address today's increasing levels of urban danger.
Just look at the Atlanta case ...
The epic flooding that hit the Atlanta area in September was so extremely rare that, six weeks later this event has defied attempts to describe it. Scientists have reviewed the numbers and they are stunning.
"At some sites, the annual chance of a flood of this magnitude was so significantly less than 1 in 500 that, given the relatively short length of streamgaging records (well less than 100 years), the U.S. Geological Survey cannot accurately characterize the probability due to its extreme rarity," said Robert Holmes, USGS National Flood Program Coordinator. "Nationwide, given that our oldest streamgaging records span about 100 years, the USGS does not cite probabilities for floods that are beyond a 0.2 percent (500-year) flood."
"If a 0.2 percent (500-year) flood was a cup of coffee, this one brewed a full pot," said Brian McCallum, Assistant Director for the USGS Georgia Water Science Center in Atlanta. "This flood overtopped 20 USGS streamgages - one by 12 feet. The closest numbers we have seen like these in Georgia were from Tropical Storm Alberto in 1994. This flood was off the charts."
The rains returned water levels in the region's two largest reservoirs, Lake Lanier and Allatoona Lake, to pre-drought levels. Lake Lanier rose by more than three feet to 1068 feet by Sept. 25 and returned to full pool in October. Allatoona Lake rose to 853.25 feet on Sept 23, more than 13 feet over full pool of 840 feet.
"The flooding in Atlanta is certainly near the top of the list of the worst floods in the United States during the past 100 years," said Holmes. "For comparable drainage areas, the magnitude of this flood was worse than the 1977 Kansas City flood, which caused tremendous destruction and loss of life. It is a testament to the diligence of county officials and emergency management teams that more lives were not lost in Georgia."
Significant property losses, however, were a near certainty from this event. According to the National Weather Service, some locations recorded up to 20 inches of rain from 8:00 pm on Sept. 20 to 8:00 pm the following day. Culverts and sewers are not usually designed for events of this magnitude because they are so rare and it is cost prohibitive.
"Applying rainfall frequency calculations, we have determined that the chance of 10 inches or more occurring at any given point are less than one hundredth of one percent", said Kent Frantz, Senior Service Hydrologist for the National Weather Service at Peachtree City. "This means that the chance of an event like this occurring is 1 in 10,000."
For this analysis, USGS reviewed high-water-mark surveys and indirect peak discharge computations throughout the flood-affected region. Scientists gather these data from the field during floods and in their immediate aftermath to supplement or in this case, to provide data after a gage is destroyed. Some notable results:
Just look at the Atlanta case ...
The epic flooding that hit the Atlanta area in September was so extremely rare that, six weeks later this event has defied attempts to describe it. Scientists have reviewed the numbers and they are stunning.
"At some sites, the annual chance of a flood of this magnitude was so significantly less than 1 in 500 that, given the relatively short length of streamgaging records (well less than 100 years), the U.S. Geological Survey cannot accurately characterize the probability due to its extreme rarity," said Robert Holmes, USGS National Flood Program Coordinator. "Nationwide, given that our oldest streamgaging records span about 100 years, the USGS does not cite probabilities for floods that are beyond a 0.2 percent (500-year) flood."
"If a 0.2 percent (500-year) flood was a cup of coffee, this one brewed a full pot," said Brian McCallum, Assistant Director for the USGS Georgia Water Science Center in Atlanta. "This flood overtopped 20 USGS streamgages - one by 12 feet. The closest numbers we have seen like these in Georgia were from Tropical Storm Alberto in 1994. This flood was off the charts."
The rains returned water levels in the region's two largest reservoirs, Lake Lanier and Allatoona Lake, to pre-drought levels. Lake Lanier rose by more than three feet to 1068 feet by Sept. 25 and returned to full pool in October. Allatoona Lake rose to 853.25 feet on Sept 23, more than 13 feet over full pool of 840 feet.
"The flooding in Atlanta is certainly near the top of the list of the worst floods in the United States during the past 100 years," said Holmes. "For comparable drainage areas, the magnitude of this flood was worse than the 1977 Kansas City flood, which caused tremendous destruction and loss of life. It is a testament to the diligence of county officials and emergency management teams that more lives were not lost in Georgia."
Significant property losses, however, were a near certainty from this event. According to the National Weather Service, some locations recorded up to 20 inches of rain from 8:00 pm on Sept. 20 to 8:00 pm the following day. Culverts and sewers are not usually designed for events of this magnitude because they are so rare and it is cost prohibitive.
"Applying rainfall frequency calculations, we have determined that the chance of 10 inches or more occurring at any given point are less than one hundredth of one percent", said Kent Frantz, Senior Service Hydrologist for the National Weather Service at Peachtree City. "This means that the chance of an event like this occurring is 1 in 10,000."
For this analysis, USGS reviewed high-water-mark surveys and indirect peak discharge computations throughout the flood-affected region. Scientists gather these data from the field during floods and in their immediate aftermath to supplement or in this case, to provide data after a gage is destroyed. Some notable results:
- In Cobb County, Sweetwater, Noonday, Butler, and Powder Springs creeks flooded so severely that the annual chance of a worse event is far smaller than 0.2 percent (500-year) flood. On Sweetwater Creek near Austell, Ga., high-water marks showed a peak stage of 30.8 feet. The peak flow (31,500 cubic feet per second) was more than double the previous peak flow recorded at this site during the last 73 years. The previous peak, caused by the remnants of Hurricane Dennis in July 2005, was almost 10 feet lower at 21.87 feet.
- In Douglas County, the Dog River near Fairplay overtopped the USGS stream gage by 12 feet. The peak stage was 33.8 feet, with a peak discharge of 59,900 cubic feet per second. This is well beyond the 0.2 percent annual exceedence probability (500-year) flood.
- Gwinnett, DeKalb and Rockdale counties also had record flooding. Suwanee Creek floods were beyond the 0.2 percent annual exceedence probability (500-year) flood.
- On the Chattahoochee, the USGS gage at Vinings reached a peak stage of 28.12 feet with 40,900 cubic feet per second, which represents between a between a 1.0 to 0.5 percent annual exceedence probability (100- to 200-year) flood.
- In Georgia the USGS maintains a network of nearly 300 streamgages that provide data in real time. Data from these streamgages are used by local, state and federal officials for numerous purposes, including public safety and flood forecasting by the National Weather Service. A map of these gages and graphs of discharge for the last seven days is available online.
- The USGS works in cooperation with other Federal, state, and local agencies, throughout Georgia that measure water level (stage), streamflow (discharge), lake levels and rainfall.
- Users can access current flood and high flow conditions across the country at the USGS WaterWatch Web site.
The United States uses less water today than it did 35 years ago, despite a 30 percent population increase.
Declines in water use are partly attributable to alternative cooling methods at power plants and more efficient irrigation systems. According to the latest USGS water use report ...
Declines in water use are partly attributable to alternative cooling methods at power plants and more efficient irrigation systems. According to the latest USGS water use report ...
- Nearly half of all water used in the United States goes to cooling thermoelectric power plants
- 31 percent is used for irrigation.
- 11 percent of water is used for public supply
- 9 percent is used for industrial, livestock, aquaculture, mining and rural domestic uses.
California regulators have opened the floodgates for using "gray water"
by issuing an emergency decision that allows residents to create simple
water-reuse systems without a construction permit.
The California Building Standards Commission had expected an overhaul of gray-water rules to take effect in 2011. But on Thursday, it adopted the regulations on an emergency basis due to the deepening drought. Local health agencies may adopt stricter conditions than the state's after they hold public hearings.
Gray water includes wastewater from showers, bathtubs, bathroom sinks, laundry tubs and washing machines, but not from toilets, kitchen sinks or dishwashers.
Roughly 1.7 million gray-water systems are installed statewide. Most are illegal because homeowners almost always avoid permits and the associated fees. Do-it-yourselfers can build a gray-water system for $200 or less, but permitting-process costs can more than double the expense.
A standard home generates about 160 gallons of gray water per day, or nearly 60,000 gallons per year, state officials said. A family of four could reuse 22,000 gallons a year by tapping the rinse water from its washing machine.
The California Building Standards Commission had expected an overhaul of gray-water rules to take effect in 2011. But on Thursday, it adopted the regulations on an emergency basis due to the deepening drought. Local health agencies may adopt stricter conditions than the state's after they hold public hearings.
Gray water includes wastewater from showers, bathtubs, bathroom sinks, laundry tubs and washing machines, but not from toilets, kitchen sinks or dishwashers.
Homeowners still must follow state guidelines for installation and use. The rules require minimal contact between people and the gray water, for instance by covering the water-release point with at least 2 inches of rock, mulch or other material.
'GRAY WATER' FACTS
New state rules provide permit exemptions for some residential gray-water systems, but people still have to follow several requirements. They include:
The system must allow users to direct water to an irrigation field or the sewer.
Ponding and gray-water runoff are prohibited.
Gray water can be released above ground, but the discharge point must be covered by at least
2 inches of mulch, rock or other material that minimizes human contact.
Water used to wash diapers or other soiled garments must be sent to the sewer.
Gray water shouldn't be used on root vegetables.
Online: For more information about California's new standards for gray-water systems, go to uniontrib.com/more/gray.
Roughly 1.7 million gray-water systems are installed statewide. Most are illegal because homeowners almost always avoid permits and the associated fees. Do-it-yourselfers can build a gray-water system for $200 or less, but permitting-process costs can more than double the expense.
A standard home generates about 160 gallons of gray water per day, or nearly 60,000 gallons per year, state officials said. A family of four could reuse 22,000 gallons a year by tapping the rinse water from its washing machine.
Drought is a devastating natural hazard, affecting more people than any other natural hazard and costing the United States an average of $6 to 8 billion annually.
By being able to monitor droughts, society and its decision makers can take action early to mitigate the detrimental affects and thereby minimize costs.
VegDRI
The Vegetation Drought Response Index, also known as VegDRI, is a valuable addition to the field of drought monitoring.
VegDRI combines information to show drought's effect on vegetation. Information is gathered from:
- historical and current satellite observations,
- climate indicators,
- ecological settings, and
- soil characteristics
Agricultural Applications
This system is particularly important to the agricultural community and can provide detailed information over broad regions of land as it reassesses the entire conterminous 48 states every other week. Ultimately, VegDRI promises to make drought response and mitigation more effective. For more information, visit the Vegetation Drought Response Index Web site.