Thursday, August 30, 2018

Groundwater the Foundation of Sustainability

To be sustainable, a population must live within the carrying capacity of its ecosystem, which represents a form of natural capital. One of the most important elements of the ecosystem is potable water. Without water there can be no life. As populations grow water is needed for drinking, bathing, to support irrigated agriculture and industry. Water is connected to all aspects of life on earth-the ecosystem, food, biodiversity, economy and society.

Unlike other natural resources or raw materials, groundwater is present throughout the world. Possibilities for its use vary greatly from place to place, owing to rainfall conditions and the distribution of aquifers (rock and sand layers in whose pore spaces the groundwater sits). Generally, groundwater is renewed only through precipitation, but can be abstracted year-round. Provided that there is adequate replenishment, and that the source is protected from pollution, groundwater can be abstracted indefinitely at a sustainable rate.

Groundwater forms the invisible, subsurface part of the natural water cycle, in which evaporation, precipitation, seepage and discharge are the main components. The “visible” components are all strongly affected by weather and climate, and although they can be contaminated quickly, they generally recover quickly too. By contrast, the subsurface processes of groundwater are much slower and longer lasting, ranging from years to millennia. However, with careful management, these different timescales can be used to create an integrated system of water supply that is robust in the face of drought.

The groundwater cycle in humid and arid regions differ fundamentally from each other. In humid climates, with high rainfall, large volumes of water seep into the groundwater, which contributes actively to the water cycle feeding streams, springs and wetlands during periods when the rainfall is lower. In semi-arid and arid climates, there is by contrast practically no exchange between the surface water and groundwater because the small volume of seepage from the occasional rainfall only rarely penetrates the thick and dry (unsaturated) soils. The groundwater is much deeper and isolated from surface contact. In these areas groundwater resources are only minimally recharged. Our understanding of the complete water cycle is only rudimentary.

Any attempt to accurately model the groundwater component of the water cycle requires adequate measurements and observations over decades. We are beginning to gather that data and improve the modeling of water resources which have incredible variability across the globe and with changing land use and climate.

Groundwater availability varies by location. Precipitation, soil type and land cover like roadways and buildings, forests, and agricultural fields,  determines how much the shallower groundwater is recharged annually. However the volume of water that can be stored is controlled by the reservoir characteristics of the subsurface rocks. Groundwater may be present today even in places with very dry climates because of the nature of the local geology and the historic climate cycles that have occurred through time. Insufficient water due to prolonged drought has contributed to the collapse of ancient civilizations.
In the north-eastern Sahara, the Nubian Sandstone Aquifer System underlies an area of more than 750,000 square miles in Chad, Egypt, Libya and Sudan, and still contains huge amounts of fresh groundwater. Giant groundwater deposits of comparable size and limited recharge are thought to exist on nearly all continents, but the amount of groundwater that can be pumped out is unknown.
Water resources can be used sustainably only if their volume and variation through time are understood. However such information is often lacking, even in so-called developed regions. Hydrology as a science is very young and so little is known. Groundwater in arid regions is finite and non-renewable given the earth’s current climate and the projections scientists are making for the climate in the near future. As droughts and water shortages appear the value of groundwater has begun to be more fully appreciated. Precious groundwater resources increasingly need to be well managed to allow for sustainable long-term use.

Groundwater is usually cleaner than surface water, but that too, is changing. Groundwater is typically protected against contamination from the surface by the soils and rock layers covering the aquifer. This is the only available clean drinking water in many parts of the world. However, rising world population, changes in land use and rapid industrialization increasingly place groundwater in jeopardy. Once contaminated, groundwater is very difficult to clean and often after removal of contaminated plumes only long term abandonment of use to allow for natural attenuation is the only possible course of action.

The demand for water is rising as population, economic activity and agricultural irrigation grow. However, worldwide resources of accessible water are decreasing, due to overuse or pollution. The balance between demand (consumption) and supply (resource) is becoming unstable. More than 30 countries suffer from serious chronic water shortage, and groundwater is increasingly being used to cover the demand.

Monday, August 27, 2018

Where does the Lead in Wells Come From

In 2012, the Macon County Health Department in North Carolina discovered county-wide water lead contamination in private wells due, they reported, to corrosion of galvanized well components. In North Carolina current well construction code requires the installation of a tap on the well; thus, they were able to differentiate lead contamination originating from household plumbing and lead contamination originating from the well.

They found "first draw samples" collected at the wellhead between 2008 and 2012 documented that 55 of 398 (14%) of newly constructed wells exceeded the U.S. Environmental Protection Agency Lead and Copper Rule action level for lead of 15 μg/L. However, there is no safe level of lead exposure, as even low water lead levels-those less than 5 μg/L- can increase a child's blood lead level. In the Macon County Health Department samples they found water with lead concentrations as high as 191 μg/L.

North Carolina like most of the eastern seaboard states has areas at high risk for corrosive water. During periods of stagnation, in water that is corrosive (with a pH less than 6) a chemical redox reaction occurs that dissolves and leaches lead into the water. Lead present in well and plumbing components is leached into the water. This lead comes from brass fittings and galvanized pipe (which has a lead- zinc coating), and plumbing components produced before 2014 when "lead-free" fixtures could have up to 8% lead. In Virginia, the Blue Ridge, Piedmont and shallow wells in the Coastal Plain have a high risk for corrosive water and lead contamination in their water.

Civil and Environment Engineering Department at Virginia Tech and the Environmental Health Services Branch of the Macon County Public Health Department and lead by Kelsey J. Pieper PhD USDA-NIFA Postdoctoral Fellow at Virginia Tech investigated lead in well water concentrations at the homes of 15 private wells in Macon County found to have elevated levels of lead in their wellhead samples. There was another part of the research but we will not discuss that here.

 Low pH water can corrode metal plumbing fixtures causing lead and copper to leach into the water and causing pitting and leaks in the plumbing system. The presence of lead in pipes and fixtures becomes a bigger problem with water with a pH less than 6. In the past lead was used to solder copper pipes together before 1988 when the 1986 ban on lead in paint and solder went into effect. Also, until 2014 when the 2011 Reduction of Lead in Drinking Water Act went into effect, almost all drinking water fixtures were made from brass containing up to 8% lead, even if they carried a plated veneer of chrome, nickel or brushed aluminum and were sold as "lead free." So even home built with PVC piping in the 2000's may have some lead in most of the faucets.

The pattern of lead release and remediation for lead contamination originating from plumbing have been extensively studied. The goal for the Virginia Tech and the Macon County Public Health Department study was to identify patterns of lead leaching/ release within the well itself. Plumbing components used within a private well are not subject to the 1986 Lead Ban or the 2011 Reduction of Lead in Drinking water Act requirements. Galvanized iron is still commonly used for well casings and fittings and drop pipes in well deeper than 600 feet. Before 2014 Prime Western grade “lead free” galvanized steel zinc coating was required to contain between 0.5%-1.4% lead. After 2014, “lead free” galvanized steel have less than 0.25% lead in the surface coatings. Nonetheless, under corrosive conditions, any lead used in coatings can be easily released to the water and pumped to the household tap or accumulate in scale layers on the pipe surface or well bottom where scale can accumulate and be released or picked up and pumped with the water.

Water lead concentration patterns and sources of contamination within the wells differed among the 15 private wells as can be seen in the diagrams below which come from Environmental Science and Technology article cited below. The scientists found that elevated lead was associated with three sources of lead release: (1) dissolution of lead from well plumbing during periods of stagnation; (2) scouring of leaded scales and sediments along the well plumbing infrastructure during initial water use; and (3) mobilization of leaded scales during continued water use.

From Pieper et al.

As you can see, water lead levels measured during well testing show that in (A) nine wells had no water lead during continued water use however, (B) six wells showed sporadic spikes in particulate lead during continued water use. The detection limit of lead in the analysis was 1 μg/L. Lead contamination in a well can come from three potential sources; galvanized iron well casings, galvanized iron and brass well components, and leaded scales and sediment which have formed over time.

Corrosive water is the primary risk for lead in well water. However, over time water with a neutral pH could dissolve the coating on galvanized iron and in brass well components. The well completion reports do not document materials used for well components in Virginia or anywhere else to my knowledge. Once installed a well casing cannot be removed. It is possible to line the casing with a plastic pipe a technique used to seal a well where the grouting has failed. All the other components of the well can be replaced, though excavation would be required to replace the exterior portions of the pitless adaptor. However, scale that has accumulated on the bottom of the well might remain a source of lead if it is not mechanically removed. Further research needs to be done to further characterize the lead in well and effective remediation techniques.

To read the complete article:

Elevated Lead in Water of Private Wells Poses Health Risks: Case Study in Macon County, North Carolina

Kelsey J. Pieper, Victoria E. Nystrom, Jeffrey Parks, Kyle Jennings, Harold Faircloth, Jane B. Morgan, Jim Bruckner, and Marc A. Edwards Environmental Science & Technology 2018 52 (7), 4350-4357 DOI: 10.1021/acs.est.7b05812 

Thursday, August 23, 2018

Lead in Well Water Rivals Flint Michigan

Flint Michigan brought to the public’s attention the serious problem of lead in drinking water. It was shown that the corrosion of drinking water infrastructure can cause water lead contamination that in Flint increased the number and percentage of children found to have elevated blood lead levels. Lead is a potent neurotoxin, and elevated blood levels of lead in childhood impacts developmental and biological processes, most notably intelligence, behavior, and overall life achievement. Elevated lead blood levels in children can come from more than water- lead based paint in older homes is a particularly notable source; but the importance of lead in water to overall lead exposure has recently come to the forefront.

Flint Michigan was not an aberration nor was it the worst incidence of lead in drinking water supplies, but rather some combination of determined population, blatant misrepresentation by public officials, and public sentiment allowed Flint to become the poster child for lead in drinking water. In a 2017 examination of data, Reuters found 3,000 communities elevated lead in drinking water.

While Flint’s corrosive drinking water source and failure to have a corrosion control may or may not be an outlier among modern municipal water systems, prior research by Kelsey J. Pieper PhD USDA-NIFA Postdoctoral Fellow at Virginia Tech found that in a group of 2,146 samples from the Virginia Rural Household Water Quality well testing program 19% of the tested systems had elevated lead concentrations (above 15 μg/L) and 12% had elevated copper concentrations (above 1.3 mg/L) in the first draw. The high lead levels during the Flint crisis were the same as she found in some homes dependent on private wells in Virginia. When Dr. Peiper put up the chart below at a groundwater conference last spring, I was surprised.

Dr. Peiper and the other authors found that the 90th percentile water lead levels in Flint during the “Water Crisis” and the lead levels found in Virginia wells were almost identical at 26.8 and 26.7 micrograms /L respectively. The 99th percentile water lead levels in Flint were 118.9 micrograms/L and in the Virginia well group was 95.0 micrograms/L. However, the U.S. Environmental Protection Agency (USEPA) Lead and Copper Rule lead action level of 15 μg/L is not a health-based standard, rather it is used to identify system-wide contamination. There is no safe level of lead exposure. Water lead levels as below 5 micrograms/L can increase a child’s blood lead level and cause permanent damage to biological and developmental processes.

Lead leaches into water primarily as a result of corrosion of plumbing and well components. Corrosion control techniques such as adjusting pH or alkalinity that are commonly used in public systems are not common in private wells where the decision to install and maintain treatment is solely the prerogative and responsibility of the homeowner. As a result, though 26% of the private wells had pH outside the neutral range of 6.5-8.5 (and 89% of these were below 6.5), only 5% of private well systems had acid neutralizers installed to control pH and corrosion within the home and 3% had reverse osmosis units that could remove lead among other contaminants. Lead does not exist in in most groundwater, rivers and lakes- the source water for most municipal and private water supplies. Instead, lead in drinking water is picked up from the pipes on its journey into a home and based on the recent research by Dr. Peiper from the metal components of a well.

The presence of lead in drinking water in homes supplied by both municipal service and private wells has been linked to the corrosion of lead-bearing plumbing components. In older homes the water service lines delivering water from the water main in the street into each home were once commonly made of lead. This practice began to fade by the 1950’s but was legal until 1988. Lead was also used to solder copper pipes together before 1988 (when the 1986 ban on lead in paint and solder went into effect). Also until very recently (2011 Reduction of Lead in Drinking Water Act) almost all drinking water fixtures were made from brass containing up to 8% lead, even if they carry a plated veneer of chrome, nickel or brushed aluminum and were sold as "lead-free." So even homes built with PVC piping in the 2000’s may have some lead in most of the faucets.

In Dr. Pieper’s study of private well supplied homes, flushing for 5 minutes reduced lead concentrations below 15 μg/L. However, 2% of households experienced an increase in lead concentrations with flushing suggesting that there may be other components within the well and plumbing system that release lead and/or particulate lead and may have been mobilized. In a second study in North Carolina, the Macon County Health Department in North Carolina found county-wide water lead contamination in private wells due to corrosion of galvanized well components. In their analysis of 29,30 First draw samples collected at the wellhead between 2008 and 2012 they found that 55 of 398 (14%) of newly constructed wells exceeded the Lead and Copper Rule lead action level, with concentrations reported as high as 191 μg/L, exceeding the Flint Michigan 99th percentile.

During follow-up testing in 2013, the water lead levels varied based on sampling location within the home and flushing intervals. If the lead was coming from the plumbing or dissolved lead shorter flushing produced good results. However if lead was coming from the well or particulate lead, sporadic spikes were seen. The result was in site-specific flushing recommendations for each home. The unique water lead pattern(s) associated with

corrosion of components in the well may impact the efficacy of current flushing and treatment remediation recommendations. Dr. Pieper and the other scientists feel that in order to develop effective remediation and prevention additional work must be done to increase our understanding of the mechanisms of lead release in well systems.

Monday, August 20, 2018

Treating the Ash Tree for EAB

On Friday, the day finally arrived to treat my ash tree for Emerald Ash Borer. In early spring I had noticed the D shaped exit holes a sign of  Emerald Ash Borer infestation on the ash tree on the side of my house. I love that tree and wanted to save it if possible. Fortunately, I noticed the infestation while there was still hope.

I engaged a tree service recommended to me by my friends at the local Extension Office and listened to their recommendations. What they told me also mirrored what the Forest Service had told me: The protocol for treating Ash trees in areas were groundwater is used for drinking water is for either emamectin benzoate or a specific formulation of imidacloprid to be injected directly into the base of the tree trunk. The insecticide will hopefully be transported within the vascular system of the tree from the roots and trunk to the branches and leaves- if it works. This reduces hazards to groundwater and to other plants from drift and protects the applicator from exposure, and has less impact on beneficial insects and other non-target organisms (like me).

So I engaged SavATree to do the work, and ended up waiting several months until they were able to perform the service. During the early summer I had watched as more of the tree’s canopy withered and worried that they might not get here until it was too late.  Ash trees with greater than 50% canopy loss should be removed and destroyed in accordance with established state guidelines. Friday, the technician arrived to treat the tree and there was still enough canopy to try and save it.

Trunk injections require physically drilling into a tree during the application of the insecticide. The technician arrived with his bucket of tools in hand. First he exposed the base of the tree. Then, he measured the circumference of the tree at about four and a half feet up. The technician, Scott, proceeded to drill a hole for ever five inches of the circumference fairly evenly spaced and attached a tubing system to the holes with a valve on each tie in. Using gloves, safety glasses and pouring  over the plastic bucket he carefully measured out the Imidacloprid and poured it into the bottle connected to the tree tubing and then used a hand pump to create a vacuum. Within minutes all the pesticide had been drawn into the tree’s vascular system.

This is not a due it yourself project. Only licensed professionals can buy this strength of the pesticide and drilling the holes has the potential to cause injury to trees (especially smaller trees), and may provide entry points for certain disease-causing fungi like the Nectria, the cause of Nectria canker. It is a good sign that the pesticide was so easily taken up and that the tree still had so much canopy left. I am hopeful that the tree will be saved. It is reported by the Forest Service that tree injections are tolerated in still healthy ash trees, especially if treatments are applied once every two years, small volumes of product are injected, and injection holes are small and shallow.

Thursday, August 16, 2018

Groundwater Rights in the West are Changing

Last winter the Supreme Court of the United States declined to hare an appeal to the Ninth Circuit Court of Appeals recognizing and protecting the Agua Caliente Tribe of Cahuilla Indians’ Reservation’s federal water right. The appeals were submitted by California Water Agencies.

For decades the Agua Caliente Tribe had for decades purchased drinking water from the local water agencies. The agencies have pumped so much water from the region's groundwater aquifers that the land is subsiding, sinking. In the first phase of their lawsuit the Agua Caliente Tribe of Cahuilla Indians’ sought to establish their priority right to groundwater under the Winter doctrine.

The Agua Caliente Tribe has fewer than 500 members, and its reservation spreads across more than 31,000 acres in a checkerboard pattern across the Coachella Valley that includes parts of Palm Springs, Cathedral City, Rancho Mirage and surrounding areas. The tribe owns two golf courses, the Spa Resort Casino in Palm Springs and the Agua Caliente Casino Resort Spa in Rancho Mirage, and has plans to build new subdivisions and another casino. Thousands of homes stand on leased tribal land.

The Agua Caliente Tribe supplies water to its businesses and residents by purchasing the water from the local water agencies, which operate wells across the Coachella Valley. The Agua Caliente Tribe’s leaders accused the local water agencies of imperiling the aquifer by allowing its levels to decline over the years as evidenced by the land subsidence. Inability to negotiate an agreement with the water agencies resulted in the three phase lawsuit to in the first phase establish the Agua Caliente Tribe’s rights to groundwater, quantify that right in phase two, and establish water quality standards in phase three.

In the first phase, the Ninth Circuit Court of Appeals found that the United States government reserved appurtenant (attached to the land) water sources – including groundwater – when it created the Agua Caliente Tribe of Cahuilla Indians’ reservation in the Coachella Valley. The court also held that the creation of the Agua Caliente Reservation carried with it an implied right to use water from the Coachella Valley aquifer and that state water rights held by the water agencies are preempted by federal reserved rights. The fact that the Agua Caliente Tribe did not historically access groundwater did not destroy its right to groundwater now. Finally, the court found that the Agua Caliente Tribe’s entitlement to state water did not affect the Tribe’s federally reserved water right.

Now, as the next phase of Agua Caliente's lawsuit unfolds in federal court, the tribe is seeking to have judges put a number on its groundwater rights, establishing how much water it can pump from the Coachella Valley aquifer. The federal reserved right is the highest priority right, it is set aside before most other users are entitled to a single drop. Unlike California’s surface water storage and delivery system, groundwater is out of sight underground and most people do not understand its limits. Groundwater is also increasingly relied upon by growing cities and farms, and it plays an important role in the future sustainability of California’s overall water supply. In an average year, roughly 35%-40% of California’s water supply comes from groundwater. All the western states face the likely prospect of demand for water outstripping the supply of legally available freshwater in by 2030.

Monday, August 13, 2018

Prevent Sewage Backups-Don’t Pour Grease Down the Drain

Do not pour cooking fats, oils and grease (FOG) down any drains or toilets in your home. In septic and sewer lines FOG catches on the pipe surface and clings to the walls of the sewer system anywhere there is a disruption, like a tree root in a joint, or sag under your yard or along a roadway, or something that might give the FOG a place to catch. All pipes have some friction points. The FOG builds up one layer at a time making a smaller, narrower path for the water and waste to travel through, ultimately causing a backup or pipe to burst. The FOG will clog sewer pipes, septic lines and can then cause sewer overflows and basement backups in your home.

FOG comes primarily from food such as cooking oil, lard, shortening, meat fats, sauces, gravy, mayonnaise, butter, ice cream and soups. Sinks, dishwashers, and food scraps put down garbage disposals deliver the FOG to the sewer system or septic system, it can be liquid when you put it down the drain, but turns viscous or solid as it cools in underground pipes. As the FOG builds up, it restricts the flow in the pipe and can cause the sewage to back up into homes or premature failure of the sewer pipes and septic systems. Generally speaking, the worst maintained pipes are the laterals and septic pipes owned by individual property owners. In most of Virginia, the laterals pipes are are owned by the properties that connect to them.

Maintaining the sewer and septic pipes, clearing tree roots and keeping grease out of the system and keeping grease out of the drains (and toilets) can prevent most sewage backups and extend the life of your drain field or peat media. When I was growing up in the middle of the last century, it seemed that everyone poured their cooking grease into and old coffee can and scrapped their plates into the trash. In our home we always had a Chock full o'Nuts coffee can under the kitchen sink because Jackie Robinson yes, The. Jackie. Robinson. was Chock full o'Nuts vice president and my Uncle, a baseball fan, insisted Chock full o'Nuts was the best coffee. When did we become a nation of people who put everything down the drain? Now counties and cities have developed education and outreach campaigns to get you to stop pouring grease down the drain.

Fats can often be reused. There are a number of fats, like bacon grease, chicken fat and duck fat that can be used for imparting their flavor into other foods. Bacon grease can be used in making corn bread or adding a little flavor to hash browns. Schmaltz is clarified chicken, duck or goose fat used for frying, cooking or as a spread on bread in Central European cuisine, particularly Ashkenazi Jewish cuisine. The whipped fat has a fluffy, rich essence of fried chicken that adds a richness of flavor when incorporated into veggies, breads and meat dishes. I am more experienced with poultry fat than bacon fat, but it’s the same idea. These fats should be stored in a sealed container in the freezer or refrigerator. Cooking oil like vegetable, canola, and peanut oil, can all be used again. Store in a tightly sealed container, in a cool, dark place. That old coffee can under the sink or refrigerator .

Once you have gotten as much use as you can out of your grease and fat, dispose of the FOG in your trash in a solid form. I line an old plastic container with aluminum foil and refrigerate it until it is hard. Pull the solid grease out and put it in a zip lock bag with my trash.

To dispose of FOG in your trash, first make sure it is in solid form:
  • For small amounts in a pan, let the grease cool and solidify and then wipe with paper towels, wiping thoroughly before washing. 
  • Pour the grease into a lidded container with wood shavings or cat litter to throw in the trash. 
  • Place the grease in a strong container (tin can, coffee can or bottle) and freeze until solid. Then dispose in the trash. 

Thursday, August 9, 2018

Wildfires and Summer Can Impact Air Quality

Sixteen forest fires are burning across California with no end in sight. The state’s largest fire on record was last year’s Ventura County fire which burned 282,000 acres. In California they name fires- it was called the Thomas Fire. This year’s Mendocino Complex fire had already burned 283,000 acres and only hopes that firefighters will manage to control those fires this week. Air quality in California north of Yuba City is “Unhealthy” due to all the smoket and particulates in the air. Air quality in the Rogue Valley of southwestern Oregon has worsened to “Hazardous” after a change in wind direction pushed more wildfire smoke from California into the area. The wind is blowing northwest.

Poor air quality can hurt the very young, the elderly and the sick. When particulate pollution is high it is best to stay indoors. On hot summer days even in areas without wildfires, air quality can be impacted. Before you drive your kids out to soccer practice or a game, check the air quality. Long term exposure to particulate pollution can cause premature death in people with pre-existing cardiac or respiratory disease, but it is simply not healthy to send the kids out to exert themselves on poor air quality days.

Air pollution in the form of fine particles with diameters smaller than 2.5 microns, called PM 2.5, lodge in the lungs which can aggravate other conditions both immediately and long term –cutting months off of lives. This fine particulate matter can have immediate health impacts: itchy, watery eyes, increased respiratory symptoms such as irritation of the airways, coughing or difficulty breathing and aggravated asthma. Long term health effects can result from both short-term and long-term exposure to particulate pollution. Two major studies pne called the "Harvard Six Cities" and the other the American Cancer Society study, both outlined the connections between human health and exposure to fine particles.

PM 2.5 is either directly emitted or formed in the atmosphere. Directly-emitted particles come from a variety of sources such as cars, trucks, buses, industrial facilities, power plants, construction sites, tilled fields, unpaved roads, stone crushing, and burning of wood and the vast fires burning California now. Other particles are formed indirectly when gases produced by fossil fuel combustion react with sunlight and water vapor. Combustion from motor vehicles, power plants, and refineries emit particles directly and emit precursor pollutants that form secondary particulates. Ammonium nitrate and ammonium sulfate are the principal components of secondary particulates.

The U.S. Environmental Protection Agency, EPA, requires states to monitor air quality and ensure that it meets minimum air quality standards. The US EPA has established both annual and 24-hour PM2.5 air quality standards (as well as standards for other pollutants). The annual standard is now 12 ug/m3 (an AQI of 39). The 24-hr standard is 35 ug/m3 (an AQI of 99.

The reason I had been thinking about air quality was the fires burning in California. This will be the second year in a row that that California has recorded the state’s “largest fire in recorded history.” California’s expanding development into the chaparral and sagebrush, lack of proper management of their forested areas combined with longer droughts seems to have brought more fires. We need to plan for the future that is coming.

Just as I keep an eye on my water quality I also spot check the local air quality. The developing world is expanding their air pollution, the United States and most of the western developed world continues to reduce air pollution. Environmental and weather events like wildfires and inversion layers can impact our air quality. If you want to take a look at real time particulate pollution levels you can see what the monitors nearest your home are reporting. Recall that the levels are reported in AQI (0-50 AQI is good air quality and 51-99 is moderate air quality). Long Park in Haymarket Virginia was reporting an AQI level of 31 as I was finishing this article. Long Park is about 3 miles from my house down route 15.

Monday, August 6, 2018

Climate Change and Cape Town

Cape Town is South Africa’s second largest city. This past spring after three years of persistent drought, the city was almost out of water. The government was forced to limit water use to 50 liters per person per day (that's 13 gallons a day) in hopes of preserving water supply until the rains or be forced to turn off most of its taps to preserve water for hospitals and other essential and urgent needs.

In fear of what the South Africans called "Day Zero” – when the city will no longer have running water, the citizens cut back. The rainy season this winter (recall that Cape Town is in the Southern Hemisphere) started early in their winter and fell at rates closer to the long term average than in the previous three years. The city’s dams are reported to be half full. Cape Town officials hope to relax water restrictions in the next few months. Residents of the Washington DC metropolitan area use about 300 liters of water per day per person- personally it is hard to imagine going months using one sixth of my usual amount of water.

The early winter rains easing the drought have given local officials and politicians the time they need to review the water augmentation schemes launched at the height of the drought crisis to establish the best mix. City of Cape Town Deputy Mayor Ian Neilson said in the South African “News24”: "Now that we have navigated our way through the immediate drought crisis, it is necessary that we review our water supply strategy and augmentation plans to ensure that what was devised in a time of crisis is appropriate for longer-term sustainability and resilience."

According to the city government the water crisis appears to have been caused by a combination of climate change- shifting weather patterns and city mismanagement. Municipal water comes primarily from surface reservoirs that rely entirely on rainwater, and were designed to withstand up to three years of lower-than-average rainfall. But with the growing population and a reported increased likelihood of drought, the city needs to have major backup or augmentation resources.

World Weather Attribution (WWA) says that their computer model using proxy data found that changing climate has made the recent drought three times more likely than in the past. WWA is a four year old international effort designed to sharpen and accelerate the scientific community’s ability to analyze and communicate the possible influence of climate change on extreme-weather events such as storms, floods, heat waves and droughts. WWA seeks to identify the human fingerprint on individual extreme-weather events. This has been the goal of the scientific community for more than a decade. Right now, studies of the attribution of extreme events such as those in the Bulletin of the American Meteorological Society (BAMS) take months to complete and are published long after the event.

A team brought together by WWA used the available southern Africa rainfall records to run several climate models. Rainfall records from Cape Town do not go back very far. The oldest rainfall records in the western cape region of Africa go back to 1930, but most are not that old. The WWA team used the data they had to run their climate models without the 1 degree C increase in temperature the earth has experienced since 1900 and then with the 1 degree C increase. The team concluded that changing climate tripled the risk of such a severe drought and if the planet warms a further degree it will triple again.

Cape Town needs to make its water supply sustainable and resilient to survive more frequent and longer droughts. With the increased demand from a growing population and economy, and with climate change models predicting a drier Cape Town, the City has realized that it cannot rely only on rainfall for future water supply.

Thursday, August 2, 2018

Space X Launches new GRACE for NASA

Near the end of May, SpaceX conducted its tenth launch of the year using the flight-proven Falcon 9 rocket . In that launch, Space X’s Falcon 9 deployed five commercial Iridium communications satellites and the GRACE Follow-On Earth science mission for NASA and the German Research Centre for Geosciences.

The dual-satellite GRACE Follow-On mission, a partnership between NASA and the German Research Centre for Geosciences (GFZ), is a successor to the GRACE satellites that ceased operations last year after fifteen years of service. In January, NASA and the German Research Centre for Geosciences announced that a SpaceX Falcon 9 would carry the two GRACE-FO satellites as well as five Iridium Next communications satellites into low earth orbit. Originally, it was expected to launch in early 2018, according to NASA’s fiscal year 2018 budget proposal.

The Grace Follow-On satellites had been booked to fly aboard Dnepr, while Iridium had contracted for launches of the Russian vehicle to carry pairs of its spacecraft into orbit for testing. This was not possible due in part to the political situation with Russia . Iridium and the GFZ – who are responsible for arranging GRACE’s ride to orbit – agreed to share a launch on SpaceX’s more powerful Falcon 9 rocket, splitting the costs.

While similar in design to GRACE, GRACE-FO incorporates lessons learned from 15 years of GRACE operations. The changes made will improve the new mission’s satellite performance and reliability, as well as mission operations. GRACE-FO will also fly a technology demonstration of a new, more precise inter-satellite laser ranging interferometer, developed by a German/U.S. instrument team, for use in future generations of GRACE-like missions.GRACE maps Earth's gravity field by making accurate measurements of the distance between the two satellites, using GPS and a microwave ranging system. This allows scientists all over the world an efficient and accurate way to map Earth's gravity field.

GRACE data has provided a global picture of water storage trends for over a decade and could be an invaluable tool for understanding water resource availability. The GRACE mission is able to monitor monthly water storage changes on the planet. Regardless of whether water is solid, liquid or vapor, visible or invisible, it has mass, which exerts a gravitational pull. By tracking the changing pull of gravity very precisely around Earth, the U.S./German Gravity Recovery and Climate Experiment, or GRACE, mission observed the movement of water around our planet from 2002 to 2017 -- from the top of the Himalayas to the depths of the ocean to deep underground. GRACE Follow-On will continue GRACE’s critical mission of tracking the evolution of Earth’s water cycle by monitoring changes in the distribution of mass on Earth.

Maintaining a consistent, continuous climate data record of water and mass transport in the Earth system over decades is essential to understand and differentiate short-term climate variability from long-term climate change. Because some climate patterns take several decades to unfold, the only way to determine whether a multi-year trend is representative of a long-term change is to extend the length of the observational record. Monitoring changes in ice sheets and glaciers, underground water storage, the amount of water in large lakes and rivers, and changes in sea level provides a unique view of Earth’s evolving climate and its water and energy cycles, with far-reaching societal benefits.

  • Tracking mass changes of Earth's polar ice sheets. 
  • Estimating global groundwater storage changes. 
  • Measuring mass changes caused by large earthquakes. 
  • Inferring changes in deep ocean currents, a driving force in climate.