Climate change could dramatically affect water supplies

It’s no simple matter to figure out how regional changes in precipitation, expected to result from global climate change, may affect water supplies. Now, a new analysis led by MIT researchers has found that the changes in groundwater may actually be much greater than the precipitation changes themselves.

For example, in places where annual rainfall may increase by 20 percent as a result of climate change, the groundwater might increase as much as 40 percent. Conversely, the analysis showed in some cases just a 20 percent decrease in rainfall could lead to a 70 percent decrease in the recharging of local aquifers – a potentially devastating blow in semi-arid and arid regions.

But the exact effects depend on a complex mix of factors, the study found – including soil type, vegetation, and the exact timing and duration of rainfall events – so detailed studies will be required for each local region in order to predict the possible range of outcomes.

The research was conducted by Gene-Hua Crystal Ng, now a postdoctoral researcher in MIT’s Department of Civil and Environmental Engineering (CEE), along with King Bhumipol Professor Dennis McLaughlin and Bacardi Stockholm Water Foundations Professor Dara Entekhabi, both of CEE, and Bridget Scanlon, a senior researcher at the University of Texas. The results are being presented Wednesday, Dec. 17, at the American Geophysical Union’s fall meeting in San Francisco.

The analysis combines computer modeling and natural chloride tracer data to determine how precipitation, soil properties, and vegetation affect the transport of water from the surface to the aquifers below. This analysis focused on a specific semi-arid region near Lubbock, Texas, in the southern High Plains.

Predictions of the kinds and magnitudes of precipitation changes that may occur as the planet warms are included in the reports by the Intergovernmental Panel on Climate Change (IPCC), and are expressed as ranges of possible outcomes. “Because there is so much uncertainty, we wanted to be able to bracket” the expected impact on water supplies under the diverse climate projections, Ng says.

“What we found was very interesting,” Ng says. “It looks like the changes in recharge could be even greater than the changes in climate. For a given percentage change in precipitation, we’re getting even greater changes in recharge rates.”

Among the most important factors, the team found, is the timing and duration of the precipitation. For example, it makes a big difference whether it comes in a few large rainstorms or many smaller ones, and whether most of the rainfall occurs in winter or summer. “Changes in precipitation are often reported as annual changes, but what affects recharge is when the precipitation happens, and how it compares to the growing season,” she says.

The team presented the results as a range of probabilities, quantifying as much as possible “what we do and don’t know” about the future climate and land-surface conditions, Ng says. “For each prediction of climate change, we get a distribution of possible recharge values.”

If most of the rain falls while plants are growing, much of the water may be absorbed by the vegetation and released back into the atmosphere through transpiration, so very little percolates down to the aquifer. Similarly, it makes a big difference whether an overall increase in rainfall comes in the form of harder rainfalls, or more frequent small rainfalls. More frequent small rainstorms may be mostly soaked up by plants, whereas a few more intense events may be more likely to saturate the soil and increase the recharging effect.

“It’s tempting to say that a doubling of the precipitation will lead to a doubling of the recharge rate,” Ng says, “but when you look at how it’s going to impact a given area, it gets more and more complicated. The results were startling.”

Strange travels

Transport phenomena in highly heterogeneous media can be dramatically different from those in homogeneous media and therefore are of great fundamental and practical interest. Anomalous transport occurs in semiconductor physics, plasma physics, astrophysics, biology, and other areas. It plays an especially important role in hydrogeology because it may govern the rate of migration and degree of dispersion of groundwater contaminants from hazardous waste sites.

A series of four articles in Special Section: Nonclassical Transport of the November 2008 issue of Vadose Zone Journal is devoted to transport phenomena in heterogeneous media in the context of geologic disposal of radioactive waste. Guest Editors Leonid Bolshov and Peter Kondratenko (Nuclear Safety Institute, Russian Academy of Sciences) and Karsten Pruess (Lawrence Berkeley National Lab.) assembled the articles, which are the results of joint investigations performed at the Nuclear Safety Institute of the Russian Academy of Sciences and Lawrence Berkeley National Laboratory in California. The work was supported by the USDOE.

The problems addressed in this research involve a broad range of space and time scales and were approached using modern methods of theoretical and computational physics, such as scaling analysis and diagrammatic techniques used before in critical phenomena theory. Special attention is paid to concentration tails. This issue is exceptionally important for the reliability assessments of radioactive waste disposal because, depending on the structure of the tails, concentrations at large distances from the source can differ by many orders of magnitude.

The first paper of this special section presents an overview of field and laboratory observations that demonstrate nonclassical flow and transport behavior in geologic media, with an emphasis on the fractal geometry of natural fracture networks and the presence of contaminant traps. The second paper is devoted to the analysis of diffusion in heterogeneous media with sharply contrasting properties; the authors show that as time progresses, three different transport regimes can be realized. In the third paper, it is shown that the solute transport regime is determined by a competition of two mechanisms: random advection through a fracture network and trapping caused by sharply contrasting properties of the medium. In the fourth paper, the authors develop a model of anomalous diffusion to simulate solute transport in highly heterogeneous media, and the new model is shown to result in reasonable agreement with experimental data on solute transport in highly heterogeneous media.

Using Ground Penetrating Radar to Observe Hidden Underground Water Processes


Researchers present applications of radar technology for exploring the properties and movement of water beneath our feet.



To meet the needs of a growing population and to provide it with a higher quality of life, increasing pressures are being placed on the environment through the development of agriculture, industry, and infrastructures.



Soil erosion, groundwater depletion, salinization, and pollution have been recognized for decades as major threats to ecosystems and human health. More recently, the progressive substitution of fossil fuels with biofuels for energy production have been recognized as potential threats to water resources and sustained agricultural productivity.



The top part of the earth between the surface and the water table is called the vadose zone. The vadose zone mediates many of the processes that govern water resources and quality, such as the partition of precipitation into infiltration and runoff, groundwater recharge, contaminant transport, plant growth, evaporation, and energy exchanges between the earth’s surface and its atmosphere. It also determines soil organic carbon sequestration and carbon-cycle feedbacks, which could substantially affect climate change.



The vadose zone’s inherent spatial variability and inaccessibility make direct observation of the important belowground (termed “subsurface”) processes difficult. Conventional soil sampling is destructive, laborious, expensive, and may not be representative of the actual variability over space and time. In a societal context where the development of sustainable and optimal environmental management strategies has become a priority, there is a strong prerequisite for the development of noninvasive characterization and monitoring techniques of the vadose zone.


In particular, approaches integrating water movement, geological, and physical principles (called hydrogeophysics) applied at relevant scales are required to appraise dynamic belowground phenomena and to develop optimal sustainability, exploitation, and remediation strategies.



Among existing geophysical techniques, ground-penetrating radar (GPR) technology is of particular interest for providing high-resolution subsurface images and specifically addressing water-related questions. GPR is based on the transmission and reception of electromagnetic waves into the ground, whose propagation velocity and signal strength is determined by the soil electromagnetic properties and spatial distribution. As the electric permittivity of water overwhelms the permittivity of other soil components, the presence of water in the soil principally governs GPR wave propagation. Therefore, GPR-derived dielectric permittivity is usually used as surrogate measure for soil water content.



In the areas of unsaturated zone hydrology and water resources, GPR has been used to identify soil layering, locate water tables, follow wetting front movement, estimate soil water content, assist in subsurface hydraulic parameter identification, assess soil salinity, and support the monitoring of contaminants.



The February 2008 issue of Vadose Zone Journal includes a special section that presents recent research advances and applications of GPR in hydrogeophysics. The studies presented deal with a wide range of surface and borehole GPR applications, including GPR sensitivity to contaminant plumes, new methods for soil water content determination, three-dimensional imaging of the subsurface, time-lapse monitoring of hydrodynamic events and processing techniques for soil hydraulic properties estimation, and joint interpretation of GPR data with other sources of information.



“GPR has known a rapid development over the last decade,” notes Sébastien Lambot, who organized the special issue. “Yet, several challenges must still be overcome before we can benefit from the full potential of GPR. In particular, more exact GPR modeling procedures together with the integration of other sources of information, such as other sensors or process knowledge, are required to maximize quantitative and qualitative information retrieval capabilities of GPR. Once this is achieved, GPR will be established as a powerful tool to support the understanding of the vadose zone hydrological processes and the development of optimal environmental and agricultural management strategies for our soil and water resources.”



The full article is available for no charge for 30 days following the date of this summary. View the abstract at: vzj.scijournals.org

Are existing large-scale simulations of water dynamics wrong?


Researchers find that a much smaller spatial resolution should be used for modeling soil water



Soils are complicated porous media that are highly relevant for the sustainable use of water resources. Not only the essential basis for agriculture, soils also act as a filter for clean drinking water, and, depending on soil properties, they dampen or intensify surface runoff and thus susceptibility to floods. Moreover, the interaction of soil water with the atmosphere and the related energy flux is an important part of modern weather and climate models.



An accurate modeling of soil water dynamics thus has been an important research challenge for decades, but the prediction of water movement, especially at large spatial scales, is complicated by the heterogeneity of soils and the sometimes complicated topography.



Simulation models are typically based on Richards’ equation, a nonlinear partial differential equation, which can be solved using numerical solution methods. A prerequisite of most solution algorithms is the partitioning of the simulated region into discrete grid cells. For any fixed region, such as a soil profile, a hill slope, or an entire watershed, the grid resolution is usually limited by the available computer power. But how does this grid resolution affect the quality of the solution?


This problem was explored by Hans-Joerg Vogel from the UFZ – Helmholtz Center of Environmental Research in Leipzig, Germany and Olaf Ippisch from the Institute for Parallel and Distributed Systems of the University of Stuttgart, Germany. The results are published in the article “Estimation of a Critical Spatial Discretization Limit for Solving Richards’ Equation at Large Scales,” Vadose Zone J. Vol. 7, p. 112-114, in the February 2008 issue of Vadose Zone Journal.



Vogel and Ippisch found that the critical limit for the spatial resolution can be estimated based on more easily available soil properties: the soil water retention characteristic. Most importantly, this limit came out to be on the order of decimeters for loamy soils, and is even lower, on the order of millimeters, for sandy soils. This is much smaller than the resolution used in many practical applications.



This study implies that large-scale simulations of water dynamics in soil may be imprecise to completely wrong. But, it also opens new options for a specific refinement of simulation techniques using locally adaptive grids. The derived critical limit could serve as an indicator that shows where a refinement is necessary. These findings should be transferable to applications such as the simulation of oil reservoirs or models for soil remediation techniques.



The full article is available for no charge for 30 days following the date of this summary. View the abstract at: http://vzj.scijournals.org/cgi/content/full/7/1/112

Large Source of Nitrate, a Nutrient and Potential Water Contaminant, Found in Near-Surface Desert Soils





Photo Caption: Desert pavement overlying soil. Image credit: Graham lab, UCR.
Photo Caption: Desert pavement overlying soil. Image credit: Graham lab, UCR.

A UC Riverside-led study in the Mojave Desert, Calif., has found that soils under “desert pavement” have an unusually high concentration of nitrate, a type of salt, close to the surface. Vulnerable to erosion by rain and wind if the desert pavement is disrupted, this vast source of nitrate could contaminate surface and groundwaters, posing an environmental risk.



Study results appear in the March issue of Geology.



Desert pavement is a naturally occurring, single layer of closely fitted rock fragments. A common land surface feature in arid regions, it has been estimated to cover nearly half of North America’s desert landscapes.



Nitrate, a water soluble nitrogen compound, is a nutrient essential to life. It is also, however, a contaminant. When present in excess in aquatic systems, it results in algal blooms. High levels of nitrate in drinking water have been associated with serious health issues, including methaemoglobinaemia (blue baby disease, marked by a reduction in the oxygen-carrying capacity of blood), miscarriages and non-Hodgkin’s lymphoma.



Salts, including nitrate, are formed in deserts as water evaporates on dry lake beds. These salts then get blown on to the desert pavement by winds. Other contributors of nitrate to desert pavement soils are atmospheric deposition (the gradual deposition of nutrient-rich particulate matter from the air), and soil bacteria, which convert atmospheric nitrogen into nitrate that is usable by plants and other organisms.



Ordinarily, in moist soils, plants and microbes readily take up nitrate, and water flushing through the soils leaches the soils of excess nitrate.



But desert pavement, formed over thousands of years, impedes the infiltration of water in desert soil, restricting plant development and resulting in desert pavement soils becoming nitrate-rich (and saltier) with time.


“After water, nitrogen is the most limiting factor in deserts, affecting net productivity in desert ecosystems,” said Robert Graham, a professor of soil mineralogy in the Department of Environmental Sciences and the lead author of the research paper. “The nitrate stored in soils under desert pavement is a previously unrecognized vast pool of nitrogen that is particularly susceptible to climate change and human disturbance. Moister climates, increased irrigation, wastewater disposal, or flooding may transport high nitrate levels to groundwater or surface waters, which is detrimental to water quality.”



In their study, Graham and his colleagues sampled three widely separated locations with well-developed desert pavement in the Mojave Desert. The locations were selected to represent a variety of landforms commonly found in the desert. The researchers found that the nitrate they observed in association with desert pavement was consistent across the landforms.



“Deserts account for about one-third of Earth’s land area,” Graham said. “If our findings in the Mojave can be extrapolated to deserts worldwide, the amount of nitrate – and nitrogen – stored in near-surface soils of warm deserts would need to be re-estimated.”



Graham and his team of researchers found that nitrate concentration in soils under desert pavement in the Mojave reached a maximum (up to 12,750 kilograms per hectare) within 0.1 to 0.6 meter depth. In contrast, at each location they studied, the soils without desert pavement had relatively low nitrate concentrations (80 to 1500 kilograms per hectare) throughout the upper meter. “In these nonpavement locations, water was able to infiltrate the soil and transport the nitrate to deeper within the soil,” Graham explained.



The researchers note in the paper that desert land use – road construction, off-road vehicle use, and military training – often disrupts fragile land surfaces, increasing surface erosion by rain and wind. According to them, nitrogen-laden dust transported by wind from disturbed desert pavement soils may impact distant nitrogen-limited ecosystems, such as alpine lakes.



Furthermore, the researchers note that increased soil moisture resulting from climate change increases the potential for “denitrification” – a naturally-occurring process in soil, where bacteria break down nitrates to return nitrogen gas to the atmosphere. “Denitrification also produces nitrous oxide, a major greenhouse gas,” Graham said.



Next in their research, Graham and his colleagues will examine the spatial distribution of desert pavement throughout the Mojave Desert to explore how different levels of nitrate are associated with different kinds of desert pavement. Together with UCR’s David Parker, a professor of soil chemistry, they will look in the desert also for perchlorate, which may be associated with nitrate.



Graham was joined in the study by Daniel Hirmas, a doctoral candidate in the Department of Environmental Sciences at UCR; Christopher Amrhein, a professor of soil chemistry at UCR; and Yvonne Wood of the University of California Cooperative Extension, Inyo-Mono Counties, Bishop, Calif. The research was funded by the University of California Kearney Foundation of Soil Science.

Researchers make geothermal discovery in Mineral County, Nevada





The discovery is part of an ongoing effort by Great Basin Center for Geothermal Energy scientists to catalogue and record all of the state's geothermal assets. (Photo by: Jean Dixon)
The discovery is part of an ongoing effort by Great Basin Center for Geothermal Energy scientists to catalogue and record all of the state’s geothermal assets. (Photo by: Jean Dixon)

Researchers with the University’s Great Basin Center for Geothermal Energy and the Desert Research Institute (DRI) recently discovered the existence of direct evidence of an active geothermal system in the Teels Marsh area of Mineral County in rural Nevada.



According to Lisa Shevenell, director of the Great Basin Center, no thermal springs or wells are known to exist in the Teels Marsh basin. She said the shallow temperature anomalies are believed to be caused by geothermal groundwater upwelling along a fault on the western margin of basin.



“After reaching the groundwater table, these fluids likely mix with non-thermal groundwaters before reaching the Teels Marsh playa, where a portion of such fluids exit to the surface to form cold springs whose chemical compositions indicate high temperatures at depth,” she said.


The discovery is part of an ongoing effort by Great Basin Center for Geothermal Energy scientists to catalogue and record all of the state’s geothermal assets. In addition to the research done at Teels Marsh, scientists from the University have also measured shallow temperature anomalies in other areas of the Great Basin, including near Tungsten Mountain in the Edwards Creek Valley of Churchill County. A shallow temperature survey is still in progress at Rhodes Marsh in Mineral County.



Many of the areas described above and on the Great Basin Center for Geothermal Energy’s website are available for nomination for inclusion in future Bureau of Land Management geothermal lease auctions. The evidence from Teels Marsh comes from mapping surprisingly high temperatures at a depth of two meters below the surface. Researchers with the project noted that the temperatures occurred in two separate zones, both of which are adjacent to the fault. The two temperature anomalies have a combined length parallel to the fault of a little more than two miles.



Maps and digital temperature data are available at the Great Basin Center for Geothermal Energy website.

A Warming Climate Can Support Glacial Ice





Sea cliff at Tilleul Beach on the coast of Normandy, France are rich in microfossils and of the same age as the marine chalks used in the study to understand Earth's climate history.
Sea cliff at Tilleul Beach on the coast of Normandy, France are rich in microfossils and of the same age as the marine chalks used in the study to understand Earth’s climate history.

New research challenges the generally accepted belief that substantial ice sheets could not have existed on Earth during past super-warm climate events. The study by researchers at Scripps Institution of Oceanography at UC San Diego provides strong evidence that a glacial ice cap, about half the size of the modern day glacial ice sheet, existed 91 million years ago during a period of intense global warming. This study offers valuable insight into current day climate conditions and the environmental mechanisms for global sea level rise.



The new study in the Jan. 11 issue of the journal Science titled, “Isotopic Evidence for Glaciation During the Cretaceous Supergreenhouse,” examines geochemical and sea level data retrieved from marine microfossils deposited on the ocean floor 91 million years ago during the Cretaceous Thermal Maximum. This extreme warming event in Earth’s history raised tropical ocean temperatures to 35-37°C (95-98.6°F), about 10°C (50°F) warmer than today, thus creating an intense greenhouse climate.



Using two independent isotopic techniques, researchers at Scripps Oceanography studied the microfossils to gather geochemical data on the growth and eventual melting of large Cretaceous ice sheets. The researchers compared stable isotopes of oxygen molecules (d18O) in bottom-dwelling and near-surface marine microfossils, known as foraminifera, to show that changes in ocean chemistry were consistent with the growth of an ice sheet. The second method in which an ocean surface temperature record was subtracted from the stable isotope record of surface ocean microfossils yielded the same conclusion.






A micrograph of two types of foraminifera, M. sinuosa and W. baltica, and uses to study climate conditions during the Cretaceous Thermal Maximum, 91 million years ago.
A micrograph of two types of foraminifera, M. sinuosa and W. baltica, and uses to study climate conditions during the Cretaceous Thermal Maximum, 91 million years ago.

These independent methods provided Andre Bornemann, lead author of the study, with strong evidence to conclude that an ice sheet about 50-60 percent the size of the modern Antarctic ice cap existed for about 200,000 years. Bornemann conducted this study as a postdoctoral researcher at Scripps Oceanography and continues this research at Universitat Leipzig in Germany.



“Until now it was generally accepted that there were no large glaciers on the poles prior to the development of the Antarctic ice sheet about 33 million years ago,” said Richard Norris, professor of paleobiology at Scripps Oceanography and co-author of the study. “This study demonstrates that even the super-warm climates of the Cretaceous Thermal Maximum were not warm enough to prevent ice growth.”



Researchers are still unclear as to where such a large mass of ice could have existed in the Cretaceous or how ice growth could have started. The authors suggest that climate cycles may have favored ice growth during a few times in the Cretaceous when natural climate variations produced unusually cool summers. Likewise, high mountains under the modern Antarctic ice cap could have been potential sites for growth of large ice masses during the Cretaceous.





Graph depicts geochemical data collected from microfossils on the growth and eventual melting of ice sheets during the Cretaceous Period.
Graph depicts geochemical data collected from microfossils on the growth and eventual melting of ice sheets during the Cretaceous Period.

Ice sheets were much less common during the Cretaceous Thermal Maximum than during more recent “icehouse” climates. Paradoxically, past greenhouse climates may have aided ice growth by increasing the amount of moisture in the atmosphere and creating more winter snowfall at high elevations and high latitudes, according to the paper’s authors.



The results from the study are consistent with other studies from Russia and New Jersey that show sea level fell by about 25-40 m (82-131 ft) at the same time that the ice sheets were growing during the Cretaceous period. Sea level is known to fall as water is removed from the oceans to build continental ice sheets; conversely, sea level rises as ice melts and returns to the sea.



The presence or absence of sea ice has major environmental implications, specifically in terms of sea level rise and global circulation patterns. As humans continue to add large amounts of carbon dioxide and other greenhouse gases that accelerate the heating of the atmosphere and oceans, research on Earth’s past climate conditions is critical to predict what will happen as Earth’s climate continues to warm.



This research study was supported by the German Research Foundation and the National Science Foundation under the management of the Joint Oceanographic Institutions.

‘Climate Crisis’ in the West Predicted with Increasing Certainty





Computerized projections of western United States snowfall levels in 2050 compared to present day.
Computerized projections of western United States snowfall levels in 2050 compared to present day.

A new analysis led by researchers at Scripps Institution of Oceanography at UC San Diego shows that climate change from human activity is already disrupting water supplies in the western United States.



Trends in snowpack, river runoff and air temperatures – three fundamental indicators of the status of the West’s hydrological cycle – point to a decline in the region’s most valuable natural resource, water, as population and demand grows in the West.



The new study focused on the western United States because of its large and growing population in a generally dry region where battles over water are becoming increasingly common. The researchers report that the declines in snowpack, warming air temperatures and earlier spring river runoff that are already seen in the region are well explained by climate impacts expected from greenhouse gas and aerosol emissions from human activities.



The team also notes that the demonstrated accuracy of the computer models used in this analysis of the current situation bolsters the credibility of their predictions of future climate trends. These results show climate change is already affecting water supplies, a limited natural resource in the western U.S., and the region is facing a looming climate crisis.



The team, which included researchers from Scripps Oceanography, Lawrence Livermore National Laboratory, University of Washington, the National Institute for Environmental Studies in Japan, and the San Diego Supercomputer Center (SDSC), relied on multiple computer models and intensive data analysis. The scientists found that observed hydroclimatic changes differ in length and strength from trends that would be expected from natural variability, changes in solar activity or large-scale precipitation changes.


The observed changes, however, do correspond to those expected from the impacts of human activity on the climate system.



Lead researcher Tim Barnett, a research marine physicist at Scripps, said the analysis is unprecedented in its sophistication and novelty of approach.



“We couldn’t shake the results,” he said. “We got the same answer no matter what analysis techniques or datasets we used.”



Team members said that the specific focus of the analysis on the real-life issues affecting one region is also new. The climate models were chosen based on their realistic portrayals of observed global climate and of region-specific climate phenomena such as the Pacific Decadal Oscillation, a pattern that has a strong bearing on the climate of the western United States. Several of the member institutions took part in the analysis while SDSC team members helped manage the more than 20 terabytes of data incorporated by the climate models.



The accuracy of the representation of past climate trends and their cause suggests that the same models are a reliable predictor of future conditions in the West. These models have forecast a serious water supply problem for those dependent on the Colorado River drainage and substantial alterations to the hydrology of the Sacramento River delta, home to many sensitive ecosystems and economically important wildlife.



The models “portend a crisis,” said Barnett. “After the performance on the last 50 years of observations, we can put high confidence in their general predictions for the next 20 years, at least in the western United States.”

Water, water everywhere but is it sustainable?





Professor Malcolm Cox
Professor Malcolm Cox

While Brisbane is flush with underground water stores, more needs to be known about refill times to aquifers and the environmental effects of large-scale freshwater extraction to ensure their sustainable use.



Internationally recognised groundwater expert, UNESCO Professor Yongxin Xu is visiting Queensland University of Technology’s Institute for Sustainable Resources on Thursday to speak about the links between surface water and groundwater systems and how to model them.



QUT hydrogeologist Associate Professor Malcolm Cox said Professor Xu had developed models to assess the effect of changing rainfall patterns on the ability of groundwater systems to recharge.



He said Professor Xu’s work had many aspects that could be applied to South- East Queensland conditions to help understand how climate change was affecting our groundwater supplies.



“SEQ has a great variation in groundwater systems which need intensive study before it can be used with confidence as a long-term, sustainable resource,” Professor Cox said.


“Unlike Sydney, which is within a large basin of groundwater, we have groundwater stored in many different rock types with varying porosity and rates of recharge (refill times). Some of the SEQ groundwater may be thousands of years old, some might be only a few weeks.”



He urged caution in utilising South-East Queensland’s subsurface water supplies without fully understanding recharge times, how aquifer systems were linked and how they were connected to the surface.



“For example, The Lockyer Valley, which produces 30 per cent of Brisbane’s vegetables, has used its alluvial groundwater intensively for irrigation,” Professor Cox said.



“The alluvium (river gravel and sand) is not being recharged because rainfall has dropped. Normally it recharges very quickly from rainfall on mountains round the Valley.



Professor Cox said not enough was known about the environmental impact of extracting a lot of freshwater from the ground, especially in coastal areas.



“Stradbroke and Bribie islands, for example, are totally reliant on rainfall recharge for their groundwater supplies therefore groundwater extraction must be carefully monitored.”



Professor Cox said that in both these areas groundwater use must also consider potential problems such as the intrusion of saltwater to replace the fresh groundwater and the effects on ecosystems that rely on groundwater.



He said the Institute for Sustainable Resources had a key focus on water resources and was supporting a number of groundwater research projects in the region.

3D model visualises underground water supplies


A 3D computer model being developed by Queensland University of Technology has the potential to map all the subsurface water supplies within South East Queensland.



Utilising visual 3D technology, QUT scientists are creating a regional hydrogeological model that will make it possible to drill “virtual” bore holes and determine the complexities of underground water systems and the geology of aquifers.



Associate Professor Malcolm Cox, from QUT’s Institute of Sustainable Resources, said groundwater was not only an important resource for water supply but also a vital component of wider, interlinked ecosystems.



“Factors such as rapid population growth and drought are producing significant impacts on groundwater resources, however, in most areas these natural systems and surface links are not well understood,” Professor Cox said.



“The objective of this project is to develop a tool that makes it possible to catalogue where and how groundwater occurs and assess any changes over time.



“The concept is to use real data to produce a computer generated block of ground and incorporate information about its water-bearing properties.”


Professor Cox said the model would include groundwater levels, flow directions, water quality and bore locations and depths.



The area covered by the model will stretch from the NSW border in the south to Noosa in the north, Toowoomba in the west and the bay islands in the east.



“This is one of the faster growing regions in Australia and one within which water resources are becoming inadequate and groundwater is increasingly being utilised,” he said.



“Within this setting many of the groundwater systems are being impacted and some are now coming under stress, especially with continuing drought conditions.”



Professor Cox said with this in mind, it was essential to properly manage groundwater systems, thereby ensuring their integrity.



“Currently no structured management system exists to provide an integrated approach to the region,” he said.



Joint researcher on the project, Dr Joseph Young of the QUT High Performance Computer group, said the project would provide scientists and managers with a regional 3D hydrogeological model that could be used for the strategic management of groundwater resources.



Development of the model, known as HYDROSEQ, is a collaborative venture involving QUT, the Queensland Cyber Infrastructure Foundation, Natural Resources and Water, Geological Survey of Queensland, CSIRO and local councils.