Category Archives: Groundwater – geofluids

Springs and seeps

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It rains quite a bit on Mamaku Plateau, the tableland underlain by volcanic debris that was violently deposited 240,000 years ago; an eruption that also gave rise to the Lake Rotorua caldera (central North Island, New Zealand). Some of that rain seeps into the myriad fractures, nooks and crannies, and heads west as groundwater. Fifty to 100 years later, that same water emerges, chilled (a cool 11oC), at Blue Springs (about 40km west of Rotorua). Spring water here flows at 42 cubic metres per minute (9,240 gallons per minute), enough to maintain a decent-sized stream (Waihou Stream). Continue reading

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The brutality of Surtsey’s laboratory

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I recently came across a local newspaper article describing a new volcanic island, rising from its own ashes above the sea floor, off the coast of Tonga.  The subtlety of memory returned me to 1963, and an announcement over our morning radio, of the birth… of a volcanic island off the coast of Iceland. Images, arriving a couple of days later (this was 1963 after all), gave witness to a natural brutality I had not seen before; the sea in boiling turmoil, torn by erupting columns of rock and steam. Beautiful, in an awe-filled way.

It has been fifty years since the cessation of volcanic activity. Surtsey has become home to plants and birds, a laboratory for the adaptable, the dispersible, and the colonial.  The only sounds that resonate now are noisy gulls and pounding North Atlantic waves. Continue reading

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Contrails, analogues, and visualizing groundwater flow

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Analogues and analogies.  Standard dictionaries define these as a comparison, correspondence, or similarity between one thing and another, that can apply to concepts, ideas or physical entities. They are tools, used to illustrate concepts, particularly abstract ideas, to help explain phenomena or theories. Science makes frequent use of analogies. It does so because many phenomena that it attempts to investigate and explain, extend beyond normal human experience, beyond what is visible to the unaided eye, beyond what we can touch.  Well-chosen analogies can help us understand the universe without, and the universe within. Continue reading

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A misspent youth serves to illustrate groundwater flow

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Groundwater is always on the move. Under some conditions, in fractures or other large conduits, it can move quickly; almost at a walking pace. Under other conditions it moves inexorably slowly, like fractions of a millimeter a year. Regardless, it is always compelled to move. Movement requires energy.  Where does this energy come from?  What drives the flow of groundwater?  Answers to these questions provide the foundations to the science of hydrogeology. Continue reading

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Stabilisation of an architectural icon; the Leaning Tower of Pisa

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Sunday in Pisa proved to be a welcome change from the usual tourist-cramped, shoulder-barging throngs of popular attractions in Tuscany.  No problem finding a seat in a decent café, en route to the Piazza del Miricoli.  Cross the street, turn a corner and there – the massive, white-marbled Pisa Duomo, Romanesque grandeur with a veneer of 21st Century scaffolding.  But the sense of balance normally attributed to cathedrals, is disrupted by the stand-alone bell tower that leans precariously, like a drunk looking for a lamppost.  The Leaning Tower of Pisa has been looking for a lamp-post for almost one thousand years.  And for a thousand years, people have been drawn to the tower not because it is particularly beautiful, but because it looks like it is about to fall over. Continue reading

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Biomarkers; forensic tools for hydrocarbon fingerprinting

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I like a good detective thriller. Danish, Norwegian, Swedish and Britain’s BBC networks have produced some quality shows over the past few years.  Forensics is usually equated with ‘who dunnit?’ but science also makes use of forensic-like tools to help unravel mysteries and solve problems.  This post looks at certain chemical compounds found in hydrocarbon deposits.  The compounds are specific, complex organic molecules called biomarkers.  Biomarkers provide scientific fingerprints of oil deposits, that help scientists and oil explorationists decipher the where, when and how such deposits formed, and environmental scientists monitoring the migration and degradation of spilled oil. Continue reading

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GRACE meets LANDSAT; Eyes in the sky monitoring long-terms changes in water resources

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You could be excused for labeling this title conspiratorial, the brutal reality encapsulated in Alan Parsons prog rock group’s signature song or a Helen Mirren thriller.  And if that is your inclination, don’t bother reading any further because this post deals with far more mundane uses of remotely sensed data.  The data sets are generated by two groups of satellites that measure very different attributes of the earth, gravity and light spectra.  Teasing the data has given us multiple stories of how systems like surface and groundwater are responding to human activities and natural processes.  Some of these stories make grim reading.

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