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Evapotranspiration and recharge over the Perth Basin

Using intensive observations to help manage a precious resource

Perth's drinking water supplies depend on rainfall recharging groundwater.  We are working with the Department of Water and Environmental Regulation, CSIRO and other partners to measure recharge in different soils, groundwater regimes and land uses.

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Measuring interception at tree scales

Improving the reliability of a novel instrument to measure how much water is held in a tree canopy

Interception of water by tree canopies accounts for 10-30% of rainfall in wooded sites, but this substantial component of the water balance is hard to predict and measure.  By measuring how much tree stems compress as water adds weight to their canopy, we are attempting to quantify interception.  The "interceptometers" being used for this purpose are still quite new technology, so there's a lot of troubleshooting taking place. (Photo courtesy Ashvath Kunadi).

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How does heating due to deforestation spread?

Using machine learning and cloud computing to understand environmental change.

National Geographic Society is supporting us in leveraging cloud computing and machine learning to find out how land use change impacts our climate.  Deforestation is known to increase temperatures, but understanding how these increases impact neighboring areas - and whether changes in how logging/clearing is conducted can influence these impacts - remains less understood.  We are focusing on four deforestation hotspots in Australia, Papua New Guinea, Borneo and Sumatra to explore these questions.  The image shows warming in a deforested site (central pixels) and temperature change in forested "control" sites (green/grey) overlaid on satellite images of forest in Papua New Guinea.

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Fire and water interactions in California's Sierra Nevada

Looking for win-win-win solutions for water, fire hazards and ecosystem health

California's Sierra Nevada Mountains supply 60% of the drinking water for more than 50 million people.  Climate change means that fire risks and water scarcity risks are increasing in this area. We are measuring and modeling how fires, water and ecosystems interact when near-natural fire regimes are restored.  Increases in water availability, diversity of habitats and reductions in the occurrence of large fires suggest that restoring frequent, small, mixed intensity fire regimes has been a win-win-win in these watersheds.  Photo shows new shrub vegetation growing beneath a former high-density forest in Illilouette Creek basin, photo courtesy Gabrielle Boisrame.

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Soil and water conservation strategies in Ethiopia

Better understanding hydrological processes to evaluate strategies to protect land and water resources.

The Ethiopian Highlands are some of the most erosion-prone landscapes on Earth, and conserving water and soil resources is essential for livelihoods, health and ecosystem services.  We are investigating what soil properties can teach us about hydrological processes in the highlands, and using this information to model the response of hillslopes to different soil and water conservation strategies that aim to de-saturate the soil and reduce positive pore water pressures that can drive erosion.  Photos show (A) terraced hillslopes, (B) typical terrace construction, and (C) a gabon checkdam in a gully.  Photos courtesy Liya Weldgebriel.

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High urban groundwater in Perth

How should urbanization proceed in the face of groundwater constraints?

Perth, like approximately 40% of major cities worldwide, is located in an area where groundwater regularly approaches or broaches the land surface.  Increasingly, land development occurs in areas with high groundwater.  Current solutions to the challenges posed by high groundwater have large financial and environmental costs - and when things go wrong, significant damage to private and public infrastructure.  An expert panel convened by the CRC for Water Sensitive Cities enabled us to explore this issue and recommend improved technical practice, changes to governance, and innovation in design and construction to improve the status quo.  The Expert Panels' final report can be found here.

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Using isotopes to constrain ecophysiology and ecohydrology

Observing and modeling tracers in trees

Where did the water used by plants originate?  The answer to this question helps us understand the risks posed to ecosystems by drought, and could help us better describe hard-to-observe below-ground features like where plants' roots are located.  Stable isotopes of water can act as a tracer for water.  Their concentrations vary between rain storms and with the length of time they've spent in the natural environment.  We are exploring a combination of chamber and pot experiments to measure isotopes of water used by plants in conjunction with other water balance and physiological variables.  These datasets will be used to test and improve models of plant water use.

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Hydrologic change in sparsely measured areas

How can we understand change when measurements are sparse?

If you make a map of hydrological measurement stations, and a map of predicted future water scarcity, they fit together almost like a jigsaw: we have the least information in the places where change is expected to be greatest and most problematic.  How can we understand our water systems where measurements are so scarce?  We have pioneered the use of the method of multiple working hypotheses to understand change in such locations.  This approach allows us to draw on multiple strands of evidence (our own field work, remote sensing, interviews, and the datasets that do exist) to reconstruct hydrological changes - an approach we've mostly applied in the Arkavathy Basin near Bangalore, India.  Photo shows a dry surface well (hand dug).  Courtesy Gopal Penny.

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Hydrodynamic understanding of salmon thermal refuges

How do cold water confluences protect fish against global warming?

Salmon species in North-Western America face extinction due to warming water temperatures.  Local cold pockets of water could save these species.  We intensively measured water temperatures in a 3D grid at the confluence of cold water tributaries with the warmer main river channel in the South Fork Eel River in California.  We've shown that existing criteria to identify cold water refugia don't do a good job of describing when and where these cold water pockets are used by fish.  We're working on models that can be used to map cold water zones across river networks, and that might explain how fish do use these environments.

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