Sally Thompson

University of Western Australia | UWA · Civil Environmental and Mining Engineering

Zero plane displacement height ( $$d_0$$ d 0 ) and momentum roughness length ( $$z_{0m}$$ z 0 m ), describe the aerodynamic characteristics of a vegetated surface. Usually, $$d_0$$ d 0 and $$z_{0m}$$ z 0 m are assumed to be constant functions of the physical characteristics of the surface. Prior evidence collected from the literature and our examin...

Water flow on plant canopies determines the partitioning of intercepted rainfall between stemflow and throughflow, yet understanding of these flow processes remains minimally developed. Plant canopies may concentrate intercepted water into rivulets that flow beneath branches. If the rivulets remain attached to branches until they encounter the main...

Terrestrial water fluxes are substantially mediated by vegetation, while the distribution, growth, health, and mortality of plants are strongly influenced by the availability of water. These interactions, playing out across multiple spatial and temporal scales, link the disciplines of plant ecophysiology and ecohydrology. Despite this connection, t...

Understanding the impact of climate change on groundwater recharge is crucial for the sustainable management of groundwater systems, especially when regulatory agencies are managing aquifers already fully allocated. Recharge emerges as the outcome of Critical Zone (CZ) processes such as interception, runoff, or plant water uptake that use or store...

covering the entire Earth's land surface every five days. However, the use of this data is significantly impacted by the presence of pixels affected by cloud and shadow. Precise and efficient cloud and cloud shadow masking methods are required for the automated use of this data. Here, we present CloudS2Mask, a new and open-source Python deep-learni...

The response of groundwater recharge to climate change needs to be understood to enable sustainable management of groundwater systems today and in the future, yet observations of recharge over long-enough time periods to reveal responses to climate trends are scarce. Here we present a meta-analysis of 60 years of recharge studies over the Gnangara...

The interception of rainfall by plant canopies alters the depth and spatial distribution of water arriving at the soil surface, and thus the location, volume, and depth of infiltration. Mechanisms like stemflow are known to concentrate rainfall and route it deep into the soil, yet other mechanisms of flow concentration are poorly understood. This s...

PREPRINT ACCEPTED. The response of groundwater recharge to climate change needs to be understood to enable sustainable management of groundwater systems today and in the future, yet observations of recharge over long enough periods to reveal responses to climate trends are scarce. Here we present a meta-analysis of 60 years of recharge studies ove...

Ecosystem evapotranspiration (ET) varies through space and time in response to environmental gradients and disturbances like fire. Field-based techniques (e.g. eddy covariance) can deliver direct measurements of how ET responds to fire, however, these measurements are localised and only represent small areas. Remotely sensed ET products have the po...

Women have played important roles in the provision, management, and pursuit of knowledge about water resources from antiquity to the present. Taking a broad perspective, this commentary begins with evidence of women's water knowledge in ancient societies, including a vignette of the famous Hellenistic scholar Hypatia of Alexandria who is widely kno...

The interception of rainfall by plant canopies alters the depth and spatial distribution of water arriving at the soil surface, and thus the location, volume, and depth of infiltration. Mechanisms like stemflow are well known to concentrate rainfall and route it deep into the soil, yet other mechanisms of flow concentration are poorly understood. T...

A quantitative understanding of actual evapotranspiration (ET a) and soil-water dynamics in a hillslope agroecosystem is vital for sustainable water resource management and soil conservation; however, the complexity of processes and conditions involving lateral subsurface flow (LSF) can be a limiting factor in the full comprehension of hillslope so...

Observations show vulnerability segmentation between stems and leaves is highly variable within and between environments. While a number of species exhibit conventional vulnerability segmentation (stem P 50 < ${P}_{50}\lt $ leaf P 50 ${P}_{50}$ ), others exhibit no vulnerability segmentation and others reverse vulnerability segmentation (stem P 50...

In drylands, runoff during storms redistributes water and nutrients from bare soil areas to vegetated patches, subsidizing vegetation with additional resources. The extent of this redistribution depends on the interplay between surface roughness and permeability; greater permeability in vegetated patches promotes run‐on to vegetation, but greater s...

Zero plane displacement length (d0) and roughness length for momentum (z0m), describe the aerodynamic characteristics of a land surface and govern its fluxes. Usually, d0 and z0m are assumed to be constants representing the physical characteristics of the surface, such as the canopy height or leaf area index. Prior evidence in the literature and ou...

Erosion of agricultural land endangers the livelihood of millions of people who depend on natural resources. Soil and water conservation practices (SWCP) are intended to reduce runoff production and erosion. Understanding surface runoff drivers are crucial for the effective design and implementation of SWCPs. We present field observations of comple...

A simple dynamical model was used to explore the forest cover dynamics for two basins in the Sierra Nevada of California, Illilouette Creek Basin (ICB) in Yosemite National Park and Sugarloaf Creek Basin (SCB) in Sequoia-Kings Canyon National Park. Since the 1970s, fire management in these basins has attempted to restore a near-natural fire regime,...

Remotely sensed evapotranspiration (ET) rates can provide an additional constraint on the calibration of groundwater models beyond typically-used water table (WT) level observations. The value of this constraint, measured in terms of reductions in model error, however, is expected to vary with the method by which it is imposed and by how closely th...

Like most water education institutions worldwide, hydrology instructors at the University of Western Australia (UWA) had to rapidly adapt traditional teaching strategies to manage the COVID-19 pandemic. With diverse student cohorts, including a large fraction of international students prevented from reaching Australia by travel restrictions, key re...

Understanding plant hydraulic regulation is critical for predicting plant and ecosystem responses to projected increases in drought stress. Plant hydraulic regulation is controlled by observable, diverse plant hydraulic traits that can vary as much across individuals of the same species as they do across different species. Direct measurements of pl...

Soil bulk density ( ρ b ) is an important indicator of soil quality, productivity, compaction and porosity. Despite its importance, ρ b is often omitted from global datasets due to the costs of making many direct ρ b measurements and the difficulty of direct measurement on rocky, sandy, very dry, or very wet soils. Pedotransfer functions (PTFs) are...

Hillslopes are a fundamental unit of surface hydrology, mediating the flow of water to fluvial networks through overland flow and subsurface pathways. We present Arc Hydro tools to delineate hillslope outlines, identify hillslope width functions and implement an overland flow model that accounts for hillslope curvature. We apply the new tool to sub...

In 2020, the Australian and New Zealand flux research and monitoring network, OzFlux, celebrated its 20th anniversary by reflecting on the lessons learned through two decades of ecosystem studies on global change biology. OzFlux is a network not only for ecosystem researchers, but also for those ‘next users’ of the knowledge, information and data t...

Predictions of urban runoff are heavily reliant on semi‐distributed models, which simulate runoff at subcatchment scales. These models often use “effective” model parameters that average across the small‐scale heterogeneity. Here we quantify the error in model prediction that arises when the optimal calibrated value of effective parameters changes...

Deforestation in the tropics causes warming which contributes to regional climate change. Forest loss occurs over a broad range of spatial scales, producing a variety of spatial patterns of cleared and forested land. Whether the spatial attributes of these patterns influence the resulting temperature change remains largely unknown. We adopted a dif...

Crop planting dates control the yield and cropping intensity of rainfed agriculture, and modifying planting dates can be a major adaptation strategy under climate change. However, shifts in rainfall seasonality may constrain farmers’ ability to adapt planting dates, and imperfect knowledge of how farmers currently select planting dates makes it dif...

Dead fuel moisture influences the risk of fire ignition events, with implications for fire hazards, risk mitigation, and the design of prescribed burning activities. Because direct fuel moisture measurements are rarely available, fuel moisture must be estimated when evaluating fire risks. Most estimates rely primarily on atmospheric conditions and...

Reducing the risk of large, severe wildfires while also increasing the security of mountain water supplies and enhancing biodiversity are urgent priorities in western US forests. After a century of fire suppression, Yosemite and Sequoia-Kings Canyon National Parks located in California's Sierra Nevada initiated programs to manage wildfires and thes...

Reducing the risk of large, severe wildfires while also increasing the security of mountain water supplies and enhancing biodiversity are urgent priorities in western US forests. After a century of fire suppression, Yosemite and Sequoia-Kings Canyon National Parks located in California’s Sierra Nevada initiated programs to manage wildfires and thes...

Plant transpiration downregulation in the presence of soil water stress is a critical mechanism for predicting global water, carbon, and energy cycles. Currently, many terrestrial biosphere models (TBMs) represent this mechanism with an empirical correction function (β) of soil moisture – a convenient approach that can produce large prediction unce...

The Rational Method is one of the most widely used methods for estimating peak discharge in small catchments. There are at least three forms of the Rational Method in use: deterministic, stochastic, and hybrid Rational Methods. These different forms are associated with distinct definitions of the runoff coefficient and produce distinct design flows...

Large-scale agriculture in the state of Mato Grosso, Brazil is a major contributor to global food supplies, but its continued productivity is vulnerable to contracting wet seasons and increased exposure to extreme temperatures. Sowing dates serve as an effective adaptation strategy to these climate perturbations. By controlling the weather experien...

Desertification processes pose a global environmental threat, impacting 61 × 106 km2 of the terrestrial land area. Changes in overland flow patterns and consequent rainwater redistribution in drylands present a potential pathway to desertification, because vegetation often relies on water inputs from runoff to sustain growth under insufficient rain...

Plant transpiration downregulation in the presence of soil water stress is a critical mechanism for predicting global water, carbon, and energy cycles. Currently, many terrestrial biosphere models (TBMs) represent this mechanism with an empirical correction function (β) of soil moisture – a convenient approach that can produce large prediction unce...

New land releases in the Perth Region on Western Australia’s Swan Coastal Plain are increasingly constrained by seasonally high groundwater (within 4m of the land surface). The measurement, modelling, and management of the effects of urbanisation in these high groundwater environments remains a challenging problem. To address this problem, the Coop...

Ecohydrological phenomena are often multiscale in nature, with behavior that emerges from the interaction of tightly coupled systems having characteristic timescales that differ by orders of magnitude. Models address these differences using timescale separation methods, where each system is held in psuedo‐steady state while the other evolves. When...

Reducing the risk of wildfire and increasing the security of water supply from mountain catchments are both urgent priorities in the Western US. These goals may be synergistic, thanks to the reductions in transpiration and fire hazard associated with reducing forest cover. Data and modeling efforts based on the Illilouette Creek Basin (ICB) in Yose...

Plants are characterized by the iso/anisohydry continuum depending on how they regulate leaf water potential (ΨL). However, how iso/anisohydry changes over time in response to year‐to‐year variations in environmental dryness and how such responses vary across different regions remains poorly characterized. ●We investigated how dryness, represented...

Managed wildfire is an increasingly relevant management option to restore variability in vegetation structure within fire-suppressed montane forests in western North America. Managed wildfire often reduces tree cover and density, potentially leading to increases in soil moisture availability, water storage in soils and groundwater, and streamflow....

Plant pathogens are a major agent of disturbance in ecosystems worldwide. Disturbance by diseases which inhibit plant water uptake can alter the hydrological function of affected ecosystems. However, many plant pathogens are also sensitive to soil moisture and can be propagated by the transport of infectious tissue or reproductive structures in sur...

Wildfires are a cause of soil water repellency (hydrophobicity), which reduces infiltration while increasing erosion and flooding from post-fire rainfall. Post-fire soil water repellency degrades over time, often in response to repeated wetting and drying of the soil. However, in mountainous fire-prone forests such as those in the Western USA, the...

In Mediterranean-type climates, asynchronicity between energy and water availability means that ecosystems rely heavily on the water-storing capacity of the subsurface to sustain plant water use over the summer dry season. The root-zone water storage capacity ( S m a x [L]) defines the maximum volume of water that can be stored in plant accessible...

Predicting the behavior of overland flow with analytical solutions to the kinematic wave equation is appealing due to its relative ease of implementation. Such simple solutions, however, have largely been constrained to applications on simple planar hillslopes. This study presents analytical solutions to the kinematic wave equation for hillslopes w...

Efforts to tackle land degradation worldwide have spurred the adoption of soil and water conservation (SWC) practices intended to reduce surface runoff and erosion. Despite their widespread implementation, missing or incomplete monitoring remains a pervasive problem preventing evaluation of how well SWC practices meet these aims. When using runoff...

The destructive wildfires that occurred recently in the western US starkly foreshadow the possible future of forest ecosystems and human communities in the region. With increases in the area burned by severe wildfire in seasonally dry forests expected to result from climate change, judicious, science‐based fire and restoration strategies will be es...

Describing the effects of surface roughness on flow resistance remains a first‐order challenge for modeling shallow overland flow using the Saint Venant equations (SVE). This challenge has resulted in a proliferation of roughness schemes relating the properties of a uniform rough surface to bulk velocity and resistance, making selection of an appro...

As rivers warm, cold‐water fish species may alleviate thermal stress by moving into localized thermal refuges such as cold‐water plumes created by cool tributary inflows. We quantified use of two tributary confluence plumes by juvenile steelhead, Oncorhynchus mykiss, throughout the summer, including how trout positioned themselves in relation to te...

Plant pathogens are a major agent of disturbance in ecosystems worldwide. Disturbance by disease can alter the hydrological function of affected ecosystems. However, many plant pathogens are also sensitive to soil moisture and can be propagated by the transport of infectious tissue or reproductive structures in surface flow, so that hydrological pr...

Drought extent and severity have increased and are predicted to continue to increase in many parts of the world. Understanding tree vulnerability to drought at both individual and species levels is key to ongoing forest management and preparation for future transitions in community composition. The influence of subsurface hydrologic processes is pa...

Human activities have resulted in rapid hydrological change around the world, in many cases producing shifts in the dominant hydrological processes, confounding predictions, and complicating effective management and planning. Identifying and characterizing such changes in hydrological processes is therefore a globally relevant problem, one that is...

Shifting precipitation phase from snow to rain has been shown to reduce streamflow from montane catchments. This phenomenon can have significant consequences in future global warming conditions when precipitation is less likely to occur as snowfall. Existing research has been limited to introducing the observations; a process-based understanding o...

Recent climate change has contributed to shifts in the seasonal interplay between precipitation and potential evapotranspiration, which have in turn increased droughts and reduced freshwater availability in Mediterranean climate regions. To overcome limitations in existing indices for comparing these seasonal hydroclimatic drivers at the global sca...

Methods are lacking to characterize critical zone (CZ) structure at spatial scales relevant to earth system and dynamic global vegetation models. This knowledge gap results in poor quantification of CZ plant-available water storage capacity, hindering realistic prediction of the response of plants and streamflow to anticipated changes in the hydrol...

The interleaving of impermeable and permeable surfaces along a runoff flow path controls the hillslope hydrograph, the spatial pattern of infiltration, and the distribution of flow velocities in landscapes dominated by overland flow. Predictions of the relationship between the pattern of (im)permeable surfaces and hydrological outcomes tend to fall...

Forest cover loss in the tropics is well known to cause warming at deforested sites, with maximum temperatures being particularly sensitive. Forest loss causes warming by altering local energy balance and surface roughness, local changes that can propagate across a wide range of spatial scales. Consequently, temperature increases result from not on...

Fire suppression in western U.S. mountains has caused dense forests with high water demands to grow. Restoring natural wildfire regimes to these forests could affect hydrology by changing vegetation composition and structure, but the specific effects on water balance are unknown. Mountain watersheds supply water to much of the western United States...

Plain Language Summary When does a shortage of precipitation become a shortage of water supply to plants? In rain‐dominated seasonally dry climates, the answer depends on how water is stored belowground. Here we propose—perhaps counterintuitively—that low water storage capacity in Earth's critical zone (which includes soil and weathered bedrock) re...

Vulnerability to embolism varies between con‐generic species distributed along aridity gradients, yet little is known about intraspecific variation and its drivers. Even less is known about intraspecific variation in tissues other than stems, despite results suggesting that roots, stems and leaves can differ in vulnerability. We hypothesized that i...

Thermal microrefugia, sites within a landscape which are relatively protected from temperature extremes and warming trends, may be necessary for the conservation of animal species as climates warm. In freshwater environments, cold water fish species such as Pacific salmonids already rely on thermal microrefugia to persist in the southern extent of...

Environmental decisions with substantial social and environmental implications are regularly informed by model predictions, incurring inevitable uncertainty. The selection of a set of model predictions to inform a decision is usually based on model performance, measured by goodness-of-fit metrics. Yet goodness-of-fit metrics have a questionable rel...

Despite the appeal of the iso/anisohydric framework for classifying plant drought responses, recent studies have shown that such classifications can be strongly affected by a plantꞋs environment. Here we present measured in‐situ drought responses to demonstrate that apparent isohydricity can be conflated with environmental conditions that vary over...