Sean W. Fleming

• PhD (Geophysics, UBC), MS (Geology/Civil Eng, OSU), MS (Geophysics, OSU), BSc (Geophysics, UBC)
• Senior Development Hydrologist at United States Department of Agriculture

The Snow Survey and Water Supply Forecasting (SSWSF) Program and the Soil Climate Analysis Network (SCAN) of the United States Department of Agriculture's Natural Resources Conservation Service (NRCS) generate key observational and predictive information for water managers. Examples include mountain climate and snow monitoring through manual snow s...

Cross‐validated principal component regression (PCR) is widely used in day‐to‐day operational forecasting systems for seasonal river runoff volume in western North America. Complexities are increasing in both predictor datasets (including climate‐science products) and in predictive models employed instead of linear regression within the PCR framewo...

Leveraging advances in artificial intelligence could revolutionize the Earth and environmental sciences. We must ensure that our research funding and training choices give the next generation of geoscientists the capacity to realize this potential.

Western US water management is underpinned by spring-summer water supply forecasts (WSFs) from hydrologic models forced primarily by winter mountain snowpack data. The US Department of Agriculture Natural Resources Conservation Service (NRCS) operates the largest such system regionally. NRCS recently developed a next-generation WSF prototype, the m...

In the largely dry and increasingly heavily populated western US, operational modeling systems for seasonal river runoff volume forecasting are key elements of the practical water and hydropower management infrastructure. Explainability of model results in terms of known hydroclimatic processes and conditions is a core requirement for these systems...

How climate change may affect land-sea linkages along the Pacific Coast and the ecological consequences of these changes for marine food webs and ecosystem processes .

Coastal margins are important areas of materials flux that link terrestrial and marine ecosystems. Consequently, climate-mediated changes to coastal terrestrial ecosystems and hydrologic regimes have high potential to influence nearshore ocean chemistry and food web dynamics. Research from tightly coupled, high-flux coastal ecosystems can advance u...

An agent-based model is presented that mechanistically simulates social interactions across two partially coupled lattices, each containing a mixture of individualists, networkers, and reciprocators. Numerical experiments reveal evidence for two spontaneously emergent and widely relevant complex behaviors: self-organized criticality generating frac...

Resource managers use forecasts to ensure future access to abundant water and provide safety from river-related hazards.

Study focus Future climate impacts on streamflow are of critical concern due to its importance for water and energy supplies. However, rigorous studies of such impacts involve complicated modeling chains that can be time-consuming and costly to implement. We examine an alternative approach by developing a method to predict the 21st century peak Mar...

Hydroelectric power generation, water supplies for municipal, agricultural, manufacturing, and service industry uses including technology-sector requirements, dam safety, flood control, recreational uses, and ecological and legal constraints, all place simultaneous, competing demands on the heavily stressed water management infrastructure of the mo...

The Colorado River basin (CRB) is one of the most important watersheds for energy, water, and food security in the United States. CRB water supports 15% of U.S. food production, more than 50 GW of electricity capacity, and one of the fastest growing populations in the United States. Energy-water-food nexus impacts from climate change are projected...

Abstract: Water and climate have always been existential drivers of human civilization and today are more relevant than ever as both enablers of progress and wealth and threats to safety and well-being. What can modern data analytics teach us about these things? Geophysical processes are, in general, nonlinear phenomena generated by complex open sy...

Increased demand associated with population or economic growth, and decreased supply under some climatic shifts, obviously contribute to water scarcity. As a fresh perspective, we offer a generic theoretical treatment using a computational “maquette,” employing parameterizations to avoid assumptions about the origin and scale of climate and demand...

The northern portion of the Pacific coastal temperate rainforest (PCTR) is one of the least anthropogenically modified regions on earth and remains in many respects a frontier area to science. Rivers crossing the northern PCTR, which is also an international boundary region between British Columbia, Canada and Alaska, USA, deliver large freshwater...

Network theory is applied to an array of streamflow gauges located in the Coast Mountains of British Columbia (BC) and Yukon, Canada. The goal of the analysis is to assess whether insights from this branch of mathematical graph theory can be meaningfully applied to hydrometric data, and, more specifically, whether it may help guide decisions concer...

Rates of glacier mass loss in the northern Pacific coastal temperate rainforest (PCTR) are among the highest on Earth, and changes in glacier volume and extent will affect the flow regime and chemistry of coastal rivers, as well as the nearshore marine ecosystem of the Gulf of Alaska. Here we synthesize physical, chemical and biological linkages th...

The southern interior ecoprovince (SIE) of British Columbia, Canada represents the northernmost extent of the great western North American deserts, it is experiencing some of the nation's fastest economic and population growth making it one of Canada's most water-stressed regions, and it includes two headwater basins of the transboundary (Canada-US...

Network theory is applied to an array of streamflow gauges located in the Coast Mountains of British Columbia and Yukon, Canada. The goal of the analysis is to assess whether insights from this branch of mathematical graph theory can be meaningfully applied to hydrometric data, and more specifically, whether it may help guide decisions concerning s...

Coastal catchments in British Columbia, Canada, experience a complex mixture of rainfall- and snowmelt-driven contributions to flood events. Few operational flood-forecast models are available in the region. Here, we integrated a number of proven technologies in a novel way to produce a super-ensemble forecast system for the Englishman River, a flo...

It is almost universally assumed in statistical hydroclimatology that relationships between large-scale climate indices and local-scale hydrometeorological responses, though possibly nonlinear, are monotonic. However, recent work suggests that northern-hemisphere atmospheric teleconnections to El Niño-Southern Oscillation (ENSO) and the Arctic Osci...

Historical streamflow and climate datasets were analyzed for low- and high-frequency hydroclimatic variability. Four glacial/non-glacial catchment pairs were considered, two from the southern Canadian Rocky Mountains and two from arctic coastal Norway. Analyses were performed using daily data, providing high seasonal resolution and facilitating the...

We introduce a groundwater sustainability index offering a novel combination of features. It is holistic in the sense that it incorporates both water quantity and water quality indicators. The former employs the signal-to-noise ratio of long-term trends estimated via robust regression; the latter uses concentration of the primary contaminant of con...

Power-law spectral scaling violates assumptions of standard analyses such as statistical change detection. However, hydroclimatic data sets may be too short to differentiate the spectra of 1/f αvs low-order linear memory processes, an ambiguity exacerbated by the ubiquity of both process types. We explore this non-uniqueness problem by applying a h...

The impacts of large-scale modes of climate variability on the annual cycle of terrestrial hydrometeorology in the Canadian Columbia River basin were assessed with the aim of updating our current understanding and identifying opportunities for climate-informed, early-season water supply forecasting. Composite analyses of streamflow from seven Water...

A systematic and holistic watershed model comparison and selection process, integrating a full range of relevant criteria, is illustrated here. The process consists of screening for a set of candidate models on the basis of prerequisite model attributes; assessing hydrologic simulation performance using various conventional statistical metrics; ass...

The evaluation of long-term trends in yearly discharge records, such as annual peak daily flow or total annual runoff, is important to a variety of issues including water resource planning, flood hazard studies, and the assessment of historical data for evidence of anthropogenic climate change effects. Prewhitening or deserialization procedures hav...

Key Points We explore generational changes in water supply dynamics over a millennium Paleohydrologic data and statistical methods are used for the Canadian Prairies Human experiential timeframes and gauge records can be misleading

This article examines the current practice of streamflow modelling, a field under development for over a century. A sample of the wide range of assessment and planning applications of streamflow models is presented. The diversity in the use of these models is mirrored in the diversity of model complexity, and modelling approaches ranging from empir...

We studied long-term monotonic trend in inflow volume to 20 reservoirs, plus a measure of system-wide hydroelectric power potentially available for generation, in British Columbia, Canada. The primary analysis involved application of a linear method with explicit signal-to-noise ratio (S:N) estimation to monthly and annual mean inflows over the per...

Fractal dynamics, defined for our purposes as log-space linear scaling of the power spectrum, are important to water resource scientists for two broad reasons. The first is fundamental: such behaviour is commonly believed to be very widespread in nature, and is therefore a central and important feature of physical systems - including watershed hydr...

Indicators and indices can be an effective method for tracking environmental conditions over time, and thus for assessing the effectiveness of policy measures or remediation activities. Relative to surface water resources, however, groundwater has received little attention in this regard. This is problematic: about 30% and 44% of the Canadian and A...

Coherent modes of ocean and/or atmosphere circulation have become a key organizing theme for understanding and, in some cases, predicting the impacts of climatic variations upon local surface meteorology and water resources. The broad effects of such climate modes were in most cases traced out by geophysical scientists years ago. It turns out, howe...

An observational time series can normally be viewed as consisting of two general components: one that we are interested in (signal), and another that we are not (noise) and that usually obscures the signal. For analysis of data sets capturing the temporal evolution of complex, open, multi-faceted systems - uch as those routinely encountered in envi...

We assessed the impacts of some key Pacific ocean‐atmosphere circulation patterns on annual cycles of temperature and precipitation across British Columbia, Yukon, and southeast Alaska. The El Niño‐Southern Oscillation (ENSO), the Pacific Decadal Oscillation (PDO), and ENSO conditional on PDO states were considered in composite analyses of 71 long,...

The Pacific Decadal Oscillation (PDO) is a large-scale climate system feature that influences the surface climate and hydrology of western North America. In this paper, we review the literature describing the PDO and demonstrate its effects on temperature, precipitation, snowfall, glacier mass balance, and streamflow with a focus on western Canada,...

1. ABSTRACT River forecasts have two broad uncertainty classes: errors associated with meteorological forecasts, and those associated with the hydrologic model. We developed a technology (dubbed Absynthe) to address the latter error class in a practical and defensible way. The technique merges the proven, Monte Carlo-based Generalized Likelihood Un...

The Pacific Decadal Oscillation (PDO) is the leading mode of North-Pacific temperature variability. This climatic oscillation is nominally dominated by regime shifts having wide-ranging impacts. An ongoing point of discussion around the PDO regards whether such regimes genuinely represent multiple, stable, discrete states in a nonlinear dynamical s...

The glaciers of western Canada and the conterminous United States have dominantly retreated since the end of the Little Ice Age (LIA) in the nineteenth century, although average rates of retreat varied from strong in the first-half of the twentieth century, with glaciers stabilizing or even advancing until 1980, and then resuming consistent recessi...

Inspired by an analogy to AM radio signals, amplitude modulation (AM) is proposed here as a useful view of nonstationary environmental periodicities, and applied to hydrologic and air quality datasets. Both example time series considered exhibit seasonally evolving diel cycles, with large (small) daily cycle amplitudes in summer (winter). The carri...

The ambiguity that can exist, for short datasets, between the observational power spectra of dynamical fractals and low-order linear memory processes is demonstrated and explained. It is argued that it could be broadly useful to have a highly practical rule-of-thumb for assessing whether a data record is sufficiently long to permit distinguishing t...

The ambiguity that can exist, for short datasets, between the observational power spectra of dynamical fractals and low‐order linear memory processes is demonstrated and explained. It is argued that it could be broadly useful to have a highly practical rule‐of‐thumb for assessing whether a data record is sufficiently long to permit distinguishing t...

climatic trends;groundwater resources;aquifer;habitat;watersheds

The Georgia Basin–Puget Sound Lowland region of British Columbia (Canada) and Washington State (USA) presents a crucial test in environmental management due to its combination of abundant salmonid habitat, rapid population growth and urbanization, and multiple national jurisdictions. It is also hydrologically complex and heterogeneous, containing a...

Urbanization often alters catchment storm responses, with a broad range of potentially significant environmental and engineering consequences. At a practical, site-specific management level, efficient and effective assessment and control of such downstream impacts requires a technical capability to rapidly identify development-induced storm hydrogr...

Relatively little prior use has been made of information theory in air quality analysis. This paper explores whether basic, but formal, quantitative measures of information content might yield fresh perspectives on seasonal variations in the ground-level ozone concentration field across the lower Fraser Valley (LFV), British Columbia, Canada. I cal...

A common feature of watershed urbanization is increased hydrograph ‘flashiness,’ whereby river discharge fluctuations grow more erratic. Such changes might be intuitively interpreted as a decrease in watershed-scale hydrologic system memory. Here, I investigate this hypothesis through a paired-catchment experiment. The serial correlation coefficien...

Two‐state, first‐order, single‐site Markov models for daily precipitation occurrence were developed for each winter rainy season over the historical period of record at five long‐term meteorological stations in the lower Fraser Valley of British Columbia, Canada. Monotonic temporal trends in the independent elements of the transition matrices were...

We integrated basic concepts from fisheries science and toxicological risk assessment to form a potential method for setting screening-level, risk-based, site-specific water quality objectives for temperature. In summary, the proposed approach: (a) uses temperature impacts upon specific growth as a measure of chronic (cumulative) temperature effect...

I assessed the performance characteristics of the feed-forward artificial neural network (ANN) as a first-order nonlinear Markov modelling technique. The ability to recover the underlying structure of five synthetic random time series was first tested. The method was then applied to an observed geophysical time series, and the results were compared...

We used climatological composite analysis to investigate El Niño-Southern Oscillation (ENSO) signals in long-term shallow ground water level observations from four wells in the lower Fraser Valley of British Columbia. Significance of differences between warm-phase, cold-phase, and neutral climate states was assessed with a Monte Carlo bootstrap tec...

We investigated the potential for glacier- and snowmelt-fed rivers to respond differently to the Arctic Oscillation (AO) by applying nonparametric statistical techniques to standardized and deseasonalized monthly hydrometric data from eight watersheds in southwest Yukon and northwest British Columbia, Canada. We first extracted regionally coherent...

We used nonparametric statistical and time-series analysis techniques to investigate the effects of watershed glacial cover upon interannual variability in a suite of hydrometric variables describing aspects of the annual hydrograph. Annual time series of eight streamflow-derived metrics were considered for each of five glacier-fed and four nival r...

Growing interest in the differential responses of glacial and nival rivers to climatic forcing, and in ecological distinctions between the two streamflow regimes, suggests the need for a better comparative understanding of how the annual hydrologic cycle differs with presence or absence of catchment glacial cover. In this study, timing and magnitud...

Thesis (Ph.D.)--University of British Columbia, 2005. Includes bibliographical references.

We applied nonparametric statistical techniques to historical streamflow data from five glacierized and four nonglacierized watersheds in southwest Yukon and northwestern British Columbia, Canada, to determine whether rivers with and without catchment glacial cover respond in significantly different ways to a warming climate. The analysis was posed...

Analytical well test solutions are a powerful approach to aquifer characterization and the parameterization of comprehensive numerical models. In addition, wellfield drawdown tests, which consist of coordinated pumping and data collection at a suite of monitoring and operating production wells, are of growing significance due to increasing pressure...

An Erratum has been published for this article in Hydrological Processes 17(4) 2003, 883. Fourier-transform-based spectral analysis and filtering techniques, although potentially very useful, have seen little practical application in hydrology. We provide an overview of the Fourier transform and spectral analysis and present examples of how these m...

Previous studies have revealed the presence of pore-scale variability in diffusivity in the Culebra (dolomite) member of the Rustler Formation, NM. In this study, eight laboratory-scale diffusion experiments on five Culebra samples were analyzed using a methodology for modeling solute diffusion through porous media in the presence of multiple matri...

We investigated multiple-rate diffusion as a possible explanation for observed behavior in a suite of single-well injection-withdrawal (SWIW) tests conducted in a fractured dolomite. We first investigated the ability of a conventional double-porosity model and a multirate diffusion model to explain the data. This revealed that the multirate diffusi...

Recent work has identified groundwater flow through basal till aquifers as a key control on melt-season pressure transients beneath alpine glaciers, with potential implications for climate change studies, glacial geomorphology, tracer test interpretation, and the sediment load and chemistry of glacially derived waters. In this study, we investigate...

Recent work has identified groundwater flow through basal till aquifers as a key control on melt-season pressure transients beneath alpine glaciers, with potential implications for climate change studies, glacial geomorphology, tracer test interpretation, and the sediment load and chemistry of glacially derived waters. In this study, we investigate...

A range of pore diffusivities, D{sub p}, is implied by the high degree of pore-scale heterogeneity observed in core samples of the Culebra (dolomite) Member of the Rustler formation, NM. Earlier tracer tests in the culebra at the field-scale have confirmed significant heterogeneity in diffusion rate coefficients (the combination of D{sub p} and mat...

Copyrighted by American Geophysical Union. Models of magnetic and gravity anomalies along two E-W transects offshore central Oregon, one of which is coincident with a detailed velocity model, provide quantitative limits on the structure of the subducting oceanic crust and the crystalline backstop. The models indicate that the backstop-forming weste...

Typescript (photocopy). Thesis (M.S.)--Oregon State University, 1999. Includes bibliographical references (leaves 122-126).

The responses of four glacier-fed and four snowmelt-fed rivers in the southwest Canadian subarctic to El Nino-Southern Oscillation (ENSO) and the Arctic Oscillation (AO; also known as the Northern Annular Mode) were empirically investigated and compared using historical streamflow data. Empirical orthogonal function, correlation, and composite anal...