Murray C Peel

University of Melbourne | MSD · Department of Infrastructure Engineering

For over a century, numerous proposals for increasing available water in central Australia have been raised, inspired in part by the natural occurrence of the ephemeral lake, Kati Thanda‐Lake Eyre. It has also been proposed that additional rainfall generated by the lake would spread beyond the lake itself, potentially opening up large tracts of unc...

Many Victorian catchments experienced a rainfall‐runoff relationship (RRR) shift during the Millennium Drought (1997–2009). Less annual streamflow was generated from annual rainfall during the drought than would have been expected for the same rainfall before the drought. Changes in weather systems, such as cyclones, fronts, and thunderstorms, were...

To accurately project future water availability under a drying climate, it is important to understand how precipitation is partitioned into other terrestrial water balance components, such as fluxes (evaporation, transpiration, runoff) and changes in storage (soil moisture, groundwater). Many studies have reported unexpected large runoff reductions...

Hydrologic models are essential tools to understand and plan for the effect of changing climates; however, they underperform in transitory climate conditions. Existing research identifies models' inadequacy to perform during prolonged drought, but falls short on pinpointing which specific aspects of model performance are affected. We study five con...

The Indo Gangetic Plain (IGP) is a food basket of South Asia and is considered a hotspot for air pollution due to persistently high emissions of anthropogenic aerosols. High levels of aerosols in the IGP not only affect the health of people but also the health of the natural system and the climate of the region. Aerosol effects on crop production i...

Cold waves are considered one of the important extreme weather events affecting winter crop production in the Indo-Gangetic Plain (IGP). In spite of media coverage of extreme cold events in the Terai area of Nepal (Nepal section of IGP) in recent years, few studies on this topic were found. This study investigates cold waves and their impact on agr...

The Modular Assessment of Rainfall–Runoff Models Toolbox (MARRMoT) is a flexible modelling framework reproducing the behaviour of 47 established hydrological models. This toolbox can be used to calibrate and run models in a user-friendly and consistent way and is designed to facilitate the sharing of model code for reproducibility and to support in...

The Modular Assessment of Rainfall–Runoff Models Toolbox (MARRMoT) is a flexible modelling framework reproducing the behaviour of 47 established hydrological models. MARRMoT can be used to calibrate and run models in a user-friendly and consistent way and is designed to facilitate the sharing of model code for reproducibility and to support interco...

Understanding long-term trends in streamflow is important for water resource management. In this study, we investigate the long-term streamflow trends at 47 gauging sites within the southern Murray-Darling Basin (MDB), Australia. This study aims to estimate regional streamflow trends while understanding the impact of catchment characteristics on th...

The Millennium Drought lasted more than a decade, and is notable for causing persistent shifts in the relationship between rainfall and runoff in many south-east Australian catchments. Research to date has successfully characterised where and when shifts occurred and explored relationships with potential drivers, but a convincing physical explanati...

“Bottom-up” methods are increasingly used to assess the vulnerability of water systems to climate change. Central to these methods is the climate “stress test”, where the system is subjected to various climatic changes to test for unacceptable outcomes. We present a framework for climate stress testing on a monthly timestep, suitable for systems wh...

“Bottom-up” methods are increasingly used to assess the vulnerability of water systems to climate change. Central to these methods is the climate “stress test”, where the system is subjected to various climatic changes to test for unacceptable outcomes. We present a framework for climate stress testing on a monthly timestep, suitable for systems wh...

This paper presents the Australian edition of the Catchment Attributes and Meteorology for Large-sample Studies (CAMELS) series of datasets. CAMELS-AUS (Australia) comprises data for 222 unregulated catchments, combining hydrometeorological time series (streamflow and 18 climatic variables) with 134 attributes related to geology, soil, topography,...

How relative humidity is changing is important for our understanding of future changes in precipitation and evaporation. For example, decreases in relative humidity have the potential to increase evaporation and evapotranspiration increasing water scarcity. Since projected precipitation changes are highly uncertain, there is significant research re...

Staying dry Is precipitation all that a watershed needs to recover from drought? Conventional wisdom says yes, but this is not necessarily true. Peterson et al. studied streamflow and precipitation in 161 watersheds in southeastern Australia across the Millennium Drought, which stuck the region during the first decade of the 21st century (see the P...

Rainfall-runoff models based on conceptual “buckets” are frequently used in climate change impact studies to provide runoff projections. When these buckets approach empty, the simulated evapotranspiration approaches zero, which places an implicit limit on the soil moisture deficit that can accrue within the model. Such models may cease to properly...

Question #20 of the UPH aspires to disentangle and reduce model prediction uncertainty. One feasible approach is to first formulate the relationship between variability (of real-world hydrological processes and catchment characteristics) and uncertainty (of model components and variables), which links the UPH theme of “modelling methods” to “time v...

This paper presents the Australian edition of the Catchment Attributes and Meteorology for Large-sample Studies (CAMELS) series of datasets. CAMELS-AUS comprises data for 222 unregulated catchments, combining hydrometeorological timeseries (streamflow and 18 climatic variables) with 134 attributes related to geology, soil, topography, land cover, a...

This paper outlines the subjective and quantitative outcomes of the introduction of the flipped classroom approach to two engineering subjects at the University of Melbourne. In this approach, lectures are delivered online as opposed to the traditional method of being provided in person. To facilitate learning, after each part of an online lecture,...

The choice of hydrological model structure, i.e. a model’s selection of states and fluxes and the equations used to describe them, strongly controls model performance and real-ism. This work investigates differences in performance of 36 lumped conceptual model structures calibrated to and evaluated on daily streamflow data in 559 catchments across...

To evaluate models as hypotheses, we developed the method of Flux Mapping to construct a hypothesis space based on dominant runoff generating mechanisms. Acceptable model runs, defined as total simulated flow with similar (and minimal) model error, are mapped to the hypothesis space given their simulated runoff components. In each modeling case, th...

Environmental policy is often implemented using market instruments. In some cases, including carbon taxing, the links between financial products and the environmental objectives, are transparent. In other cases, including water markets, the links are less transparent. In Australia’s Murray–Darling Basin (MDB), financial water products are known as...

Analysis of flood and streamflow timing has recently gained prominence as a tool for attribution of climatic changes to flooding. Such studies generally apply circular statistics to the day of maximum flow in a calendar year and use nonparametric linear trend tests to investigate changes in flooding on a local or regional scale. Here we investigate...

Rainfall‐runoff models are used across academia and industry, and the number and type have proliferated over time. In this primer we briefly introduce the key features of these models and provide an overview of their historical development and drivers behind those developments. To complete the discussion there is a brief section on model choice inc...

Supporting Information to "A brief analysis of conceptual model structure uncertainty using 36 models and 559 catchments".

Evidence suggests that catchment state variables such as groundwater can exhibit multiyear trends. This means that their state may reflect not only recent climatic conditions but also climatic conditions in past years or even decades. Here we demonstrate that five commonly used conceptual “bucket” rainfall‐runoff models are unable to replicate mult...

Hydrological models are conventionally evaluated in terms of their response surface or likelihood surface constructed with the model parameter space. To evaluate models as hypotheses, we developed the method of Flux Mapping to construct a hypothesis space based on model process representation. Here we defined the hypothesis space based on dominant...

Due to difficulties in identifying a climate change signal in flood magnitude, it has been suggested that shifts in flood timing, that is, the day of annual streamflow maxima, may be detectable. Here, we use high-quality streamflow, largely free of snowmelt, from 221 catchments across Australia to investigate the influence of shifts in soil moistur...

In the discussion of Eq. (1), reference is made to an example calculation of the metric that should have been provided in the right-hand panel of Fig. 1.

Meteorological time‐series data are a fundamental input to hydrological investigations. But sourcing data is often laborious and plagued with difficulties. In an effort to improve efficiency and rigor we present an R‐package, named AWAPer (https://github.com/peterson-tim-j/AWAPer), for the efficient estimation of daily area weighted catchment avera...

While scientific hypotheses are our best tools to represent and understand real world phenomena, we know a priori that all hypotheses are incomplete and uncertain. Particularly in domains such as Earth and environmental sciences, given the exuberance of uncertainty and inexactness associated with every step of the scientific inquiry. No single hypo...

Uncertainty analysis is an integral part of any scientific modeling, particularly within the domain of hydrological sciences given the various types and sources of uncertainty. At the center of uncertainty rests the concept of equifinality, i.e. reaching a given endpoint (finality) through different pathways. The operational definition of equifinal...

Hydrologists are commonly involved in impact, adaption and vulnerability assessments for climate change projections. This paper presents a framework for how such assessments can better differentiate between the impacts of climate change and those of natural variability, an important differentiation as it relates to the vulnerability to water availa...

Human-induced climate change poses a major threat to the reliable water supply in many highly populated regions. Here we combine hydrological and climate model simulations to evaluate risks to the water supply under projected shifts in the climate at the Paris Agreement warming levels. Modelling the primary surface water sources for Melbourne, Aust...

This paper presents the Modular Assessment of Rainfall–Runoff Models Toolbox (MARRMoT): a modular open-source toolbox containing documentation and model code based on 46 existing conceptual hydrologic models. The toolbox is developed in MATLAB and works with Octave. MARRMoT models are based solely on traceable published material and model documenta...

All models are wrong, all data are erroneous, our knowledge of real-world processes is fallible, and all model evaluations are incomplete. Despite these limitations, there is room to improve models and evaluation schemes, and due to these limitations uncertainty is an inalienable property of scientific modelling. At the heart of uncertainty lies th...

The purpose of this paper is to determine uncertainty in the gauged range of the stage-gauged discharge relationship for 622 rating curves from 171 Australian Bureau of Meteorology Hydrologic Reference stream gauging Stations (HRS). Water agencies use many methods to establish rating curves. Here we adopt a consistent method across all stations and...

This paper presents the Modular Assessment of Rainfall-Runoff Models Toolbox (MARRMoT): a modular open-source toolbox containing documentation and model code for 46 existing conceptual hydrologic models. The toolbox is developed in Matlab and works with Octave. Models are implemented following several best practices: definition of model equations (...

The assessment of direct radiative forcing due to atmospheric aerosols (ADRF) in the Indo Gangetic Plain (IGP), which is a food basket of south Asia, is important for measuring the effect of atmospheric aerosols on the terrestrial ecosystem and for assessing the effect of aerosols on crop production in the region. Existing comprehensive analytical...

Rainfall‐runoff models are often deficient under changing climatic conditions, yet almost no recent studies propose new or improved model structures, instead focussing on model intercomparison, input sensitivity and/or quantification of uncertainty. This paucity of progress in model development is (in part) due to the difficulty of distinguishing w...

Winter fog events of the Indo Gangetic plain (IGP) including the Terai area of Nepal are considered to be one of the important public concerns due to their effect on people's health, transportation, and agriculture. Unlike the IGP area of India, Pakistan and Bangladesh there are only very few fog related studies reported about the Terai region of N...

The performance of eight empirical equations for estimating ETo at 80 weather stations in Iran is evaluated. The equations assessed are Hargreaves (HGS), Trajkovic (TKC), Berti (BTI), Ravazzani (RZI), Irmak (IMK), Turc (TRC) and two Valiantzas’ methods (VTS1 and VTS2). The FAO56 reference crop Penman-Monteith (PM) equation is used as a baseline to...

Droughts are a significant stressor for water supply systems and freshwater ecosystems. Studies on drought risks and impacts have focused on the frequency, duration, and severity of droughts. While these metrics may be appropriate for understanding the risks to consumptive water supply because they directly relate to deficits in catchment yields, t...

It has been widely shown that rainfall-runoff models often provide poor and biased simulations after a change in climate, but evidence suggests existing models may be capable of better simulations if calibration strategies are improved. Common practice is to use "least squares"-type objective functions, which focus on hydrological behavior during h...

Conceptual hydrologic models, such as rainfall-runoff models (RRMs), are simplified representations of real-world systems. Conventionally, their performance and predictive capability is evaluated through pair-wise comparison of simulated and observed streamflow (i.e. aggregated response of the catchment system), accompanied by uncertainty and/or se...

Derivation of the hypsometric curve of a catchment, and properties relating to that curve, requires both use of topographical data (commonly in the form of a Digital Elevation Model – DEM), and the estimation of a functional representation of that curve. An early investigation into catchment hypsometry concluded 3rd order polynomials sufficiently d...

Equifinality is understood as one of the fundamental difficulties in the study of open complex systems, including catchment hydrology. A review of the hydrologic literature reveals that the term equifinality has been widely used, but in many cases inconsistently and without coherent recognition of the various facets of equifinality, which can lead...

The terrestrial phase of the water cycle can be seriously impacted by water management and human water use behavior (e.g., reservoir operation, and irrigation withdrawals). Here we outline a method for assessing water availability in a changing climate, while explicitly considering anthropogenic water demand scenarios and water supply infrastructur...

Assessments of climate change impacts on freshwater ecosystems are generally based on global climate models (GCMs) and ecologically relevant “time-averaged” hydrological indicators derived from long-term records. Although uncertainties from GCMs have been recognized, the influence of downscaling methods remains unclear. This paper evaluates the inf...

Water enters the terrestrial phase of the water cycle when precipitation exceeds evapotranspiration at the land surface. Downstream drainage of this water via surface and subsurface flow paths including transient storage in snowpack, soils, aquifers, and lakes combine to produce the water regimes of freshwater ecosystems. Humans have altered these...

In central Chile, increasing demand for water and decreasing runoff volumes due to drier conditions have placed catchments in this zone under water stress. However, scarcity of observed data records increases the difficulty of planning future water supply. Instrumental records suggest a reduction in streamflow over the last 56 years. However, this...

Streamflow reductions have been reported in mid-latitude Southern Hemisphere (SH) catchments, in particular in the southwest of Western Australia (SWA) and in central Chile (CC), following decreases in precipitation since the mid-1970s. Although projections from Global Climate Models (GCMs) indicate the observed trends are expected to continue duri...

Streamflow reductions have been reported in mid-latitude Southern Hemisphere (SH) catchments, in particular in the southwest of Western Australia (SWA) and in central Chile (CC), following decreases in precipitation since the mid-1970s. Although projections from Global Climate Models (GCMs) indicate the observed trends are expected to continue duri...

Hydrologic models have potential to be useful tools in planning for future climate variability. They are often used when translating projected climatic shifts (eg. in rainfall or PET) into potential shortfalls in water availability. However, recent literature suggests that conceptual rainfall-runoff models have variable performance simulating runo...

While the majority of hydrological prediction methods assume that observed interannual variability explores the full range of catchment response dynamics, recent cases of prolonged climate drying suggest otherwise. During the ∼decade-long Millennium drought in south-eastern Australia significant shifts in hydrologic behaviour were reported. Catchme...

Evaporation plays a key role in the hydrology of a catchment. World‐wide actual terrestrial evaporation is approximately two third of terrestrial precipitation. Evaporation is the focus of this study in which we describe the historical developments of models for estimating evaporation from standard meteorological data. Although Aristotle and Descar...

Demand for quantitative assessments of likely climate change impact on runoff is increasing and conceptual rainfall-runoff models are essential tools for this task. However, the capacity of these models to extrapolate under changing climatic conditions is questionable. A number of studies have found that model predictive skill decreases with change...

Hydrologic models have potential to be useful tools in planning for future climate variability. However, recent literature suggests that the current generation of conceptual rainfall runoff models tend to underestimate the sensitivity of runoff to a given change in rainfall, leading to poor performance when evaluated over multi-year droughts. This...

Abstract This study assessed the effect of using observed monthly leaf area index (LAI) on hydrological model performance and the simulation of runoff using the Variable Infiltration Capacity (VIC) hydrological model in the Goulburn-Broken catchment of Australia, which has heterogeneous vegetation, soil and climate zones. VIC was calibrated with bo...

Future projections of water supply under climate change scenarios are fundamental for efficient water resource planning. However, runoff projections are affected by uncertainties in the modelling process that limit their utility to decision makers. The main source of uncertainty in runoff projections are the Global Climate Models (GCMs) used to pro...

Anthropogenic climate change is projected to enrich the atmosphere with carbon dioxide, change vegetation dynamics and influence the availability of water at the catchment scale. This study combines a nonlinear model for estimating changes in leaf area index (LAI) due to climatic fluctuations with the variable infiltration capacity (VIC) hydrologic...