Murugesu Sivapalan

• BSc Eng (Hons) (Sri Lanka), MEng (AIT), MA, PhD (Princeton), Dr. h. c. (Delft)
• Professor (Full) at University of Illinois Urbana-Champaign

Plant responses to water stress is a major uncertainty to predicting terrestrial ecosystem sensitivity to drought. Different approaches have been developed to represent plant water stress. Empirical approaches (the empirical soil water stress (or Beta) function and the supply‐demand balance scheme) have been widely used for many decades; more mecha...

Tile drainage removes excess water and is an essential, widely adopted management practice to enhance crop productivity in the U.S. Midwest. Tile drainage has been shown to significantly change hydrological and biogeochemical cycles by lowering the water table and reducing the residence time of soil water, although such impacts and their connection...

Daily water balance modeling is important for both hydrological science and water resources management. The majority of daily water balance models express the output fluxes (including runoff and evapotranspiration) as independent functions of soil moisture store(s), and as such they involve a large number of parameters, the estimation of which is a...

Brazil's Northeast region (BRN), especially the state of Ceará (CE), has dealt historically with severe drought events since the late 1800s, which commonly led to catastrophic impacts of mass migration and deaths of thousands of people. Throughout the last century, the “Droughts Polygon” region experienced an intense infrastructural development, wi...

The contributions to this Research Topic illustrate the diversity of approaches and richness in relevant sociohydrological topics. They also show the challenges and efforts required to make progress toward adequately informing and supporting actors involved in water-related disaster-risk reduction and multi-level water governance.

Peninsular India is a unique region with major mountain ranges that govern regional atmospheric circulation and precipitation variability, the monsoons, and regional geology at range of timescales and process scales. However, the landscape and climatic feature controls on streamflow variability at a regional scale using flow duration curves (FDCs)...

Groundwater depletion has become increasingly challenging, and many cities worldwide have adopted drastic policies to relieve water stress due to socioeconomic growth. Located on the declining aquifer of the North China Plain, Beijing, for example, has developed plans to limit the size of the city’s population. However, the effect of population dis...

Given the increasing demand for high-quality food and protein, global food security remains a challenge, particularly in the face of global change. However, since agriculture, food and water security are inextricably linked, they need to be examined via an interdisciplinary lens. Sociohydrology was introduced from a post-positivist perspective to e...

Early peopling of Brazil’s Northeast region (BRN) took place under an intimate relationship between humans and water scarcity, as the region, especially the state of Ceará (CE), has dealt historically with severe drought events since the 1800’s, which commonly led to catastrophic impacts of mass migration and deaths of thousands of people. Througho...

As each catchment responds uniquely, even if they appear similar, formulating generalizable hypotheses and using routinely used signatures of catchment similarity to examine streamflow variability can be difficult. Flow Duration Curve (FDC), a concise portrayal of streamflow variability at a specific gauging station, can provide insights into hydro...

Water Security through Participatory Action Research in the Northern Province (WASPAR) is a project driven by the University of Jaffna, Sri Lanka, since March 2020. The project itself and some of the significant outcomes over the 3‐year first phase of research are outlined here. WASPAR took inspiration from two emerging fields of study: Sociohydrol...

Water Security through Participatory Action Research in the Northern Province (WASPAR) is a project driven by the University of Jaffna, Sri Lanka, since March 2020. The project itself and some of the significant outcomes over the 3‐year first phase of research will make up part of the upcoming Special Issue of this journal. As guest editors of the...

As each catchment responds uniquely, even if they appear similar, formulating generalizable hypotheses and using routinely used signatures of catchment similarity to examine streamflow variability can be difficult. Flow Duration Curve (FDC), a concise portrayal of streamflow variability at a specific gauging station, can provide insights into hydro...

While conflict-and-cooperation phenomena in transboundary basins have been widely studied, much less work has been devoted to representing the process interactions in a quantitative way. This paper identifies the main factors in the riparian countries' willingness to cooperate in the Eastern Nile River basin, involving Ethiopia, Sudan, and Egypt, f...

Excessive agricultural nitrate export to aquatic systems degrades water quality and causes downstream ecological crises. Limited understanding of their underlying mechanisms and controls hinders mitigation measures. Here we analyzed observations of nitrate concentration (C) and discharge (Q) in 83 intensively managed agricultural watersheds across...

Water reallocation decision-making is a challenge faced by most river basins around the world. In this study, a system thinking framework was developed to structurally unfold the complex interactions of water reallocations with societal, economic and ecological subsystems in the Heihe River Basin in China. The results indicate that ecological degra...

Socio-hydrology has expanded and been effective in exposing the hydrological community to ideas and approaches from other scientific disciplines, and social sciences in particular. Yet it still has much to explore regarding how to capture human agency and how to combine different methods and disciplinary views from both the hydrological and social...

This study explores the climatic controls of the long‐term energy partitioning of net radiation into sensible heat and latent heat at watershed scale, by following a data‐guided approach. Collected data shows that the relationship between the evaporative fraction (ratio of latent heat to net radiation) and the aridity index (ratio of energy supply...

While conflict-and-cooperation phenomena in transboundary basins have been widely studied, much less work has been devoted to representing the process interactions in a quantitative way. This paper identifies the main factors in the riparian countries’ willingness to cooperate in the Eastern Nile River Basin, involving Ethiopia, Sudan, and Egypt, f...

Increasing hydrological variability, accelerating population growth and urbanisation, and the resurgence of water resources development projects have all indicated increasing tension among the riparian countries of transboundary rivers. While a wide range of disciplines develop their understandings of conflict and cooperation in transboundary river...

Understanding the historical evolution of science development for rethinking science in the Anthropocene is crucial for our future survival. This paper analyzed the knowledge development of the top 95 most researched river basins in the Web of Science database in the past 3 decades (1987–2017) using a network metric-based framework, comprising one...

Climate change is leading to increasing hydrological extremes and quicker shifts between wet and dry extremes in many regions. These extremes and rapid shifts put pressure on reservoir operations, decreasing the reliability of water supply, flood control and other reservoir benefits. Decision-makers across all levels, from reservoir operators to fl...

In a recent editorial in the journal Nature Sustainability , the editors raised the concern that journal submissions on water studies appear too similar. The gist of the editorial: “too many publications and not enough ideas.” In this response, we contest this notion, and point to the numerous new ideas that result from taking a broader view of the...

Understanding of how anthropogenic droughts occur in socio-hydrological systems is critical in studying resilience of these systems. This is especially relevant when a “lock-in” toward lake desiccation occurs as an emergent outcome of coupling among social dynamics and surface and underground water processes. How the various processes collectively...

Increasing hydrologic variability, accelerating population growth, and resurgence of water resources development projects have all indicated increasing tensions among the riparian countries of transboundary rivers. This article aims to review the existing knowledge on conflict and cooperation in transboundary rivers from a multidisciplinary perspec...

A methodology using the standardised precipitation index is proposed to develop critical drought intensity-duration-frequency (IDF) curves. We define dry periods within which we recognise droughts of different durations. The most severe drought for each drought duration in each year is called the critical drought. The total probability theorem-coup...

This study unveils regional patterns of dominant streamflow generation mechanisms across the conterminous United States and identifies their climatic and physiographic controls. Six signatures describing the characteristics of rainfall-stormflow responses and the characteristics of base flow response are extracted from continuous rainfall-streamflo...

A methodology using the standardized precipitation index is proposed to develop critical drought intensity-duration-frequency (IDF) curves. We define dry periods within which we recognize droughts of different durations. The most severe drought for each drought duration in each year is called critical drought. The total probability theorem-coupled...

Lake Urmia in Iran has undergone catastrophic desiccation due to increasing anthropogenic development, especially in the agricultural sector. A paramount national goal is to restore the lake to its former healthy condition, but corresponding water governance and restoration efforts have encountered various, mostly human-related, challenges. We argu...

The transboundary Lancang–Mekong River basin has experienced dynamics of cooperation over the past several decades, which is a common emergent response in transboundary coupled human–water systems. Downstream countries rely on the Mekong River for fisheries, agriculture, navigation and ecological services, while upstream countries have been constru...

The flow duration curve (FDC) is a hydrologically meaningful representation of the statistical distribution of daily streamflows. The complexity of processes contributing to the FDC introduces challenges for the direct exploration of physical controls on FDC. In this paper, the controls of climate and catchment characteristics on FDC are explored u...

The emerging field of socio-hydrology is a special case of social-ecological systems research that focuses on coupled human-water systems, exploring how the hydrologic cycle and human cultural traits coevolve and how such coevolutions lead to phenomena of relevance to water security and sustainability. As such, most problems tackled by socio-hydrol...

The impacts of climate change and human activities are challenging water sustainability in many cities around the world. Advanced understanding of the future long-term coevolution of coupled urban human-water systems is of considerable interest in this context. This study uses a previously developed sociohydrologic model to explore the coevolutiona...

We present a data-guided framework to explore the hydrological basis of the Budyko curve, focusing on the role of soil moisture in mediating the partitioning of precipitation into runoff and evaporation and the role of climate in this partitioning. The conceptual framework for the derivation of the Budyko curve builds on empirically based power law...

The transboundary Lancang-Mekong River Basin has experienced dynamics of cooperation over the past several decades, which is a common emergent response in transboundary human-water systems. Downstream countries rely on Mekong River for fisheries, agriculture, etc., while upstream countries have been constructing dams to generate hydropower. The dam...

Eutrophication of rivers and receiving waters has become a major environmental issue worldwide, which may further intensify due to projected climate changes and expansion of urbanization or agricultural development to meet the needs of increased human population. However, our understanding of climatic and land use change impacts on riverine nutrien...

A socio-hydrological model is used to forecast future conditions in a river basin arising from changes in climate and the economy in order to learn about macroeconomic conditions that would yield pathways for sustainable development and how they may be affected by changes in climate and the economy. The study uses a system dynamics model with endog...

Droughts have long impacted humans with adverse consequences, hindering the achievement of the United Nations Sustainable Development Goals. To reduce vulnerability, multiple ways of adaptation have been developed, most of which, historically, focused on “hard-path” implementation of infrastructure. However, since water consumption plays a major ro...

We investigate how the effectiveness of green infrastructure (GI) to mitigate the frequency and magnitude of significant discharge events and combined sewer overflows (CSOs) depend on both climate and sewershed characteristics and propose a theoretical framework for a holistic assessment of GI's efficacy. The framework is based on the comparison of...

Fresh water—the bloodstream of the biosphere—is at the center of the planetary drama of the Anthropocene. Water fluxes and stores regulate the Earth's climate and are essential for thriving aquatic and terrestrial ecosystems, as well as water, food, and energy security. But the water cycle is also being modified by humans at an unprecedented scale...

The planetary boundaries framework proposes quantified guardrails to human modification of global environmental processes that regulate the stability of the planet and has been considered in sustainability science, governance, and corporate management. However, the planetary boundary for human freshwater use has been critiqued as a singular measure...

The flow duration curve (FDC) is effectively the cumulative distribution function of streamflow. For a long time, hydrologists have sought deeper understanding of the process controls on the shape of FDC, which has been a challenge due to contrasting processes controlling the fast flow and slow flow components of streamflow, and their interactions....

The planetary boundaries framework has proven useful for many global sustainability contexts, but is challenging to apply to freshwater, which is spatially heterogeneous, part of complex socio-ecological systems and often dominated by local dynamics. To date, the planetary boundary for water has been simplistically defined by as the global rate of...

The Sustainable Development Goals (SDGs) of the United Nations Agenda 2030 represent an ambitious blueprint to reduce inequalities globally and achieve a sustainable future for all mankind. Meeting the SDGs for water requires an integrated approach to managing and allocating water resources, by involving all actors and stakeholders, and considering...

The mismatch between water demand and water availability in many megacities poses vexing water management challenges. Managers are forced to take remedial efforts to address these challenges, often with a heavy focus on infrastructure solutions such as building reservoirs or interbasin transfers to meet demand, which may in fact exacerbate the prob...

Sediment yield is affected by many factors, such as climate, geology, geomorphology, land use and human activities. Sediment signatures are the statistic indices or curves that are able to effectively describe the temporal and spatial characteristics of sediment transport and evaluate the ability of the streamflow to deliver the sediment. In this s...

This paper is the outcome of a community initiative to identify major unsolved scientific problems in hydrology motivated by a need for stronger harmonisation of research efforts. The procedure involved a public consultation through on-line media, followed by two workshops through which a large number of potential science questions were collated, p...

The planetary boundaries framework has proven useful for many global sustainability contexts, but is challenging to apply to freshwater, which is spatially heterogeneous, part of complex socio-ecological systems and often dominated by local dynamics. To date, the planetary boundary for water has been simplistically defined by as the global rate of...

Increases in human water consumption (HWC) and consequent degradation of the ecological environment are common in arid regions. Understanding the mechanisms behind these processes is important for sustainable development. Analyses of changes in HWC between alternating wet and dry periods are carried out in four arid inland basins in Central Asia an...

Sociohydrology was launched as the science dealing with feedbacks between coupled human and water systems. Much of the early work in sociohydrology involved studies in spatially isolated domains (e.g., river basins) dealing with phenomena that involved emergent patterns in the time domain, with a focus on formulating and testing hypotheses about ho...

The time compression (or time condensation) approximation (TCA) is commonly used in conjunction with an infiltration capacity equation for predicting the postponding infiltration rate, or, more generally, infiltration under time-varying precipitation. In this paper a power function relationship for TCA between infiltration capacity and its time der...

Budyko-type models in hydrology are simple but efficient descriptions of the vegetation-mediated hydrologic cycle in catchments. Based on hypothesized similarities between vegetation and human water consumption interactions in terms of water demand, constraints, and system functioning as well as catchment processes and outcomes, a corresponding Bud...

Regulatory goals for the California Delta attempt to restore natural ecosystems through various water management efforts. Defining management criteria for restoration is challenging, given that the earliest data describing the hydrology of the region follow many decades of change associated with agricultural development, channel modification, and f...

The arguments presented in Melsen et al. advance ideas in the “Panta Rhei” decade (2013–2022) of the International Association of Hydrological Sciences, which focuses on change in hydrology and society. While we reiterate that, despite acknowledged shortcomings, the enterprise of integrating societal feedbacks into hydrological models is beneficial...

Food flows underpin the complex food supply chains that are prevalent in our increasingly globalized world. Recently, much effort has been devoted to evaluating the resources (e.g. water, carbon, nutrients) embodied in food trade. Now, research is needed to understand the scientific principles of the food commodity flows that underpin these virtual...

Flow-sediment relationships provide insights into the erosion and transport of materials within catchments. Investigating the flow-sediment relationships across multiple timescales can reveal trends related to the effects of natural and human-caused changes to catchments. This study chose fourteen main catchments in the Loess Plateau of China, whic...

Hydrology has undergone almost transformative changes over the past 50 years. Huge strides have been made in the transition from early empirical approaches to rigorous approaches based on the fluid mechanics of water movement on and below the land surface. However, progress has been hampered by problems posed by the presence of heterogeneity, inclu...

Sustainable water resources management relies on understanding how societies and water systems coevolve. Many place-based sociohydrology (SH) modeling studies use proxies, such as environmental degradation, to capture key elements of the social component of system dynamics. Parameters of assumed relationships between environmental degradation and t...

We present a new framework for modelling the complexities of food and water security under globalisation. The framework sets out a method to capture regional and sectoral interdependencies and cross-scale feedbacks within the global food system that contribute to emergent water use patterns. The framework integrates aspects of existing models and a...

Hydrology has undergone almost transformative changes over the past 50 years. Huge strides have been made in the transition from early empirical approaches to rigorous approaches based on the fluid mechanics of water movement on and below the land surface. However, progress has been hampered by problems posed by the presence of heterogeneity, inclu...

Along the river network, water, sediment, and nutrients are transported, cycled, and altered by coupled hydrological and biogeochemical processes. Our current understanding of the rates and processes controlling the cycling and removal of dissolved inorganic nutrients in river networks is limited due to a lack of empirical measurements in large, (n...

In this study, we use numerical experiments with a simple water balance model to understand the roles of key climate characteristics in hydrologic drought propagation and the consequence of human responses to drought events under different climates. The experiments use climate inputs from a range of places with a hypothetical catchment of fixed pro...

The water balance dynamics in lowland watersheds are influenced not only by local hydroclimatic controls on energy and water availability, but also by imports of water from the upstream watershed. These imports result in a stochastic extent of inundation in lowland watersheds that is determined by the local flood regime, watershed topography, and t...

Inspired by the work of Newton, Darwin, and Wegener, this paper tracks the drivers and dynamics that have shaped the growth of hydrological understanding over the last century. On the basis of an interpretation of this history, the paper then speculates about what kind of future is in store for hydrology and how we can better prepare for it. The hi...

This study is focused on the water-agriculture-environment nexus as it played out in the Murrumbidgee River Basin, eastern Australia, and how coevolution of society and water management actually transpired. Over 100 years of agricultural development the Murrumbidgee Basin experienced a "pendulum swing" in terms of water allocation, initially exclus...

Within China's Loess Plateau there have been concerted revegetation efforts and engineering measures since the 1950s aimed at reducing soil erosion and land degradation. As a result, annual streamflow, sediment yield, and sediment concentration have all decreased considerably. Human-induced land use/cover change (LUCC) was the dominant factor, cont...

Over recent decades, the global population has been rapidly increasing and human activities have altered terrestrial water fluxes to an unprecedented extent. The phenomenal growth of the human footprint has significantly modified hydrological processes in various ways (e.g. irrigation, artificial dams, and water diversion) and at various scales (fr...

Sustainable water resources management relies on understanding how societies and water systems co-evolve. Many place-based socio-hydrology (SH) studies use proxies, such as environmental degradation, to capture key elements of the social component of system dynamics. Parameters of assumed relationships between environmental degradation and the huma...

Water diversion for environmental purposes threatens many agricultural communities. This paper focuses on the water-agriculture-environment nexus in the Murrumbidgee River Basin, Australia, and attempts to explain how reduced water allocation to agriculture aimed at protecting the environment in turn impacted the wider economy and the community. Pr...

Understanding the causes of flood seasonality is critical for better flood management. This study examines the seasonality of annual maximum floods (AMF) and its changes before and after 1980 at over 250 natural catchments across the contiguous United States. Using circular statistics to define a seasonality index, our analysis focuses on the varia...

Over the last decades, the global population has been rapidly increasing and human activities have altered terrestrial water fluxes at an unprecedented scale. The phenomenal growth of the human footprint has significantly modified hydrological processes in various ways (e.g., irrigation, artificial dams, and water diversion) and at various scales (...

In our globalised world, food security and water security are inextricably intertwined. Food production accounts for approximately 70 % of global freshwater use, with variability in agricultural production impacting water resources and vice versa. Trade is central to determining water resource use, because when we trade food, we also trade the wate...

Characterization and understanding of the hydrological variability in Ethiopia is important to improving existing capabilities for forecasting short-term floods and long-term droughts and for sustainable water management. In this study we focus on the Omo-Ghibe River Basin, which is the second most important basin of Ethiopia in terms of water avai...

15 Water security is a multi-faceted problem, going beyond mere balancing of supply and 16 demand. Early attempts to quantify water security relied on static index based approaches 17 that failed to acknowledge that human action is intrinsic to the water cycle. 18 Human adaptation to environmental change and increasing spatial specialization in the...

Within China's Loess Plateau there have been concerted revegetation efforts and engineering measures over the last 50 years aimed at reducing soil erosion and land degradation. As a result, annual streamflow, sediment yield and sediment concentration have all decreased considerably. Human induced land use/cover change (LUCC) was the dominant factor...

Prediction is central to water resources management in planning of both "hard" 23 infrastructure and "soft-path" solutions, such as pricing and conservation incentives 24 (Gleick 2003). Typically, the goal of prediction in water management has been to generate 25 time series of future water availability and use. Water resources scientists and 26 pr...

Socio‐hydrology was introduced 4 years ago into the scientific lexicon, and elicited several reactions about the meaning and originality of the concept. However, there has also been much activity triggered by the original paper, including further commentaries that clarified the definitions, and several papers that acted on the definitions, and thro...

We explore how to address the challenges of adaptation of water resources systems under changing conditions by supporting flexible, resilient and low-regret solutions, coupled with on-going monitoring and evaluation. This will require improved understanding of the linkages between biophysical and social aspects in order to better anticipate the pos...

The paper presents a thermodynamic basis for water balance partitioning at the catchment scale, through formulation of flux-force relationships for the constituent hydrological processes, leading to the derivation of optimality conditions that satisfy the principle of Maximum Entropy Production (MEP). Application of these optimality principles at t...

River flooding can have severe societal, economic and environmental consequences. However, limited understanding of the regional differences in flood-generating mechanisms results in poorly understood historical flood trends and uncertain predictions of future flood conditions. Through systematic data analyses of 420 catchments we expose the primar...