Optimality approaches to describe characteristic fluvial patterns on landscapes

Paik, Kyungrock; Kumar, Praveen

doi:10.1098/rstb.2009.0303

Cited by 60 publications

(54 citation statements)

References 65 publications

(109 reference statements)

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“…Several authors suggest that water flow in catchments and catchment structure is in accordance with different candidate optimality principles that characterize the associated energy conversions and related thermodynamic limitations (Phillips, 2006;Paik and Kumar, 2010;Phillips, 2010). Woldenberg (1969) showed that basic scaling relationships of river basins can be derived from optimality assumptions regarding stream power.…”

Section: Organizing Principles -A Possible Link Between Catchment Strmentioning

confidence: 99%

“…Related to these energetic minimization principles, the literature debates several principles that seem to state exactly the opposite (Paik and Kumar, 2010): that systems organize themselves to maximize steady state power (MAXP proposed by Lotka (1922)), steady state net reduction of free energy (MRE -Zehe et al, 2010, 2013, or steady state maximized entropy production (MEP - Paltridge, 1979) associated with environmental flows. The MEP hypothesis has been corroborated within studies that allowed (a) successful predictions of states of planetary atmospheres (Lorenz et al, 2001), (b) identification of parameters of general circulation models (Kleidon et al, 2006), or (c) identification of hydrological model parameters to estimate the annual water balances of the 35 largest basins on earth (Porada et al, 2011).…”

Section: Organizing Principles -A Possible Link Between Catchment Strmentioning

confidence: 99%

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HESS Opinions: From response units to functional units: a thermodynamic reinterpretation of the HRU concept to link spatial organization and functioning of intermediate scale catchments

Zehe

Ehret

Pfister³

et al. 2014

Hydrol. Earth Syst. Sci.

100

103

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Abstract. According to Dooge (1986) intermediate-scale catchments are systems of organized complexity, being too organized and yet too small to be characterized on a statistical/conceptual basis, but too large and too heterogeneous to be characterized in a deterministic manner. A key requirement for building structurally adequate models precisely for this intermediate scale is a better understanding of how different forms of spatial organization affect storage and release of water and energy. Here, we propose that a combination of the concept of hydrological response units (HRUs) and thermodynamics offers several helpful and partly novel perspectives for gaining this improved understanding. Our key idea is to define functional similarity based on similarity of the terrestrial controls of gradients and resistance terms controlling the land surface energy balance, rainfall runoff transformation, and groundwater storage and release. This might imply that functional similarity with respect to these specific forms of water release emerges at different scales, namely the small field scale, the hillslope, and the catchment scale. We thus propose three different types of "functional units" -specialized HRUs, so to speak -which behave similarly with respect to one specific form of water release and with a characteristic extent equal to one of those three scale levels. We furthermore discuss an experimental strategy based on exemplary learning and replicate experiments to identify and delineate these functional units, and as a promising strategy for characterizing the interplay and organization of water and energy fluxes across scales. We believe the thermodynamic perspective to be well suited to unmask equifinality as inherent in the equations governing water, momentum, and energy fluxes: this is because several combinations of gradients and resistance terms yield the same mass or energy flux and the terrestrial controls of gradients and resistance terms are largely independent. We propose that structurally adequate models at this scale should consequently disentangle driving gradients and resistance terms, because this optionally allows Published by Copernicus Publications on behalf of the European Geosciences Union. E. Zehe et al.: HESS Opinions: Thermodynamic reinterpretation of the HRU conceptequifinality to be partly reduced by including available observations, e.g., on driving gradients. Most importantly, the thermodynamic perspective yields an energy-centered perspective on rainfall-runoff transformation and evapotranspiration, including fundamental limits for energy fluxes associated with these processes. This might additionally reduce equifinality and opens up opportunities for testing thermodynamic optimality principles within independent predictions of rainfall-runoff or land surface energy exchange. This is pivotal to finding out whether or not spatial organization in catchments is in accordance with a fundamental organizing principle.

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Section: Organizing Principles -A Possible Link Between Catchment Strmentioning

confidence: 99%

Section: Organizing Principles -A Possible Link Between Catchment Strmentioning

confidence: 99%

HESS Opinions: From response units to functional units: a thermodynamic reinterpretation of the HRU concept to link spatial organization and functioning of intermediate scale catchments

Zehe

Ehret

Pfister³

et al. 2014

Hydrol. Earth Syst. Sci.

100

103

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“…They show that these structures act to maximize dissipation of chemical potential gradients within the soil. Paik & Kumar (2010) provide a review of optimality approaches that have been proposed to characterize fluvial patterns in hydrology and geomorphology. Several of these are related to energetic properties, such as minimum stream power, minimum energy dissipation, maximum friction and minimum energy expenditure.…”

Section: Contents Of This Issuementioning

confidence: 99%

Maximum entropy production in environmental and ecological systems

Kleidon

Malhi

Cox

2010

Phil. Trans. R. Soc. B

151

107

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The coupled biosphere -atmosphere system entails a vast range of processes at different scales, from ecosystem exchange fluxes of energy, water and carbon to the processes that drive global biogeochemical cycles, atmospheric composition and, ultimately, the planetary energy balance. These processes are generally complex with numerous interactions and feedbacks, and they are irreversible in their nature, thereby producing entropy. The proposed principle of maximum entropy production (MEP), based on statistical mechanics and information theory, states that thermodynamic processes far from thermodynamic equilibrium will adapt to steady states at which they dissipate energy and produce entropy at the maximum possible rate. This issue focuses on the latest development of applications of MEP to the biosphere -atmosphere system including aspects of the atmospheric circulation, the role of clouds, hydrology, vegetation effects, ecosystem exchange of energy and mass, biogeochemical interactions and the Gaia hypothesis. The examples shown in this special issue demonstrate the potential of MEP to contribute to improved understanding and modelling of the biosphere and the wider Earth system, and also explore limitations and constraints to the application of the MEP principle.Keywords: thermodynamics; interactions; Earth system science; ecosystems THERMODYNAMICS AND ENVIRONMENTAL AND ECOLOGICAL SYSTEMSThermodynamics has long been recognized as critical for understanding complex systems ranging from the living cell to planet Earth (Boltzmann 1886;Schrö dinger 1944;Lovelock 1965). Boltzmann already noted in 1886 that:. . . the general struggle for existence of animate beings is not a struggle for raw materials-these, for organisms, are air, water and soil, all abundantly available, nor for energy which exists in plenty in any body in the form of heat, but a struggle for entropy, which becomes available through the transition of energy from the hot sun to the cold Earth.Schrö dinger (1944) extended this perspective in his seminal book What is life? in which he suggested that the living cell maintains its organized structure in a state of thermodynamic disequilibrium by depleting sources of free energy and exporting high entropy waste. At the planetary scale, Lovelock (1965) recognized that the Earth's atmospheric composition is maintained in a state far from thermodynamic equilibrium, and he attributed this unique thermodynamic state to the profound effect that life has on its environment.Taken together, these examples suggest that in order to better understand Earth's environmental and ecological systems and their couplings, we need to view these as coupled thermodynamic systems that are organized in a state far from thermodynamic equilibrium. Central to thermodynamics is the concept of 'entropy' as a measure of 'disorder' or 'randomness'. While the use of 'entropy' is often surrounded with ambiguity, it can nevertheless be used in purely quantitative terms to measure the distance of a given state from thermodynamic equilibriu...

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“…the review by Phillips, 2010 andPaik andKumar, 2010) or from stability analysis of the conservation of sediment and water and transport laws (e.g. Kirkby, 1971;Smith and Bretherton, 1972).…”

Section: River Systems and Organizational Principlesmentioning

confidence: 99%

Thermodynamics, maximum power, and the dynamics of preferential river flow structures at the continental scale

Kleidon

Zehe

Ehret

et al. 2013

Hydrol. Earth Syst. Sci.

124

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Abstract.The organization of drainage basins shows some reproducible phenomena, as exemplified by self-similar fractal river network structures and typical scaling laws, and these have been related to energetic optimization principles, such as minimization of stream power, minimum energy expenditure or maximum "access". Here we describe the organization and dynamics of drainage systems using thermodynamics, focusing on the generation, dissipation and transfer of free energy associated with river flow and sediment transport. We argue that the organization of drainage basins reflects the fundamental tendency of natural systems to deplete driving gradients as fast as possible through the maximization of free energy generation, thereby accelerating the dynamics of the system. This effectively results in the maximization of sediment export to deplete topographic gradients as fast as possible and potentially involves large-scale feedbacks to continental uplift. We illustrate this thermodynamic description with a set of three highly simplified models related to water and sediment flow and describe the mechanisms and feedbacks involved in the evolution and dynamics of the associated structures. We close by discussing how this thermodynamic perspective is consistent with previous approaches and the implications that such a thermodynamic description has for the understanding and prediction of subgrid scale organization of drainage systems and preferential flow structures in general.

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Optimality approaches to describe characteristic fluvial patterns on landscapes

Cited by 60 publications

References 65 publications

HESS Opinions: From response units to functional units: a thermodynamic reinterpretation of the HRU concept to link spatial organization and functioning of intermediate scale catchments

HESS Opinions: From response units to functional units: a thermodynamic reinterpretation of the HRU concept to link spatial organization and functioning of intermediate scale catchments

Maximum entropy production in environmental and ecological systems

Thermodynamics, maximum power, and the dynamics of preferential river flow structures at the continental scale

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