Water security, global change and land–atmosphere feedbacks

Dadson, Simon; Acreman, M.; Harding, R. J.

doi:10.1098/rsta.2012.0412

Cited by 19 publications

(18 citation statements)

References 77 publications

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“…These gaps are partially due to inherent complexity in modeling Earth system processes, which is more significant in coupled simulation modes. Apart from various computational barriers, one main challenge in online simulations is the uncertainty associated with coupling land and atmospheric models, as given a unique land-surface boundary condition, the simulations obtained by different climate models can be divergent (Koster et al, 2004;Pitman et al, 2009;Dadson et al, 2013). Another major challenge for coupled irrigationland-surface-climate simulations is the choice of appropriate temporal and spatial resolutions, at which the relevant physical processes and feedbacks between land and atmosphere should be represented and described.…”

Section: Discussionmentioning

confidence: 99%

“…For instance, irrigation can disturb the "natural" atmospheric boundary conditions (e.g., Sacks et al, 2009;Destouni et al, 2010;Gerten et al, 2011;Pokhrel et al, 2012;Hossain et al, 2012;Guimberteau et al, 2012;Dadson et al, 2013). At this stage of model development, the available quantitative understanding of these landatmospheric implications is limited.…”

Section: Modeling Human-water Interactionsmentioning

confidence: 99%

“…In particular, post-industrial human activities, from the mid-20th century onwards, have severely perturbed the Earth system (Crutzen and Steffen, 2003;Crutzen, 2006). This has initiated a new geological epoch, informally termed the "Anthropocene", in which it is recognized that the natural processes within the land surface system are highly controlled and regulated by humans (see McNeil, 2000;Steffen et al, 2007Steffen et al, , 2011.…”

Section: Modeling Human-water Interactionsmentioning

confidence: 99%

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On inclusion of water resource management in Earth system models – Part 1: Problem definition and representation of water demand

Nazemi

Wheater

2015

Hydrol. Earth Syst. Sci.

170

101

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Abstract. Human activities have caused various changes to the Earth system, and hence the interconnections between human activities and the Earth system should be recognized and reflected in models that simulate Earth system processes. One key anthropogenic activity is water resource management, which determines the dynamics of human-water interactions in time and space and controls human livelihoods and economy, including energy and food production. There are immediate needs to include water resource management in Earth system models. First, the extent of human water requirements is increasing rapidly at the global scale and it is crucial to analyze the possible imbalance between water demands and supply under various scenarios of climate change and across various temporal and spatial scales. Second, recent observations show that human-water interactions, manifested through water resource management, can substantially alter the terrestrial water cycle, affect land-atmospheric feedbacks and may further interact with climate and contribute to sea-level change. Due to the importance of water resource management in determining the future of the global water and climate cycles, the World Climate Research Program's Global Energy and Water Exchanges project (WRCP-GEWEX) has recently identified gaps in describing humanwater interactions as one of the grand challenges in Earth system modeling (GEWEX, 2012). Here, we divide water resource management into two interdependent elements, related firstly to water demand and secondly to water supply and allocation. In this paper, we survey the current literature on how various components of water demand have been included in large-scale models, in particular land surface and global hydrological models. Issues of water supply and allocation are addressed in a companion paper. The available algorithms to represent the dominant demands are classified based on the demand type, mode of simulation and underlying modeling assumptions. We discuss the pros and cons of available algorithms, address various sources of uncertainty and highlight limitations in current applications. We conclude that current capability of large-scale models to represent human water demands is rather limited, particularly with respect to future projections and coupled landatmospheric simulations. To fill these gaps, the available models, algorithms and data for representing various water demands should be systematically tested, intercompared and improved. In particular, human water demands should be considered in conjunction with water supply and allocation, particularly in the face of water scarcity and unknown future climate. Background and scope Large-scale modeling -an introduction to land-surface and global hydrological modelsThe Earth system is an integrated system that unifies the physical processes at the Earth's surface. These processes include a wide range of feedbacks and interactions between and within the atmosphere, land and oceans and cover the global cycles of climate, water and carbon that sup...

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Section: Discussionmentioning

confidence: 99%

Section: Modeling Human-water Interactionsmentioning

confidence: 99%

Section: Modeling Human-water Interactionsmentioning

confidence: 99%

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On inclusion of water resource management in Earth system models – Part 1: Problem definition and representation of water demand

Nazemi

Wheater

2015

Hydrol. Earth Syst. Sci.

170

101

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“…The principal control on run-off generation is the partitioning of rain water at the ground level between green and blue water flows. This partitioning is easily disturbed by land-use change and can alter consumptive water use through evapotranspiration [51]. L'vovich & White [52] showed that the global-scale deforestation during the period 1680-1980 for development of agriculture reduced vapour flow and increased run-off generation by the order of 2500 km 3 yr −1 .…”

Section: (B) Gradual Changes In Rainwater Partitioningmentioning

confidence: 99%

Growing water scarcity in agriculture: future challenge to global water security

Falkenmark

2013

Phil. Trans. R. Soc. A.

243

152

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As water is an essential component of the planetary life support system, water deficiency constitutes an insecurity that has to be overcome in the process of socio-economic development. The paper analyses the origin and appearance of blue as well as green water scarcity on different scales and with particular focus on risks to food production and water supply for municipalities and industry. It analyses water scarcity originating from both climatic phenomena and water partitioning disturbances on different scales: crop field, country level and the global circulation system. The implications by 2050 of water scarcity in terms of potential country-level water deficits for food self-reliance are analysed, and the compensating dependence on trade in virtual water for almost half the world population is noted. Planetary-scale conditions for sustainability of the global water circulation system are discussed in terms of a recently proposed Planetary Freshwater Boundary, and the consumptive water use reserve left to be shared between water requirements for global food production, fuelwood production and carbon sequestration is discussed. Finally, the importance of a paradigm shift in the further conceptual development of water security is stressed, so that adequate attention is paid to water's fundamental role in both natural and socio-economic systems.

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“…In parallel, a considerable proportion of the surface water diverted into irrigated areas may recharge groundwater (Döll et al, 2012). From a broader perspective, groundwater aquifers (particularly shallow groundwater) can also be an important control on soil moisture and wetlands, and thus influence atmospheric surface boundary conditions (e.g., Maxwell et al, 2007Maxwell et al, , 2011Fan and Miguez-Macho, 2011;Dadson et al, 2013). These online effects are widely unquantified at the global scale, as the sub-surface processes below the root zone have been generally assumed to be disconnected from the atmosphere (see Taylor et al, 2013).…”

mentioning

confidence: 99%

On inclusion of water resource management in Earth system models – Part 2: Representation of water supply and allocation and opportunities for improved modeling

Nazemi

Wheater

2015

Hydrol. Earth Syst. Sci.

116

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Abstract. Human water use has significantly increased during the recent past. Water withdrawals from surface and groundwater sources have altered terrestrial discharge and storage, with large variability in time and space. These withdrawals are driven by sectoral demands for water, but are commonly subject to supply constraints, which determine water allocation. Water supply and allocation, therefore, should be considered together with water demand and appropriately included in Earth system models to address various large-scale effects with or without considering possible climate interactions. In a companion paper, we review the modeling of demand in large-scale models. Here, we review the algorithms developed to represent the elements of water supply and allocation in land surface and global hydrologic models. We note that some potentially important online implications, such as the effects of large reservoirs on land-atmospheric feedbacks, have not yet been fully investigated. Regarding offline implications, we find that there are important elements, such as groundwater availability and withdrawals, and the representation of large reservoirs, which should be improved. We identify major sources of uncertainty in current simulations due to limitations in data support, water allocation algorithms, host large-scale models as well as propagation of various biases across the integrated modeling system. Considering these findings with those highlighted in our companion paper, we note that advancements in computation and coupling techniques as well as improvements in natural and anthropogenic process representation and parameterization in host large-scale models, in conjunction with remote sensing and data assimilation can facilitate inclusion of water resource management at larger scales. Nonetheless, various modeling options should be carefully considered, diagnosed and intercompared. We propose a modular framework to develop integrated models based on multiple hypotheses for data support, water resource management algorithms and host models in a unified uncertainty assessment framework. A key to this development is the availability of regional-scale data for model development, diagnosis and validation. We argue that the time is right for a global initiative, based on regional case studies, to move this agenda forward.

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Water security, global change and land–atmosphere feedbacks

Abstract: One contribution of 16 to a Theme Issue 'Water security, risk and society' .

Cited by 19 publications

References 77 publications

On inclusion of water resource management in Earth system models – Part 1: Problem definition and representation of water demand

On inclusion of water resource management in Earth system models – Part 1: Problem definition and representation of water demand

Growing water scarcity in agriculture: future challenge to global water security

On inclusion of water resource management in Earth system models – Part 2: Representation of water supply and allocation and opportunities for improved modeling

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