New functional topographic, lithology and climatic indices to define shallow groundwater systems in (un)gauged basins

2021 ◽  
Author(s):  
Ardalan Tootchi ◽  
Ali Ameli
Keyword(s):  
Large Scale ◽  
Overland Flow ◽  
Shallow Groundwater ◽  
Earth System ◽  
Hydrologic Models ◽  
System Models ◽  
Streamflow Generation ◽  
Groundwater Systems ◽  
Gauged Basins ◽  
Earth System Models

<p>The dynamics of the rainfall-runoff processes are complex and variable both spatially and temporally. There is a rich literature on physical representation of streamflow generation processes, such as saturation excess overland flow, often at small scales. Yet, continental-scale estimations of the streamflow generation processes in zones with shallow groundwater systems are still poor. This has led to inability of earth system models or large-scale hydrologic models to correctly simulate stream flows at (un)gauged basins with high potential for the presence of saturation excess overland flow. Zones with shallow groundwater have a direct impact on the hydrologic response of rainfall events. Depending on the subsurface storage, climate signals and topography, they can enhance the overland flow, or act as a buffer zone to flatten the flood hydrographs. <br>We have introduced new indices, inspired by the concept of hydrologic function, that include the interactions amongst climatic and geophysical characteristics (soil parameters, topography and lithology) to delineate zones of shallow groundwater over the United States and Canada. We have evaluated and tested the ability of these indices in locating high-resolution zones of shallow groundwater against in-situ observations of water table depth. The knowledge of the spatial pattern of shallow groundwater zones at (un)gauged basins allows an accurate inclusion of hydrologic connectivity in earth system models or large-scale hydrologic models, improving their prediction of stream peak flow. Furthermore, as a significant part of incoming precipitation is transformed to overland flow due to oversaturation, these datasets could be introduced as a useful indicator of areas with flood and erosion susceptibility.</p>

scholarly journals On an improved sub-regional water resources management representation for integration into earth system models

2013 ◽  
Vol 17 (9) ◽  
pp. 3605-3622 ◽  
Author(s):  
N. Voisin ◽  
H. Li ◽  
D. Ward ◽  
M. Huang ◽  
M. Wigmosta ◽  
...  
Keyword(s):  
Water Resources ◽  
Flood Control ◽  
Large Scale ◽  
Regulation System ◽  
Earth System ◽  
Mean Flow ◽  
System Models ◽  
Operating Rules ◽  
Reservoir Models ◽  
Earth System Models

Abstract. Human influence on the hydrologic cycle includes regulation and storage, consumptive use and overall redistribution of water resources in space and time. Representing these processes is essential for applications of earth system models in hydrologic and climate predictions, as well as impact studies at regional to global scales. Emerging large-scale research reservoir models use generic operating rules that are flexible for coupling with earth system models. Those generic operating rules have been successful in reproducing the overall regulated flow at large basin scales. This study investigates the uncertainties of the reservoir models from different implementations of the generic operating rules using the complex multi-objective Columbia River Regulation System in northwestern United States as an example to understand their effects on not only regulated flow but also reservoir storage and fraction of the demand that is met. Numerical experiments are designed to test new generic operating rules that combine storage and releases targets for multi-purpose reservoirs and to compare the use of reservoir usage priorities and predictors (withdrawals vs. consumptive demands, as well as natural vs. regulated mean flow) for configuring operating rules. Overall the best performing implementation is with combined priorities rules (flood control storage targets and irrigation release targets) set up with mean annual natural flow and mean monthly withdrawals. The options of not accounting for groundwater withdrawals, or on the contrary, of assuming that all remaining demand is met through groundwater extractions, are discussed.

scholarly journals Performance Analysis of Large Scale HPC Workflows for Earth System Models

2017 ◽  
Author(s):  
Joseph H. Kennedy ◽  
Benjamin W. Mayer ◽  
Katherine J. Evans ◽  
Jeff Duracha
Keyword(s):  
Performance Analysis ◽  
Large Scale ◽  
Earth System ◽  
System Models ◽  
Earth System Models

scholarly journals On an improved sub-regional water resources management representation for integration into earth system models

2013 ◽  
Vol 10 (3) ◽  
pp. 3501-3540 ◽  
Author(s):  
N. Voisin ◽  
H. Li ◽  
D. Ward ◽  
M. Huang ◽  
M. Wigmosta ◽  
...  
Keyword(s):  
Water Resources ◽  
Flood Control ◽  
Large Scale ◽  
Regulation System ◽  
Earth System ◽  
Mean Flow ◽  
System Models ◽  
Operating Rules ◽  
Reservoir Models ◽  
Earth System Models

Abstract. Human influence on the hydrologic cycle includes regulation and storage, consumptive use and overall redistribution of water resources in space and time. Representing these processes is essential for applications of earth system models in hydrologic and climate predictions, as well as impact studies at regional to global scales. Emerging large-scale research reservoir models use generic operating rules that are flexible for coupling with earth system models. Those generic operating rules have been successful in reproducing the overall regulated flow at large basin scales. This study investigates the uncertainties of the reservoir models from different implementations of the generic operating rules using the complex multi-objective Columbia River Regulation System in northwestern United States as an example to understand their effects on not only regulated flow but also reservoir storage and fraction of the demand that is met. Numerical experiments are designed to test new generic operating rules that combine storage and releases targets for multi-purpose reservoirs and to compare the use of reservoir usage priorities, withdrawals vs. consumptive demand, as well as natural vs. regulated mean flow for calibrating operating rules. Overall the best performing implementation is the use of the combined priorities (flood control storage targets and irrigation release targets) operating rules calibrated with mean annual natural flow and mean monthly withdrawals. The options of not accounting for groundwater withdrawals, or on the contrary, of assuming that all remaining demand is met through groundwater extractions, are discussed.

scholarly journals A global assessment of gross and net land change dynamics for current conditions and future scenarios

2018 ◽  
Vol 9 (2) ◽  
pp. 441-458 ◽  
Author(s):  
Richard Fuchs ◽  
Reinhard Prestele ◽  
Peter H. Verburg
Keyword(s):  
Land Use ◽  
Shifting Cultivation ◽  
Large Scale ◽  
Earth System ◽  
Grid Cells ◽  
Land Change ◽  
System Models ◽  
Change Dynamics ◽  
Earth System Models ◽  
Land Changes

Abstract. The consideration of gross land changes, meaning all area gains and losses within a pixel or administrative unit (e.g. country), plays an essential role in the estimation of total land changes. Gross land changes affect the magnitude of total land changes, which feeds back to the attribution of biogeochemical and biophysical processes related to climate change in Earth system models. Global empirical studies on gross land changes are currently lacking. Whilst the relevance of gross changes for global change has been indicated in the literature, it is not accounted for in future land change scenarios. In this study, we extract gross and net land change dynamics from large-scale and high-resolution (30–100 m) remote sensing products to create a new global gross and net change dataset. Subsequently, we developed an approach to integrate our empirically derived gross and net changes with the results of future simulation models by accounting for the gross and net change addressed by the land use model and the gross and net change that is below the resolution of modelling. Based on our empirical data, we found that gross land change within 0.5∘ grid cells was substantially larger than net changes in all parts of the world. As 0.5∘ grid cells are a standard resolution of Earth system models, this leads to an underestimation of the amount of change. This finding contradicts earlier studies, which assumed gross land changes to appear in shifting cultivation areas only. Applied in a future scenario, the consideration of gross land changes led to approximately 50 % more land changes globally compared to a net land change representation. Gross land changes were most important in heterogeneous land systems with multiple land uses (e.g. shifting cultivation, smallholder farming, and agro-forestry systems). Moreover, the importance of gross changes decreased over time due to further polarization and intensification of land use. Our results serve as an empirical database for land change dynamics that can be applied in Earth system models and integrated assessment models.

scholarly journals Scaling from individuals to ecosystems in an Earth System Model using a mathematically tractable model of height-structured competition for light

2014 ◽  
Vol 11 (12) ◽  
pp. 17757-17860 ◽  
Author(s):  
E. S. Weng ◽  
S. Malyshev ◽  
J. W. Lichstein ◽  
C. E. Farrior ◽  
R. Dybzinski ◽  
...  
Keyword(s):  
Large Scale ◽  
Optimal Allocation ◽  
Atmospheric Co2 ◽  
Geophysical Fluid Dynamics Laboratory ◽  
Earth System ◽  
Light Water ◽  
System Models ◽  
C Cycle ◽  
Competition For Light ◽  
Earth System Models

Abstract. The long-term and large scale dynamics of ecosystems are in large part determined by the performances of individual plants in competition with one another for light, water and nutrients. Woody biomass, a pool of carbon (C) larger than 50% of atmospheric CO2, exists because of height-structured competition for light. However, most of the current Earth System Models that predict climate change and C cycle feedbacks lack both a mechanistic formulation for height-structured competition for light and an explicit scaling from individual plants to the globe. In this study, we incorporate height-structured competition and explicit scaling from individuals to ecosystems into the land model (LM3) currently used in the Earth System Models developed by the Geophysical Fluid Dynamics Laboratory (GFDL). The height-structured formulation is based on the Perfect Plasticity Approximation (PPA), which has been shown to accurately scale from individual-level plant competition for light, water and nutrients to the dynamics of whole communities. Because of the tractability of the PPA, the coupled LM3–PPA model is able to include a large number of phenomena across a range of spatial and temporal scales, and still retain computational tractability, as well as close linkages to mathematically tractable forms of the model. We test a range of predictions against data from temperate broadleaved forests in the northern USA. The results show the model predictions agree with diurnal and annual C fluxes, growth rates of individual trees in the canopy and understory, tree size distributions, and species-level population dynamics during succession. We also show how the competitively optimal allocation strategy – the strategy that can competitively exclude all others – shifts as a function of the atmospheric CO2 concentration. This strategy is referred as an evolutionary stable strategy (ESS) in the ecological literature and is typically not the same as a productivity- or growth-maximizing strategy. Model simulations predict that C sinks caused by CO2 fertilization in forests limited by light and water will be down-regulated if allocation tracks changes in the competitive optimum. The implementation of the model in this paper is for temperate broadleaved forest trees, but the formulation of the model is general. It can be expanded to include other growth forms and physiologies simply by altering parameter values.

Is large-scale terrestrial hydrological cycling well represented in Earth System Models?

2021 ◽  
Author(s):  
Navid Ghajarnia ◽  
Zahra Kalantari ◽  
Georgia Destouni
Keyword(s):  
Climate Change ◽  
Observational Data ◽  
Large Scale ◽  
Hydrological Cycle ◽  
Good Representation ◽  
Earth System ◽  
System Models ◽  
The World ◽  
Terrestrial Hydrology ◽  
Earth System Models

<p>This paper addresses how large-scale terrestrial water cycling is represented in the land surface schemes of Earth System Models (ESMs). Good representation is essential, for example in regional planning for climate change adaptation and in preparation for hydro-climatic extremes that have recently set records world-wide in devastating consequences for societies and deaths of thousands of people. ESMs provide simulations and projections for the climate system and its interactions with the terrestrial hydrological cycle, and are widely used to study and prepare for associated impacts of climate change. However, the reliability of ESMs is unclear with regard to their representation of large-scale terrestrial hydrology and its changes and interactions between its key variables‎. Despite being crucial for model realism, analysis of co-variations among terrestrial hydrology variables is still largely missing in ESM performance evaluations. To bridge this research gap, we have studied and identified large-scale co-variation patterns between soil moisture (SM) and the main freshwater fluxes of runoff (R), precipitation (P), and evapotranspiration (ET) from observational data and across 6405 hydrological catchments in different parts and climates of the world. Furthermore, we have compared the identified observation-based relationships with those emerging from ESMs and reanalysis products. Our results show that the most strongly correlated freshwater variables based on observational data are also the most misrepresented hydrological patterns in ESMs and reanalysis simulations. In particular, we find SM and R to have the generally strongest large-scale correlations according to the observation-based data, across the numerous studied catchments with widely different hydroclimatic characteristics. Compared to the SM-R correlation signals, the observation-based correlations are overall weaker for the commonly expected closer dependencies of: R on P; ET on P; SM on P; and ET on SM. Nevertheless, this strongest SM-R correlation and the P-R correlation are the most misrepresented hydrological patterns in reanalysis products and ESMs. Our results also show that ESM outputs can perform relatively well in simulating individual hydrological variables, while exhibiting essential inconsistencies in simulated co-variations between variables. Such investigations of large-scale terrestrial hydrology representation by ESMs can enhance our understanding of fundamental ESM biases and uncertainties while providing important insights for systematic ESM improvement with regard to the large-scale hydrological cycling over the world’s continents and regional land areas.</p>

scholarly journals The generic MESSy submodel TENDENCY (v1.0) for process-based analyses in Earth system models

2014 ◽  
Vol 7 (4) ◽  
pp. 1573-1582 ◽  
Author(s):  
R. Eichinger ◽  
P. Jöckel
Keyword(s):  
Atmospheric Chemistry ◽  
Large Scale ◽  
Time Integration ◽  
Model Systems ◽  
Specific Humidity ◽  
Integration Scheme ◽  
Earth System ◽  
Prognostic Variables ◽  
System Models ◽  
Earth System Models

Abstract. The tendencies of prognostic variables in Earth system models are usually only accessible, e.g. for output, as a sum over all physical, dynamical and chemical processes at the end of one time integration step. Information about the contribution of individual processes to the total tendency is lost, if no special precautions are implemented. The knowledge on individual contributions, however, can be of importance to track down specific mechanisms in the model system. We present the new MESSy (Modular Earth Submodel System) infrastructure submodel TENDENCY and use it exemplarily within the EMAC (ECHAM/MESSy Atmospheric Chemistry) model to trace process-based tendencies of prognostic variables. The main idea is the outsourcing of the tendency accounting for the state variables from the process operators (submodels) to the TENDENCY submodel itself. In this way, a record of the tendencies of all process–prognostic variable pairs can be stored. The selection of these pairs can be specified by the user, tailor-made for the desired application, in order to minimise memory requirements. Moreover, a standard interface allows the access to the individual process tendencies by other submodels, e.g. for on-line diagnostics or for additional parameterisations, which depend on individual process tendencies. An optional closure test assures the correct treatment of tendency accounting in all submodels and thus serves to reduce the model's susceptibility. TENDENCY is independent of the time integration scheme and therefore the concept is applicable to other model systems as well. Test simulations with TENDENCY show an increase of computing time for the EMAC model (in a setup without atmospheric chemistry) of 1.8 ± 1% due to the additional subroutine calls when using TENDENCY. Exemplary results reveal the dissolving mechanisms of the stratospheric tape recorder signal in height over time. The separation of the tendency of the specific humidity into the respective processes (large-scale clouds, convective clouds, large-scale advection, vertical diffusion and methane oxidation) show that the upward propagating water vapour signal dissolves mainly because of the chemical and the advective contribution. The TENDENCY submodel is part of version 2.42 or later of MESSy.

scholarly journals The generic MESSy submodel TENDENCY (v1.0) for process-based analyses in Earth System Models

2014 ◽  
Vol 7 (2) ◽  
pp. 2217-2247
Author(s):  
R. Eichinger ◽  
P. Jöckel
Keyword(s):  
Atmospheric Chemistry ◽  
Large Scale ◽  
Time Integration ◽  
Model Systems ◽  
Specific Humidity ◽  
Integration Scheme ◽  
Earth System ◽  
Prognostic Variables ◽  
System Models ◽  
Earth System Models

Abstract. The tendencies of prognostic variables in Earth System Models are usually only accessible, e.g., for output, as sum over all physical, dynamical and chemical processes at the end of one time integration step. Information about the contribution of individual processes to the total tendency is lost, if no special precautions are implemented. The knowledge on individual contributions, however, can be of importance to track down specific mechanisms in the model system. We present the new MESSy (Modular Earth Submodel System) infrastructure submodel TENDENCY and use it exemplarily within the EMAC (ECHAM/MESSy Atmospheric Chemistry) model to trace process-based tendencies of prognostic variables. The main idea is the outsourcing of the tendency accounting for the state variables from the process operators (submodels) to the TENDENCY submodel itself. In this way, a record of the tendencies of all process-prognostic variable pairs can be stored. The selection of these pairs can be specified by the user, tailor-made for the desired application, in order to minimise memory requirements. Moreover a standard interface allows the access to the individual process tendencies by other submodels, e.g., for on-line diagnostics or for additional parameterisations, which depend on individual process tendencies. An optional closure test assures the correct treatment of tendency accounting in all submodels and thus serves to reduce the models susceptibility. TENDENCY is independent of the time integration scheme and therefore applicable to other model systems as well. Test simulations with TENDENCY show an increase of computing time for the EMAC model (in a setup without atmospheric chemistry) of 1.8 ± 1% due to the additional subroutine calls when using TENDENCY. Exemplary results reveal the dissolving mechanisms of the stratospheric tape recorder signal in height over time. The separation of the tendency of the specific humidity into the respective processes (large-scale clouds, convective clouds, large-scale advection, vertical diffusion and methane-oxidation) show that the upward propagating water vapour signal dissolves mainly because of the chemical and the advective contribution. The TENDENCY submodel is part of version 2.42 or later of MESSy.

scholarly journals Exploring the isopycnal mixing and helium-heat paradoxes in a suite of Earth System Models

2014 ◽  
Vol 11 (6) ◽  
pp. 2533-2567 ◽  
Author(s):  
A. Gnanadesikan ◽  
R. Abernathey ◽  
M.-A. Pradal
Keyword(s):  
Large Scale ◽  
Baroclinic Instability ◽  
Deep Ocean ◽  
Helium Isotopes ◽  
Earth System ◽  
System Models ◽  
Geothermal Heating ◽  
Mixing Coefficient ◽  
Earth System Models ◽  
Isopycnal Mixing

Abstract. This paper uses a suite of Earth System models which simulate the distribution of He isotopes and radiocarbon to examine two paradoxes in Earth science. The helium-heat paradox refers to the fact that helium emissions to the deep ocean are far lower than would be expected given the rate of geothermal heating, since both are thought to be the result of radioactive decay in the earth's interior. The isopycnal mixing paradox comes from the fact that many theoretical parameterizations of the isopycnal mixing coefficient ARedi that link it to baroclinic instability project it to be small (of order a few hundred m2 s−1) in the ocean interior away from boundary currents. However, direct observations using tracers and floats (largely in the upper ocean) suggest that values of this coefficient are an order of magnitude higher. Because helium isotopes equilibrate rapidly with the atmosphere, but radiocarbon equilibrates slowly, it might be thought that resolving the isopycnal mixing paradox in favor of the higher observational estimates of ARedi might also solve the helium paradox. In this paper we show that this is not the case. In a suite of models with different spatially constant and spatially varying values of ARedi the distribution of radiocarbon and helium isotopes is sensitive to the value of ARedi. However, away from strong helium sources in the Southeast Pacific, the relationship between the two is not sensitive, indicating that large-scale advection is the limiting process for removing helium and radiocarbon from the deep ocean. The helium isotopes, in turn, suggest a higher value of ARedi in the deep ocean than is seen in theoretical parameterizations based on baroclinic growth rates. We argue that a key part of resolving the isopycnal mixing paradox is to abandon the idea that ARedi has a direct relationship to local baroclinic instability and to the so called "thickness" mixing coefficient AGM.

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