scholarly journals Water as a critical zone currency: linking water storage and age to root uptake and biogeochemical transport

2020 ◽  
Author(s):  
Sylvain Kuppel ◽  
Isabelle Braud ◽  
Yves Goddéris ◽  
Sekhar Muddu ◽  
Jean Riotte ◽  
...  
Keyword(s):  
Chemical Weathering ◽  
Spatial Organization ◽  
Spatial Scales ◽  
Water Storage ◽  
Critical Zone ◽  
Root Uptake ◽  
Time Varying ◽  
Peninsular India ◽  
Transit Times ◽  
Flow Pathways

<p><span>Efforts to grasp hydrological functioning in landscapes have gradually been evolving from inferring </span><span><em>when</em></span><span> water output fluxes respond to precipitation and energy inputs in catchments, towards tracking down </span><span><em>which water</em></span><span> is present in the different flow pathways of the critical zone (CZ). In the CZ where almost all terrestrial life developed, quantifying water storage and age (residence times in stores and transit times in fluxes) is key to the understanding of how water is <em>i)</em> available to supply root uptake, <em>ii)</em> in interaction with regolith minerals and biota, and <em>iii)</em> a medium for solute transport. We propose an approach to characterize the dynamics and non-linearities of CZ functioning first by mapping time-varying transit times of water </span><span>exiting as plant transpiration as well as</span><span> soil evaporation and stream discharge, against the corresponding water storage states. This picture is then extended by assessing the resulting relationships between hydrological states and patterns of nutrient concentration in, and export out of, the critical zone. This analysis considers several spatial scales, from the hillslope to the whole catchment. To this end, we use simulations from a cascade of spatially-distributed numerical tools: a process-based ecohydrological model –</span><span> accounting for the coupling between energy balance, critical zone hydrology and vegetation dynamics</span><span>, and a modular chemical weathering model – simulating dissolution/precipitation rates of mineral phases based on kinetics laws. We particularly focus on the long-term experimental tropical catchment of Mule Hole in Peninsular India (part of both </span><span>the </span><span>Indian Kabini CZ </span><span>observatory </span><span>and </span><span>the </span><span>French CZ </span><span>observatory</span><span> network OZCAR), with a highly seasonal hydroclimate and deep unsaturated profile, and where extensive hydrometric and chemical datasets are available for model calibration and evaluation. We discuss the </span><span>interplay between distinctively mobilized critical zone compartments for each output flux,</span> <span>and</span><span> the</span><span> time-varying spatial organization of flow pathways. </span></p>

scholarly journals Modelling temporal variability of in-situ soil water and vegetation isotopes reveals ecohydrological couplings in a willow plot

2021 ◽  
Author(s):  
Aaron Smith ◽  
Doerthe Tetzlaff ◽  
Jessica Landgraf ◽  
Maren Dubbert ◽  
Chris Soulsby
Keyword(s):  
Soil Water ◽  
Biomass Allocation ◽  
Water Availability ◽  
Summer Precipitation ◽  
Water Sources ◽  
Critical Zone ◽  
Root Uptake ◽  
Water Age ◽  
Transit Times

Abstract. The partitioning of water fluxes in the critical zone is of great interest due to the implications for understanding water cycling and quantifying water availability for various ecosystem services. We used the tracer-aided ecohydrological model EcH2O-iso to evaluate water, energy, water stable isotope, and biomass dynamics at an intensively monitored study plot under two willow trees, a riparian species, in Berlin, Germany. Importantly, we assessed the value of in-situ soil and plant water isotope data to quantify xylem water sources and transit times, with coupled estimates of the temporal dynamics and ages of soil and root-uptake water. The willows showed high evapotranspiration water use, with limited percolation of summer precipitation to deeper soil layers due to the dominance of shallow root-uptake (> 80 % in the upper 10 cm). Lower evapotranspiration under grass resulted in higher soil moisture storage, greater soil evaporation and more percolation of soil water. Biomass allocation was predominantly foliage growth (57 % in grass and 78 % in willow). Shallow soil water age under grass was similar to under willows (15–17 days). Considering potential xylem transit times showed a large improvement in the model's capability to estimate xylem isotopic composition and water age, and revealed the high value of in-situ data within modelling. Root-uptake was predominately derived from summer precipitation events (56 %) and had an average age of 35 days, with xylem transport times taking at least 6.2–8.1 days. By evaluating water partitioning, energy and isotope mass-balance, along with biomass allocation, the model revealed multifaceted capabilities for assessing water cycling within the critical zone at high temporal resolution, including xylem water sources and transport, which are all necessary for short and long-term assessment of water availability for plant growth.

scholarly journals Study of water storage variations at the Pantanal wetlands area from GRACE monthly mass grids

2019 ◽  
Vol 9 (1) ◽  
pp. 133-143
Author(s):  
Ayelen Pereira ◽  
Cecilia Cornero ◽  
Ana C. O. C. Matos ◽  
M. Cristina Pacino ◽  
Denizar Blitzkow
Keyword(s):  
Water Mass ◽  
Spatial Scales ◽  
Water Storage ◽  
Transport Processes ◽  
Satellite Gravity ◽  
The North ◽  
Paraguay River ◽  
Gravity Recovery ◽  
Grace Mission ◽  
Phase Differences

Abstract The continental water storage is significantly in-fluenced by wetlands, which are highly affected by climate change and anthropogenic influences. The Pantanal, located in the Paraguay river basin, is one of the world’s largest and most important wetlands because of the environmental biodiversity that represents. The satellite gravity mission GRACE (Gravity Recovery And Climate Experiment) provided until 2017 time-variable Earth’s gravity field models that reflected the variations due to mass transport processes-like continental water storage changes-which allowed to study environments such as wetlands, at large spatial scales. The water storage variations for the period 2002-2016, by using monthly land water mass grids of Total Water Storage (TWS) derived from GRACE solutions, were evaluated in the Pantanal area. The capability of the GRACE mission for monitoring this particular environment is analyzed, and the comparison of the water mass changes with rainfall and hydrometric heights data at different stations distributed over the Pantanal region was carried out. Additionally, the correlation between the TWS and river gauge measurements, and the phase differences for these variables, were also evaluated. Results show two distinct zones: high correlations and low phase shifts at the north, and smaller correlation values and consequently significant phase differences towards the south. This situation is mainly related to the hydrogeological domains of the area.

scholarly journals Multi-scale data on intertidal macrobenthic biodiversity and environmental features in three New Zealand harbours

2019 ◽  
Author(s):  
Casper Kraan ◽  
Barry L. Greenfield ◽  
Simon F. Thrush
Keyword(s):  
New Zealand ◽  
Environmental Variables ◽  
Spatial Organization ◽  
Spatial Scales ◽  
Species Distributions ◽  
Sediment Grain Size ◽  
High Resolution Data ◽  
Multi Scale ◽  
Grain Size Distributions ◽  
Patterns And Processes

Abstract. Understanding how the plants and animals that live in the seafloor vary in their spatial patterns of diversity and abundance is fundamental to gaining insight in the role of biodiversity in maintaining ecosystem functioning in coastal ecosystems, as well as advancing the modelling of species distributions under realistic assumptions. Yet, it is virtually unknown how the relationships between abundance patterns and different biotic and environmental processes change depending on spatial scales, which is mainly due to a lack of data. Within the project Spatial Organization of Species Distributions: Hierarchical and Scale-Dependent Patterns and Processes in Coastal Seascapes at the National Institute for Water and Atmospheric Research (NIWA) in New Zealand we collected multi-scale and high-resolution data on macrobenthic biodiversity. We found 146 species, i.e. bivalves, polychaetes and crustaceans (> 500 μm) that live hidden in marine sandflats, and collected point measurements of important environmental variables (sediment grain-size distributions, chlorophyll a concentration, and visible sandflat parameters) in three large intertidal Harbours (Kaipara, Tauranga and Manukau). In each Harbour we sampled 400 points for macrobenthic community composition and abundances, as well as the full set of environmental variables. Using an elaborate sampling design, we were able to cover scales from 30 centimetres to a maximal extent of 1 km. All data and extensive metadata are available from the data publisher PANGAEA via the persistent identifier https://doi.org/10.1594/PANGAEA.903448.

scholarly journals A new stream and nested catchment framework for Australia

2013 ◽  
Vol 10 (12) ◽  
pp. 15433-15474
Author(s):  
J. L. Stein ◽  
M. F. Hutchinson ◽  
J. A. Stein
Keyword(s):  
Spatial Scales ◽  
Surface Flow ◽  
Stream Network ◽  
Australian Water ◽  
Assessment Tasks ◽  
Australian Continent ◽  
Wide Range ◽  
High Conservation ◽  
Flow Pathways ◽  
Fully Connected

Abstract. Nationally framed assessment and planning assists coordination of resource management activities across jurisdictional boundaries and provides context for assessing the cumulative effects of impacts that can be underestimated by local or regional studies. However, there were significant shortcomings in the existing spatial frameworks supporting national assessment and planning for Australia's rivers and streams. We describe the development of a new national stream and nested catchment framework for Australia that includes a fully connected and directed stream network and a nested catchment hierarchy derived using a modified Pfafstetter scheme. The directed stream network with associated catchment boundaries and Pfafstetter coding respect all distributary junctions and topographically driven surface flow pathways including across the areas of low relief and internal drainage that make up over half of the Australian continent. The Pfafstetter coding facilitates multi-scale analyses and easy tracing and query of upstream/downstream attributes and tributary/main stem relationships. Accompanying the spatial layers are 13 lookup tables containing nearly 400 attributes describing the natural and anthropogenic environment of each of the 1.4M stream segments across the Australian continent at multiple spatial scales (segment, sub-catchment and catchment). The database supplies key spatial layers to support national water information and accounting needs and assists a wide range of research, planning and assessment tasks at regional and continental scales. These include the delineation of reporting units for the Australian Water Resources Assessment, the development of an ecohydrological environment classification for Australian streams and the identification of high conservation value aquatic ecosystems for northern Australia.

Critical Zone Observatories: Building a network to advance interdisciplinary study of Earth surface processes

2008 ◽  
Vol 72 (1) ◽  
pp. 7-10 ◽  
Author(s):  
S. P. Anderson ◽  
R. C. Bales ◽  
C. J. Duffy
Keyword(s):  
Fluid Transport ◽  
Spatial Scales ◽  
Critical Zone ◽  
Watershed Scale ◽  
Spatial And Temporal Scales ◽  
Complex Interactions ◽  
Tectonic Processes ◽  
Interdisciplinary Approaches ◽  
Dynamic Interface ◽  
Interdisciplinary Study

AbstractWe live at the dynamic interface between the solid Earth and its outer fluid envelopes. This interface, extending from the outer vegetation canopy to the base of active groundwater, was recently named the Critical Zone because it supports life and is increasingly impacted by human actions. Understanding the complex interactions between processes that operate in and shape the Critical Zone requires interdisciplinary approaches that span wide spatial and temporal scales. Tectonic processes, weathering, fluid transport, and biological processes control the function and structure of the Critical Zone. Three Critical Zone Observatories recently established by the U.S. National Science Foundation are designed to integrate studies of process interactions up to the watershed scale. A goal of the program is to build the three independently conceived observatories into a network from which broader understanding — larger spatial scales but also deeper insight — can emerge.

Topographic disequilibrium, landscape dynamics and active tectonics: an example from the Bhutan Himalayas

2021 ◽  
Author(s):  
Martine Simoes ◽  
Timothée Sassolas-Serrayet ◽  
Rodolphe Cattin ◽  
Romain Le Roux-Mallouf ◽  
Matthieu Ferry ◽  
...  
Keyword(s):  
Spatial Organization ◽  
Spatial Scales ◽  
Active Tectonics ◽  
Recent Change ◽  
Climatic Conditions ◽  
Landscape Dynamics ◽  
Drainage Basins ◽  
Equilibrium Conditions ◽  
Longitudinal Band ◽  
Active Tectonic

<p>The quantification of active tectonics from geomorphological and morphometric approaches most often implies that erosion and tectonics have reached a certain balance. Such equilibrium conditions may however be seldom found in nature, in particular because drainage basins may be quite dynamic even though tectonic and climatic conditions remain constant. Here, we document this drainage dynamics from the particular case example of the Bhutan Himalayas. Evidence for out-of-equilibrium morphologies have for long been noticed in Bhutan, from major (> 1 km high) river knickpoints and from the existence of high-altitude low-relief regions within the mountain hinterland. These peculiar morphologies were generally interpreted as representing a recent change in climatic and/or tectonic conditions. To further characterize these morphologies and their dynamics, and from there discuss their origin and meaning, we perform field observations and a detailed quantitative morphometric analysis using Chi plots and Gilbert metrics of drainages over various spatial scales, from major Himalayan rivers to local streams draining the low-relief regions. We first find that the river network is highly dynamic and unstable. Our results emphasize that the morphology of Bhutan does not result from a general wave of incision propagating upstream, as expected from most previous interpretations. Also, the specific spatial organization in which all major knickpoints and low-relief regions are located along a longitudinal band in the Bhutan hinterland, whatever their spatial scale and the dimensions of the associated drainage basins, calls for a common local supporting mechanism most probably related to active tectonic uplift. Our results emphasize the need for a precise documentation of landscape dynamics and disequilibrium over various spatial scales as a first-order step in morpho-tectonic studies of active landscapes.</p>

Weathering, Soils, and Slope Processes

2009 ◽  
Author(s):  
John Wainwright
Keyword(s):  
Chemical Weathering ◽  
Life Support ◽  
Spatial Scales ◽  
Chemical Processes ◽  
Earth Systems ◽  
Erosion Processes ◽  
The North ◽  
In Situ Modification ◽  
Dry Conditions ◽  
The Mediterranean

Hillslopes are the dominant landform features of the Earth’s surface. They make up the interface between the atmosphere and Earth systems, providing a substrate that supports life and thus the basis for human activities within the Mediterranean. Their location at this interface means that hillslopes evolve through a complex interaction of different processes, operating at a range of different time and spatial scales. At longer timescales, processes of weathering convert rock and other parent materials into soils. Soils allow the growth of vegetation and thus further feedbacks between atmospheric and surface processes; in some cases these feedbacks can be seen to provide relative stability, while in others the system can become more fragile (Chapter 20). The latter case often arises as a result of erosion processes of various types. Water erosion and mass movements are a significant element of Mediterranean landscape evolution, occurring in parallel with (in response to, and affecting) tectonic processes that have moulded the configuration of the Earth’s crust (see Chapter 1), producing the unique combination of environmental characteristics of the region. Since the Late Pleistocene, depending on location, human activity has led to an acceleration of many of these processes, with important consequences for the basic ‘life-support system’ of the region and for global environmental cycles. The in situ modification of near-surface materials is typically considered to take place along a continuum relating to the dominance of mechanical or chemical processes (e.g. Birkeland 1999). The simplest control may be considered to be climatic, with mechanical breakdown of particles dominating in cold, dry conditions, and chemical processes dominating in warm, wet conditions. Comparing this model to the present day climate of the Mediterranean suggests, as with other processes, something of a north–south divide in terms of the dominant weathering process. The northern part of the basin (together with the Levant and the north-facing uplands of the Maghreb) would seem to be dominated by moderate chemical weathering; exceptions being the arid areas of south-east Spain, southern Sicily, eastern Cyprus, and parts of the Anatolian plateau as well as areas where low average temperatures would also reduce rates, such as in the Alps and parts of Slovenia and Croatia.

scholarly journals Primary weathering rates, water transit times, and concentration-discharge relations: A theoretical analysis for the critical zone

2017 ◽  
Vol 53 (1) ◽  
pp. 942-960 ◽  
Author(s):  
Ali A. Ameli ◽  
Keith Beven ◽  
Martin Erlandsson ◽  
Irena F. Creed ◽  
Jeffrey J. McDonnell ◽  
...  
Keyword(s):  
Theoretical Analysis ◽  
Critical Zone ◽  
Weathering Rates ◽  
Transit Times

scholarly journals The phylogeny of Critical Zone Observatories, or how to better structure existing observation networks to match the whole system approach

2021 ◽  
Author(s):  
Isabelle Braud ◽  
Jérôme Gaillardet ◽  
François Mercier ◽  
Sylvie Galle ◽  
Virginie Entringer
Keyword(s):  
System Approach ◽  
Spatial Scales ◽  
National Level ◽  
Monitoring Network ◽  
Critical Zone ◽  
Visualization Tool ◽  
Ecological Communities ◽  
Continental Scale ◽  
Observation Networks

<p>Implementing the Whole System Approach for long-term ecosystem, critical zone and socio-ecological system research requires going beyond existing structuration of scientific communities and observation networks. Indeed, existing observation networks were often built independently from each other, on a very disciplinary basis, with their own scientific objectives, funding mechanisms and institutional constraints. To tackle the observation challenges of the “new climatic regime” in the Anthropocene, a new type of observational platforms, more compatible with a scientific systemic approach needs to be built taking into account the history and institutional contexts of long-term observatories.</p><p><br>We have attempted to represent the diversity of critical zone observatories, sites and network of observatories that exist and that have been founded by different research institutions in France over the last 40 years and that are now gathered in the OZCAR Critical Zone network. Our representation encapsulates three main characteristics: the spatial scales of investigation (from the plot scale to the continental-scale watershed), the diversity of monitored compartments (catchments, glaciers, peatlands, aquifers…), and the institutional dimension (labeling and founding at the national level).  We found that a representation in the form of a tree, mimicking the phylogenetic tree of life, named the OZCAR-tree, was offering a visualization tool able to capture the philosophy and rationale of the network and was useful to improve the communication with the neighboring infrastructures, users and stakeholders. The branches of the tree represent the nested monitored scales, with the small branches of the tree representing monitored parcels or small catchments. The trunks represent networks of sites investigating the same compartment. For monitored catchments, the representation directly shows the various sampled scales and their nested organization from upstream to downstream. At each site, colored pie charts allow us to visualize rapidly the types of data that are collected, each part of the pie being a component of the critical zone (atmosphere, soil water, aquifers, vegetation, snow, ice…). This visualization directly shows the focus of the various sites, the completeness of measurements conducted by the different scientists, but also the missing compartments. It also shows that, if the network, as a whole is able to sample the various compartments and variables required for implementing the whole system approach, it is rarely the case when considering individual sites.</p><p>Beyond being a visualization tool, the OZCAR-tree helps representing the requirements of a “whole critical zone approach”. Because all compartments of the critical zone are connected vertically and horizontally by processes and fluxes of energy and matter, the tree is meant to represent all the components to be monitored and what should be the spatial architecture of a monitoring network fulfilling the disciplinary questions and approaches. The tree is therefore an illustration of a conceptual and idealized network (devoid of cost issues) of terrestrial surfaces monitoring infrastructure respectful of disciplinary approaches.</p><p>Finally, this representation is open to ecological and socio-ecological communities and may serve as a template for fostering collaboration with ecological and socio-ecological communities and networks and implementing observation platforms at the scale of changing territories.</p>

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