scholarly journals Ecosystem transpiration and evaporation: Insights from three water flux partitioning methods across FLUXNET sites

2020 ◽  
Vol 26 (12) ◽  
pp. 6916-6930 ◽  
Author(s):  
Jacob A. Nelson ◽  
Oscar Pérez‐Priego ◽  
Sha Zhou ◽  
Rafael Poyatos ◽  
Yao Zhang ◽  
...  
Keyword(s):  
Water Flux ◽  
Partitioning Methods ◽  
Flux Partitioning

scholarly journals Structural changes to forests during regeneration affect water flux partitioning, water ages and hydrological connectivity: Insights from tracer-aided ecohydrological modelling

2021 ◽  
Vol 25 (9) ◽  
pp. 4861-4886
Author(s):  
Aaron J. Neill ◽  
Christian Birkel ◽  
Marco P. Maneta ◽  
Doerthe Tetzlaff ◽  
Chris Soulsby
Keyword(s):  
Land Cover ◽  
Land Cover Change ◽  
Forest Regeneration ◽  
Structural Changes ◽  
Water Flux ◽  
Natural Forest ◽  
Hydrological Connectivity ◽  
Area Index ◽  
Flux Partitioning ◽  
Natural Forest Regeneration

Abstract. Increasing rates of biodiversity loss are adding momentum to efforts seeking to restore or rewild degraded landscapes. Here, we investigated the effects of natural forest regeneration on water flux partitioning, water ages and hydrological connectivity, using the tracer-aided ecohydrological model EcH2O-iso. The model was calibrated using ∼ 3.5 years of diverse ecohydrological and isotope data available for a catchment in the Scottish Highlands, an area where impetus for native pinewood regeneration is growing. We then simulated two land cover change scenarios that incorporated forests at early (dense thicket) and late (old open forest) stages of regeneration, respectively. Changes to forest structure (proportional vegetation cover, vegetation heights and leaf area index of pine trees) were modelled for each stage. The scenarios were then compared to a present-day baseline simulation. Establishment of thicket forest had substantial ecohydrological consequences for the catchment. Specifically, increased losses to transpiration and, in particular, interception evaporation drove reductions in below-canopy fluxes (soil evaporation, groundwater (GW) recharge and streamflow) and generally slower rates of water turnover. The greatest reductions in streamflow and connectivity were simulated for summer baseflows and small to moderate events during summer and the autumn/winter rewetting period. This resulted from the effect of local changes to flux partitioning in regenerating areas on the hillslopes extending to the wider catchment by reducing downslope GW subsidies that help sustain summer baseflows and saturation in the valley bottom. Meanwhile, higher flows were relatively less affected, especially in winter. Despite the generally drier state of the catchment, simulated water ages suggested that the increased transpiration demands of the thicket forest could be satisfied by moisture carried over from previous seasons. The more open nature of the old forest generally resulted in water fluxes, water ages and connectivity returning towards baseline conditions. Our work implies that the ecohydrological consequences of natural forest regeneration depend on the structural characteristics of the forest at different stages of development. Consequently, future land cover change investigations need to move beyond consideration of simple forest vs. non-forest scenarios to inform sustainable landscape restoration efforts.

Water Flux Partitioning for Eddy Covariance Data

2020 ◽  
Author(s):  
Jacob Nelson
Keyword(s):  
Eddy Covariance ◽  
Sap Flow ◽  
Meteorological Data ◽  
Water Flux ◽  
Carbon Fluxes ◽  
Seasonal Cycles ◽  
Flow Data ◽  
The Core ◽  
Core Energy ◽  
Flux Partitioning

<p>Here we present an overview of methods for partitioning evapotranspiration (ET) from eddy covariance data. We focus on methods that are designed to use the core energy and carbon fluxes, as well as meteorological data, and do not require supplemental measurements or campaigns. A comparison of three such methods for estimating transpiration (T) showed high correlations between them (R<sup>2</sup> of  daily T between 0.80 and 0.87) and higher correlations to daily stand T estimates from sap flow data (R<sup>2</sup> between 0.58 and 0.66) compared to the tower ET (R2 = 0.49). However, the three methods show significant differences in magnitude, with T/ET values ranging from 45% to 77%. Despite the differences in magnitude, the methods show plausible patterns with respect to LAI, seasonal cycles, WUE, and VPD; moreover, they represent an improvement compared to using ET as a proxy for T even when filtering for days after rain. Finally, we outline practical aspects of applying the methods, such as how to apply the methods and code availability.</p>

scholarly journals Structural changes to forests during regeneration affect water flux partitioning, water ages and hydrological connectivity: Insights from tracer-aided ecohydrological modelling

2021 ◽  
Author(s):  
Aaron J. Neill ◽  
Christian Birkel ◽  
Marco P. Maneta ◽  
Doerthe Tetzlaff ◽  
Chris Soulsby
Keyword(s):  
Land Cover ◽  
Land Cover Change ◽  
Forest Regeneration ◽  
Structural Changes ◽  
Water Flux ◽  
Natural Forest ◽  
Hydrological Connectivity ◽  
Area Index ◽  
Flux Partitioning ◽  
Natural Forest Regeneration

Abstract. Increasing rates of biodiversity loss are adding momentum to efforts seeking to restore or rewild degraded landscapes. Here, we investigated the effects of natural forest regeneration on water flux partitioning, water ages and hydrological connectivity, using the tracer-aided ecohydrological model EcH2O-iso. The model was calibrated using ~3.5 years of diverse ecohydrological and isotope datasets available for a catchment in the Scottish Highlands, an area where the impetus for regeneration of native pinewoods is growing. We then simulated two land cover change scenarios that incorporated forests at early (thicket) and late (old-open forest) stages of regeneration, respectively, and compared these to a present-day baseline simulation. Changes to forest structure (proportional vegetation cover, vegetation heights and leaf area index of pine trees) were modelled for each stage. Establishment of thicket forest had the greatest effect on water partitioning/ages and connectivity, with increased losses to interception evaporation driving reductions in below-canopy fluxes (soil evaporation, groundwater recharge and streamflow) and generally slower rates of water turnover. Effects on streamflow were most evident for low and moderate summer flows rather than winter high flows. Whilst full forest regeneration was limited to hillslopes, resultant changes to the spatial dynamics of flux partitioning could also cause drying out of the valley bottom. The more open nature of the older forest generally resulted in water fluxes, ages and connectivity characteristics returning towards baseline conditions. Our work implies that the ecohydrological consequences of natural forest regeneration on degraded land depend on the structural characteristics of the forest at different stages of development. Consequently, future land cover change investigations need to move beyond consideration of simple forest vs. non-forest scenarios to inform management that effectively balances landscape restoration with demand for ecosystem services. Tracer-aided ecohydrological models were also shown to be useful tools for land cover change simulations and further potential of such models was highlighted.

Effect of Water Flux on Solute Velocity and Dispersion

2003 ◽  
Vol 67 (2) ◽  
pp. 449 ◽  
Author(s):  
M. K. Shukla ◽  
T. R. Ellsworth ◽  
R. J. Hudson ◽  
D. R. Nielsen
Keyword(s):  
Water Flux ◽  
Effect Of Water

Effect of the structure of cellulose acetate membranes on their permeability, electrical conductivity and rejection

1990 ◽  
Vol 55 (12) ◽  
pp. 2933-2939 ◽  
Author(s):  
Hans-Hartmut Schwarz ◽  
Vlastimil Kůdela ◽  
Klaus Richau
Keyword(s):  
Electrical Conductivity ◽  
Electrical Properties ◽  
Cellulose Acetate ◽  
Reverse Osmosis ◽  
Water Flux ◽  
Cellulose Acetate Membrane ◽  
Structure Parameters ◽  
Dc Electrical Conductivity ◽  
Cellulose Acetate Membranes

Ultrafiltration cellulose acetate membrane can be transformed by annealing into reverse osmosis membranes (RO type). Annealing brings about changes in structural properties of the membranes, accompanied by changes in their permeability behaviour and electrical properties. Correlations between structure parameters and electrochemical properties are shown for the temperature range 20-90 °C. Relations have been derived which explain the role played by the dc electrical conductivity in the characterization of rejection ability of the membranes in the reverse osmosis, i.e. rRO = (1 + exp (A-B))-1, where exp A and exp B are statistically significant correlation functions of electrical conductivity and salt permeation, or of electrical conductivity and water flux through the membrane, respectively.

scholarly journals A synthesis of three decades of hydrological research at Scotty Creek, NWT, Canada

2019 ◽  
Vol 23 (4) ◽  
pp. 2015-2039 ◽  
Author(s):  
William Quinton ◽  
Aaron Berg ◽  
Michael Braverman ◽  
Olivia Carpino ◽  
Laura Chasmer ◽  
...  
Keyword(s):  
Land Cover ◽  
Water Flux ◽  
Study Region ◽  
Physical Mechanisms ◽  
Permafrost Thaw ◽  
Discontinuous Permafrost ◽  
Modelling Studies ◽  
Hydrology And Water Resources ◽  
And Storage ◽  
Storage Processes

Abstract. Scotty Creek, Northwest Territories (NWT), Canada, has been the focus of hydrological research for nearly three decades. Over this period, field and modelling studies have generated new insights into the thermal and physical mechanisms governing the flux and storage of water in the wetland-dominated regions of discontinuous permafrost that characterises much of the Canadian and circumpolar subarctic. Research at Scotty Creek has coincided with a period of unprecedented climate warming, permafrost thaw, and resulting land cover transformations including the expansion of wetland areas and loss of forests. This paper (1) synthesises field and modelling studies at Scotty Creek, (2) highlights the key insights of these studies on the major water flux and storage processes operating within and between the major land cover types, and (3) provides insights into the rate and pattern of the permafrost-thaw-induced land cover change and how such changes will affect the hydrology and water resources of the study region.

Sign in / Sign up

Export Citation Format

Share Document