Critical Zone Storage Controls on the Water Ages of Ecohydrological Outputs

Acknowledgments: This work was supported by the European Research Council (ERC, project GA 335910 VeWa). M.P. Maneta acknowledges support from the NASA Ecological Forecasting Program Award #80NSSC19K00181 and NASA EPSCoR #80NSSC18M0025M. The authors are thankful to V. Ivanov, two anonymous reviewers, and E. Anguelova, whose comments and suggestions considerably improved the manuscript. Open access funding enabled and organized by Projekt DEAL. Funding Information EC | FP7 | FP7 Ideas: European Research Council (FP7 Ideas). Grant Number: GA 335910 VeWa National Aeronautics and Space Administration (NASA). Grant Numbers: #80NSSC19K00181, #80NSSC18M0025M NASA EPSCoR. Grant Number: #80NSSC18M0025M NASA Ecological Forecasting Program. Grant Number: #80NSSC19K00181 European Research Council. Grant Number: GA 335910 Open access funding enabled and organized by Projekt DEAL.Peer reviewedPublisher PD

Changes to Snowpack Energy State from Spring Storm Events, Columbia River Headwaters, Montana

The generation and release of meltwater during the spring snowmelt season can be delayed because of spring storm episodes with snow accumulation and/or sustained subfreezing temperatures. The delayed release of snowmelt often extends beyond the particular storm event because of changes to the internal state of energy in the snowpack that prevents transmission of meltwater. Following a storm, two energy deficits internal to the snowpack must be overcome before surface melt can drain and exit the snowpack: 1) cold content created by heat lost during the episode must be removed and 2) dry pore space must be filled with liquid water to residual saturation. This study investigates the role of these two processes in spring snowmelt following past storm episodes in western Montana. The analysis addresses;10 yr of historical snowpack and air temperature data from 33 stations in the Columbia River headwaters. Results indicate that the addition of pore space has a greater impact on delaying snowmelt than does the addition of cold content, with snow accumulation events responsible for 86% of the collective energy deficit imposed on the snowpack during storm episodes. Nearly all refreezing events occur within one month of peak snowpack, but accumulation events are common up to 50 days later. Under standardized conditions representing clear weather during the spring season, these energy deficits could all be overcome in a matter of hours

A parsimonious crop-water productivity index: an application to Brazil.

An application to the São Francisco river basin; Site characteristics, data sources and methodology

A spatially distributed hydroeconomic model to assess the effects of drought on land use, farm profits, and agricultural employment.

In this paper a high-resolution linked hydroeconomic model is demonstrated for drought conditions in a Brazilian river basin.Doi: 10.1029/2008WR00753

EcH₂O-iso 1.0: water isotopes and age tracking in a process-based, distributed ecohydrological model

We introduce EcH2O-iso, a new development of the physically based, fully distributed ecohydrological model EcH2O where the tracking of water isotopic tracers (2H and 18O) and age has been incorporated. EcH2O-iso is evaluated at a montane, low-energy experimental catchment in northern Scotland using 16 independent isotope time series from various landscape positions and compartments, encompassing soil water, groundwater, stream water, and plant xylem. The simulation results show consistent isotopic ranges and temporal variability (seasonal and higher frequency) across the soil profile at most sites (especially on hillslopes), broad model–data agreement in heather xylem, and consistent deuterium dynamics in stream water and in groundwater. Since EcH2O-iso was calibrated only using hydrometric and energy flux datasets, tracking water composition provides a truly independent validation of the physical basis of the model for successfully capturing catchment hydrological functioning, both in terms of the celerity in energy propagation shaping the hydrological response (e.g. runoff generation under prevailing hydraulic gradients) and flow velocities of water molecules (e.g. in consistent tracer concentrations at given locations and times). Additionally, we show that the spatially distributed formulation of EcH2O-iso has the potential to quantitatively link water stores and fluxes with spatiotemporal patterns of isotope ratios and water ages. However, our case study also highlights model–data discrepancies in some compartments, such as an over-dampened variability in groundwater and stream water lc-excess, and over-fractionated riparian topsoils. The adopted minimalistic framework, without site-specific parameterisation of isotopes and age tracking, allows us to learn from these mismatches in further model development and benchmarking needs, while taking into account the idiosyncracies of our study catchment. Notably, we suggest that more advanced conceptualisation of soil water mixing and of plant water use would be needed to reproduce some of the observed patterns. Balancing the need for basic hypothesis testing with that of improved simulations of catchment dynamics for a range of applications (e.g. plant water use under changing environmental conditions, water quality issues, and calibration-derived estimates of landscape characteristics), further work could also benefit from including isotope-based calibration.</p