Storage dynamics in hydropedological units control hillslope connectivity, runoff generation, and the evolution of catchment transit time distributions

Acknowledgments We thank the European Research Council (ERC; project GA 335910 VEWA) and Natural Environment Research Council (NERC; project NE/K000268/1) for funding. We would like to thank Konrad Piegat for invaluable help with the fieldwork. Iain Malcolm and staff at Marine Scotland (Pitlochry) are also thanked for the provision of data from the AWS. We also thank three anonymous reviewers for their constructive comments.Peer reviewedPublisher PD

Using SAS functions and high resolution isotope data to unravel travel time distributions in headwater catchments

Acknowledgments. We are grateful to the European Research Council (ERC) VeWa project (GA335910) and NERC/JIP SIWA project (NE/MO19896/1) for funding. A.R. acknowledges the financial support from the ENAC school at EPFL. C.B. acknowledges support from the University of Costa Rica (project 217-B4-239 and the Isotope Network for Tropical Ecosystem Studies (ISONet)). Data to support this study are provided by the Northern Rivers Institute, University of Aberdeen and are available by the authors. The authors wish to thank Ype van der Velde, Arash Massoudieh, Jean-Raynald de Dreuzy and an anonymous referee for the useful review comments.Peer reviewedPublisher PD

Using high resolution isotope data and alternative calibration strategies for a tracer-aided runoff model in a nested catchment

Acknowledgements The authors would like to thank Jonathan Dick and Audrey Innes for lab analysis and preparation of the isotope samples. In addition, we would like to thank Iain Malcolm (Marine Scotland Science) for providing AWS data. Finally, we gratefully acknowledge the European Research Council ERC (project GA 335910 VeWa) for funding the VeWa project. The data used are available from the authors. CB acknowledges support from the University of Costa Rica (project 217-B4-239 and the Isotope Network for Tropical Ecosystem Studies (ISONet)).Peer reviewedPostprin

Assessing land use effects on ecohydrological partitioning in the critical zone through isotope-aided modelling

Research Funding Bundesministerium für Bildung und Forschung. Grant Numbers: 033W034A, 16LW0156 Leibniz Association Einstein Foundation Berlin Einstein Stiftung Berlin. Grant Number: ERU-2020- 609 Leverhulme Trust Article Funding Open Access funding enabled and organized by Projekt DEAL.Peer reviewedPublisher PD

Assessing land use influences on isotopic variability and stream water ages in urbanising rural catchments

Funding This work was supported by the Leverhulme Trust under Grant RPG-2018-375. Acknowledgements We are grateful to the Leverhulme ISOLAND project (RPG-2018-375) for funding and we are especially grateful to Dr A. Neill for his assistance with the creation of Figure 4.Peer reviewedPublisher PD

Assessing land use effects on ecohydrological partitioning in the critical zone through isotope‐aided modelling

Stable water isotopes are naturally occurring conservative tracers that can ‘fingerprint’ water sources and track ecohydrological fluxes across the critical zone (CZ). Parsimonious, tracer-aided models allow effective quantification of the ecohydrological partitioning of rainfall into different water fluxes. We incorporated stable water isotopes into a one-dimensional, tracer-aided model (EcoIsoPlot) to follow the pathway of precipitation through the CZ at a lowland catchment—the long-term experimental Demnitzer Millcreek Catchment (DMC), Germany—with contrasting vegetation covers (forest, agroforestry, grassland and arable). Precipitation (amount and δ2H), potential evapotranspiration (PET), leaf area index (LAI), air temperature and relative humidity were used as input data for modelling the growing season of 2021. The year had relatively average overall wetness, but a dry, cold spring with snowfall, and an exceptionally large summer storm event (~60 mm precipitation). Multi-criteria calibration of the model was conducted using depth-specific soil moisture and soil water δ2H measurements as targets. The novel incorporation of isotopes into model calibration constrained process representation of the estimated water balance with reasonable simulations and uncertainty bounds for water partitioning. Throughout the soil profile, soil moisture dynamics and stable water isotope variations were captured reasonably well. Green water fluxes (evapotranspiration) were highest at the forest site and blue water fluxes (groundwater recharge) highest at the grassland. Comparing simulations with estimated potential evapotranspiration (ET) and measured groundwater table fluctuations added further confidence to the modelling result. Overall, these may suggest a slight underestimation of ET and slight overestimation of recharge, though the results are similar to previous findings. Our study demonstrated the potential of stable water isotope data to enhance relatively simple, transferrable approaches to ecohydrological modelling of water fluxes in the CZ and to help improve model consistency. Such low-parameterised tracer-aided models have major potential for evidence-based applications to aid management and help stakeholder communication.Bundesministerium für Bildung und Forschung http://dx.doi.org/10.13039/501100002347Leibniz Association http://dx.doi.org/10.13039/501100001664Einstein Foundation Berlin http://dx.doi.org/10.13039/501100006188Einstein Stiftung Berlin http://dx.doi.org/10.13039/501100006188Leverhulme Trust http://dx.doi.org/10.13039/501100000275Peer Reviewe

A simple topography-driven and calibration-free runoff generation module

This study was supported by National Natural Science Foundation of China (41801036), National Key R&D Program of China (2017YFE0100700), the Key Program of National Natural Science Foundation of China (no. 41730646), and Key Laboratory for Mountain Hazards and Earth Surface Process, Institute of Mountain Hazards and Environment, Chinese Academy of Sciences (KLMHESP-17-02). The authors acknowledge three anonymous reviewers for their very constructive comments and suggestions that substantially improved the quality of this paper.Peer reviewedPublisher PD

Continuous in situ measurements of water stable isotopes in soils, tree trunk and root xylem: Field approval

Rationale New methods to measure stable isotopes of soil and tree water directly in the field enable us to increase the temporal resolution of obtained data and advance our knowledge on the dynamics of soil and plant water fluxes. Only few field applications exist. However, these are needed to further improve novel methods and hence exploit their full potential. Methods We tested the borehole equilibration method in the field and collected in situ and destructive samples of stable isotopes of soil, trunk and root xylem water over a 2.5-month experiment in a tropical dry forest under natural abundance conditions and following labelled irrigation. Water from destructive samples was extracted using cryogenic vacuum extraction. Isotope ratios were determined with IRIS instruments using cavity ring-down spectroscopy both in the field and in the laboratory. Results In general, timelines of both methods agreed well for both soil and xylem samples. Irrigation labelled with heavy hydrogen isotopes clearly impacted the isotope composition of soil water and one of the two studied tree species. Inter-method deviations increased in consequence of labelling, which revealed their different capabilities to cover spatial and temporal heterogeneities. Conclusions We applied the novel borehole equilibration method in a remote field location. Our experiment reinforced the potential of this in situ method for measuring xylem water isotopes in both tree trunks and roots and confirmed the reliability of gas permeable soil probes. However, in situ xylem measurements should be further developed to reduce the uncertainty within the range of natural abundance and hence enable their full potential

Improving regional flood risk assessment using flood frequency and dendrogeomorphic analyses in mountain catchments impacted by tropical cyclones

River floods frequently occur when tropical cyclones hit land. Nonetheless, systematic, long-term discharge data remain rather scarce in many tropical countries, which prevent proper analysis of peak discharges occurring during floods. The Térraba catchment is the biggest and most dynamic catchment in Costa Rica. In this study, we developed regional flood-frequency analyses combining tree-ring based estimation and measurement of peak discharge at monitoring stations during tropical cyclones to derive flood quartiles. Flood quartiles were combined with the Topographic Wetness Index (TWI) to determine regional flood hazards along floodplains. The flood risk assessment was based on a high-resolution mapping of infrastructure, population density (as a measure of exposure), and a social development index (to represent vulnerability). We show that peak discharge of cycloneinduced floods can be assessed accurately with flood-frequency analyses including dendrogeomorphic reconstructions and systematic discharge measurements. We also show that regional flood risk assessments can be performed in large-scale catchments if both coarse and detailed inputs are used. The results of this study will be useful for the development of flood risk schemes promoting resilience of local populations.Swiss Federal Commission for Scholarships/[ESKAS-Nr 2017.1072]//SuizaMinisterio de Ciencia, Innovación, Tecnología y Telecomunicaciones/[No MICITT-PINN-CON-2-1-4-17-1-002]/MICITT/Costa RicaUniversidad de Costa Rica/[OAICE-187-2017]/UCR/Costa RicaUCR::Vicerrectoría de Docencia::Ciencias Sociales::Facultad de Ciencias Sociales::Escuela de Geografí

Exploring extreme rainfall impacts on flow and turbidity dynamics in a steep, pristine and tropical volcanic catchment

A British Geomorphological Society early career grant to JG and CB allowed initiating this work. An Ideawild grant to CB contributed with an equipment donation. The University of Costa Rica Research Council (projects B4239, B8709) supported this project. We thank the ReBAMB staff and students for helping with logistics and fieldwork. CIGEFI at UCR contributed with meteorological data. The data can be obtained upon request from the corresponding author.Peer reviewedPostprin