ORCID Profile
0000-0002-0650-7369
Current Organisations
Universidade Federal do Amazonas
,
Governo do Estado do Acre
,
University of Birmingham
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Hydrogeology | Quaternary Environments | Geochemistry | Isotope Geochemistry
Ecosystem Assessment and Management of Fresh, Ground and Surface Water Environments | Effects of Climate Change and Variability on Australia (excl. Social Impacts) | Physical and Chemical Conditions of Water in Fresh, Ground and Surface Water Environments (excl. Urban and Industrial Use) |
Publisher: Pensoft Publishers
Date: 21-07-2023
Abstract: Abstract We use integrative taxonomy to formally describe a candidate species of nurse frog of the genus Allobates from southwestern Brazilian Amazonia. The new species nests within a clade that has been defined historically as A. gasconi , but it has an 8.8–11.0% genetic distance for 16S to s les from the type locality of A. gasconi . The new species differs from congeners mainly by males having a translucent white throat and vocal sac advertisement calls with a duration of 42–60 ms, two notes separated by an inter-note interval of 8–23 ms, and a dominant frequency of 4,953–6,331 Hz and exotrophic tadpoles with 2 pyramidal papillae on each end of the upper lip and 10–13 pyramidal and cylindrical papillae surrounding the lower lip. Phylogenetic analyses based on mitochondrial DNA suggest that A. gasconi sensu lato as defined previously represents a complex of as many as seven species, corroborating studies that have shown high levels of cryptic ersity within Allobates .
Publisher: Copernicus GmbH
Date: 27-05-2020
Abstract: Abstract. Tracers have been used for over half a century in hydrology to quantify water sources with the help of mixing models. In this paper, we build on classic Bayesian methods to quantify uncertainty in mixing ratios. Such methods infer the probability density function (PDF) of the mixing ratios by formulating PDFs for the source and target concentrations and inferring the underlying mixing ratios via Monte Carlo s ling. However, collected hydrological s les are rarely abundant enough to robustly fit a PDF to the source concentrations. Our approach, called HydroMix, solves the linear mixing problem in a Bayesian inference framework wherein the likelihood is formulated for the error between observed and modeled target variables, which corresponds to the parameter inference setup commonly used in hydrological models. To address small s le sizes, every combination of source s les is mixed with every target tracer concentration. Using a series of synthetic case studies, we evaluate the performance of HydroMix using a Markov chain Monte Carlo s ler. We then use HydroMix to show that snowmelt accounts for around 61 % of groundwater recharge in a Swiss Alpine catchment (Vallon de Nant), despite snowfall only accounting for 40 %–45 % of the annual precipitation. Using this ex le, we then demonstrate the flexibility of this approach to account for uncertainties in source characterization due to different hydrological processes. We also address an important bias in mixing models that arises when there is a large ergence between the number of collected source s les and their flux magnitudes. HydroMix can account for this bias by using composite likelihood functions that effectively weight the relative magnitude of source fluxes. The primary application target of this framework is hydrology, but it is by no means limited to this field.
Publisher: Copernicus GmbH
Date: 23-06-2023
DOI: 10.5194/ESSD-15-2577-2023
Abstract: Abstract. Ground-based datasets of observed snow water equivalent (SWE) are scarce, while gridded SWE estimates from remote-sensing and climate reanalysis are unable to resolve the high spatial variability of snow on the ground. Long-term ground observations of snow depth, in combination with models that can accurately convert snow depth to SWE, can fill this observational gap. Here, we provide a new SWE dataset (NH-SWE) that encompasses 11 071 stations in the Northern Hemisphere (NH) and is available at 0.5281/zenodo.7515603 (Fontrodona-Bach et al., 2023). This new dataset provides daily time series of SWE, varying in length between 1 and 73 years, spanning the period 1950–2022, and covering a wide range of snow climates including many mountainous regions. At each station, observed snow depth was converted to SWE using an established snow-depth-to-SWE conversion model, with excellent model performance using regionalised parameters based on climate variables. The accuracy of the model after parameter regionalisation is comparable to that of the calibrated model. The key advantages and strengths of the regionalised model presented here are its transferability across climates and the high performance in modelling daily SWE dynamics in terms of peak SWE, total snowmelt and duration of the melt season, as assessed here against a comparison model. This dataset is particularly useful for studies that require accurate time series of SWE dynamics, timing of snowmelt onset, and snowmelt totals and duration. It can, for ex le, be used for climate change impact analyses, water resources assessment and management, validation of remote sensing of snow, hydrological modelling, and snow data assimilation into climate models.
Publisher: IOP Publishing
Date: 11-2017
Publisher: California Digital Library (CDL)
Date: 07-11-2017
Abstract: Snowfall may have different stable isotopic compositions compared to rainfall, allowing its contribution to potentially be tracked through the hydrological cycle. This review summarizes the state of knowledge of how different hydro-meteorological processes affect the isotopic composition of snow, and, through selected ex les, discusses how stable water isotopes can provide a better understanding of snow hydrological processes. A detailed account is given of how the variability in isotopic composition of snow changes from precipitation to final melting. The effect of different snow ablation processes (sublimation, melting, and redistribution by wind or avalanches) on the isotope ratios of the underlying snowpack are also examined. Insights into the role of canopy in snow interception processes, and how the isotopic composition in canopy underlying snowpacks can elucidate the exchanges therein are discussed, as well as case studies demonstrating the usefulness of stable water isotopes to estimate seasonality in the groundwater recharge. Rain-on-snow floods illustrate how isotopes can be useful to estimate the role of preferential flow during heavy spring rains. All these ex les point to the complexity of snow hydrologic processes and demonstrate that an isotopic approach is useful to quantify snow contributions throughout the water cycle, especially in high elevation and high latitude catchments, where such processes are most pronounced. This synthesis concludes by tracing a snow particle along its entire hydrologic life cycle, highlights the major practical challenges remaining in snow hydrology and discusses future research directions.
Publisher: Copernicus GmbH
Date: 04-03-2021
DOI: 10.5194/EGUSPHERE-EGU21-14428
Abstract: & & Vegetation is the primary connection between land and atmosphere, thus the main player mediating the consequences of a changing climate on land cover and hydrology. A protected alpine catchment, with a larch grove (& em& Larix decidua& /em& ) at the upper limit of the forested area, the Vallon de Nant (Vaud alps, 1200 & #8211 3050 m. a.s.l.), was chosen as a study site in parallel with ongoing hydrological observation. We analyzed the stable isotopes of water, & #948 & sup& & /sup& O and & #948 & sup& & /sup& H, in the xylem extracted from s les of 10 trees in 2 transects just above and below 1500 m. a.s.l. over the course of the 2017 and 2018 growing seasons.& We compared isotopic ratios withconcurrent observations of isotopes in precipitation, stream, soil water, and groundwater.& Isotopic content of xylem water was found to be fairly consistent, independent of the date within the season, and closely resembled shallow soil water, suggesting that recent precipitation dominated the water source.& & Our results support that vegetation could experience a drought due to low levels of rainfall before the streamflow is impacted. Furthermore, they affirm current discussions that water source is elevation dependent for trees in mountain ecosystems, with summer precipitation being favored by higher elevation trees, such as these. This preference has significant implications when we project current changes of quantities of rain falling as snow versus rain in the future. And more importantly, changes the view of forest from that of a water & #8220 user& #8221 to that of a store and player in complex feedback mechanisms.& &
Publisher: SAGE Publications
Date: 28-07-2016
Abstract: Agricultural societies around the world have dramatically altered the natural landscape, particularly through accelerated soil erosion. The expansion of agricultural land use into steeper headwater areas during the Medieval period in central Europe is known to have caused large increases in soil erosion and sediment redistribution downstream. Although land-use practices changed and improved following this initial impact, it is currently unknown whether changes in land-use techniques also improved hillslope soil erosion and sediment redistribution rates. In this paper, we use a variety of techniques, including chrono-stratigraphy, wood charcoal analysis and a geostatistical model, to reconstruct land-use and erosion rates for the period spanning the Medieval Period to the present (1100–300 years ago) in a small headwater catchment in central Europe. Coupling land-use, hillslope erosion and sediment redistribution fluxes, we find the largest flux change occurs because of the initial deforestation at the beginning of the Medieval Period (1100 years ago). Following deforestation, we identified three main types of land-use techniques that were practised between ~1100 and 300 years ago: Horticulture, cropping agriculture and rotational birch silviculture, the last of which represents the earliest evidence for this practice found in central Europe to date. However, we find only small differences in hillslope fluxes throughout the catchment despite the variable land-use techniques employed. This is because the land-use techniques primarily influenced and increased the hillslope sediment storage capacity rather than erosion rates directly, which is an important distinction to consider for future work attempting to link changes in human land use and hillslope erosion.
Publisher: Copernicus GmbH
Date: 26-03-2022
DOI: 10.5194/EGUSPHERE-EGU22-894
Abstract: & & Anthropocene impact on atmospheric carbon has led to increased efforts to better understand the carbon cycle in terrestrial vegetation. Forests and their natural ability to assimilate carbon dioxide (CO& sub& & /sub& ) from the air have increasingly been incorporated into climate change mitigation policies. The increase in global CO& sub& & /sub& levels has also been shown to cause photosynthetic enhancement, although the extent of this CO& sub& & /sub& -fertilization effect varies across vegetation type, age, species and the availability of other resources. An important knowledge gap for the projected mitigation function of (future) forests is the currently unknown fate of this additional carbon as a result of the increased photosynthetic activity [1]. Woody biomass is still thought to harbour a substation fraction of the unaccounted for carbon [2] and by including smaller woody compartments to the well-represented stem diameter datasets this research project aims to provide more details to the standing and turned over woody biomass inventories. The branch and twig compartments might detach faster from trees pre-mortality under elevated CO& sub& & /sub& , increasing the turn-over rate of carbon within forest stands where this has previously gone unnoticed. To determine the choices of trees regarding growth under future CO& sub& & /sub& levels observation will be collected in two second-generation Free Air CO& sub& & /sub& Enrichment (FACE) facilities: BIFoR FACE, in Staffordshire UK and EucFACE in Sydney Australia. By making stand scale inventories using Terrestrial Laser Scanning (TLS) for standing biomass and line transects along with litter traps for fallen woody tissue, the fluxes of newly grown wood under eCO2 versus wood exposed to long term ambient concentrations can be compared. With additional comparisons between the two facilities, subsequent environmental factors and weather events to follow so that predictive carbon budget models can be improved. The increased CO& sub& & /sub& concentrations at these sites reach the levels estimated to be the global ambient in 30-40 years. In the current phase of this research project, the datasets resulting from the first fieldwork c aign and pipelines for array scale TLS analysis and turnover expansion factors are constructed.& & & & References& br& [1] Jiang, M., Medlyn, B. E., Drake, J. E., Duursma, R. A., Anderson, I. C., Barton, C. V., ... & Ellsworth, D. S. (2020). The fate of carbon in a mature forest under carbon dioxide enrichment. Nature, 580(7802), 227-231.& br& [2] Walker, A. P., De Kauwe, M. G., Medlyn, B. E., Zaehle, S., Iversen, C. M., Asao, S., ... & Norby, R. J. (2019). Decadal biomass increment in early secondary succession woody ecosystems is increased by CO 2 enrichment. Nature communications, 10(1), 1-13.& & & & & & &
Publisher: Copernicus GmbH
Date: 23-09-2022
DOI: 10.5194/IAHS2022-545
Abstract: & & Global warming is projected to result in changes in streamflow in West Africa with implications for recurrent droughts and floods in the region. This study assesses changes in the timing of low and high flows under climate change in the poorly gauged and transboundary Volta River basin (VRB) in West Africa. The mean annual minimum (MAM) flow of seven consecutive days is considered as low flow, while high flow is calculated as the annual maximum flow (MAF) corresponding to the highest peak flow in a calendar year. The method of circular statistics is used to estimate the timing of AMF and MAM based on the mean date of occurrence (D), and their seasonality based on the concentration of the dates of occurrence (r). River flow is simulated with the fully distributed mesoscale hydrologic model (mHM), which is thoroughly calibrated using a novel multivariate calibration based on streamflow and satellite data. The mHM model is forced with bias-corrected climate projection datasets consisting of 43 RCM and GCM model combinations from CORDEX-Africa under three representative concentration pathways (RCP2.6, RCP4.5 and RCP8.5). The changes in AMF and MAM are analysed over three future horizons (2021-2050, 2051-2080 and 2071-2100) relative to the historical baseline period (1991-2020).& & & & The results show that the date of occurrence of AMF varies between the calendar days 246 and 252 across the three sub-basins (Black Volta, White Volta, Oti), and it is projected to drop by -2 days over the twenty-first century. A strong seasonality of high flows is observed as r exceeds 0.96 on average and hardly change in the future. The date of occurrence of MAM varies between the calendar days 132 and 139. In contrast to the AMF, there is a forward shift in the date of occurrence of MAM as it is projected to increase on average by +4 to +9 days across sub-basins, and up to + 14 days under RCP8.5, which might be explained by the forward shift of the rainy season. The r of MAM is 0.6 and slightly drops in the future, denoting a higher variation in the seasonality of low flows.& &
Publisher: Copernicus GmbH
Date: 15-05-2023
DOI: 10.5194/EGUSPHERE-EGU23-12620
Abstract: Ground-based observation datasets of Snow Water Equivalent (SWE) are scarce. In contrast, numerous long-term and good quality ground observations of snow depth are available. Furthermore, an increasing number of models can accurately convert snow depth to SWE. We present a novel dataset of SWE time series over the Northern Hemisphere based on in-situ observations of snow depth. We convert snow depth to SWE using the DeltaSNOW model and we present a method to generalise the conversion model for global use. We calibrate the model over a wide range of climates with the SNOTEL dataset and we regionalise the model parameters based on climate variables. We evaluate this approach on independent datasets such as the Canadian SWE dataset and other European SWE datasets. The key strengths of the modelling approach and the SWE dataset are the excellent performance of peak SWE and timing of snowmelt season onset. The final SWE dataset contains 11,003 stations with daily SWE and snow density time series distributed across the Northern Hemisphere, including mountain regions, at the point scale, and spanning the period 1950-2022. The dataset is available and free to access. It can be used for a variety of applications including validation of remote sensing of snow, hydrological modelling, water resources assessment and climate change impact analyses.
Publisher: Copernicus GmbH
Date: 18-10-2021
DOI: 10.5194/NHESS-21-3113-2021
Abstract: Abstract. Managing water–human systems during water shortages or droughts is key to avoid the overexploitation of water resources and, in particular, groundwater. Groundwater is a crucial water resource during droughts as it sustains both environmental and anthropogenic water demand. Drought management is often guided by drought policies, to avoid crisis management, and actively introduced management strategies. However, the impact of drought management strategies on hydrological droughts is rarely assessed. In this study, we present a newly developed socio-hydrological model, simulating the relation between water availability and managed water use over 3 decades. Thereby, we aim to assess the impact of drought policies on both baseflow and groundwater droughts. We tested this model in an idealised virtual catchment based on climate data, water resource management practices and drought policies in England. The model includes surface water storage (reservoir), groundwater storage for a range of hydrogeological conditions and optional imported surface water or groundwater. These modelled water sources can all be used to satisfy anthropogenic and environmental water demand. We tested the following four aspects of drought management strategies: (1) increased water supply, (2) restricted water demand, (3) conjunctive water use and (4) maintained environmental flow requirements by restricting groundwater abstractions. These four strategies were evaluated in separate and combined scenarios. Results show mitigated droughts for both baseflow and groundwater droughts in scenarios applying conjunctive use, particularly in systems with small groundwater storage. In systems with large groundwater storage, maintaining environmental flows reduces hydrological droughts most. Scenarios increasing water supply or restricting water demand have an opposing effect on hydrological droughts, although these scenarios are in balance when combined at the same time. Most combined scenarios reduce the severity and occurrence of hydrological droughts, given an incremental dependency on imported water that satisfies up to a third of the total anthropogenic water demand. The necessity for importing water shows the considerable pressure on water resources, and the delicate balance of water–human systems during droughts calls for short-term and long-term sustainability targets within drought policies.
Publisher: Copernicus GmbH
Date: 23-03-2020
DOI: 10.5194/EGUSPHERE-EGU2020-19769
Abstract: & & The last century of hydrological research has led to significant improvements in representing different hydrological processes in rainfall-runoff models. With widely available streamflow data, such models are typically calibrated against this reference time series, which can limit their predictive power. One option to improve the realism of rainfall-runoff models is by incorporating environmental tracers such as stable isotopes of water, water temperature and electrical conductivity within the modeling setup. Conventionally, stable water isotopes have been used to learn more about the dominant hydrological processes that occur within a given catchment, which generally helps improve the hydrologic model structure, but often at the cost of increased model complexity to simulate the tracer concentration along with streamflow.& & & & In this study, we develop a framework to incorporate stable water isotopes in continuous hydrological modeling, without significantly increasing model complexity. In the first step, stable water isotopes are used along with streamflow recession analysis to initialize the model state variables. After that, a Bayesian mixing model is used to infer the proportion of slow vs fast subsurface flow, and the results are used as additional constraints during the model calibration. This framework is extensively tested in a snow-dominated experimental catchment called Vallon de Nant, located in the Southwestern Swiss Alps (1189-3051 m. a.s.l.). During the presentation, we will discuss the advantages and limitations of such a modeling approach and how it can be extended to other experimental catchments.& &
Publisher: Elsevier BV
Date: 11-2012
Publisher: Wiley
Date: 11-08-2009
Publisher: Wiley
Date: 12-11-2020
DOI: 10.1002/HYP.13937
Abstract: Estimation of young water fractions ( F yw ), defined as the fraction of water in a stream younger than approximately 2–3 months, provides key information for water resource management in catchments where runoff is dominated by snowmelt. Knowing the average dependence of summer flow on winter precipitation is an essential context for comparing regional drought severity and provides the hydrological template for downstream water users and ecosystems. However, F yw estimation based on seasonal signals of stable isotopes of oxygen and hydrogen has not yet explicitly addressed how to parsimoniously include the seasonal shift of water input from snow. Using experimental data from three high‐elevation, Alpine catchments (one dominated by glacier and two by snow), we propose a framework to explicitly include the delays induced by snow storage into estimates of F yw . Scrutinizing the key methodological choices when estimating F yw from isotope data, we find that the methods used to construct precipitation input signals from sparse isotope s les can significantly impact F yw . Given this sensitivity, our revised procedure estimates a distribution of F yw values that incorporates a wide range of possible methodological choices and their uncertainties it furthermore compares the commonly used litude ratio approach to a direct convolution approach, which circumvents the assumption that the isotopic signals have a sine curve shape, an assumption that is generally violated in snow‐dominated environments. Our new estimates confirm that high‐elevation Alpine catchments have low F yw values, spanning from 8 to 11%. Such low values have previously been interpreted as the impact of seasonal snow storage alone, but our comparison of different F yw estimation methods suggests that these low F yw values result from a combination of both snow cover effects and longer storage in the subsurface. In contrast, in the highest elevation, glacier dominated catchment, F yw is 3–4 times greater compared to the other two catchments, due to the lower storage and faster drainage processes. A future challenge, capturing spatio‐temporal snowmelt isotope signals during winter baseflow and the snowmelt period, remains to improve constraints on the F yw estimation technique.
Publisher: Wiley
Date: 10-02-2019
DOI: 10.1002/WAT2.1330
Abstract: The Fertile Crescent, its hilly flanks and surrounding drylands has been a critical region for studying how climate has influenced societal change, and this review focuses on the region over the last 20,000 years. The complex social, economic, and environmental landscapes in the region today are not new phenomena and understanding their interactions requires a nuanced, multidisciplinary understanding of the past. This review builds on a history of collaboration between the social and natural palaeoscience disciplines. We provide a multidisciplinary, multiscalar perspective on the relevance of past climate, environmental, and archaeological research in assessing present day vulnerabilities and risks for the populations of southwest Asia. We discuss the complexity of palaeoclimatic data interpretation, particularly in relation to hydrology, and provide an overview of key time periods of palaeoclimatic interest. We discuss the critical role that vegetation plays in the human–climate–environment nexus and discuss the implications of the available palaeoclimate and archaeological data, and their interpretation, for palaeonarratives of the region, both climatically and socially. We also provide an overview of how modelling can improve our understanding of past climate impacts and associated change in risk to societies. We conclude by looking to future work, and identify themes of “scale” and “seasonality” as still requiring further focus. We suggest that by appreciating a given locale's place in the regional hydroscape, be it an archaeological site or palaeoenvironmental archive, more robust links to climate can be made where appropriate and interpretations drawn will demand the resolution of factors acting across multiple scales. This article is categorized under: Human Water Water as Imagined and Represented Science of Water Water and Environmental Change Water and Life Nature of Freshwater Ecosystems
Publisher: Copernicus GmbH
Date: 27-10-2021
Publisher: Elsevier BV
Date: 03-2013
Publisher: Wiley
Date: 26-01-2021
DOI: 10.1111/ETH.13135
Publisher: Copernicus GmbH
Date: 18-03-2022
DOI: 10.5194/HESS-26-1481-2022
Abstract: Abstract. A comprehensive evaluation of the impacts of climate change on water resources of the West Africa Volta River basin is conducted in this study, as the region is expected to be hardest hit by global warming. A large ensemble of 12 general circulation models (GCMs) from the fifth Coupled Model Intercomparison Project (CMIP5) that are dynamically downscaled by five regional climate models (RCMs) from the Coordinated Regional-climate Downscaling Experiment (CORDEX)-Africa is used. In total, 43 RCM–GCM combinations are considered under three representative concentration pathways (RCP2.6, RCP4.5, and RCP8.5). The reliability of each of the climate datasets is first evaluated with satellite and reanalysis reference datasets. Subsequently, the Rank Res ling for Distributions and Dependences (R2D2) multivariate bias correction method is applied to the climate datasets. The bias-corrected climate projections are then used as input to the mesoscale Hydrologic Model (mHM) for hydrological projections over the 21st century (1991–2100). Results reveal contrasting dynamics in the seasonality of rainfall, depending on the selected greenhouse gas emission scenarios and the future projection periods. Although air temperature and potential evaporation increase under all RCPs, an increase in the magnitude of all hydrological variables (actual evaporation, total runoff, groundwater recharge, soil moisture, and terrestrial water storage) is only projected under RCP8.5. High- and low-flow analysis suggests an increased flood risk under RCP8.5, particularly in the Black Volta, while hydrological droughts would be recurrent under RCP2.6 and RCP4.5, particularly in the White Volta. The evolutions of streamflow indicate a future delay in the date of occurrence of low flows up to 11 d under RCP8.5, while high flows could occur 6 d earlier (RCP2.6) or 5 d later (RCP8.5), as compared to the historical period. Disparities are observed in the spatial patterns of hydroclimatic variables across climatic zones, with higher warming in the Sahelian zone. Therefore, climate change would have severe implications for future water availability with concerns for rain-fed agriculture, thereby weakening the water–energy–food security nexus and lifying the vulnerability of the local population. The variability between climate models highlights uncertainties in the projections and indicates a need to better represent complex climate features in regional models. These findings could serve as a guideline for both the scientific community to improve climate change projections and for decision-makers to elaborate adaptation and mitigation strategies to cope with the consequences of climate change and strengthen regional socioeconomic development.
Publisher: Copernicus GmbH
Date: 04-03-2021
DOI: 10.5194/EGUSPHERE-EGU21-12760
Abstract: & & There is strong evidence that rising temperatures mostly lead to less snow accumulation and to an earlier melt onset. However, changes in the frequency and intensity of snowmelt events remain unclear. While higher temperatures should intuitively lead to faster snowmelt, some studies find that melt rates are slower because the melt onset occurs earlier in the year when less energy is available for melt. Modelling of these snow dynamics is challenged by a lack of continuous observations on water content of the snowpack, the highly sought after SWE. However, high quality observations of snow depth can be more available in both space and time, even at higher altitudes. Therefore, an increasing number of models try to estimate SWE from snow depth and other variables. Here we first investigate if these models accurately reproduce the snow accumulation and melt dynamics, and to what extent they can be used for hydrological studies. We then convert a long-term pan-European snow depth dataset to SWE by making use of these models and we assess model performance. Historical trends of snowmelt rates, melt onset, and frequency and intensity of melt events are shown for several seasonal snow locations across Europe. Trends across a variety of timescales are generally weak and spatially inhomogeneous, suggesting local conditions dominate over regional climate trends. However, it seems that under the current climate change conditions, the decrease of snowpack depth over most of Europe causes snowpacks to melt faster (i.e. in less days) than before.& & &
Publisher: Elsevier BV
Date: 10-2008
Publisher: Copernicus GmbH
Date: 28-03-2019
DOI: 10.5194/GMD-2019-69
Abstract: Abstract. Tracers have been used for over half a century in hydrology to quantify water sources with the help of mixing models. In this paper, we build on classic Bayesian methods to quantify uncertainty in mixing ratios. Such methods infer the probability density function (pdf) of the mixing ratios by formulating pdfs for the source and target concentrations and inferring the underlying mixing ratios via Monte Carlo s ling. However, collected hydrological s les are rarely abundant enough to robustly fit a pdf to the sources. Our approach, called HydroMix, solves the linear mixing problem in a Bayesian inference framework where the likelihood is formulated for the error between observed and modelled target variables, which corresponds to the parameter inference set-up commonly used in hydrological models. To address small s le sizes, every combination of source s les is mixed with every target tracer concentration. Using a series of synthetic case studies, we evaluate the performance of HydroMix. We then use HydroMix to show that snowmelt accounts for 60–62 % of groundwater recharge in a Swiss Alpine catchment (Vallon de Nant), despite snowfall only accounting for 40–45 % of the annual precipitation. Using this ex le, we then demonstrate the flexibility of this approach to account for uncertainties in source characterization due to different hydrological processes. We also address an important bias in mixing models that arises when there is a large ergence between the number of collected source s les and their flux magnitudes. HydroMix can account for this bias by using composite likelihood functions that effectively weights the relative magnitude of source fluxes. The primary application target of this framework is hydrology, but it is by no means limited to this field.
Publisher: Elsevier BV
Date: 10-2010
Publisher: American Geophysical Union (AGU)
Date: 14-03-2017
DOI: 10.1002/2017GL072759
Publisher: Elsevier BV
Date: 02-2010
Publisher: Copernicus GmbH
Date: 28-03-2022
DOI: 10.5194/EGUSPHERE-EGU22-11859
Abstract: & & Although warming temperatures should intuitively lead to faster snowmelt, some studies suggest that melt rates might be slower in a warming world. This assumes that typically deep snowpacks are thinning and become isothermal earlier in the season when less solar radiation is available for melt. Investigating these changing snow dynamics is challenged by a lack of observations on water content of the snowpack, the Snow Water Equivalent (SWE). However, high quality observations of snow depth are generally more available in both space and time, even at higher elevations. Here we present a new dataset of historical SWE time series over the Northern Hemisphere, including a wide variety of climates. These time series are obtained converting historical ground-based snow depth time series to SWE by using the DeltaSNOW model. For the conversion to work over a range of climates, we apply a regional calibration of model parameters based on climatological data and provide model performance and uncertainty estimates. For & .000 sites characterised by seasonal snow, we investigate changes in total snow accumulation, timing of snowmelt and melt rates for the period 1980-2020. Large decreases in total melt and earlier melt timing are widely observed. However, trends in snowmelt rates are generally weak and spatially inhomogeneous. Slower snowmelt in a warmer world occurs mostly on deep snowpacks that have been heavily depleted and where the number of days with melt has not significantly changed, making melt rates slower. However, both faster and slower melt are observed on sites where both the amount of melt and number of melt days have decreased. We provide an analysis of the causes for the spatial and temporal variability in trends. We find that trends can differ depending on the definition of melt rate and peak SWE, and that the drivers of the trends differ over different climates. Strong warming generates large melt events during the late accumulation season, challenging the commonly used definition of peak SWE and making it harder to compare the snowmelt dynamics of the past and the current climate. We note that focusing on melt rate change might mask important effects on melt timing and magnitude, because a proportional reduction in total melt and number of melt days can lead to no change in melt rate.& &
Publisher: Copernicus GmbH
Date: 23-09-2022
DOI: 10.5194/IAHS2022-755
Abstract: & & There is strong evidence that rising temperatures lead to less snow accumulation and to an earlier start of the melt season. This has an effect on the magnitude and timing of streamflow generated by snowmelt in spring. Higher temperatures should intuitively lead to faster snowmelt, but some studies suggest that melt rates might be slower in a warming world because the melt onset occurs earlier in the year when less energy is available for melt. Understanding of these changing snow dynamics is challenged by a lack of observations on water content of the snowpack, the Snow Water Equivalent (SWE). However, high quality observations of snow depth are generally more available in both space and time, even at higher elevations. Here we gather several datasets of long-term observed snow depth time series over the Northern Hemisphere, and convert them to SWE. We then investigate changes in total snowmelt, timing of snowmelt and melt rates for the period 1980-2020 over a ranger of climates and regions. Large decreases in total melt and earlier melt timing are widely observed. However, trends in snowmelt rates are generally weak and spatially inhomogeneous. Slower snowmelt in a warmer world occurs mostly on deep snowpacks that have been heavily depleted, but faster melt or no significant change in melt rate are observed too. We provide an analysis of the causes for the spatial and temporal variability in trends. We find that changes and trends can differ depending on the definition of melt rate and peak SWE. Strong warming generates large melt events during the late accumulation season, challenging the commonly used definition of peak SWE and making it harder to compare the snowmelt dynamics of the past and the current climate. We highlight that focusing only on melt rate change might mask important effects on melt timing and magnitude, because a proportional reduction in total melt and number of melt days can lead to no change in melt rate.& &
Publisher: California Digital Library (CDL)
Date: 22-10-2020
DOI: 10.31223/X5B59N
Publisher: Elsevier BV
Date: 05-2014
Publisher: Copernicus GmbH
Date: 15-05-2023
DOI: 10.5194/EGUSPHERE-EGU23-11686
Abstract: Rising carbon dioxide (CO2) levels can lead to more carbon sequestration in plant biomass, and forests& #8217 natural ability to store carbonin long-lived woody tissue is of particular interest. However, the extent of CO2-fertilization in trees varies across age, species and the availability of other resources. Woody tissue encompasses more than just the tree& #8217 s trunk, and a critical knowledge gap lies in the allocation of carbon to the other woody components like branches and twigs. In addition, the flux of woody carbon from the tree to the forest floor (turnover) is more than events of single tree mortality. These fluxes come in the form of litterfall, breakage of whole branches or complete tree mortality. The goal of this study is to quantify biomass allocation patterns and subsequent turnover rates within the woody carbon pool of two contrasting forest FACE experiments, BIFoR FACE in Staffordshire UK, and EucFACE in Sydney, Australia and answer the following questions: how do these allocation patterns determine the potential for carbon sequestration and how do patterns shift with elevated CO2 concentrations?Terrestrial laser scanning provided the tools to determine canopy structure on a stand scale, and the use of algorithms on the resulting point cloud trees supplied data on the partitioning of biomass among twigs, branches and stems. These results were then used to test general hypotheses about canopy structure and how it changes with elevated CO2. The fluxes from the different wood components were quantified with monthly observations and collections, litter traps to collect the smallest material and transects to make an inventory of larger compartments like branches. The results of these studies will be combined with the canopy structure partitioning fractions to determine if the allocation patterns vary over time and between two contrasting forest types. It is worthwhile to increase our understanding of the dynamics of all woody components within forests and on a global scale beyond single tree mortality to improve the accuracy of predictive carbon budget models.
Publisher: Wiley
Date: 19-01-2017
DOI: 10.1002/ECO.1816
Publisher: Copernicus GmbH
Date: 08-02-2022
Publisher: Copernicus GmbH
Date: 15-05-2023
DOI: 10.5194/EGUSPHERE-EGU23-12171
Abstract: We measured a combination of natural tracers of water at a high frequency, including stable isotope compositions (& #948 H, & #948 O, & #948 O), electrical conductivity, and water and soil temperature to characterize hydrological processes in a snow-dominated Alpine catchment and to understand the ersity of streamflow sources and flow paths. Previous work metabarcoding eDNA from stream s les led us to suppose that subsurface connectivity was a primary driver of genetic richness in the water of an alpine catchment, however our process understanding was limited.& & By ing into temperature measurements in soil and water, electrical conductivity, and stable isotopes, we start to weave together the complexity of this subsurface connectivity.& Of particular interest in this alpine catchment is the seasonality of connectivity, which is mainly, in different forms, in melt periods occurring in spring and during rain-fed runoff events in summer and rain-on-snow events in winter.& & This is dramatically different than in non-mountain, low-elevation environments where connectivity is observed in the cold or winter season.& In this presentation, we will compare and contrast what we learn from each tracer and highlight findings that could only be learned by bringing them all together.& We will reveal how these tracers inform our understanding of the timing of snow presence and melt, the existence of sub-snowpack local flow, the magnitude of subsurface exchange, and the mixing of snowmelt with groundwater. These insights into the details of streamflow generation in such a dynamic environment were only possible due to the intense, year-round field work.
Publisher: American Geophysical Union (AGU)
Date: 10-2017
DOI: 10.1002/2017WR021593
Publisher: Elsevier BV
Date: 10-2015
Publisher: Wiley
Date: 28-03-2010
Publisher: Copernicus GmbH
Date: 30-04-2021
Abstract: Abstract. Managing water-human systems in times of water shortage and droughts is key to avoid overexploitation of water resources, particularly for groundwater, which is a crucial water resource during droughts sustaining both environmental and anthropogenic water demand. Drought management is often guided by drought policies to avoid crisis management and to actively introduce management strategies during droughts. However, the impact of drought management strategies on hydrological droughts is rarely assessed. In this study, we present a newly developed socio-hydrological model, simulating feedbacks between water availability and managed water use over three decades. Thereby, we aim to assess the impact of drought policies on both surface water and groundwater droughts. We tested this model in an idealised catchment based on climate data, water resource management practices, and drought policies in England. The model includes surface water storage (reservoir), groundwater storage for a range of hydrogeological conditions and optional imported surface water or groundwater. These modelled water sources can all be used to satisfy anthropogenic and environmental water demand. We tested four aspects of drought management strategies: 1) increased water supply, 2) restricted water demand, 3) conjunctive water use, and 4) maintained environmental flow requirements by restricting groundwater abstractions. These four strategies were evaluated in separate and combined scenarios. Results show mitigated droughts for both streamflow and groundwater droughts in scenarios applying conjunctive use, particularly in low groundwater storage systems. In high groundwater storage systems, maintaining environmental flows reduces hydrological droughts most. Scenarios increasing or restricting water demand have an opposing effect on droughts, although these scenarios are in balance when combined at the same time. Most combined scenarios reduce the severity and occurrence of hydrological droughts given an incremental dependency on imported water that satisfies up to a third of the total anthropogenic water demand. The necessity for importing water shows the considerable pressure on water resources and the delicate balance of water-human systems during droughts that calls for short-term and long-term sustainability targets within drought policies.
Publisher: Copernicus GmbH
Date: 04-03-2021
DOI: 10.5194/EGUSPHERE-EGU21-12548
Abstract: & & Managing water-human systems in times of water shortage and droughts is key to avoid overexploitation and reduce drought impacts. Drought policies are designed to structure water management response and avoid crisis management, aiming to sustain both environmental and anthropogenic water demand. However, the impact of drought policies on the hydrological cycle is rarely assessed. We developed a socio-hydrological model, simulating feedbacks between water availability and managed water use for 3 decades. Thereby, we aim to assess the impact of drought policies on both surface water and groundwater droughts. We tested this model in an idealised catchment driven by English climate data, representing English water resource management practices and drought policies. The model environment includes a surface water storage (reservoir), a range of hydrogeological conditions for the groundwater module, and an option to import surface water or groundwater that could all be used to satisfy anthropogenic and environmental water demand. Modelled scenarios represent four aspects of drought policies: 1) increased water supply, 2) restricted water use, 3) conjunctive water use, and 4) maintained environmental flow requirements that were evaluated in separate and combined scenarios. Results show that hydrological droughts are mitigated in scenarios applying conjunctive use, particularly in low groundwater storage systems. In high groundwater storage systems, maintaining environmental flows reduces hydrological droughts most, particularly for surface water droughts. Scenarios that gradually increase water supply or restrict water use have opposite impacts on droughts and these scenarios are in balance when combined according to the policies in the resources management plans. Most combined scenarios reduce the severity and occurrence of hydrological droughts, although the dependency on importing water increases, satisfying a third of the total anthropogenic water demand. The increased dependency on imported water shows the considerable pressure on water resources and the delicate balance of water-human systems during droughts that calls for short-term and long-term sustainability targets within drought policies.& &
Publisher: Copernicus GmbH
Date: 23-03-2020
DOI: 10.5194/EGUSPHERE-EGU2020-9413
Abstract: & & Effective water resource management can benefit from estimations of when water entered the catchment and how long it takes to flow to the outlet. In this context, the so-called young water fraction (F& sub& yw& /sub& ) based on seasonal input and output tracer cycles is becoming increasingly used as robust tool to compare the hydrological function of catchments. In seasonally cold environments, this F& sub& yw& & /sub& estimation is complicated by the fact that a large part of the precipitation will be in the form of snow, will be stored before melting and becoming available as water, resulting in a distinct winter low flow and summer high flow season. Nevertheless, F& sub& yw& /sub& might enclose extremely interesting information in such environments since they incorporate the relationship between late summer and autumn flow and the previous winter& #8217 s snow input.& However, most currently available methods for F& sub& yw& /sub& estimation do not explicitly account for the seasonal shift of water input from snow. Therefore, we propose a novel framework to explicitly account for this & #8220 snowmelt& #8221 delay in F& sub& yw & /sub& and explore related uncertainties using experimental data from three high-elevation Alpine catchments, the Vallon de Nant in Switzerland, and the Noce Bianco at Pian Venezia and the Bridge Creek Catchments in Italy. Experimental data from these environments expose some limitations of existing methods in accounting for unavoidable s ling inconsistencies. Using our method that explicitly accounts for snowmelt, we found extremely low F& sub& yw & /sub& in these three Alpine catchments: 6%, 13%, and 31%. In this contribution, we will present our method in detail and highlight emerging challenges and implications of the F& sub& yw& /sub& estimation.& &
Publisher: FapUNIFESP (SciELO)
Date: 06-2017
DOI: 10.1590/0001-3765201720160245
Abstract: Allobates subfolionidificans is a vulnerable and endemic leaf-litter frog from the state of Acre, Brazilian Amazonia. We monitored a population of A. subfolionidificans through regular censuses and mark-recapture of 181 in iduals during an entire breeding season to characterize its reproductive behavior. The space use of A. subfolionidificans in iduals differed between sexes, with males using smaller and more segregated spaces. Males defended territories and were aggressive against same-sex in iduals, which was not the case in females. The daily cycle of calling activity showed peaks in the morning and in the afternoon, and the occurrence of reproductive events was positively correlated with monthly rainfall. The breeding behavior comprised vocal and tactile interactions, although the species lacked reproductive lexus. Egg and larvae attendance, as well as tadpole transport to water environments was performed mostly by males but occasionally by females, probably in cases of desertion by the father. This species is characterized by performing courtship, mating, oviposition, as well as egg and larvae attendance exclusively on the under surface of leaves, a unique behavior among members of the superfamily Dendrobatoidea.
Publisher: Elsevier BV
Date: 07-2021
Publisher: Elsevier BV
Date: 11-2013
Publisher: Wiley
Date: 20-07-2021
DOI: 10.1002/JQS.3348
Abstract: Abandoned shorelines are an important archive used to constrain past fluctuations in the hydrological balance of lakes around the globe. Within Australia, the shorelines preserved at Lake George, NSW, form one of the few shoreline archives in the south‐east of the continent that record palaeoenvironmental conditions throughout the late Quaternary. Here, we examined and tested the lake‐level record for Lake George constructed in the 1970s by dating a well‐preserved shoreline sequence at Luckdale, on the lake's eastern shore, using single‐grain optically stimulated luminescence (OSL) dating. Ten stratigraphic units were identified, and these suggest a late Quaternary highstand for Lake George in MIS 3, with fluctuations superimposed upon an overall drying trend throughout MIS 2 and into the present. At Luckdale, the highest four shoreline‐associated units were deposited ~13 to 19 m above lake base and date to between 39 ± 2 and 29 ± 1 ka ago. Our study pushes back the timing of maximum lake depth at Lake George to at least MIS 3, rather than MIS 2. The overall drying trend is supported by similar reductions in both Riverine Plain fluvial activity and other associated lake‐level records from within the Murray basin.
Publisher: Geological Society of America
Date: 03-2015
DOI: 10.1130/G36346.1
Publisher: Institute of Electrical and Electronics Engineers (IEEE)
Date: 12-2014
Publisher: Copernicus GmbH
Date: 27-03-2022
DOI: 10.5194/EGUSPHERE-EGU22-3896
Abstract: & & & em& It is well-known that floodplain fine-grained alluvial sedimentation rates have been increasing due to human impact. In most catchments, the onset or acceleration of floodplain deposition is dated to medieval times, which has been attributed to increased hillslope soil erosion due to high population densities causing deforestation and slope instability. The also increasing river sediment load has then changed rivers into a single-thread, meandering channel pattern, which is now considered to be the ultima ratio in river restoration. In this presentation, we challenge this view and argue that current channel pattern and shape are related to historic channel engineering, and are hence not the product of fluvial processes associated with a meandering, or avulsing single-thread river system. Here, we present a study from a mountainous region in central Europe (Germany), in which we reconstruct the natural, pre-medieval channel pattern of two low order streams (3rd and 4th Strahler order), and their transition into the current, single-thread channel pattern which is characterised by meanders. This study is based upon a multi-proxy analysis of the chrono-stratigraphy, cross-valley ground penetrating radar, river surveying, analysis of historic maps, and hydrological data for channel pattern prediction. Finally, based on our analysis, we suggest that currently observed channel widening processes and island formation likely represent a tendency of the studied streams to re-create a braided channel pattern, which should be embraced by river management instead of forcing streams into a meandering pattern, as multi-thread, braiding channels are the most natural condition for these streams,& producing a sustainable and resilient river ecosystem.& & & /em& & &
Publisher: American Chemical Society (ACS)
Date: 23-11-2015
Abstract: The microbial oxidation of organic matter coupled to reductive iron oxide dissolution is widely recognized as the dominant mechanism driving elevated arsenic (As) concentrations in aquifers. This paper considers the potential of nanoparticles to increase the mobility of As in aquifers, thereby accounting for discrepancies between predicted and observed As transport reported elsewhere. Arsenic, phosphorus, and iron size distributions and natural organic matter association were examined along a flow path from surface water via the hyporheic zone to shallow groundwater. Our analysis demonstrates that the colloidal Fe concentration (>1 kDa) correlates with both colloidal P and colloidal As concentrations. Importantly, increases in the concentration of colloidal P (>1 kDa) were positively correlated with increases in the concentration of nominally dissolved As (<1 kDa), but no correlation was observed between colloidal As and nominally dissolved P. This suggests that P actively competes for adsorption sites on Fe nanoparticles, displacing adsorbed As, thus mirroring their interaction with Fe oxides in the aquifer matrix. Dynamic redox fronts at the interface between streams and aquifers may therefore provide globally widespread conditions for the generation of Fe nanoparticles, a mobile phase for As adsorption currently not a part of reactive transport models.
Publisher: Frontiers Media SA
Date: 10-05-2017
Publisher: Wiley
Date: 18-11-2020
DOI: 10.1002/HYP.13592
Publisher: Elsevier BV
Date: 05-2015
Publisher: American Geophysical Union (AGU)
Date: 04-2014
DOI: 10.1002/2012WR012922
Publisher: Copernicus GmbH
Date: 08-02-2022
DOI: 10.5194/HESS-2022-48
Abstract: Abstract. Hydrological processes in high elevation catchments are largely influenced by snow accumulation and melt, as well as summer rainfall input. The use of the stable isotopes of water as a natural tracer has become popular over recent years to characterize water flow paths and storage in such environments, in conjunction with electric conductivity (EC) and water temperature measurements. In this work, we analyzed in detail the potential of year round s les of these natural tracers to characterize hydrological processes in a snow-dominated Alpine catchment. Our results underline that water temperature measurements in springs, groundwater and in-stream are promising to trace flow path depth and relative flow rates. The stable isotopes of water are shown here to be particularly valuable to get insights into the interplay of subsurface flow and direct snowmelt input to the stream during winter and early snow melt periods. Our results underline the critical role of subsurface flow during all melt periods and the presence of snowmelt even during winter base flow. We furthermore discuss why reliably detecting the role of subsurface flow requires year-round water s ling in such environments. A key conclusion of our work is the added value of soil and water temperature measurements to interpret EC and isotope analyses, by giving additional information on snow-free periods and on flow path depths.
Publisher: Copernicus GmbH
Date: 03-04-2023
DOI: 10.5194/HESS-27-1403-2023
Abstract: Abstract. Hydrological processes in high-elevation catchments are strongly influenced by alternating snow accumulation and melt in addition to summer rainfall. Although erse water sources and flow paths that generate streamflow in the world's water towers emerge from these two driving inputs, a detailed process understanding remains poor. We measured a combination of natural tracers of water at a high frequency, including stable isotope compositions, electrical conductivity (EC), and water and soil temperature to characterize hydrological processes in a snow-dominated Alpine catchment and to understand the ersity of streamflow sources and flow paths. Stable isotope composition of the s led water revealed the prominence of snowmelt year-round (even during winter baseflow), and a strong flushing of the entire system with snowmelt at the start of the main melt period, sometimes referred to as the freshet, led to a reset, or return to baseline, of the isotopic values in most s led water. Soil temperature measurements help identify snow-free periods and indicate sub-snowpack local flow, for ex le, in the case of rain-on-snow events. Water temperature measurements in springs can indicate flow path depth. EC measurements reflect the magnitude of subsurface exchange and allow for the separation of subsurface snowmelt contribution to streamflow from the contribution of stored groundwater. These insights into the details of streamflow generation in such a dynamic environment were only made possible due to intense, year-round water s ling. The s led tracers are revealed to complement each other in important ways particularly because they were s led during winter and spring, both snow-covered periods, the importance of which is a key implication of this work.
Publisher: American Association for the Advancement of Science (AAAS)
Date: 14-11-2014
Abstract: Increased catchment erosion and nutrient loading are commonly recognized impacts of deforestation on global wetlands. In contrast, an increase in water availability in deforested catchments is well known in modern studies but is rarely considered when evaluating past human impacts. We used a Budyko water balance approach, a meta-analysis of global wetland response to deforestation, and paleoecological studies from Australasia to explore this issue. After complete deforestation, we demonstrated that water available to wetlands increases by up to 15% of annual precipitation. This can convert ephemeral sw s to permanent lakes or even create new wetlands. This effect is globally significant, with 9 to 12% of wetlands affected, including 20 to 40% of Ramsar wetlands, but is widely unrecognized because human impact studies rarely test for it.
Publisher: Copernicus GmbH
Date: 27-10-2021
Abstract: Abstract. A comprehensive evaluation of the impacts of climate change on water resources of the West Africa Volta River basin is conducted in this study, as the region is expected to be hardest hit by global warming. A large ensemble of twelve general circulation models (GCM) from CMIP5 that are dynamically downscaled by five regional climate models (RCM) from CORDEX-Africa is used. In total, 43 RCM-GCM combinations are considered under three representative concentration pathways (RCP2.6, RCP4.5 and RCP8.5). The reliability of each of the climate datasets is first evaluated with satellite and reanalysis reference datasets. Subsequently, the Rank Res ling for Distributions and Dependences (R2D2) multivariate bias correction method is applied to the climate datasets. The corrected simulations are then used as input to the fully distributed mesoscale Hydrologic Model (mHM) for hydrological projections over the twenty-first century (1991–2100). Results reveal contrasting changes in the seasonality of rainfall depending on the selected greenhouse gas emission scenarios and the future projection periods. Although air temperature and potential evaporation increase under all RCPs, an increase in the magnitude of all hydrological variables (actual evaporation, total runoff, groundwater recharge, soil moisture and terrestrial water storage) is only projected under RCP8.5. High and low flow analysis suggests an increased flood risk under RCP8.5, particularly in the Black Volta, while hydrological droughts would be recurrent under RCP2.6 and RCP4.5, particularly in the White Volta. Disparities are observed in the spatial patterns of hydroclimatic variables across climatic zones, with higher warming in the Sahelian zone. Therefore, climate change would have severe implications for future water availability with concerns for rain-fed agriculture, thereby weakening the water-energy-food security nexus and lifying the vulnerability of the local population. The variability between climate models highlights uncertainties in the projections and indicates a need to better represent complex climate features in regional models. These findings could serve as a guideline for both the scientific community to improve climate change projections and for decision makers to elaborate adaptation and mitigation strategies to cope with the consequences of climate change and strengthen regional socio-economic development.
Publisher: Copernicus GmbH
Date: 23-03-2020
DOI: 10.5194/EGUSPHERE-EGU2020-5467
Abstract: & & Mountain snow regimes will be significantly altered by climate warming, resulting in shallower snowpacks whose duration is also reduced. The sensitivity of snowpacks to a unit of air temperature warming depends strongly on climate in addition, for a given climate, the sensitivity also depends on the details of energy balance partitioning. A synthesis of these factors remains challenging. Here we evaluate to what extent a na& #239 ve theory of snowpack response to warming can reproduce the sensitivity which is calculated by a detailed physically based model of the snowpack (Snobal), applied to a erse global set of mountain locations. Our hypothesis is that the na& #239 ve theory will adequately predict the range of snow sensitivity values across erse climates, but not the additional impacts of inter-site differences in energy partitioning for a given climate. The potential benefits of the na& #239 ve theory are that it enables a significant reduction of the uncertainty of snowpack sensitivity, and an improved conceptual understanding of the impacts of climate parameters (e.g. the seasonality and fluctuations of temperature and precipitation) on snowpack accumulation and melt-sensitivity under warming climates.& &
Publisher: SAGE Publications
Date: 23-12-2014
Abstract: Three terrestrial climate proxies are used to investigate the evolution of Holocene palaeoenvironments in southern central Australia, all of which present a coherent record of palaeohydrology. Single-grain optically stimulated luminescence from sediments supplemented by 14 C from charcoal and lacustrine shells was obtained to date shoreline deposits (Lake Callabonna) and the adjacent Mt Chambers Creek alluvial fan. Our findings are complemented by a U/Th-based record of speleothem growth in the Mt Chambers Creek catchment, which we interpret to reflect increased precipitation. Together, these archives shed light on the timing of, and possible sources of water for, Holocene pluvial intervals. We identified several phases of elevated lake levels dated at ~5.8–5.2, 4.5, 3.5–2.7 and 1 kyr, most of which correspond to fluvial activity resulting from increased precipitation in the adjacent ranges. The enhanced hydrology during phases of the late Holocene likely increased the reliability of resources for regional human populations during a time of reduced winter rainfall. When considered within the framework of the current understanding of Holocene palaeoclimate in central Australia, our data suggest that the pattern of landscape response was broadly synchronous with larger scale climatic variability and punctuated by pluvial periods greater than today.
Publisher: Wiley
Date: 25-07-2018
DOI: 10.1002/WAT2.1311
Publisher: Copernicus GmbH
Date: 26-01-2023
DOI: 10.5194/ESSD-2023-31
Abstract: Abstract. Ground-based datasets of observed Snow Water Equivalent (SWE) are scarce, while gridded SWE estimates from remote-sensing and climate reanalysis are unable to resolve the high spatial variability of snow on the ground. Long-term ground observations of snow depth, in combination with models that can accurately convert snow depth to SWE, can fill this observational gap. Here, we provide a new SWE dataset (NH-SWE) that encompasses 11,071 stations in the Northern Hemisphere, and is available at 0.5281/zenodo.7515603 (Fontrodona-Bach et al., 2023). This new dataset provides daily time series of SWE, varying in length between one and seventy-three years, spanning the period 1950–2022 and covering a wide range of snow climates including many mountainous regions. At each station, observed snow depth was converted to SWE using an established snow-depth-to-SWE conversion model, with excellent model performance using regionalised parameters based on climate variables. The accuracy of the model after parameter regionalisation is comparable to that of the calibrated model. The key advantages and strengths of the regionalised model presented here are its transferability across climates and the high performance in modelling daily SWE dynamics in terms of peak SWE, total snowmelt and duration of the melt season, as assessed here against a comparison model. This dataset is particularly useful for studies that require accurate time series of SWE dynamics, timing of snowmelt onset, and snowmelt totals and duration. It can e.g. be used for climate change impact analyses, water resources assessment and management, validation of remote sensing of snow, hydrological modelling and snow data assimilation into climate models.
Publisher: Wiley
Date: 20-10-2015
DOI: 10.1002/ESP.3839
Publisher: Elsevier BV
Date: 10-2012
Publisher: Elsevier BV
Date: 08-2013
Publisher: Elsevier BV
Date: 12-2017
Publisher: American Geophysical Union (AGU)
Date: 02-2016
DOI: 10.1002/2015WR017503
Publisher: Copernicus GmbH
Date: 23-03-2020
DOI: 10.5194/EGUSPHERE-EGU2020-11810
Abstract: & & Snow is a key component of the hydrological cycle in many regions of the world, providing a natural storage of water by accumulating snow in winter and releasing it in spring. Many ecosystems, societies and economies rely on this mechanism as a water resource. There is strong evidence in the literature that global warming leads to decreasing snowfall and snow accumulation and shifts the onset of the melt season to earlier in the year. However, little is known about how rising temperatures affect snowmelt rates and timing, and how these can have an impact on water resources for instance by changing the time and magnitude of streamflow. Some studies predict slower snowmelt rates in a warmer world, due to the onset of melt being earlier when there is less energy available for melt, but there is not yet an observation-based study showing such trends. As a first step, here we present preliminary results of observed long term trends in snowmelt rates from different climates. We use a dataset that has already shown strong decreasing signals for winter snow accumulation. Here we also present potential avenues to investigate the sensitivity of snowpacks and snowmelt regimes in different climatic settings to further rising temperatures using modeled snow dynamics. A few possibilities on how to link the snowpack dynamics to impacts in water resources are also discussed, for instance by comparing modelled dynamics to hydrological models and observations.& &
Publisher: Elsevier BV
Date: 04-2016
Location: United Kingdom of Great Britain and Northern Ireland
Start Date: 2014
End Date: 12-2014
Amount: $150,000.00
Funder: Australian Research Council
View Funded Activity