scholarly journals Streamflow trends in Europe: evidence from a dataset of near-natural catchments

2010 ◽  
Vol 7 (4) ◽  
pp. 5769-5804 ◽  
Author(s):  
K. Stahl ◽  
H. Hisdal ◽  
J. Hannaford ◽  
L. M. Tallaksen ◽  
H. A. J. van Lanen ◽  
...  
Keyword(s):  
Large Scale ◽  
Regional Scale ◽  
Low Flow ◽  
Scale Model ◽  
Model Simulations ◽  
Continental Scale ◽  
Low Flows ◽  
Spatial Coverage ◽  
Monthly Streamflow ◽  
Streamflow Trends

Abstract. Streamflow observations from near-natural catchments are of paramount importance for detection and attribution studies, evaluation of large-scale model simulations, and assessment of water management, adaptation and policy options. This study investigates streamflow trends in a newly-assembled, consolidated dataset of near-natural streamflow records from 441 small catchments in 15 countries across Europe. The period 1962–2004 provided the best spatial coverage, but analyses were also carried out for longer time periods (with fewer stations), starting in 1932, 1942 and 1952. Trends were calculated by the slopes of the Kendall-Theil robust line for standardized annual and monthly streamflow, as well as for summer low flow and low flow timing. A regionally coherent picture of annual streamflow trends emerged, with negative trends in southern and eastern regions, and generally positive trends elsewhere (especially in northern latitudes). Trends in monthly streamflow for 1962–2004 elucidated potential causes for these changes, as well as other changes observed in hydrological regimes across Europe. Positive trends were found in the winter months in most catchments. A marked shift towards negative trends was observed in April, gradually spreading across Europe to reach a maximum extent in August. Low flows have decreased in most regions where the lowest mean monthly flow occurs in summer, but vary for catchments which have flow minima in winter and secondary low flows in summer. The study largely confirms findings from national and regional scale trend analyses, but clearly adds to these by confirming that these tendencies are part of coherent patterns of change, which cover a much larger region. The broad, continental-scale patterns of change are congruent with the hydrological responses expected from future climatic changes, as projected by climate models. The patterns observed could hence provide a valuable benchmark for a number of different studies and model simulations.

scholarly journals Streamflow trends in Europe: evidence from a dataset of near-natural catchments

2010 ◽  
Vol 14 (12) ◽  
pp. 2367-2382 ◽  
Author(s):  
K. Stahl ◽  
H. Hisdal ◽  
J. Hannaford ◽  
L. M. Tallaksen ◽  
H. A. J. van Lanen ◽  
...  
Keyword(s):  
Large Scale ◽  
Regional Scale ◽  
Low Flow ◽  
Scale Model ◽  
Model Simulations ◽  
Continental Scale ◽  
Low Flows ◽  
Spatial Coverage ◽  
Monthly Streamflow ◽  
Streamflow Trends

Abstract. Streamflow observations from near-natural catchments are of paramount importance for detection and attribution studies, evaluation of large-scale model simulations, and assessment of water management, adaptation and policy options. This study investigates streamflow trends in a newly-assembled, consolidated dataset of near-natural streamflow records from 441 small catchments in 15 countries across Europe. The period 1962–2004 provided the best spatial coverage, but analyses were also carried out for longer time periods (with fewer stations), starting in 1932, 1942 and 1952. Trends were calculated by the slopes of the Kendall-Theil robust line for standardized annual and monthly streamflow, as well as for summer low flow magnitude and timing. A regionally coherent picture of annual streamflow trends emerged, with negative trends in southern and eastern regions, and generally positive trends elsewhere. Trends in monthly streamflow for 1962–2004 elucidated potential causes for these changes, as well as for changes in hydrological regimes across Europe. Positive trends were found in the winter months in most catchments. A marked shift towards negative trends was observed in April, gradually spreading across Europe to reach a maximum extent in August. Low flows have decreased in most regions where the lowest mean monthly flow occurs in summer, but vary for catchments which have flow minima in winter and secondary low flows in summer. The study largely confirms findings from national and regional scale trend analyses, but clearly adds to these by confirming that these tendencies are part of coherent patterns of change, which cover a much larger region. The broad, continental-scale patterns of change are mostly congruent with the hydrological responses expected from future climatic changes, as projected by climate models. The patterns observed could hence provide a valuable benchmark for a number of different studies and model simulations.

scholarly journals An application of a large scale conceptual hydrological model over the Elbe region

1999 ◽  
Vol 3 (3) ◽  
pp. 363-374 ◽  
Author(s):  
M. Lobmeyr ◽  
D. Lohmann ◽  
C. Ruhe
Keyword(s):  
Land Surface ◽  
Large Scale ◽  
Sunshine Duration ◽  
Regional Scale ◽  
Scale Model ◽  
Surface Parameterization ◽  
Extreme Flood ◽  
Daily Sunshine ◽  
Surface Scheme ◽  
The Baltic

Abstract. This paper investigates the ability of the VIC-2L model coupled to a routing model to reproduce streamflow in the catchment of the lower Elbe River, Germany. The VIC-2L model, a hydrologically-based land surface scheme (LSS) which has been tested extensively in the Project for Intercomparison of Land-surface Parameterization Schemes (PILPS), is put up on the rotated grid of 1/6 degree of the atmospheric regional scale model (REMO) used in the Baltic Sea Experiment (BALTEX). For a 10 year period, the VIC-2L model is forced in daily time steps with measured daily means of precipitation, air temperature, pressure, wind speed, air humidity and daily sunshine duration. VIC-2L model output of surface runoff and baseflow is used as input for the routing model, which transforms modelled runoff into streamflow, which is compared to measured streamflow at selected gauge stations. The water balance of the basin is investigated and the model results on daily, monthly and annual time scales are discussed. Discrepancies appear in time periods where snow and ice processes are important. Extreme flood events are analyzed in more dital. The influence of calibration with respect to runoff is examined.

scholarly journals Leveraging the signature of heterotrophic respiration on atmospheric CO<sub>2</sub> for model benchmarking

2020 ◽  
Vol 17 (5) ◽  
pp. 1293-1308 ◽  
Author(s):  
Samantha J. Basile ◽  
Xin Lin ◽  
William R. Wieder ◽  
Melannie D. Hartman ◽  
Gretchen Keppel-Aleks
Keyword(s):  
Large Scale ◽  
Transport Model ◽  
Heterotrophic Respiration ◽  
Atmospheric Co2 ◽  
Scale Model ◽  
Future Research ◽  
Tracer Transport ◽  
Test Bed ◽  
Model Simulations ◽  
Soil Heterotrophic Respiration

Abstract. Spatial and temporal variations in atmospheric carbon dioxide (CO2) reflect large-scale net carbon exchange between the atmosphere and terrestrial ecosystems. Soil heterotrophic respiration (HR) is one of the component fluxes that drive this net exchange, but, given observational limitations, it is difficult to quantify this flux or to evaluate global-scale model simulations thereof. Here, we show that atmospheric CO2 can provide a useful constraint on large-scale patterns of soil heterotrophic respiration. We analyze three soil model configurations (CASA-CNP, MIMICS, and CORPSE) that simulate HR fluxes within a biogeochemical test bed that provides each model with identical net primary productivity (NPP) and climate forcings. We subsequently quantify the effects of variation in simulated terrestrial carbon fluxes (NPP and HR from the three soil test-bed models) on atmospheric CO2 distributions using a three-dimensional atmospheric tracer transport model. Our results show that atmospheric CO2 observations can be used to identify deficiencies in model simulations of the seasonal cycle and interannual variability in HR relative to NPP. In particular, the two models that explicitly simulated microbial processes (MIMICS and CORPSE) were more variable than observations at interannual timescales and showed a stronger-than-observed temperature sensitivity. Our results prompt future research directions to use atmospheric CO2, in combination with additional constraints on terrestrial productivity or soil carbon stocks, for evaluating HR fluxes.

scholarly journals Hierarchy of climate and hydrological uncertainties in transient low flow projections

2015 ◽  
Vol 12 (12) ◽  
pp. 12649-12701 ◽  
Author(s):  
J.-P. Vidal ◽  
B. Hingray ◽  
C. Magand ◽  
E. Sauquet ◽  
A. Ducharne
Keyword(s):  
General Circulation ◽  
Large Scale ◽  
Internal Variability ◽  
General Circulation Models ◽  
Low Flow ◽  
Small Scale ◽  
Total Uncertainty ◽  
Low Flows ◽  
The Difference ◽  
Flow Variables

Abstract. This paper proposes a methodology for estimating the transient probability distribution of yearly hydrological variables conditional to an ensemble of projections built from multiple general circulation models (GCMs), multiple statistical downscaling methods (SDMs) and multiple hydrological models (HMs). The methodology is based on the quasi-ergodic analysis of variance (QE-ANOVA) framework that allows quantifying the contributions of the different sources of total uncertainty, by critically taking account of large-scale internal variability stemming from the transient evolution of multiple GCM runs, and of small-scale internal variability derived from multiple realizations of stochastic SDMs. The QE-ANOVA framework was initially developed for long-term climate averages and is here extended jointly to (1) yearly anomalies and (2) low flow variables. It is applied to better understand possible transient futures of both winter and summer low flows for two snow-influenced catchments in the southern French Alps. The analysis takes advantage of a very large dataset of transient hydrological projections that combines in a comprehensive way 11 runs from 4 different GCMs, 3 SDMs with 10 stochastic realizations each, as well as 6 diverse HMs. The change signal is a decrease in yearly low flows of around −20 % in 2065, except for the most elevated catchment in winter where low flows barely decrease. This signal is largely masked by both large- and small-scale internal variability, even in 2065. The time of emergence of the change signal on 30 year low-flow averages is however around 2035, i.e. for time slices starting in 2020. The most striking result is that a large part of the total uncertainty – and a higher one than that due to the GCMs – stems from the difference in HM responses. An analysis of the origin of this substantial divergence in HM responses for both catchments and in both seasons suggests that both evapotranspiration and snowpack components of HMs should be carefully checked for their robustness in a changed climate in order to provide reliable outputs for informing water resource adaptation strategies.

Streamwater time series coupled to groundwater age tracers informs the hydrologic partitioning of rainfall, the transient age distributions and their associated reactivity

2020 ◽  
Author(s):  
Jean Marçais ◽  
Jean-Raynald de Dreuzy ◽  
Louis A. Derry ◽  
Luca Guillaumot ◽  
Aurélie Guillou ◽  
...  
Keyword(s):  
Time Series ◽  
Large Scale ◽  
Groundwater Age ◽  
Stream Water ◽  
Critical Zone ◽  
Low Flow ◽  
Scale Model ◽  
Spatial And Temporal Variability ◽  
Dissolved Silica ◽  
Key Characteristics

&lt;p&gt;&lt;span&gt;Intricated variabilities of stream water quality and of stream discharge can provide key insights of integrated processes occurring at the watershed scale. Yet it is difficult to disentangle the effects of hydrologic vs biogeochemical processes occurring in the different compartments of the critical zone, as well as the mixing associated to it. Here we developed a &lt;/span&gt;&lt;span&gt;&lt;em&gt;quasi&lt;/em&gt;&lt;/span&gt;&lt;span&gt;-2D hillslope scale model able to represent the partitioning of precipitation into real evapotranspiration, shallow subsurface lateral flow and deeper groundwater flow circulation. Enhanced with an advective-dispersive particle tracking algorithm, the model delineates the age distributions of the associated flow lines and the resulting transient streamwater transit time distributions (TTDs). To relate geochemical datasets to TTDs, we connected the biogeochemical reactivity, spatially, to the compartment (regolith vs bedrock) and, in time, to the residence time of the different flowpaths.&lt;/span&gt;&lt;/p&gt;&lt;p&gt;&lt;span&gt;We hypothesized that streamwater time series datasets (discharge and dissolved silica) and &lt;/span&gt;&lt;span&gt;&lt;em&gt;in-situ&lt;/em&gt;&lt;/span&gt;&lt;span&gt; groundwater age tracers (CFCs) would build minimal but orthogonal information upon these partitioning and tracing processes. Applied to 4 different catchments in Brittany, we were able to represent the seasonal dynamics of evapotranspiration, discharge and dissolved silica (DSi) in rivers as well as CFC concentrations in aquifers once key characteristics of the watershed have been informed (evapotranspiration ratio, amount of water stored in the regolith and in the aquifer, bedrock transmissivity, weathering capacity). We found evapotranspiration ratio (ET/P) in average equal to 54% in agreement with independent, large-scale estimates (derived from the French climate Surfex model). The model also provides estimates for typical bedrock transmissivities around 5.10&lt;/span&gt;&lt;sup&gt;&lt;span&gt;-4&lt;/span&gt;&lt;/sup&gt;&lt;span&gt; m&lt;/span&gt;&lt;sup&gt;&lt;span&gt;2&lt;/span&gt;&lt;/sup&gt;&lt;span&gt;/s, mean transit times around 10 years with an important spatial and temporal variability, a&lt;/span&gt;&lt;span&gt;mount of stored water in average equal to 160 mm (resp. 3.10 m) in the regolith (resp. bedrock) and DSi weathering capacity of 0.3 mg/L/yr, which is in accordance with previous studies carried in crystalline contexts like Brittany [Leray et al. 2012, Kolbe et al. 2016, Mar&amp;#231;ais et al. 2018]. Simplifying the transient behavior of the catchment model with some analytical considerations enabled to directly inform these key characteristics with some properties of the measured datasets (e.g. average low flow rate, mean and standard deviation of the DSi time series, average CFC apparent ages). &lt;/span&gt;&lt;/p&gt;&lt;p&gt;&lt;span&gt;This shows that these datasets can be used as standalone tracers and provide powerful indicators of critical zone characteristics described above. This also opens new avenues to spatialize the reactivity in the deep critical zone, and to integrate the information provided by different datasets (e.g. climatic forcing, discharge, solute concentrations, groundwater age tracers) measured in streams and in groundwater. Such modeling exercice paves the way toward an interdisciplinary understanding of the critical zone.&lt;/span&gt;&lt;/p&gt;

scholarly journals Flood Inundation Mapping of Low-, Medium-, and High-Flow Events Using the AutoRoute Model

2019 ◽  
Author(s):  
Michael L. Follum ◽  
Ahmad A. Tavakoly ◽  
Joseph L. Gutenson ◽  
Ricardo Vera
Keyword(s):  
Computational Efficiency ◽  
Regional Scale ◽  
High Flow ◽  
Low Flow ◽  
Flood Inundation ◽  
Post Processing ◽  
Hydrologic Modelling ◽  
Continental Scale ◽  
Modelling Framework ◽  
Extreme Flood

Abstract. This article presents improvements and development of a post-processing module for the regional scale flood mapping tool, AutoRoute. The accuracy of this model to simulate low, medium, and high flow rate scenarios is demonstrated at seven test sites within the U.S. AutoRoute is one of the tools used to create high-resolution flood inundation maps at regional- to continental-scales. The model has previously only been tested using extreme flood events. In this article flood inundation results for low-flow events are shown to be accurate (average F value of 63.3 %) but tend to be overestimated, especially in flatter terrain. Higher-flow scenarios tend to be more accurately simulated (average F value of 77.5 %). Additionally, modifications to the AutoRoute model and post-processing scripts are shown to improve computational efficiency (i.e. simulation time) by over 40 % when compared to previous versions. With improved computational efficiency and the ability to accurately simulate both low and high flow scenarios the AutoRoute model may be well suited to provide first-order estimates of flooding within an operational, regional- to continental-scale hydrologic modelling framework.

scholarly journals Leveraging the signature of heterotrophic respiration on atmospheric CO<sub>2</sub> for model benchmarking

2019 ◽  
Author(s):  
Samantha J. Basile ◽  
Xin Lin ◽  
William R. Wieder ◽  
Melannie D. Hartman ◽  
Gretchen Keppel-Aleks
Keyword(s):  
Large Scale ◽  
Net Primary Productivity ◽  
Transport Model ◽  
Heterotrophic Respiration ◽  
Atmospheric Co2 ◽  
Scale Model ◽  
Future Research ◽  
Tracer Transport ◽  
Model Simulations ◽  
Soil Heterotrophic Respiration

Abstract. Spatial and temporal variations in atmospheric carbon dioxide (CO2) reflect large-scale net carbon exchange between the atmosphere and terrestrial ecosystems. Soil heterotrophic respiration (HR) is one of the component fluxes that drive this net exchange but, given observational limitations, it is difficult to quantify this flux or to evaluate global-scale model simulations thereof. Here, we show that atmospheric CO2 can provide a useful constraint on large-scale patterns of soil heterotrophic respiration. We analyze three soil model configurations (CASA-CNP, MIMICS and CORPSE) that simulate HR fluxes within a biogeochemical testbed that provides each model with identical net primary productivity (NPP) and climate forcings. We subsequently quantify the effects of variation in simulated terrestrial carbon fluxes (NPP and HR from the three soil testbed models) on atmospheric CO2 distributions using a three-dimensional atmospheric tracer transport model. Our results show that atmospheric CO2 observations can be used to identify deficiencies in model simulations of the seasonal cycle and interannual variability in HR relative to NPP. In particular, the two models that explicitly simulated microbial processes (MIMICS and CORPSE) were more variable than observations at interannual timescales and showed a stronger than observed temperature sensitivity. Our results prompt future research directions to use atmospheric CO2, in combination with additional constraints on terrestrial productivity or soil carbon stocks, for evaluating HR fluxes.

scholarly journals Climate change, re-/afforestation, and urbanisation impacts on evapotranspiration and streamflow in Europe

2019 ◽  
Author(s):  
Adriaan J. Teuling ◽  
Emile de Badts ◽  
Femke A. Jansen ◽  
Richard Fuchs ◽  
Joost Buitink ◽  
...  
Keyword(s):  
Land Use ◽  
High Resolution ◽  
Large Scale ◽  
Forest Cover ◽  
Potential Evapotranspiration ◽  
Regional Scale ◽  
Large River ◽  
Climate Conditions ◽  
Continental Scale ◽  
The 1950S

Abstract. Since the 1950s, Europe has seen large shifts in climate and land cover. Previous assessments of past and future changes in evapotranspiration or streamflow have either focussed on land use/cover or climate contributions, or have focussed on individual catchments under specific climate conditions. Here, we aim to understand how decadal changes in climate (e.g., precipitation, temperature) and land use (e.g., de-/afforestation, urbanization) have impacted the amount and distribution of water resources availability across Europe since the 1950s. To this end, we simulate the distribution of green and blue water fluxes at high-resolution (1 × 1 km) by combining (a) a steady-state Budyko model for water balance partitioning constrained by long-term (lysimeter) observations across different land-use types, (b) a novel decadal high-resolution historical land use reconstruction, and (c) gridded observations of key meteorological variables. The continental-scale patterns in the simulations agree well with coarser-scale observation-based estimates of evapotranspiration, and also with observed changes in streamflow from small basins across Europe. We find that strong shifts in the continental-scale patterns of evapotranspiration and streamflow have occured from 1950 to 2010. In Sweden, for example, increased precipitation dominates effects of large scale re- and afforestation leading to increases in both streamflow and evapotranspiration. In most of the Mediterrenean, decreased precipitation combines with increased forest cover and potential evapotranspiration to reduce streamflow. In spite of local and regional scale complexity, the Europe-wide net contribution of land use, precipitation and potential evapotranspiration changes to changes in ET is similar with around ~ 40 km3/y, equivalent to the discharge of a large river. For streamflow, changes in precipitation dominate land use and potential evapotranspiration contributions with ~ 90 km3/y compared to ~ 45 km3/y. Locally, increased forest cover and urbanisation have lead to significant decreases and increases of available streamflow.

Estimation of distributed parameters at regional scale by history-matching of a multi-layered sedimentary aquifer

2020 ◽  
Author(s):  
Ryma Aissat ◽  
Alexandre Pryet ◽  
Marc Saltel ◽  
Alain Dupuy
Keyword(s):  
Parameter Estimation ◽  
Hydraulic Properties ◽  
Large Scale ◽  
Classical Method ◽  
Regional Scale ◽  
Scale Model ◽  
Estimation Methods ◽  
Model Parameters ◽  
Convergence Criteria ◽  
Distributed Parameters

&lt;p&gt;Large scale, physically-based groundwater models have been used for many years for water resources management and decision-support. Improving the accuracy and reliability of these models is a constant objective. The characterization of model parameters, in particular hydraulic properties, which are spatially heterogeneous is a challenge. Parameter estimation algorithms can now manage numerous model runs in parallel, but the operation remains, in practice, largely constrained by the computational burden. A large-scale model of the sedimentary, multilayered aquifer system of North Aquitania (MONA), in South-West France, developed by the French Geological Survey (BRGM) is used here to illustrate the case. We focus on the estimation of distributed parameters and investigate the optimum parameterization given the level of spatial heterogeneity we aim to characterize, available observations, model run time, and computational resources. Hydraulic properties are estimated with pilot points. Interpolation is conducted by kriging, the variogram range and pilot point density are set given modeling purposes and a series of constraints. The popular gradient-based parameter estimation methods such as the Gauss&amp;#8211;Marquard&amp;#8211;Levenberg algorithm (GLMA) are conditioned by the integrity of the Jacobian matrix. We investigate the trade-off between strict convergence criteria, which insure a better integrity of derivatives, and loose convergence criteria, which reduce computation time. The results obtained with the classical method (GLMA) are compared with the results of an emerging method, the Iterative Ensemble Smoother (IES). Some guidelines are eventually provided for parameter estimation of large-scale multi-layered groundwater models.&lt;/p&gt;

Widespread underestimation of the danger of groundwater contamination by shortcuts into aquifers

2020 ◽  
Author(s):  
Andreas Hartmann ◽  
The karst vulnerablity research consortium
Keyword(s):  
Water Quality ◽  
Groundwater Contamination ◽  
Large Scale ◽  
Scale Model ◽  
World Population ◽  
Continental Scale ◽  
Scale Modelling ◽  
Agricultural Pollutants ◽  
First Time

&lt;p&gt;Groundwater pollution threatens human and ecosystem health in many areas around the globe. Shortcuts to the groundwater through enlarged cracks and fissures, often referred to as concentrated recharge, are known to transmit short-lived pollutants into carbonate aquifers endangering water quality of around a quarter of the world population. However, the large-scale impact of concentrated recharge on water quality remains poorly understood. Here we apply a continental-scale model to quantify for the first time the danger of groundwater contamination by degradable pollutants through concentrated recharge in carbonate rock regions. We show that concentrated recharge is the primary reason for the rapid transport of contaminants to the groundwater, increasing the percentage of non-degraded pollutants from &lt;1% in areas without concentrated recharge to around 20-50% in areas where concentrated recharge is present. Our findings are most pronounced in the Mediterranean region where agricultural pollutants in groundwater recharge like Glyphosate can exceed allowed concentrations by up to 19 times. Our results imply that in regions where shortcuts to the groundwater exist, continuing industrial agricultural productivity to optimize food production may result in a widespread reduction of available drinking water and harm ecosystem services more intense than presently available large-scale modelling concepts suggest.&lt;/p&gt;

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