TY - JOUR A1 - Al-Mashaikhi, K. A1 - Oswald, Sascha A1 - Attinger, Sabine A1 - Büchel, G. A1 - Knöller, K. A1 - Strauch, G. T1 - Evaluation of groundwater dynamics and quality in the Najd aquifers located in the Sultanate of Oman JF - Environmental earth sciences N2 - The Najd, Oman, is located in one of the most arid environments in the world. The groundwater in this region is occurring in four different aquifers A to D of the Hadhramaut Group consisting mainly of different types of limestone and dolomite. The quality of the groundwater is dominated by the major ions sodium, calcium, magnesium, sulphate, and chloride, but the hydrochemical character is varying among the four aquifers. Mineralization within the separate aquifers increases along the groundwater flow direction from south to north-northeast up to high saline sodium-chloride water in aquifer D in the northeast area of the Najd. Environmental isotope analyses of hydrogen and oxygen were conducted to monitor the groundwater dynamics and to evaluate the recharge conditions of groundwater into the Najd aquifers. Results suggest an earlier recharge into these aquifers as well as ongoing recharge takes place in the region down to present day. Mixing of modern and submodern waters was detected by water isotopes in aquifer D in the mountain chain (Jabal) area and along the northern side of the mountain range. In addition, delta H-2 and delta O-18 variations suggest that aquifers A, B, and C are assumed to be connected by faults and fractures, and interaction between the aquifers may occur. Low tritium concentrations support the mixing assumption in the recharge area. The knowledge about the groundwater development is an important factor for the sustainable use of water resources in the Dhofar region. KW - Environmental isotopes KW - Groundwater KW - Najd aquifer KW - Oman KW - Recharge KW - Water quality Y1 - 2012 U6 - https://doi.org/10.1007/s12665-011-1331-2 SN - 1866-6280 VL - 66 IS - 4 SP - 1195 EP - 1211 PB - Springer CY - New York ER - TY - JOUR A1 - Ayllon, Daniel A1 - Grimm, Volker A1 - Attinger, Sabine A1 - Hauhs, Michael A1 - Simmer, Clemens A1 - Vereecken, Harry A1 - Lischeid, Gunnar T1 - Cross-disciplinary links in environmental systems science BT - Current state and claimed needs identified in a meta-review of process models JF - The science of the total environment : an international journal for scientific research into the environment and its relationship with man N2 - Terrestrial environmental systems are characterised by numerous feedback links between their different compartments. However, scientific research is organized into disciplines that focus on processes within the respective compartments rather than on interdisciplinary links. Major feedback mechanisms between compartments might therefore have been systematically overlooked so far. Without identifying these gaps, initiatives on future comprehensive environmental monitoring schemes and experimental platforms might fail. We performed a comprehensive overview of feedbacks between compartments currently represented in environmental sciences and explores to what degree missing links have already been acknowledged in the literature. We focused on process models as they can be regarded as repositories of scientific knowledge that compile findings of numerous single studies. In total, 118 simulation models from 23 model types were analysed. Missing processes linking different environmental compartments were identified based on a meta-review of 346 published reviews, model inter-comparison studies, and model descriptions. Eight disciplines of environmental sciences were considered and 396 linking processes were identified and ascribed to the physical, chemical or biological domain. There were significant differences between model types and scientific disciplines regarding implemented interdisciplinary links. The most wide-spread interdisciplinary links were between physical processes in meteorology, hydrology and soil science that drive or set the boundary conditions for other processes (e.g., ecological processes). In contrast, most chemical and biological processes were restricted to links within the same compartment. Integration of multiple environmental compartments and interdisciplinary knowledge was scarce in most model types. There was a strong bias of suggested future research foci and model extensions towards reinforcing existing interdisciplinary knowledge rather than to open up new interdisciplinary pathways. No clear pattern across disciplines exists with respect to suggested future research efforts. There is no evidence that environmental research would clearly converge towards more integrated approaches or towards an overarching environmental systems theory. (c) 2017 Elsevier B.V. All rights reserved. KW - Review KW - Interdisciplinary links KW - Integrated environmental modelling KW - Research needs Y1 - 2018 U6 - https://doi.org/10.1016/j.scitotenv.2017.12.007 SN - 0048-9697 SN - 1879-1026 VL - 622 SP - 954 EP - 973 PB - Elsevier CY - Amsterdam ER - TY - JOUR A1 - Baroni, Gabriele A1 - Schalge, Bernd A1 - Rakovec, Oldrich A1 - Kumar, Rohini A1 - Schüler, Lennart A1 - Samaniego, Luis A1 - Simmer, Clemens A1 - Attinger, Sabine T1 - A Comprehensive Distributed Hydrological Modeling Intercomparison to Support Process Representation and Data Collection Strategies JF - Water resources research N2 - The improvement of process representations in hydrological models is often only driven by the modelers' knowledge and data availability. We present a comprehensive comparison between two hydrological models of different complexity that is developed to support (1) the understanding of the differences between model structures and (2) the identification of the observations needed for model assessment and improvement. The comparison is conducted on both space and time and by aggregating the outputs at different spatiotemporal scales. In the present study, mHM, a process‐based hydrological model, and ParFlow‐CLM, an integrated subsurface‐surface hydrological model, are used. The models are applied in a mesoscale catchment in Germany. Both models agree in the simulated river discharge at the outlet and the surface soil moisture dynamics, lending their supports for some model applications (drought monitoring). Different model sensitivities are, however, found when comparing evapotranspiration and soil moisture at different soil depths. The analysis supports the need of observations within the catchment for model assessment, but it indicates that different strategies should be considered for the different variables. Evapotranspiration measurements are needed at daily resolution across several locations, while highly resolved spatially distributed observations with lower temporal frequency are required for soil moisture. Finally, the results show the impact of the shallow groundwater system simulated by ParFlow‐CLM and the need to account for the related soil moisture redistribution. Our comparison strategy can be applied to other models types and environmental conditions to strengthen the dialog between modelers and experimentalists for improving process representations in Earth system models. KW - hydrological models KW - assessments KW - monitoring strategies KW - improvements Y1 - 2019 U6 - https://doi.org/10.1029/2018WR023941 SN - 0043-1397 SN - 1944-7973 VL - 55 IS - 2 SP - 990 EP - 1010 PB - American Geophysical Union CY - Washington ER - TY - GEN A1 - Baroni, Gabriele A1 - Zink, Matthias A1 - Kumar, Rohini A1 - Samaniego, Luis A1 - Attinger, Sabine T1 - Effects of uncertainty in soil properties on simulated hydrological states and fluxes at different spatio-temporal scales T2 - Postprints der Universität Potsdam Mathematisch-Naturwissenschaftliche Reihe N2 - Soil properties show high heterogeneity at different spatial scales and their correct characterization remains a crucial challenge over large areas. The aim of the study is to quantify the impact of different types of uncertainties that arise from the unresolved soil spatial variability on simulated hydrological states and fluxes. Three perturbation methods are presented for the characterization of uncertainties in soil properties. The methods are applied on the soil map of the upper Neckar catchment (Germany), as an example. The uncertainties are propagated through the distributed mesoscale hydrological model (mHM) to assess the impact on the simulated states and fluxes. The model outputs are analysed by aggregating the results at different spatial and temporal scales. These results show that the impact of the different uncertainties introduced in the original soil map is equivalent when the simulated model outputs are analysed at the model grid resolution (i.e. 500 m). However, several differences are identified by aggregating states and fluxes at different spatial scales (by subcatchments of different sizes or coarsening the grid resolution). Streamflow is only sensitive to the perturbation of long spatial structures while distributed states and fluxes (e.g. soil moisture and groundwater recharge) are only sensitive to the local noise introduced to the original soil properties. A clear identification of the temporal and spatial scale for which finer-resolution soil information is (or is not) relevant is unlikely to be universal. However, the comparison of the impacts on the different hydrological components can be used to prioritize the model improvements in specific applications, either by collecting new measurements or by calibration and data assimilation approaches. In conclusion, the study underlines the importance of a correct characterization of uncertainty in soil properties. With that, soil maps with additional information regarding the unresolved soil spatial variability would provide strong support to hydrological modelling applications. T3 - Zweitveröffentlichungen der Universität Potsdam : Mathematisch-Naturwissenschaftliche Reihe - 545 KW - global sensitivity analysis KW - hydraulic conductivity KW - pedotransfer functions KW - parameter uncertainty KW - physical properties KW - solute transport KW - model KW - rainfall KW - Evapotranspiration KW - impact Y1 - 2019 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:kobv:517-opus4-419174 SN - 1866-8372 IS - 545 ER - TY - JOUR A1 - Baroni, Gabriele A1 - Zink, Matthias A1 - Kumar, Rohini A1 - Samaniego, Luis A1 - Attinger, Sabine T1 - Effects of uncertainty in soil properties on simulated hydrological states and fluxes at different spatio-temporal scales JF - Hydrology and earth system sciences : HESS N2 - Soil properties show high heterogeneity at different spatial scales and their correct characterization remains a crucial challenge over large areas. The aim of the study is to quantify the impact of different types of uncertainties that arise from the unresolved soil spatial variability on simulated hydrological states and fluxes. Three perturbation methods are presented for the characterization of uncertainties in soil properties. The methods are applied on the soil map of the upper Neckar catchment (Germany), as an example. The uncertainties are propagated through the distributed mesoscale hydrological model (mHM) to assess the impact on the simulated states and fluxes. The model outputs are analysed by aggregating the results at different spatial and temporal scales. These results show that the impact of the different uncertainties introduced in the original soil map is equivalent when the simulated model outputs are analysed at the model grid resolution (i.e. 500 m). However, several differences are identified by aggregating states and fluxes at different spatial scales (by subcatchments of different sizes or coarsening the grid resolution). Streamflow is only sensitive to the perturbation of long spatial structures while distributed states and fluxes (e.g. soil moisture and groundwater recharge) are only sensitive to the local noise introduced to the original soil properties. A clear identification of the temporal and spatial scale for which finer-resolution soil information is (or is not) relevant is unlikely to be universal. However, the comparison of the impacts on the different hydrological components can be used to prioritize the model improvements in specific applications, either by collecting new measurements or by calibration and data assimilation approaches. In conclusion, the study underlines the importance of a correct characterization of uncertainty in soil properties. With that, soil maps with additional information regarding the unresolved soil spatial variability would provide strong support to hydrological modelling applications. Y1 - 2017 U6 - https://doi.org/10.5194/hess-21-2301-2017 SN - 1027-5606 SN - 1607-7938 VL - 21 SP - 2301 EP - 2320 PB - Copernicus CY - Göttingen ER - TY - GEN A1 - Heße, Falk A1 - Comunian, Alessandro A1 - Attinger, Sabine T1 - What We Talk About When We Talk About Uncertainty BT - Toward a Unified, Data-Driven Framework for Uncertainty Characterization in Hydrogeology T2 - Postprints der Universität Potsdam Mathematisch-Naturwissenschaftliche Reihe T3 - Zweitveröffentlichungen der Universität Potsdam : Mathematisch-Naturwissenschaftliche Reihe - 754 KW - Bayesianism KW - uncertainty analysis KW - hydrogeology KW - data science KW - opinion KW - prior derivation Y1 - 2019 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:kobv:517-opus4-436582 SN - 1866-8372 IS - 754 ER - TY - JOUR A1 - Heße, Falk A1 - Comunian, Alessandro A1 - Attinger, Sabine T1 - What We Talk About When We Talk About Uncertainty BT - Toward a Unified, Data-Driven Framework for Uncertainty Characterization in Hydrogeology JF - Frontiers in Earth Science KW - Bayesianism KW - uncertainty analysis KW - hydrogeology KW - data science KW - opinion KW - prior derivation Y1 - 2019 U6 - https://doi.org/10.3389/feart.2019.00118 SN - 2296-6463 VL - 7 PB - Frontiers Media CY - Lausanne ER - TY - JOUR A1 - Houben, Timo A1 - Pujades, Estanislao A1 - Kalbacher, Thomas A1 - Dietrich, Peter A1 - Attinger, Sabine T1 - From dynamic groundwater level measurements to regional aquifer parameters - assessing the power of spectral analysis JF - Water resources research N2 - Large-scale groundwater models are required to estimate groundwater availability and to inform water management strategies on the national scale. However, parameterization of large-scale groundwater models covering areas of major river basins and more is challenging due to the lack of observational data and the mismatch between the scales of modeling and measurements. In this work, we propose to bridge the scale gap and derive regional hydraulic parameters by spectral analysis of groundwater level fluctuations. We hypothesize that specific locations in aquifers can reveal regional parameters of the hydraulic system. We first generate ensembles of synthetic but realistic aquifers which systematically differ in complexity. Applying Liang and Zhang's (2013), , semi-analytical solution for the spectrum of hydraulic head time series, we identify for each ensemble member and at different locations representative aquifer parameters. Next, we extend our study to investigate the use of spectral analysis in more complex numerical models and in real settings. Our analyses indicate that the variance of inferred effective transmissivity and storativity values for stochastic aquifer ensembles is small for observation points which are far away from the Dirichlet boundary. Moreover, the head time series has to cover a period which is roughly 10 times as long as the characteristic time of the aquifer. In deterministic aquifer models we infer equivalent, regionally valid parameters. A sensitivity analysis further reveals that as long as the aquifer length and the position of the groundwater measurement location is roughly known, the parameters can be robustly estimated. KW - spectral analysis of groundwater level fluctuations KW - proof of concept in numerical environments KW - homogeneous KW - stochastic and deterministic numerical model design KW - regional aquifer parameters KW - sensitivity analysis with field data KW - plausibility test with field data Y1 - 2022 U6 - https://doi.org/10.1029/2021WR031289 SN - 0043-1397 SN - 1944-7973 VL - 58 IS - 5 PB - Wiley CY - New York ER - TY - JOUR A1 - Jing, Miao A1 - Hesse, Falk A1 - Kumar, Rohini A1 - Kolditz, Olaf A1 - Kalbacher, Thomas A1 - Attinger, Sabine T1 - Influence of input and parameter uncertainty on the prediction of catchment-scale groundwater travel time distributions JF - Hydrology and earth system sciences : HESS N2 - Groundwater travel time distributions (TTDs) provide a robust description of the subsurface mixing behavior and hydrological response of a subsurface system. Lagrangian particle tracking is often used to derive the groundwater TTDs. The reliability of this approach is subjected to the uncertainty of external forcings, internal hydraulic properties, and the interplay between them. Here, we evaluate the uncertainty of catchment groundwater TTDs in an agricultural catchment using a 3-D groundwater model with an overall focus on revealing the relationship between external forcing, internal hydraulic properties, and TTD predictions. Eight recharge realizations are sampled from a high-resolution dataset of land surface fluxes and states. Calibration-constrained hydraulic conductivity fields (Ks fields) are stochastically generated using the null-space Monte Carlo (NSMC) method for each recharge realization. The random walk particle tracking (RWPT) method is used to track the pathways of particles and compute travel times. Moreover, an analytical model under the random sampling (RS) assumption is fit against the numerical solutions, serving as a reference for the mixing behavior of the model domain. The StorAge Selection (SAS) function is used to interpret the results in terms of quantifying the systematic preference for discharging young/old water. The simulation results reveal the primary effect of recharge on the predicted mean travel time (MTT). The different realizations of calibration-constrained Ks fields moderately magnify or attenuate the predicted MTTs. The analytical model does not properly replicate the numerical solution, and it underestimates the mean travel time. Simulated SAS functions indicate an overall preference for young water for all realizations. The spatial pattern of recharge controls the shape and breadth of simulated TTDs and SAS functions by changing the spatial distribution of particles' pathways. In conclusion, overlooking the spatial nonuniformity and uncertainty of input (forcing) will result in biased travel time predictions. We also highlight the worth of reliable observations in reducing predictive uncertainty and the good interpretability of SAS functions in terms of understanding catchment transport processes. Y1 - 2019 U6 - https://doi.org/10.5194/hess-23-171-2019 SN - 1027-5606 SN - 1607-7938 VL - 23 IS - 1 SP - 171 EP - 190 PB - Copernicus CY - Göttingen ER - TY - JOUR A1 - Jing, Miao A1 - Hesse, Falk A1 - Kumar, Rohini A1 - Wang, Wenqing A1 - Fischer, Thomas A1 - Walther, Marc A1 - Zink, Matthias A1 - Zech, Alraune A1 - Samaniego, Luis A1 - Kolditz, Olaf A1 - Attinger, Sabine T1 - Improved regional-scale groundwater representation by the coupling of the mesoscale Hydrologic Model (mHM v5.7) to the groundwater model OpenGeoSys (OGS) JF - Geoscientific model development : an interactive open access journal of the European Geosciences Union N2 - Most large-scale hydrologic models fall short in reproducing groundwater head dynamics and simulating transport process due to their oversimplified representation of groundwater flow. In this study, we aim to extend the applicability of the mesoscale Hydrologic Model (mHM v5.7) to subsurface hydrology by coupling it with the porous media simulator OpenGeoSys (OGS). The two models are one-way coupled through model interfaces GIS2FEM and RIV2FEM, by which the grid-based fluxes of groundwater recharge and the river-groundwater exchange generated by mHM are converted to fixed-flux boundary conditions of the groundwater model OGS. Specifically, the grid-based vertical reservoirs in mHM are completely preserved for the estimation of land-surface fluxes, while OGS acts as a plug-in to the original mHM modeling framework for groundwater flow and transport modeling. The applicability of the coupled model (mHM-OGS v1.0) is evaluated by a case study in the central European mesoscale river basin - Nagelstedt. Different time steps, i.e., daily in mHM and monthly in OGS, are used to account for fast surface flow and slow groundwater flow. Model calibration is conducted following a two-step procedure using discharge for mHM and long-term mean of groundwater head measurements for OGS. Based on the model summary statistics, namely the Nash-Sutcliffe model efficiency (NSE), the mean absolute error (MAE), and the interquartile range error (QRE), the coupled model is able to satisfactorily represent the dynamics of discharge and groundwater heads at several locations across the study basin. Our exemplary calculations show that the one-way coupled model can take advantage of the spatially explicit modeling capabilities of surface and groundwater hydrologic models and provide an adequate representation of the spatiotemporal behaviors of groundwater storage and heads, thus making it a valuable tool for addressing water resources and management problems. Y1 - 2018 U6 - https://doi.org/10.5194/gmd-11-1989-2018 SN - 1991-959X SN - 1991-9603 VL - 11 IS - 5 SP - 1989 EP - 2007 PB - Copernicus CY - Göttingen ER -