scholarly journals A global-scale two-layer transient groundwater model: development and application to groundwater depletion

2016 ◽  
Author(s):  
Inge E. M. de Graaf ◽  
Rens L. P. H. van Beek ◽  
Tom Gleeson ◽  
Nils Moosdorf ◽  
Oliver Schmitz ◽  
...  
Keyword(s):  
Surface Water ◽  
Groundwater Flow ◽  
Global Scale ◽  
Groundwater Depletion ◽  
Groundwater Model ◽  
Confined Aquifer ◽  
Flow Paths ◽  
Groundwater Head ◽  
Aquifer Systems ◽  
Confining Layers

Abstract. Groundwater is the world's largest accessible source of freshwater to satisfy human water needs. Moreover, groundwater buffers variable precipitation rates over time, thereby effectively sustaining river flows in times of droughts as well as evaporation in areas with shallow water tables. Lateral flows between basins can be a significant part of the basins water budget, but most global-scale hydrological models do not consider surface water-groundwater interactions and do not include a lateral groundwater flow component. In this study we simulate groundwater head fluctuation and groundwater storage changes in both confined and unconfined aquifer systems using a global-scale high-resolution (5 arc-minutes) groundwater model by deriving new estimates of the distribution and thickness of confining layers. Inclusion of confined aquifer systems (estimated 6 % to 20 % of the total aquifer area) changes timing and amplitude of head fluctuations, as well as flow paths and groundwater-surface water interactions rates. Also, timing and magnitude of groundwater head fluctuations are better estimated when confining layers are included. Groundwater flow paths within confining layers are shorter then paths in the underlying aquifer, while flows within the confined aquifer can get disconnected from the local drainage system due to the low conductivity of the confining layer. Lateral groundwater flows between basins are significant in the model, especially for areas with (partially) confined aquifers were long flow paths are simulated crossing catchment boundaries, thereby supporting water budgets of neighboring catchments or aquifer systems. The two-layer transient groundwater model is used to identify hotspots of groundwater depletion resulting in an estimated global groundwater depletion of 6700 km3 over the 1960–2010, consistent with estimates of previous studies.

scholarly journals A high resolution global scale groundwater model

2014 ◽  
Vol 11 (5) ◽  
pp. 5217-5250 ◽  
Author(s):  
I. E. M. de Graaf ◽  
E. H. Sutanudjaja ◽  
L. P. H. van Beek ◽  
M. F. P. Bierkens
Keyword(s):  
Groundwater Flow ◽  
Land Surface ◽  
Regional Scale ◽  
Land Surface Model ◽  
Global Scale ◽  
Water Levels ◽  
Natural State ◽  
Surface Model ◽  
Groundwater Model ◽  
Aquifer Systems

Abstract. Groundwater is the world's largest accessible source of fresh water. It plays a vital role in satisfying needs for drinking water, agriculture and industrial activities. During times of drought groundwater sustains baseflow to rivers and wetlands, thereby supporting ecosystems. Most global scale hydrological models (GHMs) do not include a groundwater flow component, mainly due to lack of geohydrological data at the global scale. For the simulation of lateral flow and groundwater head dynamics a realistic physical representation of the groundwater system is needed, especially for GHMs that run at finer resolution. In this study we present a global scale groundwater model (run at 6' as dynamic steady state) using MODFLOW to construct an equilibrium water table at its natural state as the result of long-term climatic forcing. The aquifer schematization and properties were based on available global datasets of lithology and transmissivities combined with estimated aquifer thickness of an upper unconfined aquifer. The model is forced with outputs from the land-surface model PCR-GLOBWB, specifically with net recharge and surface water levels. A sensitivity analysis, in which the model was run with various parameter settings, showed variation in saturated conductivity causes most of the groundwater level variations. Simulated groundwater heads were validated against reported piezometer observations. The validation showed that groundwater depths are reasonably well simulated for many regions of the world, especially for sediment basins (R2 = 0.95). The simulated regional scale groundwater patterns and flowpaths confirm the relevance of taking lateral groundwater flow into account in GHMs. Flowpaths show inter-basin groundwater flow that can be a significant part of a basins water budget and helps to sustain river baseflow, explicitly during times of droughts. Also important aquifer systems are recharged by inter-basin groundwater flows that positively affect water availability.

scholarly journals A high-resolution global-scale groundwater model

2015 ◽  
Vol 19 (2) ◽  
pp. 823-837 ◽  
Author(s):  
I. E. M. de Graaf ◽  
E. H. Sutanudjaja ◽  
L. P. H. van Beek ◽  
M. F. P. Bierkens
Keyword(s):  
Groundwater Flow ◽  
Land Surface ◽  
Regional Scale ◽  
Unconfined Aquifer ◽  
Global Scale ◽  
Water Levels ◽  
Natural State ◽  
Groundwater Model ◽  
Groundwater Levels ◽  
Aquifer Systems

Abstract. Groundwater is the world's largest accessible source of fresh water. It plays a vital role in satisfying basic needs for drinking water, agriculture and industrial activities. During times of drought groundwater sustains baseflow to rivers and wetlands, thereby supporting ecosystems. Most global-scale hydrological models (GHMs) do not include a groundwater flow component, mainly due to lack of geohydrological data at the global scale. For the simulation of lateral flow and groundwater head dynamics, a realistic physical representation of the groundwater system is needed, especially for GHMs that run at finer resolutions. In this study we present a global-scale groundwater model (run at 6' resolution) using MODFLOW to construct an equilibrium water table at its natural state as the result of long-term climatic forcing. The used aquifer schematization and properties are based on available global data sets of lithology and transmissivities combined with the estimated thickness of an upper, unconfined aquifer. This model is forced with outputs from the land-surface PCRaster Global Water Balance (PCR-GLOBWB) model, specifically net recharge and surface water levels. A sensitivity analysis, in which the model was run with various parameter settings, showed that variation in saturated conductivity has the largest impact on the groundwater levels simulated. Validation with observed groundwater heads showed that groundwater heads are reasonably well simulated for many regions of the world, especially for sediment basins (R2 = 0.95). The simulated regional-scale groundwater patterns and flow paths demonstrate the relevance of lateral groundwater flow in GHMs. Inter-basin groundwater flows can be a significant part of a basin's water budget and help to sustain river baseflows, especially during droughts. Also, water availability of larger aquifer systems can be positively affected by additional recharge from inter-basin groundwater flows.

Flow and Radionuclide Transport From Rock to Surface Systems: Characterization and Modelling of Potential Repository Sites in Sweden

2007 ◽  
Author(s):  
Kent Werner ◽  
Emma Bosson ◽  
Sten Berglund
Keyword(s):  
Surface Water ◽  
Groundwater Flow ◽  
Water Flow ◽  
Exit Point ◽  
Flow Paths ◽  
Near Surface ◽  
Mike She ◽  
Mike 11 ◽  
Surface Water Flow ◽  
Safety Assessments

The safety assessments of potential geological repositories for spent nuclear fuel in Sweden are supported by modelling of groundwater flow in rock, to predict locations (exit points) where radionuclides from the deep repository may enter land, surface waters and associated ecosystems above the rock. This modelling includes detailed rock descriptions, but simplifies the upper part of the flow domain, including representations of meteorological processes and interactions with hydrological objects at the surface. Using the Laxemar candidate site as example, this paper investigates some potentially important consequences of these simplifications. Specifically, it compares particle tracking results obtained by a deep-rock groundwater flow model (CONNECTFLOW) and by MIKE SHE-MIKE 11, which contains detailed descriptions of near-surface/surface water flow. Overall, the models predict similar exit point patterns, occurring as clusters along streams in valleys, at a lake, and in sea bays. However, on a detailed level there are some prediction differences, which may be of importance for biosphere-focused safety assessments. CONNECTFLOW essentially predicts flow paths through the repository that follow fractures and deformation zones, outcropping in valleys. In comparison, MIKE SHE-MIKE 11 provides more detailed information on near-surface water flow paths, including the associated exit points and inputs to assessments of radionuclide retention.

Evaluation of three global gradient-based groundwater models in the Mediterranean region

2020 ◽  
Author(s):  
Nahed Ben-Salem ◽  
Alexander Wachholz ◽  
Michael Rode ◽  
Dietrich Borchardt ◽  
Seifeddine Jomaa
Keyword(s):  
Water Table ◽  
Mediterranean Region ◽  
Global Scale ◽  
Groundwater Table ◽  
Groundwater Depletion ◽  
Groundwater Model ◽  
Anthropogenic Pressures ◽  
Groundwater Levels ◽  
Gradient Based ◽  
The Mediterranean

<p>The Mediterranean region is recognized as one of the most sensitive regions in the world to water scarcity, due to both climate change and consistently increasing anthropogenic pressures. Groundwater is considered as a strategic freshwater reserve in the Mediterranean region; however, its status remains poorly characterized and its total budget uncertain. In recent years, groundwater modelling has moved from local to regional/global scale, offering insights into the status of data-scarce regions. However, it remains unclear to what extent those models can be used to support management decisions. This study aims to compare and evaluate the performance of three groundwater models to represent the steady-state groundwater levels in the Mediterranean region. Thus, the groundwater models of Reinecke et al. (2019), de Graaf et al. (2017) and Fan et al. (2013) will be utilized in this study. The preliminary results indicate that, in the northern part of the Mediterranean region, the models of Reinecke et al. (2019) and de Graaf et al. (2017) predict similar water table patterns. However, both models simulate completely different groundwater regimes in the desert regions; the predicted groundwater table of de Graaf et al. (2017) model is significantly deeper than of Reinecke et al. (2019) model. This could be, probably, because of the calibration of de Graaf et al. (2017) model compared to Reinecke et al. (2019) model, which is not yet calibrated. A detailed comparison between simulated and measured water table depth of different Mediterranean aquifers having different climatic, geologic and anthropogenic conditions will be presented.</p><p><strong>References</strong></p><p>Reinecke, R. et al. Challenges in developing a global gradient-based groundwater model (G3M v1.0) for the integration into a global hydrological model. Geosci. Model Dev 12, 2401-2418 (2019).</p><p>de Graaf, I. et al. A global-scale two-layer transient groundwater model: Development and application to groundwater depletion. Adv. Water Resour 102, 53-67 (2017).</p><p>Fan, Y. et al. Global patterns of groundwater table depth. Science 339, 940-943 (2013).</p><p> </p>

scholarly journals Analytical Solution of Tidal Loading Effect in a Submarine Leaky Confined Aquifer System

Geofluids ◽  
2019 ◽  
Vol 2019 ◽  
pp. 1-15
Author(s):  
Zongzhong Song ◽  
Hailong Li ◽  
Qian Ma ◽  
Chunmiao Zheng ◽  
Jiu Jimmy Jiao ◽  
...  
Keyword(s):  
Analytical Solution ◽  
Confined Aquifer ◽  
One Dimensional ◽  
Aquifer System ◽  
Groundwater Level Fluctuations ◽  
Groundwater Head ◽  
Aquifer Systems ◽  
Groundwater Fluctuation ◽  
Loading Effects ◽  
Tidal Loading

Although there are many existing analytical studies of tidal groundwater level fluctuations in coastal aquifer systems, few of them focus on an offshore submarine aquifer. Here, we consider tidal groundwater head fluctuations in a submarine leaky confined aquifer overlain by a semipermeable seabed. Both the seabed and the confined aquifer are assumed to extend horizontally infinitely. A one-dimensional mathematical model is established to describe the problem, and the analytical solution is derived. The impacts of the tidal loading efficiency, hydraulic conductivity and elastic storage of the semipermeable layer and aquifer on the groundwater head fluctuations in the aquifer system are analyzed and discussed. Solution analyses indicated that tidal loading effects tend to enhance the amplitude of the tidal groundwater fluctuation in the confined aquifer system and to reduce the phase shift between the groundwater head and the sea tide fluctuations.

Towards aquifer deformation models integrating SAR remote sensing: preliminary land subsidence results using GEP tools

2021 ◽  
Author(s):  
Guadalupe Bru ◽  
Pablo Ezqerro ◽  
Carolina Guardiola-Albert ◽  
Marta Béjar-Pizarro ◽  
Gerardo Herrera ◽  
...  
Keyword(s):  
Remote Sensing ◽  
Drinking Water ◽  
Groundwater Flow ◽  
Land Subsidence ◽  
Surface Deformation ◽  
Salt Water ◽  
Groundwater Resources ◽  
Groundwater Depletion ◽  
Web Tool ◽  
Aquifer Systems

<p>Groundwater is a critical resource that provides fresh drinking water to at least 50% of the global population and accounts for 43% of all of the water used for irrigation (Siebert et al., 2010; UNESCO, 2012). A main consequence of groundwater depletion in overexploited aquifers is land subsidence, which ensues other impacts, such as increasing flooding risk (specially in coastal areas), damages to infrastructures and reduction of storage capacity in aquifer systems. Aquifer deformation and groundwater flow models are essential to design sustainable management strategies. In this context, A-DInSAR techniques provide valuable surface displacement data to understand the deformational behaviour of the aquifer and to characterise its properties.</p><p>RESERVOIR project, which is part of the PRIMA programme supported by the European Union, aims to provide new products and services for a sustainable groundwater management model to be developed and tested in four water-stressed Mediterranean pilot sites. Each of them is representative of a different aquifer system flow scheme. They are located in Italy (coastal aquifer of Comacchio), Spain (Alto Guadalentín Basin), Turkey (Gediz River Basin) and Jordan (Azraq Wetland Reserve). The water usages of these aquifers are irrigation, drinking water and/or power generation. Each site is prone to different issues such as land subsidence, salt water intrusion, water pollution, over-exploitation and insufficient recharge.</p><p>One of the primary objectives of the project is the use of advanced satellite-based Earth Observation (EO) techniques for the hydrogeological characterization and their integration into numerical groundwater flow and geomechanical models. This will lead to improve the knowledge about the current capacity to store water and the future response of aquifer systems to natural and human-induced stresses. Free Sentinel-1 SAR acquisitions available at the Copernicus Open Access Hub will be used to perform A-DInSAR processing in representative areas of each pilot site. Additionally, the InSAR processing tools of the Geohazards Exploitation Platform (GEP) funded by the European Space Agency, will be used for a first assessment of ground deformation. In this work we present the preliminary results obtained with Sentinel-1 images using the P-SBAS web tool on GEP (De Luca et al., 2015) at the four pilot sites.</p><p> </p><p><em>De Luca, C., Cuccu, R., Elefante, S., Zinno, I., Manunta, M., Casola, V., Rivolta, G., Lanari, R., and Casu, F., 2015, An on-demand web tool for the unsupervised retrieval of earth’s surface deformation from SAR data: The P-SBAS service within the ESA G-POD environment: Remote Sensing, v. 7, no. 11, p. 15630-15650.</em></p><p><em>Siebert, S., Burke, J., Faures, J.-M., Frenken, K., Hoogeveen, J., Döll, P., and Portmann, F. T., 2010, Groundwater use for irrigation—a global inventory: Hydrology and earth system sciences, v. 14, no. 10, p. 1863-1880.</em></p><p><em>UNESCO, 2012, World’s Groundwater Resources Are Suffering from Poor Governance, UNESCO Publishing: Paris, France, UNESCO Publishing.</em></p>

scholarly journals A global-scale two-layer transient groundwater model: Development and application to groundwater depletion

2017 ◽  
Vol 102 ◽  
pp. 53-67 ◽  
Author(s):  
Inge E.M. de Graaf ◽  
Rens L.P.H. van Beek ◽  
Tom Gleeson ◽  
Nils Moosdorf ◽  
Oliver Schmitz ◽  
...  
Keyword(s):  
Model Development ◽  
Global Scale ◽  
Groundwater Depletion ◽  
Groundwater Model

scholarly journals Conceptualization and development of multi-layered groundwater model in transient condition

2021 ◽  
Vol 11 (10) ◽  
Author(s):  
Padam Jee Omar ◽  
Shishir Gaur ◽  
P. K. S. Dikshit
Keyword(s):  
Groundwater Flow ◽  
Water Resource ◽  
Groundwater Modeling ◽  
Ganga River ◽  
Population Increase ◽  
Model Parameters ◽  
Groundwater Model ◽  
Groundwater Head ◽  
Comparison Results ◽  
Groundwater Demand

AbstractEffective management of water resource is essential in arid and semi-arid areas of India. In Bihar, for drinking purpose humans, livestock is dependent on the groundwater as well as in agricultural areas groundwater plays an important role in irrigation directly or indirectly. There is rise in the groundwater demand due to rapid population increase and fast industrialization. To meet this groundwater demand, excessive withdrawal of groundwater is a point of concern due to limited storage of it. Assessment of the groundwater was done by preparing a numerical model of the groundwater flow. This model is capable of solving large groundwater problems and associated complexity with it. In this study, a transient multi-layered groundwater flow model was conceptualized and developed for the Koshi River basin. In north Bihar plains, the Koshi River is one of the biggest tributaries of the Ganga River system. Koshi originates from the lower part of Tibet and joins the Ganga River in Katihar district, Bihar, India. After model development, calibration of the model was also done, by considering three model parameters, to represent the actual field conditions. For validation of the model, fifteen observation wells have been selected in the area. With the help of observation well data, computed and observed heads were compared. Comparison results have been found to be encouraging and the computed groundwater head matched with the observed water head to a realistic level of accuracy. Developed groundwater model is used to predict the groundwater head and flow budget in the concerned area. The study revealed that groundwater modeling is an important method for knowing the behavior of aquifer systems and to detect groundwater head under different varying hydrological stresses. This type of study will be beneficial for the hydrologist and water resource engineers to predict the groundwater flow behavior, before implementing any project or to implement a correction scheme.

scholarly journals Groundwater storage dynamics in the world's large aquifer systems from GRACE: uncertainty and role of extreme precipitation

2020 ◽  
Vol 11 (3) ◽  
pp. 755-774 ◽  
Author(s):  
Mohammad Shamsudduha ◽  
Richard G. Taylor
Keyword(s):  
Land Surface ◽  
Global Scale ◽  
Groundwater Depletion ◽  
P Value ◽  
Groundwater Storage ◽  
Aquifer Systems ◽  
Surface Models ◽  
Gravity Recovery

Abstract. Under variable and changing climates groundwater storage sustains vital ecosystems and enables freshwater withdrawals globally for agriculture, drinking water, and industry. Here, we assess recent changes in groundwater storage (ΔGWS) from 2002 to 2016 in 37 of the world's large aquifer systems using an ensemble of datasets from the Gravity Recovery and Climate Experiment (GRACE) and land surface models (LSMs). Ensemble GRACE-derived ΔGWS is well reconciled to in situ observations (r=0.62–0.86, p value <0.001) for two tropical basins with regional piezometric networks and contrasting climate regimes. Trends in GRACE-derived ΔGWS are overwhelmingly non-linear; indeed, linear declining trends adequately (R2>0.5, p value <0.001) explain variability in only two aquifer systems. Non-linearity in ΔGWS derives, in part, from the episodic nature of groundwater replenishment associated with extreme annual (>90th percentile, 1901–2016) precipitation and is inconsistent with prevailing narratives of global-scale groundwater depletion at the scale of the GRACE footprint (∼200 000 km2). Substantial uncertainty remains in estimates of GRACE-derived ΔGWS, evident from 20 realisations presented here, but these data provide a regional context to changes in groundwater storage observed more locally through piezometry.

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