HS5.16 | Groundwater monitoring, data analysis and modelling for sustainability
EDI
Groundwater monitoring, data analysis and modelling for sustainability
Including HS Division Outstanding Early Career Scientist Award Lecture
Convener: Rebekah HintonECSECS | Co-conveners: Robert Reinecke, Andreas Hartmann, Sebastian GnannECSECS, Fanny SarrazinECSECS, Robert Kalin, Dahlia Sabri
Orals
| Thu, 27 Apr, 14:00–18:00 (CEST)
 
Room 2.44
Posters on site
| Attendance Thu, 27 Apr, 10:45–12:30 (CEST)
 
Hall A
Posters virtual
| Attendance Thu, 27 Apr, 10:45–12:30 (CEST)
 
vHall HS
Orals |
Thu, 14:00
Thu, 10:45
Thu, 10:45
Groundwater provides about 40% of all human water abstractions and is an essential water source for freshwater biota in rivers, lakes, and wetlands. Groundwater is, therefore, essential to ensuring sustainable water availability and a critical part of reaching sustainable development goal 6 (SDG6): “Ensuring availability and sustainable management of water and sanitation for all”.
The development of groundwater models and the analysis of groundwater data from national monitoring networks to global datasets have helped to push the boundaries of our understanding of groundwater processes. In particular, knowledge of the exchange between surface and subsurface waters is essential for determining the water balance at larger scales. Surface and subsurface water exchanges and inter-catchment groundwater flow affect water, pollutant, and nutrient fluxes, bio-organisms in streams, and the groundwater itself. Additionally, human activities (e.g., pumping/irrigation) increasingly affect groundwater flow processes and the exchange between surface and subsurface waters.
In this session, we focus on how groundwater monitoring, data analysis and modelling is critical for achieving sustainable water management. In particular, we highlight the increasing interest in the large-scale study of groundwater availability, quality, and processes (including groundwater recharge) and discuss current obstacles related to data availability and model design. We also focus on the implications of such research in informing effective policy in groundwater management.
Therefore, we seek contributions that address issues including:
• Regional to global groundwater-related datasets and big-data assessments
• Transboundary and inter-catchment assessments of groundwater processes
• Identification of dominant controls on groundwater processes across large domains
• Surface-subsurface water exchange at catchment to global scales and its effects on hydrological extremes (drought/flood), water availability, and solute/pollutant transport
• Effects of climate change, land use change, and change in water demand on large-scale groundwater
• Implications of groundwater monitoring and modelling, integrated water management, and global water policies
• Policy considerations in groundwater management ensuring adequate access to water resources
Solicited authors:
Nils Moosdorf

Orals: Thu, 27 Apr | Room 2.44

Chairpersons: Rebekah Hinton, Robert Reinecke
14:00–14:30
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EGU23-11454
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HS5.16
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solicited
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HS Division Outstanding Early Career Scientist Award Lecture
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On-site presentation
Inge de Graaf

Groundwater is het largest available freshwater resource on earth and is critical to humans and the environment. Groundwater is especially important for irrigated agriculture, and thus for global crop production and food security; approximately 40% of the today’s irrigated agriculture depends on groundwater. In many regions around the world, unsustainable groundwater pumping exceeds recharge from precipitation and rivers. This leads to substantial drops in groundwater levels and losses of groundwater from its storage, especially in intensively irrigated regions, as well as reduction of river flows with possible devastating impacts on freshwater ecosystems.

In my research I simulate groundwater flows and groundwater surface water interactions globally, using a high resolution coupled groundwater and surface water model, and study the impacts of groundwater pumping from the recent past until the far future. In this talk I will present recent findings on current and projected impacts of groundwater pumping on river flows, including an estimate where and when environmentally critical thresholds for groundwater discharge are reached. Second, I will present novel developments and future research steps me and my team will take towards estimating global groundwater availability that can be sustainably exploited and the trade-off between sustainable groundwater use and crop production.

How to cite: de Graaf, I.: Groundwater availability and sustainability, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-11454, https://doi.org/10.5194/egusphere-egu23-11454, 2023.

14:30–14:40
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EGU23-8930
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HS5.16
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ECS
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Highlight
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On-site presentation
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Xander Huggins, Tom Gleeson, Karen G. Villholth, Juan C. Rocha, and James S. Famiglietti

Groundwater resources do not exist in isolation but are deeply connected with social and ecological systems. As humans continue to modify the land surface, drive climate change, and place greater pressures on global freshwater resources, it is increasingly necessary to assess global groundwater resources through their relationships to these coupled systems. While several global classifications of physical groundwater systems exist, there is no data-driven global typology based on groundwater interactions with connected social and ecological systems. Though physical attributes remain hydrogeologically important, a more expansive systems-oriented classification is needed for policy development, applied research, and to develop the next generation of global hydrological models.

We fill this gap by producing a spatially-explicit, moderate resolution (5 arcminute) global map of groundwater system archetypes based on groundwater interactions with social and ecological systems. These include interactions with streamflow, ecosystems, climate, agriculture, the economy, and water governance and management, all underpinned by existing global data. Archetypes, each with a unique set of interaction strengths and combinations, form a finite set of characteristic “fingerprints” that represent the dominant modes of interactions between groundwater and connected social and ecological systems. We find all WHYMAP large aquifer systems of the world are characterized by multiple social-ecological archetypes, suggesting that differentiated, context-appropriate approaches are necessary within large aquifers that are often assumed as uniform in global assessments and initiatives.

We derive archetypes using multiple clustering algorithms and assign archetype membership based on majority agreement across clustering methods after cluster reclassification to create comparable maps. This multiple-method approach renders the archetypes more robust and less contingent on a single clustering algorithm while simultaneously enabling greater representation of archetype uncertainty.

We additionally provide an outlook on sustainable development opportunities and challenges for each archetype. We summarize data sets that represent notable social-ecological outcomes  related to the UN Sustainable Development Goals (SDGs), including: crop yield gaps (SDG 2), remotely sensed groundwater storage trends (SDG 6), economic inequality (SDG 10), human modification of terrestrial systems (SDG 15), and likelihood for hydropolitical interaction (SDG 16), among others. 

This work provides a number of useful contributions. First, the combination of archetyping (i.e., system characterization) and archetype-specific SDG outlook analysis provides a robust, data-driven overview of the role of groundwater in the global sustainability discourse. Secondly, the archetypes identify social-ecological system similarities across the globe, which may support interregional cooperation and networking, coordinated investment and interventions. Thirdly, as we harness the rapid growth in global data that document groundwater system interactions as the basis for our analysis, we simultaneously provide a synthesis and snapshot of the pertinent global data space. This snapshot can be used to identify the need for further data collection, especially on socio-economic interactions that remain underrepresented in global data. And finally, the archetypes raise awareness, build capacity, and shift mental models about the emerging perspective that it is necessary to conceptualize groundwater as a socially and ecologically connected resource.

How to cite: Huggins, X., Gleeson, T., Villholth, K. G., Rocha, J. C., and Famiglietti, J. S.: Global groundwater archetypes: a new typology of groundwater interactions with social and ecological systems and an outlook for sustainable development, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-8930, https://doi.org/10.5194/egusphere-egu23-8930, 2023.

14:40–14:50
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EGU23-2342
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HS5.16
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On-site presentation
Belinda Flem and Lars Stalsberg

Insufficient and fragmented management of TBAs might affect sustainable development both within and beyond a country's borders. There are several examples worldwide of disagreements over whether a certain infrastructure scheme planned by one riparian country would have negative impacts on a riparian state. Transborder cooperation and knowledge of transboundary aquifers (TBAs) has evolved through an inventory under the convention on the protection and use of transboundary watercourses and international lakes (Water Convention) from 1992. Within EU countries, the Water Framework Directive (WFD), 2000/60/EC, intends to contribute to achieve the objectives of the Water Convention. The national groundwater management systems in Norway and Sweden and their implementation of the WFD has been studied as a case area. Emphasis has been placed on international river basin districts (IRBD) and transborder cooperation. The findings offer recommendations for authorities and policymakers on how they could improve the long-term management and ensuring transparent decision-making of transboundary groundwater management.

In Norway and Sweden, TBAs play a minor role in supplying freshwater resources and sustaining socio-economic development in transborder areas. The analysis shows that surface water overrules ‘the invisible’ groundwater. The study highlights several factors that need to be addressed. First, the Norwegian national water management systems are fragmented and over-complex, which complicates national and transnational cooperation. Second, Swedish legislation must be revised to meet the requirements of the WFD regarding IRBD delineation. Finally, transborder dialogue and joint projects on groundwater mapping are necessary for mobilising resources and the necessary political support to obtain knowledge on TBAs.

More information on the study preformed through funding from the EEA and Norway Grants Fund for Regional Cooperation can be achieved from Flem at al., (2022).

Acknowledgements:

This study has been done within project No.2018-1-0137 “EU-WATERRES: EU-integrated management system of cross-border groundwater resources and anthropogenic hazards” which benefits from a € 2.447.761 grant from Iceland, Liechtenstein and Norway through the EEA and Norway Grants Fund for Regional Cooperation. The aim of the project is to promote coordinated management and integrated protection of transboundary groundwater by creating a geoinformation platform.

References:

Flem, B., Stalsberg, L., Seither, A., 2022. Groundwater governance in international river basins - An analysis of the Norwegian-Swedish transborder area. J. Hydrol. Reg. Stud, 44, 2022, 101216. https://doi.org/10.1016/j.ejrh.2022.101216

How to cite: Flem, B. and Stalsberg, L.: International River Basin Planning Under the Water Framework Directive and the SDG indicator 6.5.2 – Case area: Norway - Sweden, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-2342, https://doi.org/10.5194/egusphere-egu23-2342, 2023.

14:50–15:00
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EGU23-13896
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HS5.16
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On-site presentation
Rudy Rossetto, Esteban Rafael Caligaris, Laura Ercoli, Alessio Barbagli, Alessandra Francini, Federico Lazzaroni, Alessandra Pei, Valentina Menonna, Marco Masi, Mirko Brilli, Claudio Benucci, Franca Palumbo, Roberta Maggiorelli, Lorenzo Rotelli, and Alessandro Fabbrizzi

While several studies deal with description and causes leading to aquifer overexploitation, relatively few face the challenge of reverting unbalanced situations. Since 60 years, intensive exploitation of groundwater of the lower Cornia valley aquifer system (Tuscany, Italy) resulted in consistent head lowering and water balance deficit, subsidence, reduction of groundwater dependent terrestrial ecosystems, and salinization of freshwater resources. There, groundwater is the only source of water for drinking, irrigation, industrial purposes and it also contributes to the water needs of the nearby Elba island. We present here the main results achieved within the EU funded LIFE REWAT project (sustainable WATer management in the lower Cornia valley through demand REduction, aquifer Recharge and river REstoration; http://www.liferewat.eu) aiming at rebalancing the water budget of the Cornia river hydrologic system by means of innovation and participatory processes.

Since 2018, five demonstration measures (river restoration works; Managed Aquifer Recharge; reuse of treated wastewater for irrigation; high irrigation efficiency scheme; leakage management in water distribution systems) were built and set in operation for promoting sustainable groundwater resource management, along with capacity building and participatory actions.

Results show an increase in recharge/storage of about 2.5 Mm3 per year, with noticeable effects related to the increase in natural recharge from the Cornia riverbed to the aquifer (for about 1.5 Mm3/year) due to morphological restoration works. The Managed Aquifer Recharge two-stage infiltration basin of Suvereto guaranteed an increase in recharge of about 0.5 Mm3/year. Additional storage increase is related to the reduction in leakage losses from drinking water network and thanks to a more careful use of irrigation water in farming. In about two years, thanks also to favorable hydrologic conditions, the groundwater head generally arose of about 2 to 3 m in the Cornia plain. All the technical works have been complemented by a two years long participatory process leading to the signature of The Cornia River Contract. This is a voluntary agreement among the main stakeholders to promote a shared vision on next 50 years needed actions to achieve environmental sustainability along with proper water resources management. The results achieved so far provide a clear trend towards the Cornia aquifer restoration by means of low-impact and nature-based solutions along with a large involvement of the main stakeholders in creating a shared knowledge on the value of the groundwater resource.

Acknowledgement

This contribution is presented within the framework of the LIFE REWAT project. The LIFE REWAT project received funding from the European Union's Life Programme LIFE 14 ENV/IT/001290.

How to cite: Rossetto, R., Caligaris, E. R., Ercoli, L., Barbagli, A., Francini, A., Lazzaroni, F., Pei, A., Menonna, V., Masi, M., Brilli, M., Benucci, C., Palumbo, F., Maggiorelli, R., Rotelli, L., and Fabbrizzi, A.: Restoring an overexploited aquifer: insights from the Val di Cornia coastal aquifer (Italy), EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-13896, https://doi.org/10.5194/egusphere-egu23-13896, 2023.

15:00–15:10
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EGU23-8380
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HS5.16
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ECS
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On-site presentation
Vadim Yapiyev, Ashirgul Kozhagulova, Leila Karabayanova, Aisulu Kalitova, Vyacheslav Zavaley, Antoine Dillinger, Ayana Karakozhayeva, John Holbrook, Saken Kurbaniyazov, Nurlan Ongdas, Catalin Stefan, and Milovan Fustic

The mountains often “subsidize” water resources to lowlands in arid and semi-arid regions. In the case of Central Asia (CA), the mountain cryosphere is the “water tower” for the population residing in the intermountain valleys and lowland plains. Much of the water research in CA is focused on surface water provision by mountain glaciers and snow such as rivers, lakes, and reservoirs, whilst groundwater recharge is much less investigated. The preliminary hydrogeologic models of deep (up to 3km) groundwater recharge for sedimentary basins (southern Kazakhstan) in the upper Ily and lower Syr Darya river valleys are derived from interpretations of stable isotopes of oxygen, hydrogen, and tritium. The results show that in these basins groundwater at different depths (both shallow and deep) bears depleted abundance of heavy stable-isotope species indicative of winter precipitation (snow). In Ily basin (Zharkent depression) the proportion of snow(melt) contribution increases with depth with water from very deep geothermal wells (~3000 m, the upper cretaceous aquifer) being more isotopically depleted compared to shallower geothermal wells (i.e. depths up to 650m) and shallow groundwaters. Additionally, formation water in the deep geothermal wells (Zharkent area) had no detectible tritium (< 0.71 TU) pointing to an absence of modern recharge (within the past ~ 70 years). Geothermal water from wells (shallow ground water and depth of ~ 1200 m) and a spring in the lower Syr Darya river and the North Aral area, also shows deleted stable water isotope imprints suggesting strong winter recharge contributions. This is surprising as the Aral Sea depression has very low precipitation (less than 200 mm/year) and very little snowfall. These isotope data suggest regional aquifers are recharged primarily by lateral groundwater flows via deep flow paths from mountain regions. This is further corroborated by low salinity (< 1 g/l) of most deep geothermal water samples pointing to dilution by snowmelt. We suggest the aquifers in these CA regions may be replenished mostly by Mountain Block and/or Front recharge mechanisms, but this hypothesis requires further investigation.

How to cite: Yapiyev, V., Kozhagulova, A., Karabayanova, L., Kalitova, A., Zavaley, V., Dillinger, A., Karakozhayeva, A., Holbrook, J., Kurbaniyazov, S., Ongdas, N., Stefan, C., and Fustic, M.: Mountain Block and Front Recharge to the aquifers in sedimentary basins in Kazakhstan: evidence from geothermal studies and water isotopes, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-8380, https://doi.org/10.5194/egusphere-egu23-8380, 2023.

15:10–15:20
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EGU23-491
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HS5.16
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ECS
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On-site presentation
Abdulrahman Shuaibu, Robert M. Kalin, and Vernon Phoenix

The assessment of groundwater quality and its geochemical mechanism is crucial for the sustainable use and management of groundwater resources in arid and semi-arid regions of developing nations. 120 groundwater samples were collected from the Komadugu-Yobe basin to determine its overall quality and the factors that controls the geochemical mechanisms of the groundwater of the study region. The pH, electrical conductivity (EC), and total dissolved solids (TDS) of the groundwater samples were analysed in situ using a handheld (Model 99720 pH/Conductivity meter). The concentrations of Na+, Ca2+, Mg2+, and K+ were analyzed using ICP-OES, iCAP 6200, Thermo Fisher Scientific while Cl-, F-, SO42-, and NO3- were analysed using Ion Chromatography (Metrohm 850 Professional IC). Moreover, the total Alkalinity and bicarbonate were determined using KONE Aquakem v. 7.2.AQ2 equipment by titrimetric method. The hydrochemical analysis results reveals that less than 10% of the groundwater samples exceeded the maximum permissible limits for Electrical conductivity, total dissolved solids, total hardness, sodium, potassium, calcium, magnesium, chloride, sulfate, and fluoride for drinking purposes as recommended by the world Health Organization (WHO, 2018) standards except for bicarbonate and nitrate. The Gibbs diagrams reveals that rock-weathering/rock water interaction is the dominant mechanism controlling groundwater of the study region. However, the chemical relationships in Piper trilinear plots identified Ca2+-Mg2+- HCO-3 water type predominated the study area constituting about 59% of the groundwater samples collected. The findings of the study are paramount for implementing a sustainable management strategy of groundwater resources in the Komadugu-Yobe basin towards the realization of Goal 6 of sustainable development goals.

Keywords: Groundwater, Komadugu-Yobe basin, Geospatial analysis, Water quality, Rock-water interaction

How to cite: Shuaibu, A., M. Kalin, R., and Phoenix, V.: Groundwater Quality Assessment and Geochemical Mechanism of Groundwater of Komadugu-Yobe Basin, West Africa, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-491, https://doi.org/10.5194/egusphere-egu23-491, 2023.

15:20–15:30
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EGU23-891
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HS5.16
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ECS
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Virtual presentation
Steve Kumwenda, Muthi Nhlema, Given Ngwira, Peter Banda, and Tony Nyasulu

Key Words: Groundwater Infrastructure, Functionality, Accountability, Right to water

The Malawi 2018 Sector Performance Report produced by the Ministry of Water and Sanitation found that the proportion of people with access to safe water in the country was 86%, with 57% of improved water points in rural areas being boreholes with hand-pumps. However, a persistent sustainability challenge plagues the water sector: for over 20 years, the functionality of improved water points has remained between 69% and 77%. A study on borehole forensics conducted by the CJF programme found that 30% of hand-pumps fail within five years of installation.

Over the past decade hand pump non-functionality has been attributed to poor community ownership and lack of responsibility to manage the operation and maintenance of the wells. However, in some cases this has been merely hypothetical as the non-functionality of some boreholes has been due to factors that are beyond what communities can manage in terms of operation and maintenance.

BASEflow with support from the Scottish Government conducted Borehole Forensics, which is a detailed investigation of a borehole and hand pump performance.  Twenty one (21) boreholes were technically assessed and out of these, 13 were found to have unacceptable low yield as per the required Government constant pumping rate test standard of 0.25 liters per second for not less than 4 hours. The failure of the 13 boreholes indicate that the boreholes were developed and constructed to completion and handed over to users when they did not have enough water to meet the required standards.

These findings were shared with the relevant stakeholders at Community, District and National level. One major policy recommendation at National level is for the need for adherence to water infrastructure construction standards and the need to empower citizens of rights to water and to hold service providers accountable for failed groundwater supply infrastructure.

How to cite: Kumwenda, S., Nhlema, M., Ngwira, G., Banda, P., and Nyasulu, T.: Triggering social accountability for failed groundwater supply infrastructure in rural Malawi: Chiradzulu case study, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-891, https://doi.org/10.5194/egusphere-egu23-891, 2023.

15:30–15:40
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EGU23-758
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HS5.16
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ECS
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Virtual presentation
Gender inequalities in groundwater access and use: a case from SE Brazil
(withdrawn)
Bárbara Zambelli Azevedo, Ana Maciel de Carvalho, Marcela Barcelos Barbosa, Jessica Barcellos, Isabella Nogueira Bittar de Castilho Barbosa, Gabriela Alves Marinho, Izabella Gontijo Palles, Juliana Couto, and Maria Clara Morgado
15:40–15:45
Coffee break
Chairpersons: Rebekah Hinton, Robert Reinecke
16:15–16:30
16:30–16:40
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EGU23-9452
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HS5.16
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On-site presentation
Nils Moosdorf, Robert Reinecke, and Kevin Befus

The spatial and temporal resolution of global-scale hydrological modeling has enormously increased in recent years. Outputs are becoming available at spatial resolutions of 1x1 km, showing regional structures and changes, often in beautiful figures and large datasets covering the entire globe. The complexity of the underlying models has increased in parallel, as did the amount of input data. Model outputs start more and more to look like the actual planet.

If humanoids start to look more and more like actual humans, an adverse emotional reaction can be seen in humans. In robotics and other disciplines, the term “uncanny valley” was coined for this phenomenon of the creepy impression that humanoids that are too human-like leave on humans.

The increasing resolution of global hydro (geo)logical modeling outputs is partly mirrored by the increasing resolution of input data, e.g., satellite-derived climate data or vegetation information. However, input data based on in-situ observations can remain limited in resolution and remain highly uncertain. In addition, higher resolution models do not necessarily entail that our process understanding has improved. Here, we review and analyze the primary input data of global hydro(geo)logical models, identify critical datasets and discuss the implications of the reliance on these datasets for modern hydro(geo)logical model results. Moreover, we discuss if results that look more and more like the real planet should lead to skepticism in their interpretation similar to the emotional reaction to the uncanny valley in robotics.  

How to cite: Moosdorf, N., Reinecke, R., and Befus, K.: Global hydro(geo)logical modeling: are we missing an uncanny valley?, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-9452, https://doi.org/10.5194/egusphere-egu23-9452, 2023.

16:40–16:50
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EGU23-2565
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HS5.16
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On-site presentation
Gunnar Lischeid and Jörg Steidl

In the course of climate change serious effects on groundwater resources are expected. Future groundwater recharge is usually assessed via hydrological models. Various studies have shown that most models fail in depicting pronounced trends observed in groundwater monitoring data at regional scales. Likewise, global hydrological models seem to systematically underestimate the low-frequency dynamics of regional water storages in the GRACE mission data (Scanlon et al. 2018) or long-lasting memory effects in terms of discharge (Fowler et al. 2022). Thus groundwater recharge modelling appears to have some fundamental problems that go far beyond the usual model uncertainties in each individual case.

This was systematically investigated. The empirical basis was given by the analysis of groundwater data of the authorities’ monitoring networks in Northeast Germany, covering an area of more than 50,000 km2. About 240 long-term time series of groundwater head and lake water level were studied. It could be shown that at weekly or monthly time scales lake water level dynamics very closely mimicked that of the adjacent groundwater body.

A very close correlation between the direction and strength of the trends and the degree of damping of the signal of groundwater recharge was found. The probability of long-term trends systematically increased with the thickness of the vadose zone. This indicates the crucial role of long-term accumulation of soil moisture deficits in the deeper unsaturated zone.

In contrast, models of groundwater recharge generally consider only the uppermost soil layers. In addition, modellers usually assume initial steady-state equilibrium conditions and thus ignore long-term memory effects in the subsurface. Simulations with different models clearly showed that this resulted in a systematic underestimation of long-term trends. Finally, it was found that model parameterizations which had been optimized with respect to discharge or topsoil moisture dynamics were not necessarily optimal for the simulation of groundwater recharge. Based on these findings clear recommendations for monitoring and model-based assessment of groundwater recharge will be given.

 

References:

Scanlon et al. (2018), PNAS, http://ww.pnas.org/cgi/doi/10.1073/pnas.1704665115

Fowler et al. (2022), WRR, https://doi.org/10.1029/2021WR031210

Lischeid et al. (2021), JHyd, https://doi.org/10.1016/j.jhydrol.2021.126096

How to cite: Lischeid, G. and Steidl, J.: Why do our models underestimate regional groundwater trends?, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-2565, https://doi.org/10.5194/egusphere-egu23-2565, 2023.

16:50–17:00
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EGU23-4052
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HS5.16
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ECS
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On-site presentation
Barry van Jaarsveld, Frances Dunn, Edwin H. Sutanudjaja, Rens van Beek, Marc F. P. Bierkens, and Niko Wanders

If not addressed and remedied, the unsustainable use of non-renewable groundwater will negatively impact many future generations. To effectively manage global groundwater reserves, we first need accurate estimates of its current availability and how much of this we can feasibly extract. Landscape characteristics have a high impact on local groundwater recharge, groundwater-surface water interactions, and abstractions. It is therefore key to model groundwater at an appropriate spatial resolution so that landscape heterogeneities are captured. Our objective is to enable groundwater modelling at fine spatial (~ 1 km) resolution, with the final aim to assess the physical limits of groundwater withdrawal by providing the first global estimates of fresh groundwater availability (attainable volumes and supply) subject to past human water use. The first step to attaining this objective is the ability to simulate groundwater recharge and surface water levels at 1 km spatial resolution using a global hydrological model. In this study, we aim to tackle this challenge and present the first global case of the PCR-GLOBWB at the 1 km spatial resolution. To do this, we implemented a statistical downscaling routine for meteorological forcing, created a new global 1km land surface parameterization and improved the parallelization of the PCR-GLOBWB model. The meteorological downscaling approach followed here provides outputs that are at a finer resolution than the original meteorological forcing products. This approach relies on Worldclim data to provide realistic sub-grid distributions of precipitation and temperature. In addition, sub-grid distributions of potential reference evaporation were retrieved from the Global Aridity Index and Potential Evapotranspiration Climate Database, which uses Worldclim data to calculate potential reference evaporation following the Penman-Monteith formulation.

We investigate whether these high-resolution meteorological fields, in combination with an improved 1km land surface parameterization, provided improved outcomes by validating against remote sensing observations (soil moisture, total water storage) and local observations of discharge and compare these to simulation at coarser 10 & 50km resolutions. Furthermore, we discuss the computational challenges encountered along the way and outline future directions and opportunities in high-resolution groundwater modelling.

How to cite: van Jaarsveld, B., Dunn, F., Sutanudjaja, E. H., van Beek, R., Bierkens, M. F. P., and Wanders, N.: Hyper resolution hydrological modeling: the need and benefit of improving spatial resolutions of global models, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-4052, https://doi.org/10.5194/egusphere-egu23-4052, 2023.

17:00–17:10
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EGU23-10289
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HS5.16
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ECS
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On-site presentation
Ehsan Sharifi, Andreas Güntner, Julian Haas, Wouter Dorigo, Adrian Jäggi, and Claudia Ruz Vargas and the G3P team

The Global Gravity-based Groundwater Product (G3P) developed a satellite-based groundwater storage anomaly (GWSA) data set as a prototype for a future product within the EU Copernicus Climate Change Service. As the world’s largest distributed freshwater storage, GW is a key resource for mankind, industrial, and agricultural demands. In Copernicus, there is no service available yet to deliver data on this fundamental resource, nor is there any other data source worldwide that operationally provides information on changing groundwater resources in a consistent way, observation-based, and with global coverage. Therefore, G3P developed the global data set of groundwater storage variations as a cross-cutting extension of the existing Copernicus portfolio. G3P capitalizes from the unique capability of GRACE and GRACE-FO satellite gravimetry as the only remote sensing technology to monitor subsurface mass variations, and from other satellite-based water storage products to provide a data set of groundwater storage change for large areas with global coverage. G3P is obtained by using a mass balance approach, i.e., by subtracting satellite-based water storage compartments (WSCs) such as snow water equivalent, root-zone soil moisture, glacier mass, and surface water storage from GRACE/GRACE-FO monthly terrestrial water storage anomalies (TWSA). For a consistent subtraction of all individual WSCs from GRACE-TWSA, the individual WSCs are filtered in a similar way as GRACE-TWSA, where optimal filter types were derived by analyses of spatial correlation patterns. G3P groundwater variations are provided for almost two decades (from 2002 to 2020), with a monthly resolution, and at a 0.5-degree spatial resolution globally.

In this contribution, we also illustrate selected results of the G3P-based GWSA data set, including the global trends of groundwater storage and the uncertainties of the GWSA data as well as of the contributing storage compartments. The GWSA is also evaluated against in-situ groundwater observations, using 13 large aquifers worldwide with available in-situ groundwater observations. Results show a high correlation between the variations of in-situ groundwater data and G3P-based GWSA for most of the aquifers, such as the Ogallala aquifer, Floridan aquifer, Paris Basin, South of Outer Himalayas aquifer.

This study has received funding from the European Union’s Horizon 2020 research and innovation programme for G3P (Global Gravity-based Groundwater Product) under grant agreement nº 870353.

How to cite: Sharifi, E., Güntner, A., Haas, J., Dorigo, W., Jäggi, A., and Ruz Vargas, C. and the G3P team: G3P: A global data set of groundwater storage variations based on satellite gravimetry, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-10289, https://doi.org/10.5194/egusphere-egu23-10289, 2023.

17:10–17:20
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EGU23-15124
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HS5.16
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On-site presentation
Markus Giese, Jean-Baptiste Charlier, Andreas Hartmann, and Yvan Caballero

Groundwater resources are generally evaluated by quantifying groundwater recharge and its storage into the aquifer using for example conceptual or numerical models. Recharge modelling provides a preliminary estimation of the renewable part of the groundwater resource. Moreover, results of regional groundwater recharge models may be used as input data for models on a smaller scale, i.e. at the catchment scale dedicated to water management for present and future conditions. It is thus necessary to constrain the recharge models for example by comparing their outputs to historical long-term observations of groundwater flows that can be derived from time series of groundwater levels or spring discharge.

Karst systems with their high infiltration rate and preferential flow in enlarged conduit networks, react quickly to climatic events and changes. Thus, they can be used as proxies to evaluate the impact of global change on groundwater resources. Karst systems are present in different climatic regions of Europe, which allows comparing long-term trends of groundwater recharge with spring discharge (similar or opposing trends). In our study, two different regional recharge models covering entire Europe – one calculating potential groundwater recharge using simple soil water balance methods and one calculating groundwater recharge over karst areas only using 1-D physical equations for infiltration – are compared to the measured spring discharge from a large European database of more than 100 monitored karst systems. To identify and highlight changes in dominant recharge processes related to changing climatic or physiographic (land cover / land use) conditions, different variables used in the regional recharge models will be correlated to indices describing dynamics of karst spring discharge. The results of our study will help to understand the impact of climatic and groundwater recharge related influences on various geographic locations and give insights on uncertainties in the model structure of the applied regional groundwater recharge models.

How to cite: Giese, M., Charlier, J.-B., Hartmann, A., and Caballero, Y.: Groundwater evolution in Europe - comparing recharge model outputs with spring discharge from hydroclimatic sensitive karst areas, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-15124, https://doi.org/10.5194/egusphere-egu23-15124, 2023.

17:20–17:30
|
EGU23-16714
|
HS5.16
|
ECS
|
On-site presentation
|
Dubois Emmanuel and Larocque Marie

Large scale and long-term estimates of groundwater recharge (GWR) are strategic for assessing the relative impacts of climate change and land cover (LC) change on groundwater resources. This is especially true in cold and humid climates where global change has a high disrupting potential. Therefore, this work aims to determine the driving processes of long-term and large-scale GWR in cold and humid climates. Using a parsimonious model, GWR was simulated in the cold and humid region of southern Quebec, Canada (35 800 km2) over the past decades (1961-2017) and for potential future conditions (12 scenarios, 1951-2100). Constant and time-variant LC were used, with a monthly time step and a 500 m x 500 m spatial resolution. The datasets and model are open source. The simulated past and future results showed the importance of seasonality for GWR and the key role of annual temperature in the spatial distribution of GWR rates. They highlighted the high responsiveness of the cold and humid region hydrology to long-term interannual climate variability and the importance of simulating the snow and freezing processes when estimating GWR in these climates. In the future, warmer temperatures during the cold months (less precipitation as snow, earlier snowpack melting) led to more liquid water available when the vegetation was dormant, leading to higher GWR. Warmer temperatures during the rest of the year extended the growing period and increased plant water uptake, directly decreasing the water available for GWR. The direction of the annual changes in GWR thus depended on whether the increase during the cold months could offset the decrease during the rest of the year. The sensitivity of GWR to climate change increased with the increase in LC change intensity. The spatial distribution of LC changes was identified as another driver of GWR change as afforestation took place on agricultural areas, located on the flattest and clayey areas, thus reducing the GWR rates for forested area over time. This work called for a more systematic inclusion of LC changes in long-term groundwater resource simulation and proposes a computationally-affordable methodology to tackle it.

How to cite: Emmanuel, D. and Marie, L.: Driving processes of long-term large scale groundwater recharge in cold and humid climates, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-16714, https://doi.org/10.5194/egusphere-egu23-16714, 2023.

17:30–17:40
|
EGU23-2090
|
HS5.16
|
ECS
|
On-site presentation
Marialaura Bancheri, Marco Acutis, Marco Botta, Francesco Fusco, Giuliano Langella, Daniele Lezzi, Alessia Perego, and Angelo Basile

This work presents two web-based, freely-available dynamical tools for the assessment and the mapping of the groundwater vulnerability to both pesticides and nitrate, within the geospatial Decision Support system (s-DSS) LandSupport (www.landsupport.eu).

The pesticide fate tool simulates the transport of reactive solutes, i.e., pesticides, and maps the percentage of pollutant mass that reaches the groundwater depth within a user defined time-interval. The tool is based on the extended transfer function model (TFM-ext) and its main inputs are: the soil and, eventually, the vadose zone physical and hydrological properties, the climate, the groundwater table depth, the investigated crop and its management (sowing and harvesting dates, pesticides doses and time of application).

The nitrate fate tool simulates the crop growth dynamics and assess the transport of nitrate through the unsaturated zone till the groundwater table depth. The output maps represent the number of years for the arrival to the groundwater of the 50% of the mass of nitrate leachate from the root zone. The tool is based on the coupling of the dynamical crop-growth ARMOSA model and of the TFM-ext model and its main inputs are: the type of crop and/or crop-rotation and related managements (tillage, irrigation, fertilization and residues), the soil physical and hydrological properties, the climate and the groundwater table depth.

Eventually, both tools were extended using the COMPSs programming framework that allows to parallelize the execution of multiple model runs.

The work presents the implementations of both tools for different case studies across three European regions (Campania Region-IT, Marchfeld Region-AT, Zala County-HU), characterized by different spatial scales, pedo-climatic conditions and land-use, showing some examples of applications in support of local farmers, public authorities and environmental planners for the Water, Pesticides and Nitrate Directive applications.

How to cite: Bancheri, M., Acutis, M., Botta, M., Fusco, F., Langella, G., Lezzi, D., Perego, A., and Basile, A.: A DSS for the dynamical assessment and mapping of the groundwater vulnerability: the pesticide and the nitrate fate tools  , EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-2090, https://doi.org/10.5194/egusphere-egu23-2090, 2023.

17:40–18:00

Posters on site: Thu, 27 Apr, 10:45–12:30 | Hall A

Chairpersons: Rebekah Hinton, Robert Reinecke
A.58
|
EGU23-421
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HS5.16
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ECS
Sara Nazari and Nils Moosdorf

Groundwater is the largest global liquid freshwater source and is vital for providing reliable water resources for growing water consumption. To meet an increasing freshwater demand, the groundwater resources have been excessively exploited, which can cause groundwater depletion and its further consequences, such as land subsidence. Groundwater recharge is a major factor for the sustainable management of groundwater abstraction. One of the most uncertain parts of our knowledge of the global scale hydrological cycle is global groundwater recharge. Yet, measuring groundwater recharge requires detailed knowledge of environmental parameters and is observation-intensive. Therefore, we developed a global groundwater recharge model to analyze global groundwater recharge and estimate its spatial and temporal distribution.

The model is a global hydrology grid-based concept implemented in python with a spatial resolution of 0.1°×0.1° and daily temporal resolution. The model comprises three soil layers: topsoil (root zone), subsoil, and aquifer. It simulates the exchange between topsoil and atmosphere performed by meteorological variables, as well as surface runoff, topsoil recharge, soil layers water volume, subsoil recharge, capillary rise from the subsoil to the topsoil, and groundwater recharge. Meteorological and soil properties data from various sources such as ERA5, IMERG, and SoilGrid250m were gathered to build the model and simulate fluxes. The groundwater recharge model applies the water balance budget concept on each soil layer to simulate the daily cell average fluxes values.

With the implementation of the global groundwater recharge model from 2001 to 2020, each global basin’s groundwater recharge was calculated. It is estimated that the global average groundwater recharge is 150 mm a-1 varying from zero to 1260 mm a-1. Moreover, a linear regression was applied for the decades 2001-2010 and 2011-2020 to evaluate how recharge has changed. An increasing trend in groundwater recharge was identified found in 68% of the world’s basins in the period 2001 to 2010. For the period from 2011 to 2020, this percentage has decreased to 48%. Basins with declining recharge show the opposite trend, comprising 32% of the basins in the first period and 52% in the second.

Global groundwater resources status and the possibility of groundwater shortage can be discovered by applying global groundwater recharge model results. An increasing number of river basins show a decreasing trend of groundwater recharge. These outputs provide insight into uneven global groundwater recharge spatial and temporal distributions and indicate that the groundwater recharge decline in recent years threatens more basins. In addition, the results can be used to identify the regions where groundwater resources are or will be at risk of unsustainability.

 

How to cite: Nazari, S. and Moosdorf, N.: Global groundwater recharge assessment over the last two decades, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-421, https://doi.org/10.5194/egusphere-egu23-421, 2023.

A.59
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EGU23-784
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HS5.16
|
ECS
Seeke Mohuba and Tamiru Abiye

This research contributes to the protection of members of the West Rand communities from radiological harm emanating from drinking water through the establishment of radionuclide levels in drinking water and the associated health risks of ingestion. The long-standing history of gold mining and processing in the Witwatersrand Basin has resulted in an exponential increase in the amount of radionuclides released into the environment, including the water system. As such, it is paramount to ensure the public and environment are protected from any pollution related to gold mining. The aim of this study was to assess and quantify radionuclide levels in drinking water (groundwater and municipal water) and the health risks associated with the ingestion of the water in residential communities of the West Rand region. Activity concentrations of 238U, 235U, 234U, 232Th, 230Th, 228Th, 228Ra, 226Ra and 224Ra in 22 drinking water samples were determined using alpha spectrometry, which were subsequently used to evaluate the radiological risks related to the ingestion of 238U in the water. The results indicate that groundwaters largely contain elevated activity concentrations of most radionuclides owing to the untreated nature of the water as opposed to the municipal-supplied water. Similarly, annual effective dose and cancer morbidity and mortality risk estimates were found to be higher in groundwater. Annual effective dose estimates in all samples were well below the prescribed limit of 0.1mSv/y, with a range of 0.0237–0.3106 mSv/yr. Cancer morbidity and mortality risk estimates were higher in females than males in all samples due to the higher life expectancy of females. Nevertheless, all morbidity and mortality risk estimates were significantly lower than the prescribed radiological risk limit of 0.001. All sampled drinking water was found to be radiologically safe for human consumption. Based on the findings of this study, continuous monitoring of the drinking water with an emphasis on groundwater should be implemented to ensure that radionuclide levels and associated health risks remain below local and international prescribed regulatory limits.

 

Keywords: Gold mining, drinking water, radionuclides, annual effective dose, cancer risk

How to cite: Mohuba, S. and Abiye, T.: Assessment of radionuclide levels in drinking water from communities in the West Rand region of the Gauteng Province, South Africa, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-784, https://doi.org/10.5194/egusphere-egu23-784, 2023.

A.60
|
EGU23-6892
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HS5.16
|
ECS
Pia Ebeling, Rohini Kumar, Rafael Chávez García Silva, Jan H. Fleckenstein, and Andreas Musolff

Regional groundwater resources are crucial for water supply, maintaining environmental stream flows and the integrity of aquatic ecosystems. At the same time, however, these resources are increasingly threatened by the effects of climate change. More extreme weather conditions like exceptional droughts are expected to increase water stress by increasing water demand and decreasing water availability even in humid regions such as Germany. To identify consistent long-term trends and areas vulnerable to droughts, it is important to characterize and understand similarities and differences in groundwater dynamics across sites. Herein, we analyze groundwater head responses to climatic variability at more than 6500 groundwater wells over the last 30 years in Germany to identify response clusters. Principal component analysis (PCA) revealed that about two-thirds of the observed groundwater level variability across all wells can be explained by five typological time series. These time series represent different response patterns to climatic forcing capturing distinct dampening effects and time lags, with different weights (loadings) being assigned to each groundwater well. The subsequently identified clusters of the wells reveal clear regional structures suggesting underlying spatial controls. In the next step, groundwater drought characteristics (e.g., severity, duration) will be considered and linked to climate and landscape properties. This study may help to understand regional controls and to identify zones vulnerable to groundwater droughts where water supplies are at risk in the long term and mitigation measures are needed.

How to cite: Ebeling, P., Kumar, R., Chávez García Silva, R., Fleckenstein, J. H., and Musolff, A.: Similarities and differences in groundwater responses to droughts across Germany, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-6892, https://doi.org/10.5194/egusphere-egu23-6892, 2023.

A.61
|
EGU23-6325
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HS5.16
|
ECS
|
Nicole G. Otoo, Edwin H. Sutanudjaja, Michelle T.H. van Vliet, Aafke M. Schipper, and Marc F.P. Bierkens

The increase in global population has led to the expansion of water demands for agriculture, domestic and industrial use in areas with limited precipitation and surface water sources, increasing the dependency on groundwater resources. An increase in groundwater pumping combined with low recharge rates has increased the rate of groundwater depletion globally. An increase in water demand alongside a decrease in recharge rates can lead to reductions in groundwater levels and groundwater discharge, which may adversely affect groundwater-dependent ecosystems (GDEs) and their unique biodiversity and ecosystem services.

Mapping and classifying groundwater-dependent ecosystems (GDEs) are key steps for understanding ecosystem-groundwater interactions as well as for optimizing the allocation of groundwater resources. However, manual mapping of GDEs is tedious, especially across large areas. Here, we aim to calibrate and apply a global groundwater model to map and classify GDEs across large extents. Our initial focus is on Australia, which is characterized by a large dependency of ecosystems on groundwater and for which GDE locations have been mapped across the continent, facilitating model calibration and validation.

We use a recently developed high-resolution (30 arc-seconds) global groundwater model GLOBGM hydrology forced with recharge and surface water levels from the global hydrological model PCR-GLOBWB 2, to map three types of GDE, namely aquatic (streams, rivers and lakes), wetlands (fens, marshes and swamps) and terrestrial GDEs (phreatophytes). The model maps all ecosystems that depend on groundwater recharge in a steady state. To validate model output, it is compared to the Australian GDE atlas using a hit rate analysis and a 90% hit rate was found with aquatic GDEs. In the next steps, we seek to quantify the dependency level of these GDEs on groundwater recharge by running the groundwater model in a transient state globally. This assessment is useful for decision-makers in terms of groundwater allocation and biodiversity conservation within high-dependency GDE regions.

How to cite: Otoo, N. G., Sutanudjaja, E. H., van Vliet, M. T. H., Schipper, A. M., and Bierkens, M. F. P.: Continental mapping of groundwater-dependent ecosystems based on a high-resolution global groundwater model, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-6325, https://doi.org/10.5194/egusphere-egu23-6325, 2023.

A.62
|
EGU23-7947
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HS5.16
|
ECS
Marlen Hunt, Dāvis Borozdins, Andres Marandi, Magdaleena Männik, Jekaterina Demidko, Krišjānis Valters, Jānis Bikše, Konrāds Popovs, Inga Retiķe, and Liina Hints

Coordinating transboundary aquifer management is becoming increasingly important worldwide to minimize adverse transboundary impacts. Moreover, the global trend of groundwater consumption is increasing, and groundwater abstraction exceeds sustainable limits in many parts of the world. To avoid future international disputes and maximize the rational and equitable use of common transboundary aquifers, it is imperative to accurately and comprehensively assess groundwater resources' development potential in these aquifers.

As part of this study, a transient hydrogeological model using MODFLOW-NWT was developed to assess the changes in groundwater balance and groundwater flow in the transboundary area between Estonia and Latvia in northeast Europe. The model consists of eleven layers that discretize four main aquifers (Quaternary aquifer, Upper-Devonian aquifer, Upper-Middle-Devonian aquifer, and Lower-Middle-Devonian-Silurian aquifer) and represents an area of 45 000 km2. The cell size of the model varies from 0.25 to 1.00 km. The model was used to simulate three scenarios: (1) the base case scenario, which involved no abstraction, (2) the current abstraction, and (3) the maximum abstraction allowed. A detailed water balance for eight transboundary groundwater bodies for all three scenarios was calculated to assess water balance changes and groundwater flow along the national border.

Model results indicate that the groundwater balance between groundwater bodies remained the same in Simulations 1 (base case scenario) and 2 (current water extraction), which indicates that the existing water extraction in the territory does not significantly affect the transboundary groundwater flow. Some minor changes were observed in Simulation 3 (maximum water abstraction rates), mostly in the Upper-Devonian groundwater bodies. However, significant changes in cross-border groundwater flow patterns were not expected even with the maximum possible water abstraction.

The study has been founded by Iceland, Liechtenstein and Norway through the EEA and Norway Grants Fund for Regional Cooperation project No.2018-1-0137 “EU-WATERRES: EU-integrated management system of cross-border groundwater resources and anthropogenic hazards”.

How to cite: Hunt, M., Borozdins, D., Marandi, A., Männik, M., Demidko, J., Valters, K., Bikše, J., Popovs, K., Retiķe, I., and Hints, L.: Modeling the water balance of transboundary aquifers for assessing groundwater flow along the Latvia-Estonia national border, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-7947, https://doi.org/10.5194/egusphere-egu23-7947, 2023.

A.63
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EGU23-11510
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HS5.16
|
ECS
Inge de Graaf

In many regions of the world more groundwater is used than recharged by precipitation or infiltrating river water. While overuse of groundwater can have a variety of undesirable effects, among the most immediate and visible effects are reduction of river flows and the impact on freshwater ecosystems can be devastating.

In an alluvial aquifer, groundwater pumping can reduce the flow of water in a river in two ways: 1) pumping can intercept water that would otherwise discharge into the river; 2) pumping draws groundwater levels down below the level of the river and river water will infiltrate. In this study the impacts of groundwater pumping on river flow are estimated using a coupled global-scale groundwater-surface water model. Results show that nearly half of the pumped groundwater reduces river flow. Globally, approximately 20% of the pumped groundwater comes from increased river capture and 16% from a reduction in storage (averaged over the model period 1960-2010). Critical thresholds for groundwater discharge to support ecological integrity have already been crossed due to groundwater pumping in 15-21% of all river basins and are likely to be crossed in more than half of all river basins by 2050.

How to cite: de Graaf, I.: Impact of groundwater pumping on river flow, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-11510, https://doi.org/10.5194/egusphere-egu23-11510, 2023.

A.64
|
EGU23-880
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HS5.16
|
ECS
Limbikani Chitsundi Banda and the Limbikani Chitsundi Banda

The future of Malawi depends on the sustainable development of groundwater resources, and this study provides a detailed stable isotopic-hydrochemical baseline characterisation and conceptualisation of the Linthipe River Basin in the Lake Malawi Basin at the southern extreme of the East Africa Rift System. The Linthipe River Basin is essential for Lilongwe, Malawi's capital city, when it comes to key water supplies. It is also critical to the water supplies for the rural population whose reliance on groundwater resources is predominant. The study flagged groundwater as a potential source of water supply because the key source of water supply in the basin, the Kamuzu Dam along Lilongwe River, is constrained and imperilled by severe catchment degradation among other adverse factors. Sustainable groundwater resource development and management require proper monitoring and assessment, and isotope hydrology is a valuable tool for conducting comprehensive groundwater monitoring and assessment. The study showed the usefulness of isotope hydrology as an effective tool for examining groundwater conditions, its seasonal variations over time, its interactions with surface water, and its replenishment. The study also showed that isotope hydrology is a good way to look at the saltiness of groundwater and other chemical contaminants, considering that high salinity and other chemical contaminants limit and threaten its availability and quality, making it harder to reach the Sustainable Development Goals (SGDs). The study demonstrated how an understanding of the relationship between the stable isotopic composition of groundwater and surface water is crucial for the development of a conceptual model in a hydrologically complex river basin The study developed a stable isotopic-hydrochemical signature conceptual model that has the potential to shed new light on the most pressing issues in Integrated Water Resources Management (IWRM) systems in Malawi. The hydraulic complexity of the groundwater and surface water interactions revealed by the study is critical to IWRM and warrants high-resolution studies, for which the use of isotopic tools plays a critical role in tracking SDG 6 targets. The stable isotopic-hydrochemical baselines developed will improve the forensic study of potential future consequences stemming from environmental drivers like land development, climate change, and water mixing, all of which influence IWRM systems. Hence, the study valuably contributes to Malawi’s drive of achieving SDG 6 by 2030.

Key references:

  • Monjerezi, M.; Vogt, R.D.; Aagaard, P.; Saka, J.D.K. Using δ87Sr/δ86Sr, δ18O and δ2H isotope data along with major chemistry composition to assess groundwater salinization in lower Shire River Valley, Appl. Geochem. 2011, 26, 2201–2214. [CrossRef]
  • Chavula, G.M.S. Malawi. In Groundwater Availability and Use in Sub-Saharan Africa: A Review of Fifteen Countries; Pavelic, P., Giordano, M., Keraita, B., Ramesh, V., Rao, T., Eds.; International Water Management Institute: Colombo, Sri Lanka, 2012; Available online: http://www.iwmi.cgiar.org/Publications/Books/PDF/ groundwater_availability_and_use_in_sub-saharan_africa_a_review_of_15_countries.pdf (accessed on 15 October 2019).
  • Rivett, M.O.; Robinson, H.L.; Wild, L.M.; Melville, J.; McGrath, L.; Phiri, P.; Flink, J.; Wanangwa, G.J.; Mleta, P.; MacLeod, S.S.P.; et al. Arsenic occurrence in Malawi groundwater. J. Appl. Sci. Environ. Manag. 2018, 22, 1807–1816. [CrossRef]

How to cite: Chitsundi Banda, L. and the Limbikani Chitsundi Banda: Isotopic Characterisation and Conceptualisation of Linthipe River Basin to underpin Sustainable Groundwater Development and Management, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-880, https://doi.org/10.5194/egusphere-egu23-880, 2023.

A.65
|
EGU23-130
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HS5.16
|
ECS
|
Enoh Jeanot Fongoh, Helene Celle, Bertil Nlend, Suzanne Ngo Boum-Nkot, Ako Andrew Ako, Frederic Huneau, Nicolas Caillon, and Marie Joseph Ntamak-Nida

Shallow groundwater resources, especially in hard rock environment, constitute an important part of urban water supply in developing countries, appropriate to the low level of economic development. However, increasing urban population and dependence on shallow groundwater systems make it imperative to evaluate the availability and the contamination of these resources, and define new strategies of water exploitation taking into accounts these findings and constrains. This study has been carried out on the shallow groundwaters of Yaounde, central Africa. Based on head slug-in tests, chemical and isotope analyses, we demonstrate the importance of geomorphological and geological settings that constrain hydrogeology, urban occupation and therefore, water exploitation and contamination.  Slug test results show spatial variability of well recovery rates with higher values recorded in the valleys compare to the hills, presenting saturated hydraulic conductivity of 10-6-10-8 m/s. Groundwater evolves from recharge zone as Ca-HCO3 in the hillside lateritic system to discharge zone in the slope/valley colluvium/alluvium system as NaK-NO3. The groundwater composition dominated by silicates/water interaction in the hillside lateritic system, and anthropogenic processes in the slopes and valleys. δ15N and δ18O of nitrates indicates that nitrate pollution of groundwater is mainly from sewage and human waste. Shallow groundwater in the hillside/new urban district and to a lesser extent slopes should therefore be protected and prioritised for usability and sustainability of the resources while ensuring the abstraction of the deeper part of the shallow aquifer in the valley/central districts due to the presence of denitrification. The proposed conceptual scheme for Yaounde can then be used as a guide in the development, exploitation and management of local wells in hard rocks system of Africa.

How to cite: Fongoh, E. J., Celle, H., Nlend, B., Ngo Boum-Nkot, S., Ako, A. A., Huneau, F., Caillon, N., and Ntamak-Nida, M. J.: Hydrogeological proxies of urban weathered hard rock aquifers in Central Africa: Contribution for a sustainable water management and supply in high populated city, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-130, https://doi.org/10.5194/egusphere-egu23-130, 2023.

A.66
|
EGU23-11998
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HS5.16
Mauro Rossi, Marco Donnini, and Giulio Beddini

Groundwater recharge (GR) is the amount of water that infiltrates into the soil recharging aquifers. For Italy, we applied a water balance method for estimating GR, along with other balance components, using gratis/libre open access data and open source software. The results were compared with the data available from the literature on Central Italy, to validate the model and to investigate the variation in the GR, while considering different lithologies. The comparison of the GR results with anthropogenic water withdrawals enabled the evaluation of sustainable water use in Italy. The results show that in Italy the annual averaged GR is ~110 × 109 m3. This estimate may vary for specific years; in 1992 and 2015, the GR exceeded the value by 3% and 27%, respectively. According to these and related estimations, the 1981–2010 average groundwater withdrawals for civil, industrial and agricultural use were estimated to be ~14% of the averaged GR for the same period. In 1992, the withdrawals for the mineral water industry was about 0.01% of the GR and that for civil use was ~10% in 2015. In this study, we observed significant differences in the GR at the regional level, mostly influenced by the precipitation distribution and elevation. The proposed approach can provide quantitative data in line with the Goal 6 (Targets 6.4 and 6.5) of the 2030 Agenda for Sustainable Development of United Nations (https://sdgs.un.org).

How to cite: Rossi, M., Donnini, M., and Beddini, G.: Nationwide groundwater recharge evaluation for a sustainable water withdrawal over Italy, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-11998, https://doi.org/10.5194/egusphere-egu23-11998, 2023.

A.67
|
EGU23-16049
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HS5.16
|
ECS
Overview of Sudan Groundwater Resources Under Challenged Political Conditions
(withdrawn)
Hisham Abdel-Magid
A.68
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EGU23-13845
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HS5.16
|
ECS
|
Xinyang Fan, Tim Peterson, Benjamin Henley, and Meenakshi Arora

Climate change is projected to impact water resources in many countries around the world, but the projections are highly uncertain due to numerous assumptions of the hydrological stationarity, model structures, and complex hydrodynamics in the surface and subsurface. Quantifying the historic impact of climate variability and change on water resources allows for an improved understanding of the hydrological and climate processes which is necessary for accurate projections. Due to the long memory in groundwater systems of the impacts of climate variability and change, there is an opportunity to investigate the historic impact of long-term changes on water resources. Analysing groundwater hydrographs over multiple decades potentially allows for the quantification of the response of groundwater head to climatic changes. However, there are challenges in using this long-term information to quantify historic climate impacts. One of the challenges is to separate the impact of climatic change on groundwater from other influential drivers, such as pumping for agricultural irrigation, land use and land cover changes, and natural climate variability. In addition, the often short and interrupted nature of groundwater records limits the investigation of long-term impacts. In this study, we establish and test methods to quantify the response of groundwater to climate variability and change at natural sites (not affected by anthropogenic activities) identified across Australia, overcoming the aforementioned challenges. Results show that location, climate, and aquifer hydraulic property play a role in controlling the response of groundwater head and recharge to climate variations, compared with land use changes. This implies that future climate change may significantly impact groundwater availability by altering the response of groundwater. Quantifying the response of groundwater to climatic changes is needed to understand the future of groundwater systems globally. With this improved understanding we can work towards effective adaptive water management strategies for both human and natural systems.

How to cite: Fan, X., Peterson, T., Henley, B., and Arora, M.: Groundwater response to historic climate variability and change, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-13845, https://doi.org/10.5194/egusphere-egu23-13845, 2023.

Posters virtual: Thu, 27 Apr, 10:45–12:30 | vHall HS

Chairpersons: Rebekah Hinton, Robert Reinecke
vHS.15
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EGU23-12044
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HS5.16
|
Elco Luijendijk and Etienne Bresciani

The transmissivity of the subsurface controls groundwater flow but is highly variable and often uncertain. Here we use large datasets of groundwater level measurements and surface drainage to calculate transmissivity for 5000 points in the conterminous US. We designed a new algorithm that uses water table data, elevation and surface water location data to reconstruct the groundwater flow path, the groundwater discharge location and the groundwater divide for each data point. We subsequently calculate the ratio of recharge over transmissivity for each point using an analytical solution of the groundwater flow equation. Finally, we use independent estimates of groundwater recharge to estimate transmissivity. The results demonstrate the viability of combining large sets of water level data to quantify the spatial distribution of transmissivity. The algorithm will be published as an open-source code that can be used to automatically find groundwater flow paths and estimate transmissivity for large water level datasets.

How to cite: Luijendijk, E. and Bresciani, E.: Estimation of transmissivity across the conterminous US using large water table and surface water datasets, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-12044, https://doi.org/10.5194/egusphere-egu23-12044, 2023.