Conference Abstracts

Abstract

Groundwater discharge is crucial for transporting terrestrial carbon into streams and rivers, but the effects of groundwater flow paths on terrestrial carbon inputs are poorly understood. Here, we investigated environmental tracers (EC, Cl-, 2H, 18O, 220Rn, and 222Rn) and carbon concentrations in riparian groundwater, streambed groundwater, and stream water over six groundwater-stream monitoring sites. Significantly high 220Rn and 222Rn activities in the stream and endmember analysis results of the environmental tracers reveal that vertical groundwater discharge from the streambed (VGD) and lateral groundwater discharge from the riparian zone (LGD) is of equal importance for the stream. We quantified VGD by modelling the detailed 222Rn and Cl- profiles at the streambed and then combined differential flow gauging to estimate LGD. VGD (2.9 ± 1.4 m2 d-1) prevailed in relatively wide and shallow channels, while LGD (2.6 ± 2.6 m2 d-1) dominated narrow and deep channels. Carbon measurements indicate that LGD had the highest CO2, CH4, DIC, and DOC, while VGD had relatively higher CO2 but lower CH4, DIC, and DOC than stream water. Our findings suggest that LGD is the primary carbon source for the stream, while VGD mainly dilutes the stream (except CO2). Finally, we observed that groundwater discharge and temperature overrode metabolism in controlling stream carbon dynamics, implying the importance of groundwater discharge for understanding stream carbon cycling. Overall, this study identified the impacts of groundwater flow paths on carbon exchanges between terrestrial and stream ecosystems.

Abstract

Water balance partitioning within dryland intermittent and ephemeral streams controls water availability to riparian ecosystems, the magnitude of peak storm discharge and groundwater replenishment. Poorly understood is how superficial geology can play a role in governing the spatiotemporal complexity in flow processes. We combine a new and unusually rich set of integrated surface water and groundwater observations from a catchment in semi-arid Australia with targeted geophysical characterisation of the subsurface to elucidate how configurations of superficial geology surrounding the stream control the variability in streamflow and groundwater responses. We show how periods of stable stream stage consistently follow episodic streamflow peaks before subsequent rapid recession and channel drying. The duration of the stable phases increases in duration downstream to a maximum of 44±3 days before reducing abruptly further downstream. The remarkable consistency in the flow duration of the stable flow periods, regardless of the size of the preceding streamflow peak, suggests a geological control. By integrating the surface water, groundwater and geological investigations, we developed a conceptual model that proposes two primary controls on this behaviour which influence the partitioning of runoff: (1) variations in the permeability contrast between recent channel alluvium and surrounding deposits, (2) the longitudinal variations in the volume of the recent channel alluvial storage. We hypothesise optimal combinations of these controls can create a ‘Goldilocks zone’ that maximises riparian water availability and potential for groundwater recharge in certain landscape settings and that these controls likely exist as a continuum in many dryland catchments globally.

Abstract

A major surface water–groundwater interaction difficulty is the complex nature of groundwater resources due to heterogenic aquifer parameters. Wholistic research is needed to inform the conceptual understanding of hydrological processes occurring at surface and groundwater interfaces and their interactions at watershed scales. Sustainable water resource use and protection depend on integrated management solutions involving cross-disciplinary studies and integrated hydrological modelling. Choosing appropriate methods such as spatial and temporal scales, measurable indicators, differences in software parameters, and limitations in application often results in uncertainties.

The study aims to conduct a comparative literature analysis, integrating case studies focusing on surface water–groundwater interaction. Literature reviews from case studies focus on several factors, including soils and vegetation studies, hydrochemical signatures, hydrodynamics of the main stem channels, desktop land use assessments, surface water quality profiling, conceptual hydrogeological modelling and numerical modelling in support of understanding surface water – groundwater interaction and highlight the challenges of methods used to indicate baseflow transition. This paper considers the methodologies demonstrated in the literature and their use in numerical modelling to obtain measurable indicators related to the two hydrological disciplines comprising (i) the surface water component and (ii) the groundwater component. These outcomes should be used to inform the potential future impacts on water quality from activities such as mining, irrigation, and industrial development. Water management protocols related to integrated surface water and groundwater studies for the future are critical in ensuring sustainable water management methods on a catchment scale.

Abstract

Since 2018, the North China Plain has started a large-scale ecological water replenishment project for rivers and lakes, with 17.5 billion cubic meters total from the South–North Water Transfer Project and other water sources. It is a key question of how much water infiltration into aquifers will affect groundwater and how to characterize and evaluate this effect quantitatively. The groundwater numerical model of the Beijing-Tianjin- Hebei region as the main part of the North China Plain was established using a numerical simulation method, and the groundwater level variation under the replenishment condition was simulated and predicted. By comparing the two scenarios, the relative rise method of groundwater level was proposed to characterize the influence of river water infiltration on groundwater level, and the unstructured grid method was used to refine cells near the river to improve simulation accuracy. Simulation results show that the groundwater level around some rivers has risen significantly in the past four years, especially in the alluvial fan regions with better infiltration properties. Accordingly, at the Piedmont alluvial fan region, there is also a large influence range on groundwater level. The maximum influence distance is more than 10km (0.1m relative rise of groundwater level was taken as the influential boundary). According to the prediction, if the water replenishment project continues, the range of influence can continue to expand, but the expansion rate will slow down due to the reduction of the hydraulic gradient.

Abstract

Case studies illustrate a conceptual framework for shallow groundwater flow systems’ temporal and spatial variability with groundwater-surface water interactions in the Boreal Plains of Canada. The framework was developed using a twenty-year hydrometric dataset (e.g., climatological and streamflow data, hydraulic heads, vertical hydraulic head gradients, geochemical and isotopic signatures). The region is characterized by low-relief glacial landscapes, with a mosaic of forestlands and peatlands, and a subhumid climate, resulting in spatially heterogeneous storage and transmission properties, variable recharge and evapotranspiration potentials, and highly complex patterns of water movement. Two primary spatiotemporal scales were examined to create a holistic, variable-scale conceptual model of groundwater movement: the large scale (e.g., glacial landforms, regional topography, decadal climate cycles) and the small scale (e.g., individual landcover, local hummocks, annual moisture deficits). Water table behaviour, evapotranspiration rates, and runoff were controlled by a hierarchy of interactions between hydrological processes occurring at different spatiotemporal scales; however, the specific order of controls depends on the hydrogeological setting. The case studies, supported by empirical and numerical modelling, demonstrate that smaller-scale heterogeneities in geology and recharge can dominate over topographic controls, particularly in areas with high conductivity or hummocky terrain, where the climate, geology, and topographic relief are similar. Many hydrogeological studies rely on surface topography as a first‐order control; however, with field observations and modelling, this conceptual framework demonstrates the need to consider the potential dominance of subsurface characteristics and processes, plus climate, especially in landscapes with low recharge and low relief.

Abstract

Electromagnetic (EM) techniques were used to map groundwater salinity and clay layers in the Netherlands. The EM method used the so-called time domain system, is towed behind an ATV and is therefore called towed TEM. The results revealed a detailed 3-dimensional insight into the subsurface’s sequence of clay and sandy layers. Also, shallow saline groundwater, far from the coast, has been detected related to a subsurface salt dome. The rapid, non-destructive data acquisition makes the tTEM a unique tool. Electromagnetic (EM) techniques detect electrical conductivity contrasts in the subsurface with depth. EM data can often be interpolated into a 3D model of electrical conductivity. Expert knowledge of the regional geohydrologist, together with existing (borehole) data, is paramount for the interpretation. The towed Transient Electro-Magnetic system (tTEM) is developed to acquire data up to 60-80m depth by driving a transmitter and a receiver behind an ATV. With a speed of 10-15 km/h, measurements are collected every 5m. On fields, the distance between lines is typically 20m, resulting in a dense network of data that is inverted into 1D resistivity models, showing the variation of conductivity with depth. Interpolating 1D resistivity models into a 3D model allows for further interpretation in terms of geology, lithology, and groundwater quality. The tTEM technique bridges the gap between point measurements and more expensive and lower-resolution airborne EM data collection. The technique is sensitive to disturbance by man-made conducting infrastructure.

Abstract

Test-pumping drawdown curves do not always sufficiently indicate aquifer characteristics and geometry and should never be analysed in isolation. Using derivative analysis and flow dimension theory, inferring the regional geometries and flow characteristics of fractured aquifers that are otherwise unknown or inconclusive is possible. As the drawdown and/or pressure front propagates through the aquifer, it reaches various hydrogeological objects that influence flow regimes and imprints a sequence of signatures in the drawdown derivative curve. The conjunctive interpretation of these flow regime sequences and hydrogeological data results in a robust, well-informed conceptual model (in terms of both local groundwater flow and the aquifer), which is vital for sustainable groundwater resource management. Derivative and flow regime analysis was applied to the test-pumping data of confined and unconfined Nardouw Aquifer (Table Mountain Group) boreholes within Steenbras Wellfield (Western Cape). Major NE-SW trending folding and transtensional Steenbras-Brandvlei Megafault Zone, in association with cross-cutting faults/fractures and younger False Bay Suite dykes, make the Nardouw Aquifer (and deeper Peninsula Aquifer) hydrogeologically complex. The sequential flow regime analyses reveal domains of conceptual flow models, including open vertical fractures, T-shaped channels, double (triple) porosity models, and leaky/recharge boundary models, amongst others. Appropriate analytical flow models (type curve fitting) are then applied for accurate aquifer parameter estimations, which are used to evaluate recommended long-term yields through predictive pumping scenarios. The outcome is an improved hydrogeological understanding and enhanced conceptual model of the aquifer, which informs numerical modelling, ecological protection, and groundwater resource management.

Abstract

Annually, UNICEF spends approximately US$1B in water, sanitation and hygiene programming (WASH), approximately half of which is spent in humanitarian contexts. In emergencies, UNICEF supports the delivery of water, sanitation and hygiene programming under very difficult programming contexts – interruptions to access, power supply and a lack of reliable data. Many of these humanitarian situations are in contexts where water scarcity is prevalent and where the demand and competition for water are increasing, contributing to tension between and within communities. While water scarcity is not new to many of these water-scarce areas, climate change is compounding the already grave challenges related to ensuring access to safe and sustainable water services, changing recharge patterns, destroying water systems and increasing water demand. Incorrectly designed and implemented water systems can contribute to conflict, tension, and migration. Ensuring a comprehensive approach to water security and resilient WASH services can reduce the potential for conflict and use water as a channel for peace and community resilience. This presents an enormous opportunity for both humanitarian and development stakeholders to design water service programmes to ensure community resilience through a four-part approach: 1. Groundwater resource assessments 2. Sustainable yield assessments (taking into consideration future conditions) 3. Climate risk assessments 4. Groundwater monitoring/early warning systems UNICEF promotes this approach across its WASH programming and the sector through technical briefs, support and capacity building.

Abstract

Slug tests are preliminary tests applied to determine the hydraulic conductivity and whether it is necessary to perform a pumping test on the borehole under investigation and should never be recommended as a substitute for a pumping test. For this reason, slug tests cannot be related to sustainable yield because slug tests cannot detect boundary conditions. The aim was to develop a methodology to relate slug tests to a potential yield estimation, investigating and reviewing the applicability and accuracy of the slug test methodology in South Africa, applied on fractured rock aquifers as established in 1995. The aim was achieved by reviewing the methodology applied for slug tests that are related to potential yield estimations, identifying the limitations of slug tests, investigating the possibility of updating the potential yield estimation method of 1995, and investigating the possibility of relating slug tests, to potential yield and transmissivity estimations through groundwater modelling. The investigation revealed that using transmissivity values determined through slug test homogenous modelling can be utilised to estimate the potential yield of a borehole under investigation by implementing correlation statistics. Note that this is not an absolute and is subject to limitations.

Abstract

Underground coal gasification (UCG) is a high-temperature mining method that gasifies coal in situ to produce a synthetic gas that can be used as feedstock for industrial purposes. Coal conversion leads to mineral transformation in the gasifier, which ultimately interacts with the rebounding groundwater post-gasification. This poses a groundwater contamination risk, the biggest environmental risk from a UCG geo reactor. There is currently no model for UCG operators and regulators to assess the total risk of groundwater contamination from UCG operations. This study collates literature on groundwater contamination from UCG operations and presents a workable but comprehensive groundwater risk assessment model for a spent UCG chamber. The model follows the source-pathway-receptor arrangement where groundwater contamination sources are identified as ash, char, roof and floor. All possible pathways are assessed for hydraulic connections with the spent geo-reactor via acceptable geochemical tests, including stable isotopes, hydrochemistry and stratification analysis. Finally, the receptor aquifers (e.g. shallow aquifers) are monitored periodically to determine if contamination has occurred.

Abstract

The Netherlands produces about 2/3 of drinking water from groundwater. Although there is seemingly abundant groundwater, the resource needs to be carefully managed and used wisely to safeguard the resource for future generations and in case of disasters whilst also preventing negative impacts from groundwater extraction on other sectors such as nature. Provincial governments are responsible for the protection of existing groundwater abstractions for water supply against pollution. To secure groundwater resources for the future, two additional policy levels have been introduced: Provincial governments have been made responsible for mapping and protecting Additional Strategic Reserves. These allow for additional groundwater abstractions to meet growing demands in coming decades (horizon 2040/2050). The National Government is responsible for mapping and protecting the National Groundwater Reserves (NGRs) as a third level of resource protection. NGRs serve multiple goals: to protect natural groundwater capital for future generations, to provide reserves for large-scale disasters affecting water supply and to provide reserves for possible use as structural water supply in the far future (horizon 2100 and beyond). NGRs are being delineated in 3D using detailed existing geological models and the Netherlands’ national (fresh-saline) hydrological model. The dynamics of the groundwater system are analysed through scenario analyses. Reserves for potential structural use are selected such that negative impacts on nature are prevented if future abstractions are to be realised. The policies being developed must balance interests of water supply against other sectoral interests such as the green-energy transition with increased use of geothermal energy and aquifer-thermal-energy-storage.

Abstract

Groundwater is an important freshwater supply that has a significant role in the economy. However, water is increasingly becoming scarce in several regions. Huai Krachao Subdistrict in Kanchanaburi Province is an example of an area that has been experiencing a severe drought for decades due to the impacts of climate change. This study was conducted to delineate the groundwater potential zones in hard-rock terrains using geographic information system (GIS) techniques. The study aims to explore deep groundwater resources in challenging areas and propose alternative methods supporting traditional groundwater exploration. This finding revealed that the groundwater potential zones were classified into high, moderate, and low potential zones based on the groundwater potential index (GWPI), integrated using the Weighted Index Overlay Analysis. The computed weights from the Analytical Hierarchy Process were acceptable and consistent. The high potential zones mainly occur in the Silurian-Devonian metamorphic rocks. The GIS-based analytical results were later prepared for detailed field investigation, including collecting well information and conducting the 2-dimensional geophysical survey. To prove the GWPI map, 9 groundwater wells were drilled in the high potential zones. Consequently, well yields obtained from the pumping-test analysis ranged from 24-40 m3 / hr, some of which are springs rich in dissolved minerals. Accordingly, a significant amount of water could meet the water demand, supplying about 1 million m3 /year. Under these circumstances, discovering new groundwater resources can support roughly 5,000 people and agricultural lands no less than 480 hectares (4.8 km2 ).

Abstract

Knowledge of the nature and extent of groundwater-dependent ecosystems (GDE) at an aquifer scale enables incorporating ecological water requirements in integrated groundwater resource management activities, including transboundary aquifer cases (TBA). This way, sustainable groundwater management and functional ecosystem services can be achieved. Therefore, understanding groundwater- ecosystems-surface water interactions is crucial for assessing resources’ resilience or susceptibility towards certain impacts. Unfortunately, this subject is widely under-researched with fragmented information, especially in southern Africa. This study was thus initiated to understand groundwater processes controlling the maintenance of Tuli-Karoo TBA (Botswana, South Africa, Zimbabwe) GDEs towards developing a model that can be utilised in impact assessments, especially in climate change. The employed approach included stable isotope analysis (mainly 2 H and 18O) for groundwater, streams, springs, rainwater, vegetation, and soil; spatial imagery and GIS classification (incl. NDVI, NDRE, NDWI); and plant moisture stress techniques. Identified GDEs in the study area (characterized by intergranular alluvium aquifer underlain by the Karoo sandstone of intergranular and fractured secondary aquifer type) are riparian vegetation, floodplain and depression wetlands, and springs. Precipitation recharged alluvium aquifer’s contribution to Limpopo River baseflow is negligible as the discharge is mainly through springs and evapotranspiration. Monitoring data scarcity and skewed availability among sharing countries hamper research and its output applicability to TBA’s entirety. Therefore, data generation, exchange, and joint databases development are crucial for sustainable comanagement of groundwater and supported ecosystems and science-based decision-making.

Abstract

Due to technical, social, and economic limitations, integrated groundwater management presents a significant challenge in developing countries. The significance of this issue becomes even more pronounced in groundwater management, as this resource is often overlooked and undervalued by decision-makers due to its status as a “hidden resource,” despite the fact that it provides multiple ecosystem services. This study aims to establish the technical hydrogeological foundation in rural basins of central Bolivia through alternative, simplified, and cost-effective methods and tools. The study includes applying geophysical techniques, such as Electrical Resistivity Tomography, to determine the conceptual hydrogeological model of a micro-basin. In addition, a soil water balance approach was applied, characterizing 24 biophysical variables to identify groundwater recharge zones, while global circulation models provided a substitute for unreliable meteorological data. Furthermore, a participatory model was developed to identify recharge areas in upper basin areas within the framework of developing a municipal policy for their protection. The participatory model included local knowledge in all stages of methodology development, considering the characteristics of the local plant communities and the spatial distribution of local rainfall. The research findings have already contributed to resolving socio-environmental conflicts in Bolivia and establishing a foundation for effective water governance by empowering local rural communities. This study has demonstrated the feasibility of using alternative, simplified, and low-cost methods and tools to establish the technical hydrogeological basis, which can inform public policies to promote sustainable groundwater management in developing countries.

Abstract

Groundwater in flooded abandoned mines could be used for geothermal purposes using heat pumps and an open loop involving pumping and re-injection. Hydraulic conductivity values of the mined rock zones have been artificially increased. However, long-term efficiency and the possible impacts of geothermal doublets must be studied involving a series of hydrogeological challenges. Hot water would be pumped from the deep parts of the mine works, and cold water would be re-injected in a shallower gallery or shallow fractured rocks, with a seasonal flow inversion for building cooling during the hot season. Indeed, a ‘short-cut’ groundwater flow is to be avoided between the mine’s deep and shallow parts. The true geometry of the interconnected network of open galleries and shafts can be highly complex and must be conceptualized realistically to ensure that the model is feasible and reliable.

This model must involve groundwater flow and heat transport, with temperature-dependent density and viscosity, in a complex 3D heterogeneous domain of highly fractured rocks and partially collapsed exploitation zones, galleries, and shafts. Such a model is nevertheless widely recommended to design and optimize the short--, mid-, and long-term efficiency of the geothermal system and assess possible environmental impacts. An example of simulations on a synthetic case will be used for illustration and preparation work before further application in a real case study.

Abstract

Recent findings allow a better insight into the interaction between two aquifers and their vulnerabilities at the groundwater extraction site of Velm, which produces drinking water for around 55,000 households. The shallow aquifer that is exploited is situated in the Formation of Hannut. This aquifer is vulnerable to pollution, especially from the agricultural lands close to the extraction site and is sensitive to natural recharge. In this case, the groundwater is captured in a basin via a naturally occurring spring flow. The second aquifer is situated in the Cretaceous at 50 to 100 m below the surface and is pumped by four wells. The drinking water quality is guaranteed by mixing and treating these two waters. To optimize the central decalcification and the pollution risks, the production volume in the deep aquifer was increased from 2017 to 2021 at the expense of the shallow aquifer. This led to a decrease in the available volumes of the shallow aquifer, which indicated a leakage from the shallow to the deeper aquifer, which was unexpected. Groundwater modelling and time series analysis have been used to assess the impact of the increased production volumes and the longer dry periods. Based on this data, a maximum production volume of 1,000,000 m3 /year is considered best for the cretaceous aquifer. With this extraction rate in the Cretaceous, it is possible to supply sufficient drinking water and limit the impact on the Formation of Hannut.

Abstract

The devastating socioeconomic impacts of recent droughts have intensified the need for improved drought monitoring in South Africa (SA). This study has shown that not all indices can be universally applicable to all regions worldwide, and no single index can represent all aspects of droughts. This study aimed to review the performance and applicability of the Palmer drought severity index (PDSI), surface water supply index (SWSI), vegetation condition index (VCI), standardised precipitation index (SPI), standardised precipitation evapotranspiration index (SPEI), standardised streamflow index (SSI), standardised groundwater index (SGI), and GRACE (Gravity Recovery and Climate Experiment)-based drought indices in SA and provide guidelines for selecting feasible candidates for integrated drought monitoring. The review is based on the 2016 World Meteorological Organization (WMO) Handbook of Drought Indicators and Indices guidelines. The PDSI and SWSI are not feasible in SA, mainly because they are relatively complex to compute and interpret and cannot use readily available and accessible data. Combining the SPI, SPEI, VCI, SSI, and SGI using multi-index or hybrid methods is recommended. Hence, with best fitting probability distribution functions (PDFs) used and an informed choice between parametric and non-parametric approaches, this combination has the potential for integrated drought monitoring. Due to the scarcity of groundwater data, investigations using GRACE-based groundwater drought indices must be carried out. These findings may contribute to improved drought early warning and monitoring in SA.

Abstract

Groundwater (GW) is a target of climate change (CC), and the effects become progressively more evident in recent years. Many studies reported the effects on GW quantity, but of extreme interest is also the assessment of qualitative impacts, especially on GW temperature (GWT), because of the consequences they could have. This study aims to systematically review the published papers dealing with CC and GWT, to determine the impacts of CC on GWT, and to highlight possible consequences. Scopus and Web of Science databases were consulted, obtaining 144 papers. However, only 45 studies were considered for this review after a screening concerning eliminating duplicate papers, a first selection based on title and abstract, and an analysis of topic compatibility through examination of the full texts. The analysed scientific production from all five continents covers 1995-2023 and was published in 29 journals. As a result of the review, GWT variations due to CC emerged as of global interest and have attracted attention, especially over the past two decades, with a multidisciplinary approach. A general increase in GWTs is noted as a primary effect of CC (especially in urban areas); furthermore, the implications of the temperature increase for contaminants and groundwater-dependent ecosystems were analysed, and various industrial applications for this increase (e.g. geothermy) are evaluated. It’s evident from the review that GWT is vulnerable to CC, and the consequences can be serious and worthy of further investigation.

Abstract

The drinking water health issues have been considered due to improved living standards in recent years. Finding and developing high-quality groundwater with high-level minerals has become key to improving human health. The hydrochemical test data of 66 springs in Zhaojue County were analyzed using various methods, and the spatial distributions of H2 SiO3 -rich groundwater, hydrogeochemical characteristics, formation conditions and genesis were revealed. The main results including: 1) the groundwater with H2 SiO3 (≥25mg / L) was identified as the low salinity and alkaline water, which distributed in the six areas with the basement rocks of basalt,with a distribution area of about 79 square kilometers. The H2 SiO3 concentration was generally 25.74~46.04 mg/L; the low mineralization characterized the H2 SiO3 -rich groundwater of study area while the main hydrochemical types of groundwater are HCO3 - Ca·Mg, HCO3 -Ca, and HCO3 -Na; the Pearson correlation coefficient between the content of H2 SiO3 in groundwater and the content of pH is relatively high, indicating that the level of H2 SiO3 in groundwater in the study area is significantly affected by the pH value of the solution; the H2 SiO3 -rich groundwater was influenced by the water-rock interactions, the distribution range and solubility of silicate minerals ,the development of surrounding rock fissures, and water conservation and recharge conditions in the county, among which the water-rock interactions play a critical role. The results can provide a basis for the development of mineral water industry and the construction of urban and rural high-quality water sources in Zhaojue County.

Abstract

Managed Aquifer Recharge (MAR) provides an integrated water governance solution that improves water security for communities and farmers by storing water in aquifers and managing groundwater extractions to ensure water supplies are available during droughts. Quantitative analysis of levelised costs and benefit-cost ratios (BCRs) of 21 MAR schemes from 15 countries and qualitative assessment of additional social and environmental benefits demonstrates the benefits of MAR compared to water supply alternatives. Cost-benefit analysis provides a systematic method for comparing alternative water infrastructure options. Levelised cost is a widely accepted method of comparing MAR with alternative water infrastructure solutions when market valuations of water are unavailable.

The benefits of MAR can be estimated by the cost of the cheapest alternative source of supply or the production value using water recovered from aquifer storage. MAR schemes recharging aquifers with natural water using infiltration basins or riverbank filtration are relatively cheap with high BCRs. Schemes using recycled water and/or requiring wells with substantial drilling infrastructure and or water treatment are more expensive while offering positive BCRs. Most MAR schemes have positive or neutral effects on aquifer conditions, water levels, water quality, and environmental flows. Energy requirements are competitive with alternative sources of supply. This analysis demonstrates strong returns to investment in the reported MAR schemes. MAR provides valuable social and environmental benefits and contributes to sustaining groundwater resources where extraction is managed.

Abstract

While traditional well and spring sampling are limited to the integration of point data and the interpolation of the data across large scales. Electrical measurements of aquifers can be extended across a range of scales and integrated to provide an improved quantitative understanding of groundwater systems. At a site in Oklahoma, USA, a karst-managed aquifer recharge research site is being used to test electrical techniques for aquifer characterization on the kilometer scale and monitoring the aquifer on the meter scale. At the kilometer scale, the data illustrate fault locations, siphons in flow paths, and previously uncharacterized conduits. At the metre scale, the monitoring data illustrate porosity structure, flow paths, and potential biological changes in the subsurface. The results indicate that electrical approaches can significantly change aquifer conceptual models and provide targeted sampling locations in karstic bedrock aquifers.

Abstract

The lack of reliable groundwater level monitoring data hinders the comprehensive understanding and sustainable management of our aquifers. New remotely sensed data products could present novel possibilities to fill in situ data gaps. For example, continuous monthly groundwater storage anomaly estimates at a spatial resolution of 0.25° (28 km) are made available through the Global Data Assimilation System Version 2.2 (GLDAS-2.2) data products that assimilate Gravity Recovery and Climate Experiment (GRACE) data. In this study, it was hypothesised that the open-source, higher resolution Climate Hazards Group InfraRed Precipitation With Station Data (CHIRPS) precipitation data and Moderate Resolution Imaging Spectroradiometer (MODIS) evapotranspiration data could be used to downscale groundwater storage anomalies (GWSA) for local scale investigations. Using an intergranular and fractured aquifer, as well as a karst aquifer as case studies, both enclosed within the Steenkoppies Catchment (A21F), two respective random forest regression (RFR) models were developed to downscale GLDAS-2.2 GWSA. Sampling monthly training data without accounting for temporal lagging resulted in an increased correlation, index of agreement (IA) and improved RMSE for the intergranular and fractured aquifer. Where the correlation between the observed groundwater storage changes and the GLDAS-2.2 groundwater storage estimates were weaker, however, accounting for the temporal lags resulted in an improved RMSE. The final product is a 0.05° (5.5 km) grid of monthly time-series GWSA estimates that can improve groundwater resource assessments, understanding aquifer recharge, modelling accuracies and better overall decision-making regarding Integrated Water Resource Management (IWRM).

Abstract

Nearly 1.9 billion people live in marginal environments, including drylands, semiarid, arid, and hyperarid environments. Obscure but ubiquitous circular pockmark depressions dot these lands. These circular depressions can range from a few meters to kilometers, and the depth of these depressions varies from a few centimeters to over 10 m. However, the genesis of the circles has been investigated among scientists for many years because of their obscure nature. Some researchers believe that termites cause fairy circles, while others believe they are caused by plants competing for water and nutrients. This study documented the Africa-wide prevalence and extent of the pockmarks for the first time, and it further classified the pockmarks according to their genesis and hydrological roles. We further investigated their relevance in serving as nature-based solutions to overcome water scarcity in dryland regions. So far, field evidence in Ethiopia and Somalia showed that these features potentially have water security significance in a) organizing surface water flows over arid/semi-arid landscapes, b) serving as the site of temporary surface water storage, and c) serving as the site of focused groundwater recharge into the underlying aquifers. This presentation will highlight the spatial prevalence, extent, and genesis model of the pockmarks across the drylands in Africa (South Africa, Namibia, Somalia, Ethiopia, Kenya, Chad, Senegal, Mali, Niger, etc.).

Abstract

Previous studies have shown that river-aquifer connectivity exists. However, an integrated approach that consists of multiple measuring methods to quantify and characterise such connectivity still needs improved scientific understanding due to the underlying principles and assumptions of such methods, mainly when such methods are applied in a semi-arid environment. Three techniques (hydrogeochemistry, stable water isotopes, and baseflow separations) were applied to quantify and characterize river-aquifer interactions. The study’s objective was to improve knowledge and understanding of the implications of the results from the three methods. Field measurement, laboratory assessment, and record review were used to collect primary and secondary data. Results showed that Na- HCO3 water type dominated the upper stream, discharging onto the surface and forming stream sources. Na-HCO3 water type was an outlier when the area’s geology and land use activities were assessed. The isotope results showed that the studied aquifer had 9% recently recharged water. Being the upstream, the freshwater in such a mountainous aquifer was expected. The baseflow index (BFI) results showed that the dependency of the total river flow to aquifer discharge contributed 7.24 % in the upper stream, 7.31% in the middle stream, and 7.32% in the lower stream. These findings provided empirical evidence that hydrochemistry, stable isotopes, and baseflow separation methods provide key insights into aquifer-stream connectivity. Such findings inform choosing appropriate and relevant measures for protecting, monitoring, and allocating water resources in the catchments.

Abstract

In 2021-23, northern Italy suffered a severe drought due to the absence of rainfall, which strongly affected the pre-alpine lake levels, affecting energy production, agriculture and sustainable river flows. This led to harsh consequences on agriculture, which in the Lombardy region almost completely relied on flooding irrigation methods using water from lakes through Ticino and Adda rivers. As part of the INTERREG Central- Europe project “MAURICE”, which focuses on Integrated Water Resources Management, the winter irrigation practice is proposed as a climate change adaptation strategy. The main project idea is to store surface water in aquifers in periods of exceedance (autumn/winter) using the very dense channels irrigation network as a “natural” infiltration system. The underground storage would increase the groundwater levels, bringing two main advantages during the spring/summer seasons: a good flow rate at plain springs and, in periods of water scarcity, the possibility to extract groundwater for agricultural purposes. Relying on the slow groundwater velocity (about 350 m/y), this practice keeps water stored in the subsoil just below the irrigated areas where the water is needed.

In the early project stage, a basin-scale numerical model is presented to test the potentiality of such practice. A specified water volume was distributed on the crop fields during the winter period, and the effects of such managed recharge were evaluated, also considering the possible problems deriving from the groundwater levels increase. The model demonstrates the adaptation measure feasibility, which will be tested at a field scale in a Pilot Area.

Abstract

In the context of climate change, this work aims to model the piezometric levels of the foothill aquifer located in the middle-high Brenta river plain (Veneto, Italy) to support managing a groundwater system that provides drinking water for most of the Veneto Region. Using a Data-Driven approach, predictive Multiple Linear Regression Models were developed for the piezometric level at different wells, and scenarios of groundwater level evolution were achieved under dry periods. Results highlighted the high sensitivity of the aquifer to climate extremes, as well as the need to plan actions for mitigating the effects on such a strategic water supply system. Groundwater hosted in the foothill aquifer represents an important resource. However, these systems are highly sensitive to the variation of Meteo-climatic regimes. At the same time, the exploitations can lead to excessive groundwater drawdown and consequent threats of water scarcity. The Data-Driven approach adopted using long time series of meteorological, hydrometric and piezometric data can represent a valid example in these terms. The groundwater level evolution has been well-reproduced by these models. The equations describing models show the close dependence of groundwater from the Brenta River and the high sensitivity of the aquifer to meteo-climate regimes. Given this sensitivity, the forecast of groundwater level evolution under a dry period, similar to 2022, was performed. Results point out a progressive drawdown of groundwater level. These predictive models can be useful for local authorities to maintain these levels over specific critical values.

Abstract

he Danakil Depression of the Afar Rift forms part of the north/south-trending Ethiopia-Eritrean arm of the East African Rift System, whereas the western margin of the depression forms part of an active plate boundary between the western Nubian and eastern Danakil tectonic blocks. Dallol (within the Danakil Depression) currently holds the record for the highest average temperature for an inhabited place on Earth, with annual average temperatures of ~35-36°C. The isolated area was initially explored geologically in the late 1960s, with recent geological and hydrogeological interest in its northeast Ethiopian portion due to easier access, geo-tourism and potash-ore exploration. Potash mining is proposed via solution-extraction techniques, requiring large volumes of water in one of the driest hyper-arid regions. Various hydrogeological investigations were therefore conducted between 2014 and 2016 as part of a feasibility and water resource study towards developing a water resource estimate for the region and proposed mining operations. Alluvial fans on the west side of the rift basin form a major, regional primary aquifer – fan boreholes have yields of 50 litres per second, although groundwater is highly saline (up to 3-5 times the salinity of seawater) and can reach temperatures of 50°C. Groundwater yields of hundreds of millions of cubic metres per annum are potentially available from the saline alluvial fan primary aquifers for potash solution mining. In contrast, groundwater from karstic limestone aquifers could provide a freshwater resource to settlements within the Lelegheddi River basin and the Danakil.

Abstract

To explore the sources of pollution and health risk profile of heavy metal elements in groundwater,41 sets of representative groundwater samples from the southwest subbasin of the Shiqi River were examined for 10 heavy metal elements, correlation analysis and principal component analysis were used to resolve the possible sources of heavy metal contamination in groundwater. The concentration characteristics and health risk levels of the 10 heavy metals were assessed using the single factor contamination index (Pi), the Nemerow comprehensive contamination index (PN) and the health risk model. The results show that: 1) The average values of heavy metal elements of the groundwater in the study area all met the limit of class III water standard in the quality standard for groundwater; only the maximum value of Al was exceeded, followed by a large variation in the concentrations of Al, Mn and Cr. The heavy metal element with the largest average contribution was Al (65.74%). 2) The results of the single factor contamination index evaluation show that only the heavy metal element Al exceeds the level, and the results of the Nemerow comprehensive contamination index evaluation show that the study area is basically at low pollution levels and the quality of groundwater is good. 3) The results of the multivariate statistical analysis show that Zn, Co and Mn are mixed sources of geological formation and domestic waste, Al, As, and Cu are agricultural sources, Cd, Cr and Ni are industrial sources, and Hg comes from long-range atmospheric transport.

Abstract

Diverse tools exist to study the transfer of contamination from its source to groundwater and related springs. A backward approach, i.e. sampling spring water to determine the origin of contamination, is more complex and requires multiple information. Microbial source tracking (MST) using host-specific markers is one of the tools, which, however, has shown to be insufficient as a stand-alone method, particularly in karst groundwater catchments. A karst spring in the Swiss Jura Mountains was studied concerning the occurrence and correlation of a set of faecal indicators, including classical parameters and bacteroidal markers. Sporadic monitoring proved the impact on spring water quality, mainly during high water stages. Additional event-focused sampling evidenced a more detailed and divergent pattern of individual indicators. A multiple-tool approach, complementing faecal indicator monitoring with artificial tracer experiments and measuring natural tracers, could specify the origin of ruminant and human faecal contaminations. Natural tracers allowed for distinguishing between water components from the saturated zone, the soil/epikarst storage, or freshly infiltrated rainwater. Additionally, the breakthrough of injected dye tracers and their remobilization during subsequent recharge events were correlated with the occurrence of faecal markers. The findings hypothesize that human faecal contamination is related to septic tanks overflowing at moderate rainfall intensities. Linkage with vulnerability assessment and land-use information can finally better locate the potential point sources. Such a toolbox provides useful basics for groundwater protection and catchment management and insight into general processes governing the fate and transport of faecal contaminants in karst environments.

Abstract

Water resources, including groundwater, are under threat globally from abstraction and pollution, making studies of water flows ever more urgent. South Africa has a growing population, a relatively dry climate and abundant mining activity, all of which increase the importance of water management. Mooiplaas Dolomite Quarry, southeast of Pretoria, has been mining metallurgical grade dolomite since 1969 and is located in the productive karst aquifers of the Malmani Subgroup, Transvaal Supergroup. The site was investigated by sampling precipitation, surface water, groundwater and mine water for hydrochemical and stable isotope analysis from 2011 to 2017, totalling over 400 samples. Nitrate levels in groundwater and mine water were marginally above drinking water limits from explosives residues, and ammonia in the nearby Hennops River was unacceptably high due to municipal sewage outfalls, but otherwise, water quality was very good. Alkalinity from rock weathering, aided by the crushing of dolomite, was the main control on water chemistry. Combined analysis of dissolved matter (TDS, nitrate, Mg, etc.) suggested that the dewatering of the mine and resultant recharge from slime dams caused an aerated zone of groundwater, which mixed with regional groundwater flowing beneath the site. Stable isotopes, with an evaporated signature from mine open water bodies, also showed how mine operations cause recharge to groundwater and subsequent seepage back into the pit lakes. The mine appears not to contaminate the regional groundwater. However, mine designs should avoid situations where process water flows via groundwater back into pits, causing excessive dewatering costs.

Abstract

South Africa faces serious water scarcity challenges not only because it is a semi-arid country but also due to climate change. One of the most significant effects of climate change is an increase in temperature, which inevitably increases evaporation. Increased evaporation directly reduces the availability of surface water resources. Groundwater is less susceptible than surface water resources to evaporation and thus offers resilience against the impacts of climate change. Many South African cities, communities, and farmers depend on groundwater for domestic or other socio-economic purposes. This implies that groundwater resources which are currently or potentially utilisable should be identified, and suitable legal measures should be implemented to protect these resources from potential risks of harm or damage posed by anthropogenic activity. First, This article evaluates the effectiveness of the country’s existing regulatory framework to effectively protect South Africa’s groundwater resources and finds that the framework can be improved significantly. Secondly, it explores regulatory opportunities within the existing legal framework to strengthen South Africa’s groundwater governance regime, including using land use planning instruments to facilitate the implementation of groundwater protection zones

Abstract

Top-down governance systems are not well designed to secure the protection, use and management of groundwater at the local level and, on the contrary, perpetuate ‘wicked’ problems of poor groundwater management and protection. Citizen science promises solutions to these ‘wicked’ problems. We present findings from a project in the Hout Catchment, Limpopo, where citizen scientists monitor water in wells in remote rural settings. We redress the bias towards the natural sciences and pay attention to human systems as it is through engaging with people’s ‘ordinary’ citizens that they will protect their environment for better planetary health. To better understand these human systems that impact groundwater, we emphasise diversity and difference and argue for a HOPE model (heralding optimal participatory equity). HOPE has intrinsic and extrinsic value (equity) (addressing a hydrological void and understanding groundwater features). To achieve this, we open up a toolkit providing very practical methods. Using these tools, we propose that citizen science - taking science away from remote institutions, out of libraries and laboratories - and bringing it close to people is emancipatory and addresses new ways of understanding polycentric governance. Citizen science is transformative; citizens move from a passive state of non-engagement with science to acting as scientists. Disempowered people now have a sense of being part of the betterment of their world and improved water resources management. Narrowing the natural and social sciences divide is crucial for improved polycentric governance.

Abstract

This study focused on improving the understanding of flow regimes and boundary conditions in complex aquifer systems with unusual behavioural responses to pumping tests. In addition, the purpose was to provide a novel analysis of the hydrogeological properties of aquifers to deduce inferences about the general expected aquifer types to inform new practices for managing groundwater. In this paper, we report that using derivative analysis to improve understanding of complexities in aquifer flow systems is difficult and rarely used in groundwater hydraulics research work. Thus, we argue that if derivatives are not considered in the characterizing flow regime. The heterogeneity of aquifers, boundary conditions and flow regimes of such aquifers cannot be assessed for groundwater availability, and the decision to allocate such water for use can be impaired. A comprehensive database was accessed to obtain pumping tests and geological data sets. The sequential analysis approach alongside derivative analysis was used to systematically perform a flow dimension analysis in which straight segments on drawdown-log derivative time series were interpreted as successive, specific, and independent flow regimes. The complexity of using derivatives analyses was confirmed. The complexity of hydraulic signatures was observed by pointing out n sequential signals and noninteger n values frequently observed in the database. We suggest detailed research on groundwater flow systems using tracer methods like isotopes and numeric models must be considered, especially in multilayered aquifer systems such as the Heuningnes catchment.

Abstract

Monitoring regional groundwater levels provides crucial information for quantifying groundwater depletion and assessing environmental impacts. Temporal variation of groundwater levels is the response of the groundwater system to natural and artificial stresses in terms of groundwater recharge and discharge. The complexity and extent of the variation rest on the nature and storage properties of the aquifer system. High groundwater levels are usually found in the recharge zones and low in the discharge zones, resulting in groundwater flow from recharge areas to discharge areas. Continuous decline of groundwater levels has been observed in some of the monitoring boreholes within the National Monitoring Network. Groundwater level decline has been caused either by over-exploitation or reduction of groundwater recharge. Generally, the pattern of spatial and temporal variations of groundwater levels is the consequence of incorporating climatic, hydrological, geological, ecological, topographical, and anthropogenic factors. Therefore, understanding the pattern of spatial and temporal variations in groundwater levels requires a combined approach. A combination approach of National long-term groundwater level monitoring data, Hydrological stresses, Anthropogenic interferences, and characteristics of the groundwater system was used to understand the continuous decline of groundwater levels in selected monitoring stations across the country.

Abstract

Groundwater governance and risk management in the Murray-Darling Basin in Australia (MDB) are being challenged by the increasing demand for water and the growing scarcity and variability of water supply owing to climate change. Over the past 20 years, consideration of risk related to groundwater in the MDB has evolved from concerns about the impact of groundwater extraction on surface water resources to an integrated assessment of risks to connected water resources and ecosystems. The Basin Plan includes a comprehensive framework for assessing risks to Basin water resources and ecosystems, but further scientific and policy developments are required to implement the plan. Consistent definition and improved assessment of groundwater-surface water connectivity are required, together with longer planning timeframes. Multi-year planning rules and policies must be developed to exploit opportunities for integrated management of groundwater and surface water resources and storage to manage droughts and floods. Risks to groundwater quality and groundwater-dependent ecosystems must be adequately assessed and monitored to avoid adverse impacts on communities and long-term loss of ecosystem services. Further improvements can be made in assessing cumulative risks from coal seam gas and coal mining. Additional research can be targeted towards knowledge gaps and uncertainties that pose the greatest risk to connected groundwater and surface water resources and ecosystem viability. Most importantly, further training and capacity building in water management agencies is critical to enable effective and transparent monitoring and management of Basin water resources.

Abstract

The Anglo-American Municipal Capability & Partnership Program (MCPP) has partnered with the Council for Scientific and Industrial Research (CSIR) to implement programs focused on Strategic Water Management and Strategic Planning within the Gamagara and Tsantsabane Local municipalities within the Northern Cape Region. The CSIR appointed GEOSS South Africa (Pty) Ltd to assist with Municipal Groundwater Capacity Development and Support for these two municipalities. This work explores multi-level groundwater governance systems between the local municipality, government, the mining industry, and the private groundwater sector. The scope of the work focused on developing a comprehensive and practical groundwater management plan detailing the standard operating procedures for each municipality. These operating procedures have been drawn up using principles of best practice guidelines for groundwater monitoring and management but have taken site-specific details of the groundwater supply to the respective Municipalities into account. Workshops were conducted where Municipal staff were trained in basic principles pertaining to groundwater and practical skills in monitoring and managing their supply. This has proved very successful in informing Municipalities about their local groundwater system and aquifer. The capacity-building development aspect will ensure that Municipalities have the resources and the knowledge to manage their groundwater resource effectively. GEOSS has undergone several training workshops and offers weekly technical support to the two Municipalities. As the confidence of the municipal staff to manage their resource grows, their independence from the mining companies should lessen.

Abstract

Globally, losses of excess nitrogen (N) from agriculture are affecting our air and water quality. This is a well-known environmental threat and is caused by food production for an ever-growing population. Since the 1980s, many European countries, such as Denmark, have successfully combatted N pollution in the aquatic environment by regulating and introducing national agricultural one-size-fits-all mitigation measures. However, further reduction of the N load is still required to meet the demands of, e.g., the EU water directives. Scientifically and politically, implementing additional targeted N regulation of agriculture is a way forward. A comprehensive Danish groundwater and modelling concept has been developed to produce high-resolution groundwater N retention maps showing the potential for natural denitrification in the subsurface. The concept’s implementation aims to make future targeted N regulation successful environmentally and economically. Quaternary deposits, formed by a wide range of glacial processes and abundant in many parts of the world, often have a very complex geological and geochemical architecture. The results show that the subsurface complexity of these geological settings in selected Danish catchments results in large local differences in groundwater N retention. This indicates a high potential for targeted N regulation at the field scale. A prioritization tool is presented that has been developed for cost-efficient implementation at a national level to select promising areas for targeted N regulation.

Abstract

The recent uncertainties in rainfall patterns have resulted in shortages in the availability of water resources, posing significant risk to the sustainability of all living organisms, livelihoods and economic prosperity. The fact that hidden groundwater resources in semi-arid regions present a challenge to understanding and managing the resources. Various groundwater studies have been undertaken; however, the quantification is generally over-simplified due to a limited understanding of the groundwater flow regime and consideration being mostly given to water supply. Thus, the data is often not comprehensive enough and generally limited in determining how much groundwater is available to supply rural areas. The Komati catchment area is dominated by coal mining in the upper reaches and irrigation and agriculture in the lower reaches, with human settlements competing for these water resources. Five significant dams in the Komati catchment are constructed to deal with the increasing water demand for commercial agriculture in the region. However, given uncertain weather patterns, the water mix approach is imperative. This study focused on understanding the groundwater potential, characterised the aquifer system, delineated the groundwater resource units, quantified baseflow and calculated the groundwater balance that can be used as a guide for the groundwater management protocol for the catchment area. The box model approach (surface-groundwater interaction) was used to characterize the groundwater regime and understand the spatial distribution of the aquifer types, water quality and significant aquifers of interest to protect this important resource.

Abstract

he Namphu and Rangbua subdistricts in Ratchaburi province, in western Thailand, are affected by groundwater contamination. According to site characterization results, the aquifer has been contaminated with volatile organic compounds and heavy metals since 2014. Membrane filtration technology is an alternative method for treating groundwater to produce safe drinking water for household use. Nanofiltration membrane is a relatively recent development in membrane technology with characteristics that fall between ultrafiltration and reverse osmosis (RO). This study aimed to determine the hydrochemistry of contaminated groundwater and examine the efficiency of nanofiltration membranes for removing pollutants in groundwater and the potential implementation of the membrane. The membrane module used in this study is cylindrical in shape of 101.6 cm long and 6.4 cm in diameter, and the membrane surface charge is negative with monovalent rejection (NaCl) of 85-95%.

The filtration experiments were conducted at a pressure of 0.4-0.6 MPa, which yielded flow rates of approximately 2 L/min. To examine the nanofiltration membrane efficiency, groundwater samples were extracted from four monitoring wells and were used as feed water. According to laboratory results, the nanofiltration maximum removal efficiencies for 1,2-dichloroethylene, vinyl chloride, benzene, nickel, and manganese were 97, 99, 98, 99, and 99%, respectively. However, the treatment efficiency depends on several factors, including pretreatment requirements, influent water quality and the lifespan of the membrane. Further research should be conducted to determine the maximum concentration of VOCs and heavy metals in the feed water before applying this treatment method to a large scale.

Abstract

Groundwater modelling at the mine sites involves assumptions from the geological model, mining stages, parametrization, and fractures, among others. Modelling work mainly focuses on calibrating against historical measurements before operations (pre-mining) or afterwards (transient calibration). Calibration is carried out mainly with gradient-based algorithms. However, the majorlimitation is the number of model runs, since the number of parameters can easily reach hundreds or more. PEST has become the common tool for parameter estimation. The Jacobin calculation required for the Levenberg Marquardt algorithm requires several model runs. This, a limited factor for the calibration and, subsequently, uncertainty quantification. The next generation of PEST, named PESTPP, is gained popularity in the groundwater community. The great advantage of PESTPP,, compared to the classical PEST, is its new module, Iterative Ensemble Smoother (IES). PESTPP-IES covers both parameter estimation and uncertainty quantification in one goal. Its empirical formulation of the Jacobian matrix reduces the number of runs; thus, the numerical bottleneck can be significantly reduced. PESTPP-IES has been extensively tested in an open-pit mine at the geological complex conditions in the Peruvian Andes. The work involves the task of model simplification, e.g., from a regional model to a detailed local pit model, calibration and uncertainty quantification of pit dewatering volumes. Detailed model was kept calibrated based on hydraulic-head measurements, and dewatering volumes were predicted. All these consider transient changes in the mining plan within the same FEFLOW model. Results validate the methodology and practicability in mining applications.

Abstract

In recent years, practical applications of vector and raster multi-layers overlay analysis to enhance outcomes of conventional hydrogeological methods for allocation of productive boreholes have been applied in arid and semi-arid lands and is currently being tested in Ethiopia, Kenya, Somalia and Angola in cooperation with UNICEF. Advanced Remote Sensing (RS) and Geographic Information Systems (GIS) techniques combined with traditional geological, hydrogeological and geophysical methods are being used for improved access to sustainable drinking water supply boreholes in the scope of a WASH program. Identifying suitable areas with a good potential for sustainable groundwater resources exploitation mainly depends on a) consistent/reliable aquifer recharge and b) favourable hydrogeological conditions for groundwater abstraction. Multi-layer analyses and attribution of layer scores to the hydrogeological information layers – aquifer recharge, aquifer class, lineaments, slope, land cover, and presence of streams – combine into a qualitative Groundwater Suitability Map, using pairwise comparison (weights) to determine their relative importance with the Analytic Hierarchy Process (AHP). Additionally, traditional field methods enhance the quality of outputs and delineate Target Areas for detailed investigations: validation of hydrogeological conceptual models, hydrogeological assessment, groundwater sampling and finally, geophysical methods. Downscaling the remote sensed information of the groundwater suitability map with field verifications is required to recommend borehole drilling sites. The engagement of stakeholders is vital for the data collection and validation of the weighting criteria analyses (AHP method), as well as for the cooperation on the ground, validation of the Target Areas selection and implementation.

Abstract

In the social sciences, there has been a ‘posthuman’ turn, which seeks to emphasise the role of non-human agents as co-determining social behaviours. In adopting a ‘more-than-human’ approach, the academy seeks to avoid claims of human exceptionalism and extend the social to other entities. In this paper, we explore the extent to which the more-than-human approach might be applied to groundwater and aquifers and the implications that this may have for groundwater science. The role of groundwater in complex adaptive socio-ecological systems at different scales is increasingly well-documented. Access to groundwater resources positively influences societal welfare and economic development opportunities, particularly in areas where surface waters are scarce. The potential adverse effects of human activities on the quantity or quality of groundwaters are also widely reported. Adopting a ‘properties’ approach, traditional social science perspectives typically describe aquifers as structuring the agency of human actors. To what extent might aquifers also have agency, exhibited in their capacity to act and exert power? Drawing on insights from 5 cities across sub-Saharan Africa, we argue for the agency of aquifers in light of their capacity to evoke change and response in human societies. In doing so, we draw on the concept of the more-than-human to argue for a more conscious consideration of the interaction between the human and non-human water worlds whilst acknowledging the critical role played by researchers in shaping these interactions.

Abstract

To increase the security of groundwater resources, managed aquifer recharge (MAR) programs have been developed and implemented globally. MAR is the intentional recharge and storage of water in an aquifer, which will be recovered later. It was previously known and implemented as Artificial Recharge (AR). In South Africa, the documented practice dates back 40 years. There are five main MAR methods: Well-Shaft-Borehole, Spreading-induced bank infiltration, In-channel modifications, and Runoff harvesting. Two regional-scale MAR suitability maps for the Spreading Method (SM) and the Well-Shaft-Borehole (WSB) Method were compiled for South Africa, using the Geographic Information System combined with Multi-Criteria Decision Analysis (GIS-MCDA) methodology. Parameters used to compute the maps included the nature of the different aquifers, groundwater level, water quality (EC), distance to river, terrain slope, mean annual rainfall, land cover, soil moisture availability and clogging (Fe-iron content). To create a suitability map, the parameters were combined using the weighted overlay method and the Analytic Hierarchy Process (AHP – specifically the pairwise comparison). The site suitability maps indicated that most areas in South Africa are suitable for the Spreading and Well-Shaft-Borehole methods. The results were verified with the location of existing MAR schemes and were found to agree. However, these maps are not applicable for siting projects at a local scale but can serve as a guide and screening tool for site-specific studies looking for highly suitable or target areas for MAR implementation

Abstract

The National Park Plitvice Lakes (NPPL) in the Republic of Croatia was declared in 1949 due to its exceptional natural beauty. However, in addition to its attraction, the NPPL also encompasses an area of significant karstic water resources in the Dinaric karst region, on the border between the Black Sea and the Adriatic Sea catchment. In some parts, groundwater connections to the Klokot Spring and Una River in Bosnia and Herzegovina have been assumed by hydrogeological research and proven by tracing tests, which confirm transboundary aquifer. Assessing transboundary aquifer systems already presents challenges in managing this area, considering not only the well-defined physical catchment. Therefore, comprehensive protection is necessary, which must reconcile people’s aspirations for spatial development with the sustainability of natural systems. Protecting karstic water resources can be achieved through separate analyses of the natural vulnerability of surface and groundwater and their integration into a comprehensive protection system. Protection should be layered through three levels: (1) protecting the area from the impact of the upstream catchment, (2) protecting surface water in the catchment that is most affected by anthropogenic influences, and (3) protecting the surrounding area from the impact of the NPPL, which with numerous visitors every year and tourist facilities, also represents significant pressure on downstream catchments. The ultimate goal is a scientifically based proposal for sustainable development of the protected area, in line with the needs of protection and spatial use, and based on an assessment of the overall risk to water resources.

Abstract

Research on Fracking in the Karoo basin yielded results that, if not considered “unexpected”, can be considered as “should have been foreseen”. Some aspects substantially impacting research on fracking are often overlooked when undertaking scientific research on an emotional topic such as fracking. This presentation aims to provide insights and recommendations based on the experiences and outcomes of current research on hydraulic fracturing or “fracking” in the Karoo basin of South Africa. Fracking has been a subject of significant research and debate over the past decade. Topics, each with its challenges, include 1) The scale of exploration/production extent (Site specifics), 2) Importance of robust and independent research, 3) Need for stakeholder engagement and participation, 4) The complexity of environmental risks and impacts, 5) The need for a precautionary approach, 6) Regulatory and policy challenges. Several methodologies can be relied upon to compare outcomes of different aspects of fracking research in the Karoo, such as 1) Comparative analysis, 2) Meta-analysis, 3) Stakeholder mapping and analysis and 4) Data visualisation. A combination of these methodologies can be used to compare outcomes of different aspects of fracking research in the Karoo and provide insights and recommendations for future decision-making and planning. Ultimately, the decision to allow Fracking should be based on a balanced assessment of potential risks and benefits, considering long-term impacts on the environment, economy, and communities.