Impacts of Desalinated and Recycled Water in the Abu Dhabi Surficial Aquifer

In Abu Dhabi, one of the most arid regions in the world, in recent decades, desalinated water has been identified as a prime solution in solving the water demand issues. In this study, a three-dimensional coupled density-dependent flow and solute transport model was set up in order to study the effect of the artificial recharge using desalinated water and the influence of nonconventional water with a salt concentration in the range 0.1–2 g/L The results confirm that this region demands the adoption of a more rational use of irrigation water or additional usage of desalinated water and recycled water together with optimizing groundwater pumping at locations that are vulnerable to further quality degradation and depletion. The long-term storage of desalinated freshwater with a maximum radial distance of 653 m in the dune surface is ensured with the formation of the transition zone, and change in the groundwater head up to 5 km. The maximum recovery obtained by immediate recovery is 70%. The study expresses the long-term feasibility of desalinated freshwater storage and the need for further management practices in quantifying the contribution of desalinated and recycled water for agriculture activities which might have improved groundwater quality and increased hydraulic head at some locations.

GIS-SWIAS: Tool to Summarize Seawater Intrusion Status and Vulnerability at Aquifer Scale

In this paper, we introduce GIS-SWIAS, a novel generalized ArcGIS ArcToolbox that helps to analyze seawater intrusion (SWI) status and vulnerability at aquifer scale (SWIAS). It is a user-friendly tool that can be applied to any aquifer and is fully integrated in the ArcGIS environment, which is a widely available software tool. It is the first ArcGIS tool with these characteristics focusing on SWI analyses that we can find in the literature. GIS-SWIAS is able to deal with georeferenced information; it is easy to introduce the required data (inputs) and to efficiently perform the demanding computational operations required. Its outputs are in the form of shapes, reports, and images (maps, conceptual cross sections, and time series of lumped indices) to summarize the magnitude, intensity, and temporal evolution of SWI within an aquifer for specific dates or by showing statistics for a chosen time period. It can be applied to assess historical SWI dynamic in cases where there is no groundwater flow model. In those cases, the spatial distribution is assessed by applying simple interpolation techniques. Nevertheless, if we want a rational quantitative analysis of the sustainability of alternative management scenarios to the SWI problem, the GIS-SWIAS tool requires that information on hydraulic head and chloride concentration distribution is generated from simulations of their impacts by a calibrated density-dependent flow model. In such cases, adaptation strategies to potential future scenarios—whose distributed impacts have to be propagated within the previously calibrated models—could usefully be analyzed and compared using this tool. Given all these ways that the GIS-SWIAS tool can be applied, it provides a valuable tool for both the researcher and technician to assess SWI dynamics and aquifer resilience under different scenarios. It can support the decision-making process by helping to make a rational selection of sustainable management strategies. Its performance for the analyses of historical and potential future scenarios has been tested and confirmed in two case studies described in previous research works.

Mapping the Vulnerability of Groundwater to Wastewater Spills for Source Water Protection in a Shale Gas Region

Source water protection in areas of shale gas development encompasses identifying areas that are the most vulnerable to groundwater quality deterioration due to spills of natural gas production wastewater. This study uses the density-dependent flow and transport code TOUGH2 to quantify the time and distance of travel of saline wastewater plumes for different hydrogeological settings in Northeast British Columbia. The models were designed to address three main factors identified from the DRASTIC method for vulnerability assessment: (1) depth to water, (2) impact of vadose zone, and (3) conductivity of the aquifer materials. The vadose zone permeability and depth to water table are dominant controls on the wastewater migration rate and footprint. Overall, the vulnerability in the region is relatively low, with exceptions near river valleys and areas with shallow water tables. The vulnerability maps can be used as a preliminary risk assessment tool, as they are based on the main factors influencing the potential of a wastewater spill to contaminate an aquifer.

Combination of Basin Scale Data Analysis and Numerical Simulations for the Interpretation of the Coexistence of Thermal Water and Hydrocarbon Accumulations

<p>During the evolutionary stages of sedimentary basins, different processes are active. Secondary migration means the movement from the source area to the trap and it has most likely the tendency to move along with water. Thus, the secondary migration of petroleum is directly affected by the different driving forces which also influence the ambient groundwater (Tóth 1988). In other words, understanding the regional groundwater flow systems and driving forces may support petroleum exploration. In this theoretical framework, a hydrogeological evaluation of the broader environment of Ebes-Hajdúszoboszló area(Eastern Hungary, Pannonian basin) was executed on the interpretation of the coexistence of thermal water and hydrocarbon accumulations in the specific area.</p><p>The study is based on the application of two different methods. At first a basin-scale hydrogeological evaluation of the recent fluid flow condition including archive hydraulic, chemical, borehole temperature data interpretation, and regional pressure field evaluation was carried out. These data confirmed the superposition of an over-pressured flow regime driven by tectonic compression and compaction and the upwelling of fluids in the gravity driven-flow system in the upper part (Zentai-Czauner et al., 2018).</p><p>The data analysis could provide initial understanding and conceptual framework for 2D numerical evaluation of superposition of the topography differences and overpressure as driving forces It was carried out using the Heat Flow Smoker software version 7.0 developed by (Molson, 2014) which can simulate density-dependent flow and advective-dispersive transport of thermal energy, mass or residence time in three-dimensional porous or fractured media.</p><p>The interpretation of the 2D simulation of the cross-section was compared with the results of the data analysis and it can show the relationship between the hydrocarbon accumulations and the existence of thermal water is due to groundwater flow.</p><p>The regional data analysis and subsequent 2D simulation could confirm the favorable conditions for hydraulic trapping of hydrocarbons and the heat accumulation in groundwater due to advective heat transport.</p><p>This work is part of a project that has received funding from the European Union’s Horizon 2020 research and innovation program under grant agreement No 810980.</p><p><strong>Keywords:</strong></p><p>Groundwater-flow, thermal water, hydraulic trapping, hydrocarbons, migration, accumulation.</p><p><strong>References:</strong></p><ul><li>Szabó Zs., Zentai-Czauner B., Mádl-Szőnyi J., 2018 Hydrogeological evaluation of the broader environment of Ebes concession area for the understanding of recent fluid flow conditions, final report of Vermillion Energy Hungary.</li> <li>Toth J., 1988, Groundwater and hydrocarbon migration, in back, W., Rosenshein, J. S., and Seaber, P. R., eds., Hydrogeology: Boulder, Colorado, Geological Society of America, The geology of North America, v. O-2, chap. 48, pp. 485-502.</li> <li>John W. Molson, 2019. Heat Flow Smoker, Version 7.0, density-dependent flow and advective-dispersive transport of thermal energy, mass or residence time in three-dimensional porous or fractured porous media, université Laval, University of Waterloo.</li> </ul><p> </p>

Anthropogenic wetlands due to over-irrigation of desert areas: a challenging hydrogeological investigation with extensive geophysical input from TEM and MRS measurements

During the last century, many large irrigation projects were carried out in arid lands worldwide. Despite a tremendous increase in food production, a common problem when characterizing these zones is land degradation in the form of waterlogging. A clear example of this phenomenon is in the Nubariya depression in the Western Desert of Egypt. Following the reclamation of desert lands for agricultural production, an artificial brackish and contaminated pond started to develop in the late 1990s, which at present extends for about 2.5 km2. The available data provide evidence of a simultaneous general deterioration of the groundwater system. An extensive hydrogeophysical investigation was carried out in this challenging environment using magnetic resonance sounding (MRS) and ground-based time-domain electromagnetic (TEM) techniques with the following main objectives: (1) understanding the hydrological evolution of the area; (2) characterizing the hydrogeological setting; and (3) developing scenarios for artificial aquifer remediation and recharge. The integrated interpretation of the geophysical surveys provided a hydrogeological picture of the upper 100 m sedimentary setting in terms of both lithological distribution and groundwater quality. The information is then used to set up (1) a regional groundwater flow and (2) a local density-dependent flow and transport numerical model to reproduce the evolution of the aquifer system and develop a few scenarios for artificial aquifer recharge using the treated water provided by a nearby wastewater treatment plant. The research outcomes point to the hydrological challenges that emerge for the effective management of water resources in reclaimed desert areas, and they highlight the effectiveness of using advanced geophysical and modeling methodologies.