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This study assesses the detailed water budget of the Saq-Ram Aquifer System (520 000 km²) over the 2002-2019 period using satellite-gravity data from the Gravity Recovery And Climate Experiment (GRACE). The three existing GRACE solutions (JPL, CSR, GSFC) were tested for their local compatibility to compute groundwater storage variations in combination with soil moisture datasets (VIC, CLSM, NOAH) available from the Global Land Data Assimilation System (GLDAS) land surface models. Accounting for groundwater pumping (15.7 ± 1.1 mm yr-1), artificial recharge (2.2 ±

0.8 mm yr-1) and natural discharge (0.3 ± 0.06 mm yr-1) uniformly distributed over the Saq-Ram domain, the GRACE-derived water mass balance calculation yields a long-term estimate of the domain-averaged natural recharge of 2.4 ± 1.4 mm yr-1, corresponding to 4.4 ± 2.6% of the annual average rainfall.

Beyond the global approach proposed here, spatial heterogeneities regarding the groundwater recharge were identified. The first source of heterogeneity is of anthropogenic origin. Within agricultural plots, irrigation excess is great enough to artificially recharge the aquifer (i.e. 167 ± 83 mm yr-1 distributed over irrigated areas). However, on the outskirts of these crop areas subjected only to the natural recharge but still influenced by pumping drawdown, there is a risk of relative disconnection from the infiltration front with the declining water table (i.e.  the unsaturated zone thickens faster than percolation flows through it), making effective recharge locally zero. The second source of recharge heterogeneity identified here is natural: Volcanic lava deposits (called Harrats on the Arabian Peninsula) which cover 8% of the Saq-Ram Aquifer domain but contribute to more than 50% of the total natural recharge. Hence, in addition to this application on the Arabian Peninsula, this study strongly indicates a major control of geological context on arid aquifer recharge which has been poorly discussed hitherto.

How to cite: Séraphin, P., Gonçalvès, J., Hamelin, B., Stieglitz, T., and Deschamps, P.: Influence of intensive agriculture and geological heterogeneity on the recharge of an arid aquifer system (Saq-Ram, Arabian Peninsula), IAHS-AISH Scientific Assembly 2022, Montpellier, France, 29 May–3 Jun 2022, IAHS2022-102, https://doi.org/10.5194/iahs2022-102, 2022.

The Continental Intercalaire aquifer (CI) (North Africa) is one of the largest transboundary aquifer systems in the world. It contains around 20 000 × 10⁹ m³ of groundwater. The recharge comes mainly from the occidental part of the aquifer (southern foothills of the Saharan Atlas, Algeria) going east to the outlet area in South Tunisia. Several studies have showed, using ¹⁴C, that the principal recharge has taken place in Late Pleistocene and Holocene. However, doubts exist about the results of some of these studies as it was demonstrated that samples containing less than 10pmc could have been contaminated by modern air during the sampling procedure.

Based on a new field survey and the combination of new ¹⁴C and ³⁶Cl data, the data of the previous studies are reviewed and new insights on the groundwater age are given. Close to recharge area, ¹⁴C age showed a significant amount of modern recharge (less than 2Ky B.P.). Any sample was found to have an age between 2 to 11Ky P.B. This means that during this period, Northern Sahara was dominated by a hyperarid climate. From 11 to 30Ky, it is observed that there is cyclicity of approximately 4Ky between given ages. This indicates that this period is dominated by an arid climate. Those ¹⁴C ages are calculated using F&G model.

Beyond 30 Ky P.B., the use ¹⁴C is critical because of its limited half-time. ³⁶Cl is more relevant in that case (half-time equal to 301Ky). Samples close to recharge area, where ¹⁴C activities are sufficiently high and halite dissolution is not significant, are explored in order to define initial values of ³⁶Cl. There, the initial ³⁶Cl/Cl ratio is around 145 × 10^-15 at/at and the initial chlorine concentration is around 175mg/L. Based on these values, the age of CI groundwater in the Great Oriental Erg basin and South Tunisia has to be 300 to 700Ky old instead of 40 to 50Ky calculated by ¹⁴C. This is supported by the ages calculated by ⁸¹Kr performed in the South Tunisia. However, the applicability limit of each technic has to be investigated.

How to cite: Hakimi, Y., Orban, P., Deschamps, P., and Brouyère, S.: Review of groundwater age of a transboundary aquifer system using 14C and 36Cl, case of the Continental Intercalaire aquifer in Algerian Sahara and Southern Tunisia, IAHS-AISH Scientific Assembly 2022, Montpellier, France, 29 May–3 Jun 2022, IAHS2022-56, https://doi.org/10.5194/iahs2022-56, 2022.

Drylands are characterized by their limited water supply, low and highly variable rainfall, and recurrent drought. Almost 40% of land in the world is considered drylands, which are the most sensitive areas to climate change and human activities. Representative Concentration Pathways (RCPs) projections data show an increase of drylands by 50% near the end of this century. With the expansion of drylands, and the increasing population in West Bengal (85° 40'E-88° 15'E longitudes and 21° 45'N-24° 45'N latitude), this puts pressure on water managers to accurately plan, prepare, and implement new measures for increasing water sustainability and sources of water. Future climate projections will require finding alternative and reusable water sources for present and future use. The goal of this study is to design a methodology to evaluate current existing groundwater resources, and to identify future potential zone for artificial groundwater recharge activities to improve groundwater storage during rain events. We also evaluate locations for rainwater harvesting, the state-of-the science of wastewater reuse and alternative crop rotations to minimize water use while maximizing production and benefits to farmers. Our work is applicable to other dryland areas around the world experiencing accelerated warming and desertification. 

How to cite: Bera, Dr. K., E. Newcomer, Dr. M., and Banik, P. P.: Climate Risk Analysis for Water Resources in Dryland Area of West Bengal, IAHS-AISH Scientific Assembly 2022, Montpellier, France, 29 May–3 Jun 2022, IAHS2022-157, https://doi.org/10.5194/iahs2022-157, 2022.

The Garonne river is the third longest river in France and the most important one for the southwest part of the country. Its hydrology is influenced by the Mediterranean and oceanic climate and the snow melt. The surrounding Quaternary alluvial aquifer is considered as a large regional reservoir and an important source for the agricultural activities well developed in the Garonne valley. The hydraulic exchange between this aquifer and the river is depending on the river’s water level. The overexploitation of water resources and the effects of climate change lead to river discharge and aquifer level to decrease over the past several years. However, this affects the economy and threaten the related ecosystems.

The Techno pole Agen-Garonne (TAG) project, green and temperate peri-urban zone, is under construction within an area of about 240 ha close to the Agen City. The project and surrounding areas, about 20 km², is taken as a study area (Fig 1). Runoff from the TAG is collected in retention basins and used as a potential source to recharge the shallow alluvial aquifer.

In the present work, the three-dimensional (3D) groundwater model was used to evaluate the effects of the groundwater artificial recharge on the aquifer level and the maintenance of ecological low flows of the Garonne River during dry periods. The calibrated model demonstrates a good agreement between observed and simulated groundwater levels (Fig. 2).

Groundwater level measurements close to the retention basin show that the water level increases about 1 m after the rainstorm event (Fig.3). The result of the simulation illustrates that the infiltrated water, takes about 3-4 months to reach and sustain the river during low-flow summer period (Fig. 4). The relatively low temperature of inflowing groundwater into the river can be considered as an important factor to control the ecosystem function.

For better sustainable water resource management in the study area, further modelling can be performed in the context of using surface water and groundwater as a single source taking into account the agricultural and ecological needs and water scarcity.

Figure. 1

Figure 2

Figure 3

Figure 4

How to cite: Asmael, N. and Dupuy, A.: Artificial Recharge of Shallow Alluvial Aquifer as an Adaptation Strategy in the Garonne Valley, France, IAHS-AISH Scientific Assembly 2022, Montpellier, France, 29 May–3 Jun 2022, IAHS2022-401, https://doi.org/10.5194/iahs2022-401, 2022.

Access to drinking water for all is a major challenge for all countries, especially developing ones. In Côte d'Ivoire, many efforts are still being made to sastify the water needs of the population. This is the case in Guibéroua where geophysical campaigns have been carried out beforehand in order to increase the success rate of drilling. At the end of a geophysical campaign, sites (F1, F2 and/or F3) are identified in order of priority in each locality. However, these sites, as well as the proposed preferred drilling order, may not be the best ones. The problem then arises of identifying relevant geophysical criteria in order to increase the chances of success at the first drilling attempt. This work proposes an approach to interpreting electrical drag data in order to make a judicious choice of drilling sites. From the electrical resistivity data, electrical profiles are constructed. On these profiles, different anomaly shapes are identified and fracturing indices (FI) are calculated. The results obtained show that the anomaly shapes commonly encountered are the "U", "V", "W" shapes; those of "M" shape are rare. The highest average fracture index (IFm) is observed in the "V" shaped anomalies. This indicates that these correspond to the most fractured zones and therefore the most likely to be water-bearing. Moreover, the boreholes that have been drilled there have provided good flows for village hydraulics. U-shaped anomalies have a low mFI. They therefore describe less fractured sites. This is confirmed by the very low flow rates of the boreholes that have been installed there. As for the "W" anomalies, although the mFI is low, they are ideal for drilling because of the high flow rates obtained.

This study shows that in addition to the shape of the anomaly, the fracture index is an important parameter that must be taken into account when choosing drilling sites. The use of these two parameters can guarantee a high success rate of drillings.

KEYWORDS : Electrical resistivity, Electrical profiles, Conductive anomaly, Fracturing index, Drilling.

How to cite: Coulibaly, A., Kouassi, K. A., and Kouassi, F. W.: Interpretative approach of electrical resistivity data for efficiency implantation of drilling on basement zone : Case of Guibéroua (Côte d’Ivoire), IAHS-AISH Scientific Assembly 2022, Montpellier, France, 29 May–3 Jun 2022, IAHS2022-221, https://doi.org/10.5194/iahs2022-221, 2022.

This presentation gives an overview of an investigation of the potential for managed aquifer recharge (MAR) in three established or emerging irrigated cotton-growing regions in Australia: the Lower Murrumbidgee and Lower Namoi basins in western NSW and the Gilbert River catchment in far northern Queensland. Ongoing interest in MAR as a strategy to support irrigated agriculture has not translated into much investment in Australia. The aim was to evaluate how MAR might be feasible for irrigated cotton production and associated cropping systems in the focus regions and make recommendations on next-step actions that could incrementally develop the knowledge, confidence and expertise needed to invest in MAR. The broad approach taken was to draw on evidence from a holistic feasibility assessment to scope a set of plausible scenarios for MAR, to test and refine these scenarios with local and state government stakeholders and researchers, and to develop recommendations to support any efforts to proceed with MAR by the funder (the Cotton Research and Development Corporation) or other parties.

The scenarios varied in their scale (e.g. single farm, irrigation schemes), purpose (e.g. managing drawdown, reducing evaporative losses), infrastructure and governance arrangements. Together they highlighted the critical need to improve knowledge on local hydrogeological conditions and develop MAR policy and regulations that enhance the strengths of MAR whilst minimising risks. A water accounting grade estimate of recharge is critical to being confident that MAR provides an advantage over investing in reducing infiltration “losses”, allowing an allocation to be issued. As an initial step, MAR pilot studies could work with state government to test water accounting of recharge quantification methods in dedicated trial infiltration basins and test injection wells. Reducing uncertainty about evaporation and recharge rates is critical to comparing MAR as a low loss water storage solution to other evaporation or infiltration reduction alternatives. If land managers invest in improving understanding of aquifers under their land and quantifying seepage and evaporation over time, this will incrementally reduce uncertainty on the effectiveness and viability of MAR. 

How to cite: Merritt, W., Guillaume, J., Harvey, N., Ticehurst, J., and Croke, B.: Feasibility assessment of MAR, IAHS-AISH Scientific Assembly 2022, Montpellier, France, 29 May–3 Jun 2022, IAHS2022-318, https://doi.org/10.5194/iahs2022-318, 2022.

Qatar is a hyper-arid country in the northeastern coast of the Arabian Peninsula. Over the last five decades, the built environment in the country’s metropolitan Doha, the capital city in Qatar, grew 60 times. Future plans include extra-urban development before 2030. Tough, the impact of such urban development on the country’s aquifers still unexplored. This study quantifies such impact through the end of the century. First, six periods represented the main stages of urban development during the last five decades in Doha. These periods are 1987, 1991, 1998, 2003, 2009, and 2013. Then, climatic data and groundwater parameters in addition to land use maps were used in a physically-based spatially distributed hydrological model (WetSpass) to calculate groundwater recharge values during these six periods. The variations in groundwater recharge quantities were then quantified spatially and temporally. Results showed significant variations with a deficiency in groundwater recharge increases with urban development increase. Groundwater recharge value in 2013 was 62% lower than that in 1987. Results also showed a particular trend of spatial variations in groundwater recharge. The study finally determined the main spots for applying managed aquifer recharge (MAR) as ways to replenish the aquifers. The findings of this study are keys to understanding the consequences of urban development changes in groundwater recharge, including impacts on agriculture and water balance. The proposed approach is applicable in similar regions, characterized by hasty urban development.

How to cite: Ajjur, S. B. and Al-Ghamdi, S. G.: Quantifying the impact of rapid urban development on groundwater recharge (case study Qatar), IAHS-AISH Scientific Assembly 2022, Montpellier, France, 29 May–3 Jun 2022, IAHS2022-726, https://doi.org/10.5194/iahs2022-726, 2022.