Groundwater-recharge connectivity between a hills-and-plains’ area of western Taiwan using water isotopes and electrical conductivity

The lack of adequate information on groundwater recharge mechanisms in the basement rock area of Sahelian regions does not allow to estimate recharge rates. Thus, this study, which aims to improve the knowledge of the groundwater recharge mechanisms of the Tougou (catchment of 37 km2 representing a basement rock in Sahel of West Africa) aquifers was initiated. The first step was to characterize the geology in terms of geometry and structure. The ERT profile (1.2 km length) crossing perpendicularly the river and lithologs from 10 observation wells (Average depth: 25m) and 1 borehole (Depth: 60 m) were used to make the correspondence between geological and geophysical data. The second step was to characterize vertically and laterally aquifers recharge mechanisms under the ephemeral river and two river banks. Hence, hourly to daily groundwater levels, electrical conductivity, and temperature of groundwater have been measured in those 10 observation wells and 1 borehole (Period: 2016-2020). The river water levels and the rainfall were also collected. The cross-correlation function was used between the rainfall or river water levels and the hydraulic heads time series. The geological characterization showed from top to bottom:<ul><li>Residual soils: 1 m to 2 m thick, present in the riverbed and on the right bank;</li> <li>Laterite (lateritic clays and lateritic cuirass): 2 m to 14 m thick, absent in the riverbed and present on the two banks;</li> <li>Laterally continuous clayey saprolite: 10 m to 22 m thick;</li> <li>Weathered schist: 32 m thick in the river. A bedrock was found at a depth of 55 m.</li> </ul>This geological conceptual model was a grounding for interpreting the results incurred from other data collected. It was ascertained that the weathered schist aquifer below the river is semi-confined (Average water depth: 9.5 m < top: 25 m) and vertically recharged by the saprolite aquifer. Laterally, the clayey saprolite aquifer is recharged by two main flows from:<ul><li>The river: the electrical conductivity and temperature of the groundwater in the clayey saprolite aquifer below the river vary at the same time as the water table increases during the rainy season. In addition, mean hydraulic head differences of +0.3 m and +2 m have been observed between the piezometer located in the river and respectively, the piezometer located at 20 m from the river on the left bank and other piezometers located on the right bank (up to 600 m from the river). A maximum good cross-correlation between hydraulic heads and river water levels rather than with rain was found in all piezometers, but mostly in the one located in the river (cross-correlation = 0.56). These indicate an indirect recharge process.</li> <li>The left bank: An mean hydraulic head difference (+3 m) which is related to a transfer of hydraulic pressure from probably a nearby recharge area was noted between the piezometers located at 300 m and the riverbed.</li> </ul>For further studies, the information obtained will be used to estimate the recharge through different methods including numerical modeling.

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Advantages and challenges of using soil water isotopes to assess groundwater recharge dominated by snowmelt at a field study located in Canada

Hydrological Sciences Journal ◽

10.1080/02626667.2018.1442577 ◽

2018 ◽

Vol 63 (5) ◽

pp. 679-695 ◽

Cited By ~ 4

Author(s):

Romain Chesnaux ◽

Christine Stumpp

Keyword(s):

Field Study ◽

Groundwater Recharge ◽

Soil Water ◽

Water Isotopes

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A 35 ka record of groundwater recharge in south-west Australia using stable water isotopes

The Science of The Total Environment ◽

10.1016/j.scitotenv.2019.135105 ◽

2020 ◽

Vol 717 ◽

pp. 135105

Author(s):

Stacey C. Priestley ◽

Karina T. Meredith ◽

Pauline C. Treble ◽

Dioni I. Cendón ◽

Alan D. Griffiths ◽

...

Keyword(s):

Groundwater Recharge ◽

Water Isotopes ◽

Stable Water Isotopes ◽

South West

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Aquifer Storage and Recovery Feasibility Study With Flowing Fluid Electrical Conductivity Logging in Shallow Aquifers of South Bihar, India

Frontiers in Water ◽

10.3389/frwa.2021.802095 ◽

2022 ◽

Vol 3 ◽

Author(s):

Anurag Verma ◽

Prabhakar Sharma

Keyword(s):

Electrical Conductivity ◽

Groundwater Recharge ◽

Large Scale ◽

Rainwater Harvesting ◽

Groundwater Resources ◽

Injection Rate ◽

Aquifer Storage And Recovery ◽

Shallow Aquifers ◽

Flowing Fluid ◽

Aquifer Storage

Growing dependence on groundwater to fulfill the water demands has led to continuous depletion of groundwater levels and, consequently, poses the maintenance of optimum groundwater and management challenge. The region of South Bihar faces regular drought and flood situations, and due to the excessive pumping, the groundwater resources are declining. Rainwater harvesting has been recommended for the region; however, there are no hydrogeological studies concerning groundwater recharge. Aquifer storage and recovery (ASR) is a managed aquifer recharge technique to store excess water in the aquifer through borewells to meet the high-water demand in the dry season. Therefore, this paper presents the hydrogeological feasibility for possible ASR installations in shallow aquifers of South Bihar with the help of flowing fluid electrical conductivity (FFEC) logging. For modeling, the well logging data of two shallow borewells (16- and 47-m depth) at Rajgir, Nalanda, were used to obtain the transmissivity and thickness of the aquifers. The estimated transmissivities were 804 m2/day with an aquifer thickness of 5 m (in between 11 and 16 m) at Ajatshatru Residential Hall (ARH) well. They were 353 and 1,154 m2/day with the aquifer thicknesses of 6 m (in between 16 and 22 m) and 2 m (in between 45 and 47 m), respectively, at Nalanda University Campus (NUC) well. Despite the acceptable transmissivities at these sites, those aquifers may not be fruitful for the medium- to large-scale (more than 100-m3/day injection rate) ASR as the thickness of the aquifers is relatively small and may not efficiently store and withdraw a large amount of water. However, these aquifers can be adequate for small (up to 20-m3/day injection rate) ASR, for example, groundwater recharge using rooftop water. For medium- to large-scale ASR, deeper aquifers need to be further explored on these sites or aquifers with similar characteristics.

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