Factors determining the hydrogeochemical processes occurring in shallow groundwater of coastal alluvial aquifer, India

Abstract. This study presents strontium isotope and major ion data of shallow groundwater and river water from the Ile du Chambon catchment, located on the Allier river in the Massif Central (France). There are large variations in the major-element contents in the surface- and groundwater. Plotting of Na vs. Cl contents and Ca, Mg, NO3, K, SO4, HCO3, Sr concentrations reflect water–rock interaction (carbonate dissolution for Ca, Mg, HCO3 and Sr because the bedrock contains marly limestones), agricultural input (farming and fertilising) and sewage effluents (for NO3, K, SO4), although some water samples are unpolluted. Sr contents and isotope ratios (87Sr/86Sr vary from 0.70892 to 0.71180 along the hydrological cycle) in the groundwater agree with previous work on groundwater in alluvial aquifers in the Loire catchment. The data plot along three directions in a 87Sr/86Sr v. 1/Sr diagram as a result of mixing, involving at least three geochemical signatures–Allier river water, and two distinct signatures that might be related to different water-rock interactions in the catchment. Mixing proportions are calculated and discussed. The alluvial aquifer of the Ile du Chambon catchment is considered, within the Sr isotope systematic, in a larger scheme that includes several alluvial aquifers of the Loire Allier catchment. Keywords: : Loire river, major and trace elements, Sr isotopic ratio, alluvial aquifer, hydrology

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Temporal dependence of potentiometric levels and groundwater salinity in alluvial aquifer upon rainfall and evapotranspiration

RBRH ◽

10.1590/2318-0331.0217170059 ◽

2017 ◽

Vol 22 (0) ◽

Author(s):

Robertson Valério de Paiva Fontes Júnior ◽

Abelardo Antônio de Assunção Montenegro

Keyword(s):

Temporal Dynamics ◽

Potential Evapotranspiration ◽

Shallow Groundwater ◽

Temporal Analysis ◽

Alluvial Aquifer ◽

Monthly Precipitation ◽

Groundwater Salinity ◽

Temporal Dependence ◽

Time Pattern ◽

Groundwater Levels

ABSTRACT Rainfall uncertainty and high evapotranspiration rates in the semiarid regions not only play an important impact on surface water scarcity, but interfere on shallow groundwater quantity and quality. The aim of this study was to apply geostatistical methodology to analyze the time dependence of potentiometric levels and groundwater salinity in an intensively monitored alluvial aquifer upon agroclimatological variables, and thus investigate possible monthly and annual correlations. Statistically stable piezometers were considered for the temporal analysis, representing the mean behavior of the whole aquifer. It has been verified that stable piezometers for groundwater levels exhibited temporal dependence of 7 months, similar to the temporal scale of variation for monthly precipitation and potential evapotranspiration, which is consistent to the resulting crossed-semivariogram. Meanwhile, stable piezometers for electrical conductivity showed high uncertainty on temporal dependence scale, which ranged from 3 to 8 months. Thus, rainfall and evapotranspiration alone did not properly explain the temporal dynamics of groundwater salinity. The produced maps successfully identified the long term time pattern of groundwater variation, constituting an important support for water resources evaluation.

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Hydrogeochemical Processes in the Quaternary Alluvial Aquifer, Wadi Na'man Basin, Saudi Arabia Investigations by Factor Analysis

Journal of King Abdulaziz University-Earth Sciences ◽

10.4197/ear.23-1.7 ◽

2012 ◽

Vol 23 (1) ◽

pp. 111-123

Author(s):

Ahmed Basamed ◽

Ezzat Korany

Keyword(s):

Factor Analysis ◽

Saudi Arabia ◽

Alluvial Aquifer ◽

Hydrogeochemical Processes

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Quantifying the Impact of Evapotranspiration at the Aquifer Scale via Groundwater Modelling and MODIS Data

Water ◽

10.3390/w13070950 ◽

2021 ◽

Vol 13 (7) ◽

pp. 950

Author(s):

Nicolò Colombani ◽

Mattia Gaiolini ◽

Gianluigi Busico ◽

Matteo Postacchini

Keyword(s):

Model Performance ◽

Shallow Groundwater ◽

Alluvial Aquifer ◽

Statistical Parameters ◽

Monitoring Wells ◽

Moderate Resolution ◽

Resolution Imaging ◽

Moderate Resolution Imaging Spectroradiometer ◽

Set Up ◽

The Impact

In shallow alluvial aquifers characterized by coarse sediments, the evapotranspiration rates from groundwater are often not accounted for due to their low capillarity. Nevertheless, this assumption can lead to errors in the hydrogeological balance estimation. To quantify such impacts, a numerical flow model using MODFLOW was set up for the Tronto river alluvial aquifer (Italy). Different estimates of evapotranspiration rates were retrieved from the online Moderate Resolution Imaging Spectroradiometer (MODIS) database and used as input values. The numerical model was calibrated against piezometric heads collected in two snapshots (mid-January 2007 and mid-June 2007) in monitoring wells distributed along the whole alluvial aquifer. The model performance was excellent, with all the statistical parameters indicating very good agreement between calculated and observed heads. The model validation was performed using baseflow data of the Tronto river compared with the calculated aquifer–river exchanges in both of the simulated periods. Then, a series of numerical scenarios indicated that, although the model performance did not vary appreciably regardless of whether it included evapotranspiration from groundwater, the aquifer–river exchanges were influenced significantly. This study showed that evapotranspiration from shallow groundwater accounts for up to 21% of the hydrogeological balance at the aquifer scale and that baseflow observations are pivotal in quantifying the evapotranspiration impact.

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Integrated MASW and ERT Imaging for Geological Definition of an Unconfined Alluvial Aquifer Sustaining a Coastal Groundwater-Dependent Ecosystem in Southwest Portugal

Applied Sciences ◽

10.3390/app10175905 ◽

2020 ◽

Vol 10 (17) ◽

pp. 5905 ◽

Cited By ~ 1

Author(s):

Maria Paz ◽

Francisco Alcalá ◽

Ana Medeiros ◽

Pedro Martínez-Pagán ◽

Jaruselsky Pérez-Cuevas ◽

...

Keyword(s):

Electrical Resistivity ◽

Shallow Groundwater ◽

Time Lapse ◽

Alluvial Aquifer ◽

Geological Structures ◽

Coastal Groundwater ◽

Accommodation Space ◽

Normalized Error ◽

Multichannel Analysis ◽

Definition Of

This paper integrates multichannel analysis of surface waves (MASW) and time-lapse electrical resistivity tomography (ERT) to define aquifer geometry and identify transient groundwater features of the Cascalheira Stream Basin Holocene alluvial aquifer (aquifer H), which contributes to the Santo André Lagoon, part of a coastal groundwater-dependent ecosystem (GDE), located in southwest Portugal. MASW measures shear-wave velocity (VS), allowing one to obtain steady geological models of the subsurface, and ERT measures subsurface electrical resistivity (ER), being subjected to ambient changes. MASW enables disambiguation of geological structures in low ER environments, such as coastal areas. This research covered one natural year and involved one MASW campaign, four ERT campaigns, and additional geological field surveys and groundwater monitoring to assist interpretation of results. In the area, the conjugate NW–SE and NE–SW strike-slip fault systems determine compartmentalization of geological structures and subsequent accommodation space for Holocene sedimentation. MASW and ERT surveys show how the NW–SE system deepens these structures toward the coast, whereas the NE–SW system generates small horsts and grabens, being one of these occupied by aquifer H. From upstream to downstream, aquifer H thickness and width increase from 10 m to 12 m and from 140 m to 240 m, respectively. Performance of VS and ER models was satisfactory, with a normalized error of the VR and ER models in the 0.01–0.09 range, meaning that a quantitative quota of uncertainty can be segregated from the overall uncertainty of groundwater models without substantially affecting its simulations accuracy. This methodology seeks to improve the design of shallow groundwater research in GDE preservation policies.

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