Isotope Tracking of Surface Water Groundwater Interaction in the Beninese Part of the Iullemeden Aquifer System

The Kandi basin is located in northeast Benin (West Africa). This study is focused on the estimation of water fluxes exchanged between the river Niger (and its tributaries) and the transboundary Iullemeden Aquifer System. In that framework, an innovative approach based on the application of the Bayesian Mixing Model (MixSIAR) analysis on water isotopes (oxygen-18, deuterium and tritium) was performed. Moreover, to assess the relevance of the model outputs, Pearson’s correlation and Principal Component Analysis (PCA) have been done. A complex relationship between surface water and groundwater has been found. Sixty percent (60%) of groundwater samples are made of more than 70% river water and rainwater;while 31.25% of surface water samples are made of about 84% groundwater. To safeguard sustainable water resources for the well-being of the local communities, surface water and groundwater must be managed as a unique component in the Kandi basin.

Hydrogeochemical Characterization of Aquifer Systems and Surface Water/Groundwater Relations in the Lower Senegal River Valley

This study assesses the chemical quality of water resources in the Lower Senegal River valley, based on 35 samples collected in November 2022. Major ion concentrations in surface water and groundwater were analyzed using classical geochemical interpretation diagrams (Piper, GIBBS, etc.) and multivariate geostatistical analyses, including hierarchical cluster analysis (HCA) and principal component analysis (PCA). The results revealed three types of facies: Ca-Mg-HCO3-type facies, characteristic of poorly mineralized waters such as surface waters and groundwater from dune formations and the alluvial plain close to the hydraulic axis;Na-Cl type facies associated with well waters located in the alluvial plain that tap Inchirian or Nouakchottian shallow reservoirs and Maastrichtian deep borehole waters;and mixed Ca-Cl and Na-HCO3 type facies observed in certain floodplain and dune reservoirs. The results showed a strong correlation between sodium, chlorides, bromides, and electrical conductivity, indicating a significant contribution of these ions to groundwater mineralization. The various sources of water mineralization include mixing processes between surface water or rainwater, or calcite or dolomite dissolution processes (for weakly mineralized waters), basic exchanges or inverse basic exchanges between the aquifer and the water table (for moderately mineralized waters), and evaporation processes, halite dissolution, and paleosalinity during periods of marine transgression and regression (for highly mineralized waters). The study also highlighted the high vulnerability of the alluvial aquifer to pollution from intensive irrigated agriculture, as significant quantities of sulfates and nitrates were measured in some samples. These results also highlight the importance of water quality management in the Lower Senegal Valley, particularly as concerns the protection of the alluvial aquifer against pollution from irrigated agriculture.

The Damaging Effects of Abstracting the Deep Aquifers’Groundwater in Jordan-Quality Constraints

The deep aquifers in Jordan contain non-renewable and fossil groundwater and their extraction is quasi a mining process, which ends in the depletion of these resources. Although aquifers in the majority of groundwater basins in Jordan are vertically and horizontally interconnected stratification in different water quality horizons with generally increasing water salinity with the depth is observed. Many officials and planners advocate the extraction of deep salty and brackish water to be desalinated and used in household, industrial, and agricultural uses. In this article, the quality of the groundwater in the different deep aquifers and areas in Jordan is discussed. The results of this study show that the consequences of the deep groundwater exploitation are not restricted to depletion of the deep aquifers but also that the overlying fresh groundwater will, due to vertical and horizontal interconnectedness of the different aquifers, percolate down to replace the extracted deep groundwater. This will cause the down-percolating fresh groundwater to become salinized in the deep saline aquifers, which means that extracting the deep brackish and saline groundwater is not only an emptying process of the deep groundwater but also it is an emptying process of the fresh groundwater overlying them. The results allow to conclude that any extraction of the deep groundwater in areas lying to the north of Ras en Naqab Escarpment will have damaging impacts on the fresh groundwater in the overlying fresh groundwater aquifers. This article strongly advises not to extract the deep brackish and saline groundwater, but to conserve that groundwater as a base supporting the overlying fresh groundwater resources, and that will help in protecting the thermal mineralized water springs used in spas originating from these deep aquifers. The increasing water needs of the country can be covered by the desalination of seawater at Aqaba, which is the only viable option for Jordan at present and in the coming decades.

Investigation of Groundwater Quality with Borehole Depth in the Basin Granitoids of the Ashanti Region of Ghana

The dependence of groundwater quality on borehole depth is usually debatable in groundwater studies, especially in complex geological formations where aquifer characteristics vary spatially with depth. This study therefore seeks to investigate the relationship between borehole depth and groundwater quality across the granitoid aquifers within the Birimian Supergroup in the Ashanti Region. Physicochemical analysis records of groundwater quality data were collected from 23 boreholes of public and private institutions in the Ashanti Region of Ghana, and the parametric values of iron, fluoride, total hardness, pH, nitrate, and nitrite were used to study the groundwater quality-depth relationship. The results showed that the depth-to-groundwater quality indicated a marginal increase in water quality in the range of 30 to 50 m, which is mathematically represented by the low-value correlation coefficient (r2 = 0.026). A relatively significant increase occurs in the depth range of 50 to 80 m, which is given by a correlation coefficient of r2 = 0.298. The mean percent parameter compatibility was 74%, 82%, 89%, and 97% at 50, 60, 70, and 80 m depths, respectively. The variations in groundwater quality per depth ratio ranged from 1.48, 1.37, 1.27, and 1.21 for 50, 60, 70, and 80 m depth, respectively. The recommended minimum borehole depth for excellent groundwater quality is suggested with a compatibility per meter depth ratio of 1.37. This results in a range between 50 and 70 m as the most desirable drilling depth for excellent groundwater quality within the granitoids of the Birimian Supergroup of the Ashanti Region in Ghana.

Assessment of groundwater quantity, quality, and associated health risk of the Tano river basin, Ghana

In the Tano River Basin,groundwater serves as a crucial resource;however,its quantity and quality with regard to trace elements and microbiological loadings remain poorly understood due to the lack of groundwater logs and limited water research.This study presents a comprehensive analysis of the Tano River Basin,focusing on three key objectives.First,it investigated the aquifer hydraulic parameters and the results showed significant spatial variations in borehole depths,yields,transmissivity,hydraulic conductivity,and specific capacity.Deeper boreholes were concentrated in the northeastern and southeastern zones,while geological formations,particu-larly the Apollonian Formation,exhibit a strong influence on borehole yields.The study identified areas with high transmissivity and hydraulic conductivity in the southern and eastern regions,suggesting good groundwater avail-ability and suitability for sustainable water supply.Sec-ondly,the research investigated the groundwater quality and observed that the majority of borehole samples fall within WHO(Guidelines for Drinking-water Quality,Environmental Health Criteria,Geneva,2011,2017.http://www.who.int)limit.However,some samples have pH levels below the standards,although the groundwater generally qualifies as freshwater.The study further explores hydrochemical facies and health risk assessment,highlighting the dominance of Ca–HCO3 water type.Trace element analysis reveals minimal health risks from most elements,with chromium(Cr)as the primary contributor to chronic health risk.Overall,this study has provided a key insights into the Tano River Basin’s hydrogeology and associated health risks.The outcome of this research has contributed to the broader understanding of hydrogeologi-cal dynamics and the importance of managing groundwater resources sustainably in complex geological environments.

Developing three-dimensional groundwater flow modeling for the Erbil Basin using Groundwater Modeling System (GMS)

This study presents the development of a comprehensive three-dimensional groundwater flow model for the Erbil Basin utilizing the Groundwater Modeling System(GMS).The Erbil Basin,situated in the Kurdistan Region of Iraq,is a vital water resource area facing increasing water demands and environ-mental challenges.The three-dimensional nature of the groundwater flow system is crucial for accurately understanding and managing water resources in the basin.The modeling process involved data collection,geological and hydrogeological characterization,conceptual model development,and numerical simulation using GMS software MODFLOW 2000 package.Various parameters such as hydraulic conductivity,recharge rates,and boundary conditions were integrated into the model to represent the complex hydrogeo-logical conditions of the basin.Model calibration was performed by comparing simulated groundwater levels with observed data from monitoring wells across the basin,using the automatic calibration method of automated Parameter Estimation(PEST).Pilot points were applied to adjust the hydraulic conductivity in the model area spatially.Sensitivity analysis was conducted to assess the influence of key parameters on model predictions and to identify areas of uncertainty.The developed three-dimensional groundwater flow model provides valuable insights into the dynamics of groundwater flow,recharge-discharge mechanisms,and potential impacts of future scenarios such as climate change and water resource management strategies.It serves as a useful tool for decision-makers,water resource managers,and researchers to evaluate differ-ent management scenarios and formulate sustainable groundwater management policies for the Erbil Basin.In conclusion,this study demonstrates the effectiveness of using GMS for developing three-dimensional groundwater flow models in complex hydrogeological settings like the Erbil Basin,contributing to improved understanding and management of groundwater resources in the region.

Evaluation of aquifer hydraulic properties from resistivity and pumping test data in parts of Gwagwalada,Northcentral Nigeria

Population upsurge in Gwagwalada increased water demand in the area,thereby stressing water resources in the area.Aquifer properties in parts of Gwagwalada in North-Central Nigeria were therefore investigated using resistivity and hydrogeological approaches.Static water level measurements of hand dug wells were used to determine the groundwater flow direction for the area which coincides with the North East-South West joint direction.Constant rate pumping test was adopted for the research and 10 boreholes were pumped.The weathered/fractured basement range from 7.5 m to 56.7 m.The transmissivity values in the area ranged from 0.35 m^(2)/d to 3.63 m^(2)/d while the hydraulic conductivity range from 0.045 m/d to 0.18 m/d.The Vertical Electrical Soundings(VES)were carried out on the area.The geoelectric sections revealed four to five layers and the longitudinal conductance varied from 0.11Ω^(-1)to 0.37Ω^(-1).The results of the investigation characterized the groundwater potential in the study area into low and moderate while the aquifer protective capacity into weak and moderate zones.The efficacy of resistivity and pumping test data in quantifying aquifer properties has been established in this study.The findings of this study shed light on the properties of ground water and aquifer protective capacity in the area,hence assist in the effective future groundwater resources exploitation.

Hydrogeological and Physico-Chemical Study of the Groundwater of Mitendi South-East in the Commune of Mont-Ngafula around the Kimwenza Quarry (Province of Kinshasa, DR Congo)

The exploitation of groundwater by drilling in the Mitendi South-East district constitutes a solution to the water shortage in this peripheral part of the Mont-Ngafula township in Kinshasa, the capital of the DR Congo. Individuals exploit groundwater in boreholes to serve the population without taking into account certain necessary aspects such as the origin of the groundwater table and the quality which constitute the major problems of this work such as: What is the quantity of water from the recharge of our aquifer? What is the state of the Mitendi South-East aquifer water in relation to some physico-chemical parameters? The cardinal objective of this work is to provide chemical data and trace elements in each analyzed borehole and determine the type of recharge of the underground aquifer. The specific objectives are as follows: analyze the potability of groundwater on a physico-chemical level and their chemical facies, take the geographical coordinates of water samples from the aquifer in each targeted borehole in order to develop the sampling map of the area under study;also check each parameter analyzed in relation to WHO standards. We carried out a general investigation of the study area by carrying out observations, sampling and in-situ measurements of each borehole, as well as the good conservation of the samples taken in a cooler. The various measurements that we took in-situ: pH, electrical conductivity, turbidity, salinity, temperature, and TDS were carried out by using a multi-parameter probe in the laboratory of appropriate methods such as titled-sorting, spectrophotometry, atomic absorption spectrometry, ArcGise and Excel software. With regard to the results from laboratory analysis (physical and chemical analysis), the parameters showed that the standards recommended by the WHO were not respected. We affirm that the water consumed in the Mitendi South-East district in Mont-Ngafula town ship is not drinkable. Since, it can cause several water-borne diseases. It would be better to treat that water before being drunk. .

Calculation of groundwater head distribution with a close barrier during excavation dewatering in confined aquifer

When pumping is conducted in confined aquifer inside excavation pit(waterproof curtain),the direction of the groundwater seepage outside the excavation changes from horizontal to vertical owing to the existence of the curtain barrier.There is no analytical calculation method for the groundwater head distribution induced by dewatering inside excavation.This paper first analyses the mechanism of the blocking effects from a close barrier in confined aquifer.Then,a simple equation based on analytical solution is proposed to calculate groundwater heads inside and outside of the excavation pit with waterproof curtain(hereafter refer to close barrier)in a confined aquifer.The distribution of groundwater head is derived according to two conditions:(i)pumping with a constant water head,and(ii)pumping with a constant flow rate.The proposed calculation equation is verified by both numerical simulation and experimental results.The comparisons demonstrate that the proposed model can be applied in engineering practice of excavation.

Geochemistry of rare earth elements in groundwater from deep seated limestone aquifer in Renlou Coal Mine,Anhui Province,China

Rare earth element （REE） concentrations were measured by ICP-MS for groundwater collected from deep seated Taiyuan Fm limestone aquifer （from -400 to -530 m） in Renlou Coal Mine, northern Anhui Province, China. It can be concluded that the groundwater is warm （34.0-37.2 ℃） C1-Ca, Na type water with circum-neutral pH （7.35-8.28） and high total dissolved solids （TDS, 1 746-2 849 mg/L）. The groundwater exhibits heavy REEs enrichment relative to light REEs compared with Post Archean Average Shale （PAAS）, as well as their aquifer rocks （limestone）. The enrichment of REEs is considered to be controlled by terrigeneous materials （e.g. zircon） in aquifer rocks, whereas the fractionation of REEs is controlled by marine derived materials （e.g. calcite）, to a less extent, terrigeneous materials and inorganic complexation. The Ce anomalies normalized to PAAS and aquifer rocks are weak, which probably reflects the signature of the aquifer rock rather than redox conditions or pH. The similarities of REE patterns between groundwater and aquifer rocks imply that aquifer rocks play important roles in controlling the REE characteristics of groundwater, and then provide a probability for discrimination of groundwater sources by using REEs.

Optimal Groundwater Development in Coastal Aquifers Near Beihai, China

Groundwater resources occur in a multi aquifer system in the alluvial coastal plain near Beihai, China. The aquifers receive recharge from precipitation, canal and reservoir infiltration, and discharge through subterranean drainage into the sea and through artificial pumping. A quasi three dimensional finite element model has been used to simulate the spatial and temporal distribution of groundwater levels in the aquifers. Various input parameters were considered in the simulation model. A linear optimization model has been developed for groundwater development within the coastal aquifers. The objective function of the model is to maximize the total groundwater pumpage from the confined aquifer. The control of sea water intrusion is examined by the restriction of the water levels at points along the coast and of the pumping rates in coastal management cells. The response matrix used in the optimization model was generated from the simulation model by forecasting drawdown produced by pumping at a unit impulse discharge. Groundwater development can be primarily optimized by the alteration of the pumping rates of the existing wells.

Variation characteristics of aquifer parameters induced by groundwater source heat pump operation under variable flow

The variation characteristics of aquifer parameters,induced by groundwater source heat pump(GWSHP) operation under variable flow,were theoretically analyzed through a case study,in which the characteristics of building air conditioning load were considered.The results,compared with the constant flow operation,indicate that the influence on the variations of porosity,hydraulic conductivity and confined water head is decreased by 48%,51% and 71%,respectively,under variable flow operation.The security of variable flow operation is superior to that of constant flow.It is also concluded that the climate region and function of the buildings are primary factors which affect the suitability of variable flow operation in GWSHP.

Identification of Contaminant Source Characteristics and Monitoring Network Design in Groundwater Aquifers: An Overview

The groundwater system is often polluted by different sources of contamination where the sources are difficult to detect. The presence of contamination in groundwater poses significant challenges to its delineation and quantification. The remediation of a contaminated site requires an optimal decision making system to identify the pollutant source characteristics accurately and efficiently. The source characteristics are generally identified using contaminant concentration measurements from arbitrary or planned monitoring locations. To effectively characterize the sources of pollution, the monitoring locations should be selected appropriately. An efficient monitoring network will result in satisfactory characterization of contaminant sources. On the other hand, an appropriate design of monitoring network requires reliable source characteristics. A coupled iterative sequential source identification and dynamic monitoring network design, improves substantially the accuracy of source identification model. This paper reviews different source identification and monitoring network design methods in groundwater contaminant sites. Further, the models for sequential integration of these two models are presented. The effective integration of source identification and dedicated monitoring network design models, distributed sources, parameter uncertainty, and pollutant geo-chemistry are some of the issues which need to be addressed in efficient, accurate and widely applicable methodologies for identification of unknown pollutant sources in contaminated aquifers.

Groundwater Flow Modeling for Qushtapa Plain Unconfined Aquifer in Southern Erbil Basin, Kurdistan Region, Iraq

Increasing population growth and water demand for various purposes such as irrigation, domestic and industrial production in many parts of the Kurdistan Region is causing deficit in fresh water and rising groundwater dependence. Drilling many deep wells in the area unsystematically and continuously increased pumping water from groundwater reservoirs results in lowering of water table. Therefore, it is essential to assess the management of water resources. The study focuses on the groundwater modeling for the Qushtapa District plain area in particular under steady state flow conditions. The aquifer was simulated under unconfined condition and is represented by a single layer of 100 m thickness. MODPATH was used to measure contamination track lines and travel times. This approach involved the introduction of particles at sources of contaminants in the wells and the recharge area, then the identification of the path lines and the determination of the special distribution of contaminants through steady state flow conditions. The simulation of the groundwater head shows that the groundwater head starts from the northeastern part of the plain and decreases towards Lesser Zab River in the south of the plain from 420 m to 140 m above sea level. The modeled layer was calibrated under steady state conditions using hydraulic parameters obtained from observation and pumping wells. The calibrated model is effective in producing steady-state groundwater head distribution and good compliance with observed data. The standard error was estimated as 4.88 m, the normalized root mean square error is 8.3% and the residual mean is 15.79 m. The results of the forward tracking show the source of potential pollutants from the recharge area after different travel time, the particles released at the northern boundary travels to the center and the western part toward the pollution sources. The results of the backward tracking show that the particles located in the extraction wells moved toward the recharge area in the north and northeastern part of the study area.

Simulation of Regional Karst Aquifer System and Assessment of Groundwater Resources in Manatí-Vega Baja, Puerto Rico

The North Coast karst aquifer system of Puerto Rico, the most productive aquifer of the island, is a vital water source for drinking water and local ecosystems. High freshwater demands alter the coastal groundwater system that impacts both human populations and coastal ecosystems of the island. To predict how this system might respond to rainfall events and high pumping demands, we used the equivalent porous medium (EPM) technique to develop a three-dimensional groundwater flow model to estimate hydrogeological parameters and assess groundwater resources in the Manatí-Vega Baja karst aquifer. The approach is based on the hypothesis that the simplified EPM approach will reproduce groundwater hydrodynamics in this complex karst environment. The steady-state model was calibrated with trial and error and parameter estimation methods using an observed groundwater table of 1995 (r = 0.86, p < 0.0001, n = 39). The large-scale simulation suggested that groundwater flow roughly follows the elevation slope (i.e. south to north). Calibrated hydraulic conductivities range from 0.5 to 86 m/d, whereas the hydro-geologic data strongly suggest higher permeability in the middle karst section of the study area. The transient model adequately estimates the observed groundwater fluctuations in response to rainfall events from 1980 until 2014. The transient results indicate that the conceptual model accuracy is more acceptable with a mean error (ME) of -0.132 m, mean absolute error (MAE) of 0.542 m and root mean square (RMSE) error of 0.365 m. The results of water budget simulation show that the total recharge satisfies the total groundwater withdrawal rate in the past, but continuous closure of more contaminated wells causes groundwater levels to increase in the future. The results indicate that the assumption of applicability of EPM approach is sustained and supported by measured data in the study area. Taking future water demands into account, this model could be applied further to predict the changes of groundwater levels and mass balance under different exploitation scenarios.

Hydrogeological Conceptual Model of Groundwater from Carbonate Aquifers Using Environmental Isotopes (¹⁸O, ²H) and Chemical Tracers: A Case Study in Southern Latium Region, Central Italy

The present work provides hydrochemical and stable isotope data and their interpretations for 54 springs and 20 wells, monitored from 2002 to 2006, in the Southern Latium region of Central Italy to identify flow paths, recharge areas and hydrochemical processes governing the evolution of groundwater in this region. The hydrogeological conceptual model of the carbonate aquifers of southern Latium was based on environmental isotopic and hydrochemical investigation techniques to characterize and model these aquifer systems with the aim of achieving proper management and protection of these important resources. Most of the spring samples, issuing from Lepini, Ausoni and Aurunci Mts., are characterized as Ca-Mg-HCO3 water type, however, some samples show a composition of Na-Cl and mixed Ca-Na-HCO3-Cl waters. Groundwater samples from Pontina Plain are mostly characterized by Na-Cl and Ca-Cl type waters. Geochemical modeling and saturation index computation of the Lepini, Ausoni Aurunci springs and Pontina Plain wells shows an interaction with carbonate rocks. Most of the spring and well water samples were saturated with respect to calcite and dolomite, however all sampled waters were undersaturated with respect to gypsum and halite. The relationship between δ18O and δ2H, for spring and well water samples, shows shifts of both the slope and the deuterium excess when compared to the world meteoric (WMWL) and central Italy meteoric (CIMWL) water lines. The deviation of data points from the meteoric lines can be attributed to evaporation both during the falling of the rain and by run-off on the ground surface before infiltration. Most springs and wells have a deuterium excess above 10 ‰ suggesting the precipitation in the groundwater comes from the Mediterranean sector. On the basis of local isotopic gradients, in combination with topographic and geologic criteria, four recharge areas were identified in the Aurunci Mountains. In Pontina Plain, the elevations of the recharging areas suggest that the Lepini carbonate aquifers are feeding them.

Groundwater solute chemistry,hydrogeochemical processes and fluoride contamination in phreatic aquifer of Odisha,India

The work investigates the major solute chemistry of groundwater and fluoride enrichment(F^(-))in the shallow phreatic aquifer of Odisha.The study also interprets the hydrogeochemical processes of solute acquisition and the genetic behavior of groundwater F^(-)contamination.A total of 1105 groundwater samples collected from across the state from different hydro-geomorphic settings have been analyzed for the major solutes and F^(-) content.Groundwater is alkaline in nature(range of pH:6.6-8.7;ave.:7.9)predominated by moderately hard to very hard types.Average cation and anion chemistry stand in the orders of Ca^(2+)>Na^(+)>Mg^(2+)>K^(+) and HCO_(3)^(-)>Cl^(-)>SO_(4)^(2-)>CO_(3)^(2-) respectively.The average mineralization is low(319 mg/L).The primary water types are Ca-Mg-HCO_(3) and Ca-Mg-Cl^(-)HCO_(3),followed by Na-Cl,Ca-Mg-Cl,and Na-Ca-Mg-HCO_(3)^(-)Cl.Silicate-halite dissolution and reverse ion exchange are the significant processes of solute acquisition.Both the geogenic as well as the anthropogenic sources contribute to the groundwater fluoride contamination,etc.The ratio of Na^(+)/Ca^(2+)>1.0 comprises Na-HCO_(3)(Cl)water types with F^(-)>1.0 mg/L(range 1.0-3.5 mg/L)where the F^(-)bears geogenic source.Positive relations exist between F^(-)and pH,Na^(+),TDS,and HCO_(3)^(-).It also reflects a perfect Na-TDS correlation(0.85).The ratio of Na^(+)/Ca^(2+)<1.0 segregates the sample population(F^(-)range:1.0-4.0 mg/L)with the F derived from anthropogenic sources.Such water types include Ca-Mg-HCO_(3)(Cl)varieties which are recently recharged meteoritic water types.The F^(-) levels exhibit poor and negative correlations with the solutes in groundwater.The Na-TDS relation remains poor(0.12).In contrast,the TDS levels show strong correlations with Ca^(2+)(0.91),Mg^(2+)(0.80)and even Cl^(-)(0.91).The majority of the monitoring points with the anthropogenic sources of groundwater F^(-) are clustered in the Hirakud Canal Command area in the western parts of the state,indicating the role of irrigation return flow in the F^(-) contamination.

Multi-Criteria Analysis Using Remote Sensing and GIS: Insight into Groundwater Potential of the Fissured Aquifers in the Liptako Socle (Southwestern Niger)

In the basement of southwestern Niger, weathering and fractured zones concentrate most of the groundwater. This study focuses on fractured media and aims to identify areas of productivity in this aquifer to improve the region’s water coverage. The cartographic approach developed made it possible to establish synthetic maps based on multi-criteria analysis. The hydrogeological parameters selected include fracturing data, drainage system, slope and piezometric level as well as shallow and deep lithology. The choice of these criteria is based on their physical meaning but also on the availability of data. The integration of all the criteria in a GIS allowed to generate maps of recharge and potential productivity of fractured aquifers in the area. The validation of these thematic maps with independent data confirms their utility as reference standards for accessibility for future resource exploitation. Like any spatialization tool, potential recharge maps will provide valuable information about areas where infiltration is more important, and help control and manage risk zoning. The upward evacuation effect is even more prominent along the lineaments, faults or fractures: thus, to avoid possible pollution and to locate the future hydraulic structures, the analysis of the potential recharge zones remains necessary. The potential productivity index map, in addition to the very punctual sites identified by the fracturing study, made it possible to define areas of high potential productivity.

Groundwater Monitoring in the Gneisso-Basaltic Fractured Rock Aquiferous Formations of Kumba, Southwest Region Cameroon: Seasonal Variations in the Aqueous Geochemistry and Water Quality

The objective was to determine and monitor seasonal changes during four hydrological seasons: Wet season (September), Wetdry season (December), Dry season (March) and Drywet season (June) in the groundwater aqueous geochemistry and its domestic-agro-industrial quality using physicochemical parameters and hydrogeochemical tools: Temperature, Electrical Conductivity EC, pH, Total dissolved solids TDS, Ionic ratios, Gibbs diagrams, Piper diagrams Durov diagrams, total hardness HT, Water quality index WQI, Sodium adsorption ratio SAR, Percent Sodium %Na, Kelly’s Ratio KR, permeability index PI, Magnesium adsorption ratio MAR, Residual sodium carbonate RSC and Wilcox diagram. Field physicochemical parameters ranged from: Wet season;pH 3.9 - 6.9;Temperature, 23.3°C - 29.1°C;EC, 10 - 1900 μS/cm;TDS, 6.7 - 1273 mg/L;Wetdry, pH, 5.7 - 11.7;Temperature, 23.6°C - 28.3°C;EC, 1 - 1099 μS/cm, TDS, 0.67 - 736.33 mg/L;Dry pH, 5.7 - 13.1;Temperature, 26.3°C - 30.2°C;EC, 12 - 770 μS/cm, TDS, 8.04 - 515.9 mg/L and Drywet, pH, 4 - 7.4;Temperature, 25.8°C - 30.7°C;EC, 10 - 1220 μS/cm, TDS, 6.7 - 817.4 mg/L. Seventy-two groundwater samples, 18 per season were analysed. All ionic concentrations fell below acceptable World Health Organization guidelines in all seasons. The sequence of abundance of major ions are;Wet, Ca+ > Mg2+ > Na+ = K+ > NH4+, HCO3? > Cl? > NO3? > SO42? > HPO42?;Wetdry Ca+ > K+ > Mg2+ > Na+ > NH4+, HCO3? > Cl? > SO42? > NO3? > HPO42?;Dry Ca+ > K+ > Mg2+ > Na+ > NH4+, HCO3? > Cl?> NO3? > SO42? > HPO42?;Drywet NH4+ > Ca+ > K+ > Mg2+ > Na+;Cl? > HCO3? > NO3? > SO42? > HPO42?. Groundwater ionic content was due to rock weathering and ion exchange reactions. CaSO4 is the dominant water type in Wet and Wetdry seasons;followed by CaHCO3, Na + K-Cl Wet, CaSO4 and CaHCO3 Wetdry;MgCl Dry and Drywet followed by CaCl, CaHCO3 Dry and CaSO4, CaHCO3 Dry-Wet. The dominant hydrogeochemical facies are Ca-Mg-Cl-SO4 followed by Na-K-SO4 Wet and Ca-Mg-HCO3? in all other seasons. Ion exchange, Simple dissolution and uncommon dissolution are the processes determining groundwater character. The water quality indices;WQI, HT, SAR, %Na, KR, PI, MAR,RSC and Wilcox diagrams, indicate that groundwater in Kumba is 80% - 100% excellent during the Drywet &Wet seasons, 5% - 10% unsuitable during the Wetdry & Dry seasons for domestic use while being excellent-good for Agro-Industrial uses in all other seasons. Physicochemical parameters in some areas exceeded permissible limits for drinking. All hydrogeochemical parameters vary with seasons and these variations show the impact of annual cycles of seasonal changes on the aqueous geochemistry of groundwater in Kumba.

Iron and Manganese in Groundwater of Rrogozhina Aquifer, Western Albania

This paper aims to advance previous studies on the iron and manganese content in groundwater of Rrogozhina aquifer （western Albania） and to show the factors which control the content of both iron and manganese in groundwater of this aquifer. Rrogozhina aquifer represents an important groundwater source of the country whose relevance was highly increased during recent years because of the demographic expansion in this region. This is a typically multi-layered artesian aquifer which consists of sandstone and conglomerate with high heterogeneous permeability. The groundwater mostly belongs to HCO3-Mg-Ca hydrochemical type. The content of soluble iron and manganese in groundwater ranges from 0.004 mg/L to 0.7 mg/L, and from 0.0 mg/L to 1.147 mg/L, respectively. Deeper the groundwater occurs and longer the distance from the recharge zone, higher is the content of Fe2＋ in groundwater due to gradual depletion of Oe in groundwater. The content of iron is higher than that WHO and EU recommended, which were 21% and 25% respectively, while the content of manganese were 17% and 23%, respectively. Abstraction of groundwater with high quantities by deeper wells would be accompanied by increase of dissolved iron and manganese content in groundwater which should be treated （with aeration） in order to decrease the content of these two elements in the water before using it.