Stiffness Patterns Research Articles

Evaluation of groundwater for drinking and irrigation applications concerning physicochemical and ionic parameters through multiple indexing approach: a case study around the industrial zone, Punjab, India.

The seasonal quality of groundwater and its appropriateness for drinking and irrigation were assessed using a multiple indexing approach in this study. Physicochemical and ionic parameters were examined in groundwater samples near the industrial zone of Rupnagar, Punjab. To assess groundwater quality, water quality index (WQI) and pollution index were used. The Durov's, piper, wilcox and stiff diagrams were plotted to understand the hydro-chemistry. Similarly, the irrigation indices, i.e., salinity hazard, sodium adsorption ratio, soluble sodium percentage (Na%), magnesium adsorption ratio, residual sodium carbonate, permeability index and Kelley's ratio were applied to ascertain the water quality for agricultural purposes. As a result, total hardness, calcium (Ca2+), magnesium (Mg2+) and fluoride (F-) were found above the standard permissible limits. WQI analysis showed 12% samples of pre-monsoon (PRE-M) and 28% samples of post-monsoon (POS-M) were of poor quality, which may pose health risks. Hydrochemistry revealed the predominance of Ca2+, Na+, Mg2+ and HCO3- ions in the groundwater attributed to natural and anthropogenic sources. Piper diagram revealed Ca2+-Mg2+-Cl-, Na+-Cl-, Ca2+-Na+- HCO3-, Ca2+- HCO3- and Ca2+-Cl, Ca2+-HCO3- water types exist in the study area. USSL diagram showed that the samples from both seasons come under the low salinity hazard. In addition, total dissolved solids and electrical conductivity showed a strong positive association, indicating the saline nature of groundwater. Furthermore, hierarchical clustering classified groundwater into three groups (I, II and III), revealing that groundwater quality varies due to natural and anthropogenic effects. Based on the findings, the groundwater was found marginally suitable for drinking and irrigation purposes. It is therefore recommended that the groundwater is examined on a regular basis in order to maintain its quality.

Sub-Bottom Profiler and Side Scan Sonar investigations, with the assistance of hydrochemical and isotopic analysis of Sawa Lake, Al-Muthana Governorate, Southern Iraq

A marine geophysical survey are including Sub Bottom Profilers and Side Scan Sonar integrating with under-water imagery, as well as hydrochemical and isotopic investigations have been carried out for Sawa Lake, one of the unique, shallow and closed water body in Iraq. The results showed that the depth of the Lake is shallow, ranged between 1 m in areas near the edges of the Lake and 2 m in the Lake center. The Recharge site has been detected exactly (this is a first recording (Nov. 2012)), as a hole. It has a longitudinal an axis of 50 m with NW-SE tren, which resembles the trending of the longitudinal axis of the Lake and Abu-Jir fault trending. The maximum width of this hole ranging from 23.0-29.5 m. The hole depth about 20 m, but may be greater then, because the emergence of a high proportion of noise in the geophysical sections. The Lake bottom is homogeneity and does not has any diacritical features. Also, the results showed discontinuous layers on either side of the hole due to the existance a number of caves under the bottom of the Lake extends into several meters with different dimensions and forms. Hydrochemical analysis of the water samples collected from different depths inside the hole by scientific diving with specefic equibments and the result showed that the water is NaCl type, with domination of Mg and Cl over Ca and SO4. The Stiff diagram, detected that very high TDS arising mainly from sodium and chloride, it is mostly typical marine water. Values of δ18O and δ2H in water samples of Sawa Lake, when plotted along the global meteoric water line shows that the three collected water samples from the lake, which have a similar isotopic composition, indicating that all of them are receiving water from the same flow zones, with diffuse recharge type. Also, the isotopic parameter showed that the Sawa lake water suffering from strong evaporation.

Hydrogeochemical Characterization and Identification of Factors Influencing Groundwater Quality in Coastal Aquifers, Case: La Yarada, Tacna, Peru.

The coastal aquifer La Yarada has anthropogenic and geogenic contamination that adversely affect the quality of groundwater for population and agricultural use. In this scenario, multivariate statistical methods were applied in 20 physicochemical and isotopic parameters of 53 groundwater pumping wells in October 2020, with the aim of characterizing the hydrogeochemical processes that dominate the groundwater of the coastal aquifer and the factors that cause them to optimize the effective management of water resources, delimiting areas affected by more than one salinization process. The samples were grouped into three clusters (C1, C2, and C3) with cluster analysis, the spatial distribution of C2 and C3 (reclassified in stiff diagrams), evidenced hydrogeochemical facies associated with the flow and recharge directions governed by the structural lineaments (NE-SO), favoring some areas more than others, arising different facies and hydrogeochemical processes. Factor analysis was applied from three different approaches: (1) main elements, (2) trace elements, and (3) physicochemical and isotopic parameters; exposing 6 distinguishable hydrogeochemical processes in the aquifer and factors that cause them: (i) salinization—marine intrusion, (ii) fertilizer leaching and dissolution of (Ca2+, Mg2+), (iii) wastewater mixture (NO3−), (iv) reducing conditions (Fe, Mn, Al), (v) contributions of (B, Sr), (vi) conservative mixtures and dissolution (As, F). It was validated with water quality indices (WQI) according to the national limits, delimiting 67 km2 parallel to the coast with “bad” to “very bad” quality for human consumption and unsuitable for irrigation according to the Wilcox diagram thus pre-treatment in this area is indispensable.

Effects of multi-factors on the spatiotemporal variations of deep confined groundwater in coal mining regions, North China

Natural processes and anthropogenic activities simultaneously control the long-term spatial and temporal variations of groundwater hydrogeochemistry in coalfields. In this study, the spatiotemporal variations and primary controlling factors of deep groundwater hydrogeochemistry in the Carboniferous limestone aquifer of the Huaibei coalfield, North China were investigated using cluster analysis combined with geological conditions, water-rock interactions and mining activities. The analysis data of 176 groundwater samples collected over five years from 20 monitoring wells were subdivided into six clusters through hierarchical cluster analysis. Moreover, principal component analysis, box plots and Piper and Stiff diagrams were employed to analyze the statistical and hydrogeochemical characteristics of each cluster, and to reveal the differences and connections between the clusters. The results show that there are significantly spatial variations in groundwater hydrogeochemistry, while the temporal variations are not evident with only a few notable exceptions. Geological conditions dominate the groundwater hydrogeochemistry by controlling the hydraulic connection between groundwater and meteoric water and the flow conditions of groundwater. Moreover, the types and degrees of diverse water-rock interactions in different regions are another important factor controlling the spatial variations of groundwater hydrogeochemistry. Anthropogenic activities are mainly pumping and drainage, which has led to the overall decline in groundwater levels and the temporal variations of hydrogeochemistry in some zones. The findings of this study not only have important implications for deep groundwater resources management in the Huaibei coalfield, but also provide a research template for other highly exploited coalfields in North China.

Hydrogeochemical and Characteristics of Groundwater in Teluk Nilap Area, Rokan Hilir, Riau

Groundwater plays important role as the main water resource for human needs. The vulnerability of groundwater to contaminants both naturally and by human activities can be not avoided as a trigger for groundwater quality degradation. Hydrogeochemical become important highlights in groundwater studies because groundwater conditions in quality and quantity influenced by the geological formation of rock minerals in aquifer. Naturally, the condition of the research area which consists of peat swamps can also affect the characteristics of groundwater. The aims of this research are to determine groundwater types and groundwater facies in study area with an analytical approach using stiff diagram and piper diagram. The method used was purposive sampling by collecting data from dug wells at the research site. 5 samples from dug wells were used as representatives in the groundwater facies analysis. The groundwater facies analysis was carried out by measuring the concentration of major ions such as Na, K, Ca, Mg, Cl, SO4, and HCO3. The highest groundwater level was in the northern part of study area (7,84 m) while the lowest groundwater level was in the southwest part of study area (2,05 m). The results showed three types of groundwater based on stiff diagram as sodium chloride (NaCl), sodium sulfate (NaSO4) and magnesium sulfate (MgSO4). The lithology conditions that composed the aquifer affected the facies or origin of groundwater. The alluvium layer in the research area which rich in sodium (Na+) minerals with chloride (Cl-) or sulfate (SO42-) anions forms chloride sulfate facies (Cl+SO4) which were located in the middle to the south of the study area and sodium (potassium) chloride (sulfate) facies (Na(K)Cl(SO4)) which were distributed in the northern part of study area.

Dampak Siklon Tropis Savannah Terhadap Karakteristik Hidrogeokimia Aliran pada Mata Air Guntur, Kawasan Karst Gunungsewu

Tropical Cyclones often occur in Indonesia and have disastrous impacts. Until now, no research has focused on time series data related to groundwater discharge and chemistry due to tropical cyclones. Therefore, this study aims to analyze and compare the characteristics of the hourly time series, both discharge and chemistry of the Guntur karst springs. Guntur Spring was affected by the tropical cyclone of Savannah on March 17, 2019. The method used in this study consisted of two parts, namely the analysis of the discharge and chemistry of Guntur Spring. Discharge analysis was performed by correlation test with rain intensity. Chemical analysis was carried out using the Minister of Health Regulation No. 90 of 2002 and expert standards. Other chemical analyzes were performed using a triangular piper, rectangular piper, and stiff diagram of the parameters Na+, K+, Ca2+, Mg2+, SO42-, Cl-, and HCO3-. The results of the relationship between discharge and rain intensity are directly proportional and increase significantly during a cyclone. The results of analysis of the Guntur Springs during Tropical Cyclone Savannah, all parameters are in accordance with the quality standard. In addition, there was a reduction in ion content due to the dilution process of Ca2+, Mg2+, Cl-, HCO3-., DHL, and pH ions compared to non-cyclone, Beton Resurgence, and Gremeng Resurgence ions. The chemical results when the cyclone is different compared to non-cyclone, Gremeng Resurgence and Beton Resurgence with a characteristic decrease in ionic content.

Spring Water Geochemistry: A Geothermal Exploration Tool in the Rhenohercynian Fold-and-Thrust Belt in Belgium

Spring water geochemistry is applied here to evaluate the geothermal potential in Rhenohercynian fold and thrust belt around the deepest borehole in Belgium (Havelange borehole: 5648 m MD). Fifty springs and (few) wells around Havelange borehole were chosen according to a multicriteria approach including the hydrothermal source of “Chaudfontaine” (T ≈ 36 °C) taken as a reference for the area. The waters sampled, except Chaudfontaine present an in-situ T range of 3.66–14.04 °C (mean 9.83 °C) and a TDS (dry residue) salinity range of 46–498 mg/L. The processing methods applied to the results are: hierarchical clustering, Piper and Stiff diagrams, TIS, heat map, boxplots, and geothermometry. Seven clusters are found and allow us to define three main water types. The first type, locally called “pouhon”, is rich in Fe and Mn. The second type contains an interesting concentration of the geothermal indicators: Li, Sr, Rb. Chaudfontaine and Moressée (≈5 km East from the borehole) belong to this group. This last locality is identified as a geothermal target for further investigations. The third group represents superficial waters with frequently high NO3 concentration. The application of conventional geothermometers in this context indicates very different reservoir temperatures. The field of applications of these geothermometers need to be review in these geological conditions.

Merging Water Research, Analytical Chemistry, and Agile Management to Shape Prospective Professionals through the Project-Centred Collaborative Approach Focusing on Water Bodies rather than Water Samples

Professionals of different disciplines, including chemists and chemical engineers, engage in water research, even though they might not have been extensively trained in it during their studies. We describe a project-centred master level subject “Water as a Hydrogeological, Ecological, and Analytical System”, which, by focussing on waterbodies instead of a particular aspect of water quality, merges total analytical process with water research and, by a considerate choice of chemical parameters, enables students to apply water-research-specific data-treatment techniques, including the Piper and Stiff diagram, to discuss water genesis, processes in water, and influences on waterbodies. Agile management, initiated in computer engineering in 2001, is believed to contribute to better products in a shorter time. We demonstrate how its incorporation into the organisational scheme helped students self-organise, handle their projects, and collaborate within and between groups. Student’s expressions confirm their overall satisfaction, motivation, and that the omission of the final classical exam had no adverse effects on the learning outcomes. Their consent with different benefits of the project-centred collaborative approach and their self-efficacy beliefs, respectively, expressed as mean values in a five-grade Likert scale ranged from 4.26 to 5.00 and from 4.32 to 5.00. Regarding the students’ time investment, the project-centred approach as the mean grade 3 confirmed is not recognised as an easier way. We provide partially self-calculating, self-notifying Excel spreadsheet tables to ease the implementation of water research data-treatment techniques, which help students collaborate and discuss their subject extensively.

Hydrogeochemical properties and the exhaustion groundwater reserve from Dammam aquifer at Al-Najaf Governorate, middle Iraq

One of Iraq’s most significant groundwater-bearing limestone aquifers is the Dammam Formation. The aquifer groundwater has been studied hydrogeochemically. It is suitable for irrigation, as indicated by sodium adsorption ratio (SAR) and total dissolved solids (TDS), which are 4.15 and 1971 ppm (in average) respectively. Through the vision of the Stiff diagram, the predominant ions are Cl-, SO4 2+ and Na+ while the HCO-3 and Mg2+ are relatively poor. There is plenty of flowing wells in the study area in Najaf Governorate producing groundwater from the Dammam aquifer. In recent years, many wells have been drilled in an irregular pattern for forming fish breeding lakes. These lakes’ water drains 4.715 m3/s into the Najaf depression by Wadi Al- Khur and artificial channels, where it mixes with brine water, rendering it useless. This lead to the exhaustion huge amount of precious groundwater resource. Many signs that confirm the Piezometric pressure drop and groundwater levels descent in the Dammam aquifer in the region. The groundwater flow has been halted in several flowing wells in the study area especially in Wadi Al-Khur due to the exhaustion of the reserve and a decrease in the level of the hydrostatic pressure of the aquifer. A significant decline in values transmissivity and specific capacity of the Dammam aquifer when compared with previous studies in the years 1996 and 2009. Through observation of the monitoring well (W/7), a decrease in groundwater levels of flowing wells in the study area.

An origami inspired quasi-zero stiffness vibration isolator using a novel truss-spring based stack Miura-ori structure

In this paper, an origami-inspired vibration isolator is proposed and numerically investigated to achieve a quasi-zero-stiffness (QZS) property. A truss-spring based stack Miura-ori (TS-SMO) structure is introduced in the vibration isolation system to provide a desired stiffness for high-static-low-dynamic requirement. The proposed TS-SMO structure is different from the traditional origami structures which include rigid facets and deformable creases. It uses coil spring sets to replace all the creases, to improve the physical realization in engineering applications. Nonlinear force response and the QZS feature can be achieved through the geometric nonlinearity and its unique Poisson’s ratio profile. The static force and stiffness characteristics of the developed TS-SMO structure are numerically discussed to meet specific feature requirements. Then a QZS vibration isolator is presented under specific parameter design. The force–displacement response and stiffness diagram are obtained to verify the static performance as an isolation system. Furthermore, the displacement transmissibility is derived through dynamic analysis by employing both harmonic balance method (HBM) and numerical simulations. The isolation performance under variable viscous damping is also discussed to examine the effects of the system damping.

Hydrochemical analysis of groundwater quality along the coastal aquifers in part of Ogun Waterside, Ogun State, southwestern Nigeria

Hydrochemical investigation of groundwater was carried out on the coastal aquifers of Ogun Waterside, Southwestern Nigeria. Groundwater samples were collected and assayed for physicochemical parameters during wet season (August, 2016) and dry season (March, 2017). The analysed data were further subjected to correlation analysis (CA), principal component analysis (PCA), hydrochemical facies and descriptive statistics. Results revealed that the groundwater is slightly acidic with fresh to saline character. The CA showed very strong associations between TDS, EC and Cl concentrations in both wet and dry seasons. PCA confirmed the main factor influencing the groundwater chemistry in the study area to be component I (salinity component). Piper plots also revealed that the aquifer is mainly of Na−Cl water type. Schoeller and Stiff diagrams showed that the groundwater comprises relative abundance of major ions in the following order: Na+>K+>Mg2+>Ca2+ for the cations and Cl−>HCO3−>SO42− for the anions. Thus, the primary process influencing the hydrochemistry of the study area is saltwater invasion while mineral dissolution and rainwater infiltration play less significant roles. Most parameters fall within the permissible limit proposed by the World Health Organization (2011) and Nigerian Standard for Drinking Water Quality (2007). However, higher concentrations of chloride and bicarbonate ions observed towards the southern flank of the study area suggest signs of impairment. Assessment of the sampled water for agricultural purposes with respect to salinity hazard, Total Hardness (TH), percentage sodium (%Na) and Sodium Adsorption Ratio (SAR) revealed that the water is suitable for agricultural activities.

Hydrogeochemical Evidence of Earthquake‐Induced Anomalies in Response to the 2017MW5.5 Pohang Earthquake in Korea

AbstractSignificant changes in groundwater systems were observed after the 2017Mw5.5 Pohang earthquake. Groundwater level changes cannot be explained solely by poroelastic responses to the earthquake. In this study, we analyzed hydrogeochemical data, including environmental isotopes (18O,2H,87Sr/86Sr, and222Rn) of water samples as well as time‐series data of groundwater level, temperature, and electrical conductivity. Principal component analysis (PCA) and physical modeling of pore pressure changes were also used. Some anomalies in time‐series data could be explained by the distributions of pore pressure changes based on modeling. However, the other wells, which did not have the correlation between time‐series data and modeling results, exhibited abnormal patterns in hydrogeochemical and isotope data. Stiff diagrams showed differing patterns of temporal change among groundwater wells. These diagrams and isotopic anomalies revealed possible mechanisms underlying the aftereffects of earthquakes, including saline water mixing, water‐rock interactions, deep fluid upwelling, and bedrock fracture opening. These anomalous phenomena were related to the clusters derived by PCA and depended on the distance to the epicenter, faults, and sea water. This study highlights that a single measurement is insufficient to reliably interpret groundwater responses, whereas a combined hydrogeochemical and physical interpretation may provide critical information for clarifying anomalies related to earthquakes.

Investigation of Groundwater Flow Using Δ18O and ΔD in a Sulfur Mine in Japan

The A sulfur mine is located in the Iwate Prefecture of Japan. This mine has both surface and underground parts and was operatedfrom the late 1800s to the late 1900s. Since the early 1900s, acid mine drainage (AMD) has been reported in this mine, and the wastewater has been neutralized in a treatment plant since the mine was closed. Recently, reducing the AMD volume by decreasing waterinflow to the underground mine has been considered as a way to reduce the AMD treatment cost. The first step in such an approachis to understand in detail the groundwater flow around the mine. However, part of the study area is covered by lava and comprisescrystalline rocks with complicated structures, making it difficult to understand the groundwater flow. Therefore, the present studyinvestigated the groundwater flow around this mine by focusing on water quality, such as pH and electrical conductivity (EC), stableisotopes (i.e. δ18O and δD) and 3H in the surface and ground water. The spatial distributions of pH, Stiff diagrams, and δ18O and δDvalues in the surface and ground water indicated that the groundwater flow system was divided into three basins in the study area,as predicted from geomorphological information. Moreover, the spatial distribution of δ18O and δD in the surface and ground watersuggested that the groundwater recharged at the highest altitudes in the B mountain in the northwest of the mine might flow in theunderground mine. Furthermore, the 3H values in the waste water discharged from the underground part of mine implied that thegroundwater age was no more than approximately 60 years old.

Hydrogeochemical characteristics and water quality of Aji-Chay river, eastern catchment of Lake Urmia, Iran

The Aji-Chay river is the most important river discharging into endangered Lake Urmia in NW of Iran. The present study investigates the hydrogeochemical characteristics and origin of dissolved ions in the Aji-Chay river and some of its tributaries passing through Tabriz plain which is located at the east side of Lake Urmia. For this purpose, 317 water samples were collected during 9 years (2005–2014) from four stations and clustered to nine groups using K-means algorithm. Major cations and anions were considered to distinguish the hydrogeochemical evolution of water. The Piper, Langelier–Ludwig and Stiff diagrams classified water samples into predominant Na–Cl endmember and Ca–HCO3 only in the upstream zone. With respect to Gibbs diagrams, mineral saturation indices and geology of the area, water chemistry of the Aji-Chay river reflects that water–rock chemical interactions including dissolution/precipitation of carbonate and sulfate minerals known as dedolomitization and dissolution of evaporitic salts along the flow path are the dominant factors controlling the water chemistry; furthermore, evaporation, silicate weathering, and ion exchange reactions change the chemistry of water to some extent. Overall, water quality is evaluated as poor. Furthermore, intense halite dissolution increases Na concentration in water which in turn reduces its suitability for irrigation purposes.

Evaluation of Hydrochemical Facies and Suitability of Water in Tilaiya Dam Reservoir of the Jharkhand State in India

The reservoir at Tilaiya Dam in the Jharkhand state of India is one of the most important freshwater sources in the region. The water of the reservoir is primarily used for domestic, drinking, and irrigation. Water quality of the reservoir was monitored at five locations during pre-monsoon, monsoon, and post-monsoon seasons in 2017-2018 to understand spatiotemporal variation and also, the suitability of water for existing uses. A hydro-geochemical analysis of reservoir water was undertaken with the help of Piper Diagram, Schoeller-Berkaloff diagram, Stiff diagram, U.S Salinity Laboratory diagram, Water Quality Index, Salinity Index, Sodium Percentage, Sodium Absorption Ratio, Magnesium Hazard, etc. The hydrochemical facies in the present study showed that water was of Ca-HCO3 water type. Factor analysis revealed two predominating factors, both geogenic in nature, that influenced reservoir water quality, accounting for 81.992 % of the variance in data. Slight variation in water quality was observed with time and space but it was non- significant statistically. Water Quality Index had increasing trends at three sites from monsoon to pre-monsoon through post-monsoon and winter seasons. The study revealed that the water of the reservoir is good and suitable for drinking, domestic use, irrigation, and industry in all the seasons during 2017-18.

Hidrogeoquímica como ferramenta para o reconhecimento de aquíferos em lacunas de perfis litológicos de poços tubulares

A área estudada, situada 30 km a norte de Belo Horizonte, engloba toda Área de Proteção Ambiental Carste de Lagoa Santa e arredores, perfazendo 505 km². Os aquíferos cárstico-fissurais, desenvolvidos nas rochas carbonáticas dos membros inferior (impuro) e superior (puro) da Formação Sete Lagoas - Pedro Leopoldo e Lagoa Santa, respectivamente, são mais explorados, seguidos dos fissurais em metapelitos da Formação Serra de Santa Helena, granitos do embasamento do Complexo Belo Horizonte, e granulares de cobertura. Apesar do grande número de poços tubulares operantes, ocorre grande precariedade de descrição litológica nos perfis desses poços, comprometendo sua utilização. Visando ladear esse problema, segundo resultados hidroquímicos obtidos e dados litológicos disponíveis, classificou-se, por unidades aquíferas, 21 amostras de água sub-superficial, e 85 de circulação profunda. A divisão foi avaliada por diagramas de Piper e Stiff e tratamento estatístico dos dados, incluindo Boxplots e análise de Cluster. A classificação mostrou-se eficaz, especialmente na separação das unidades silicáticas e carbonáticas. A distinção entre as duas unidades carbonáticas pode ser ampliada com análises complementares.

Hydro-geochemical analysis and quality evaluation of surface water in the Mamu River basin, southeastern Nigeria

Mamu basin is a major tributary of Anambra drainage basin and a reservoir for wastewater from agricultural and runoff processes within the basin. Water quality of the Mamu basin was evaluated to determine its suitability for potable water and agrarian uses. This study utilized 24 water samples collected during the rainy and dry season from the upstream and downstream segments of the sub basins within River Mamu. Hdyro-geochemical analytical results were employed in the evaluation of several water quality criteria such as QWI, SAR, TH, SSP, MAR, PI, KR, Na% and %E of the water from the basin. The results suggested that the surface water is unfit for ingestion when compared with the WHO and Standard Organization of Nigeria (SON) standards. However, the QWI result showed that 66.7% of the water samples are good for consumption in the rainy season, while 75% of the samples are classified unfit for drinking in the dry season. Parameters such as Fe2+, Mn2+, TDS, temperature and total coliform (p < 0.001) exhibited temporal variation unlike pH, EC, Ce, Ca2+, Mg2+, Cl−, K + , NO3, PO43−, Na+, HCO3−, Zn2+, TSS, SO4, DO, BOD and turbidity which showed no response to season. Based on the results of SAR, TH, SSP, PI, KR, Na% and US salinity plots, the surface water is suitable for irrigation. Conversely, the MAR and %E results pointed out that water treatment is vital before use. The basin water is associated with permanent hardness due to CaCl2 coupled with the dominance of Mg2+ and SO42−. Gibbs plots and Stiff diagram showed that geology and dissolution process have an influence on the water chemistry via weathering and rock–mineral interactions, while chemical ratios and correlation coefficients (R2) point on anthropogenic activities.

Physical and chemical properties of the groundwater of the Santo Domingo-Salinas ranges, South Central Pyrenees

ABSTRACT The Santo Domingo-Salinas ranges represent a unique Natural Area in the south-central Pyrenees, and they were declarationas a Protected Landscape in 2015. Available biological and geological knowledge is extensive but lacks of information on groundwater quality. In this work we provide new hydrogeological results and integrate them with previously available hydrogeological data. To do so, we have: (i) compiled existing hydrogeological information, (ii) exhaustively developed an inventory of water points, (iii) sampled, analyzed and interpreted the hydrochemical facies detected, and (iv) developed a preliminary conceptual model for the hydrogeological functioning of the area. These information has been integrated in an map that displays the chemical analyses of the two new campaigns (Stiff diagrams), the flow rates and the three aquifer systems defined. This new information improves and synthetizes the knowledge of the hidrogeology of the Santo Domingo-Salinas ranges Protected Landscape and it will help in its future management and planning.

Assessment of potential seawater intrusion in a coastal aquifer system at Abomey - Calavi, Benin

Severe sea-water intrusion can be detected several kilometers inland and represents a high risk for coastal region groundwater. The coastal aquifer of the continental terminal of the township of Abomey-Calavi (Benin) has been highly exploited for intensive drinking water capture to supply the most important cities of Abomey-Calavi, Sèmè and Cotonou in Benin. During the past 15 years, extracted water quantities for drinking water supply to those cities rose to the point where saline intrusion was suspected. The present study aims at determining the intensity and the extent of saline intrusion, if any, in those regions. Elaboration of Piper diagrams, related graphs and Stiff diagrams resulted in the ascertainment that groundwater in the district of Godomey is probably contaminated by sea water and revealed Togbin to be an area of intrusion of seawater into groundwater. This study has helped in setting the boundaries where seawater intrusion into groundwater occurs in the township of Abomey-Calavi. These results confirm previous findings, which had detected an early saline intrusion in this Godomey pumping area.

Experimental assessment of the static stiffness of machine parts and structures by changing the magnitude of the hysteresis as a function of loading

Abstract Static stiffness is determined by one-sided loading and unloading of machine parts relative to the selected base. For each structure, there will be some loss of potential energy due to the dissipative forces that occur during the loading inside the structure. This loss is manifested in hysteresis in the stiffness diagram. A new approach to the assessment of static stiffness consists in gradual, bilateral loading and unloading of the structure through the effect of static forces of different magnitude. In this process, the stiffness hysteresis varies, depending on the intrinsic nature of the dissipative forces, a specific property suitable for assessing the condition of machines.