Piezometric Measurements Research Articles

Numerical forecast of groundwater inflow to the mines of the Legnica-Głogów Copper District with a particular emphasis on the “Polkowice-Sieroszowice” mine

The paper presents the results of work on the numerical hydrogeological model of the mines of theLegnica-Głogów Copper District (LGCD) in Poland. Due to the extensive impact on the rock mass and the multi-layer depression cone caused by drainage, the model covers an area of 3,049 km2 . The complicated, mutual hydraulic connections of the multi-aquifer hydrogeological system required the model to cover the area beyond the range of mining areas, and to separate 17 numerical layers. The research was carried out in the GMS software environment using Modflow computing modules. The model was updated successively, since its structure, parameters, and boundary conditions are subject to change. It was also additionally calibrated based on new data from measurements in piezometers and changes recorded in inflows to the excavations. The simulations made it possible to determine the exact water balance, with a particular emphasis on the Sieroszowice mining area, where sudden unexpected inflows were noted. Subsequently, two prognostic simulations were performed to estimate dynamic water inflows to mine workings in the years 2020 and 2025.

A note on a transverse magnetic field controlled co-current bubble column

An experimental study has been carried out investigating the fluidization behavior of a bubble column with a bottom magnetic particle bed controlled by an external transverse magnetic field. The magnetization-first/gas-scanning mode was applied, at up to 45 kA m-1 field intensity, with liquid superficial velocities of up to 20 mm s-1 and with a gas flowrate of up to 8 m3 h-1. Particle fractions of two different sizes of up to 1 mm were used. The focus has been both on the three-phase magnetic particle bed expansion playing the role of a gas distributor and the gas holdup of the abovepositioned two-phase section, as well as related column parameters. Piezometric measurements have been performed that provided detection of the position of the interface between the two column sections without visual observation, as well as the gas holdup in the two-phase zone. The bed expansion was strongly affected by the bed state created by the initially established liquid flow rate. The results showed that the intensity of the field applied to the magnetic solids allows control both of bed expansion and internal bed structure, so the applicability of magnetically assisted three-phase beed as a gas distributor in bubble column seems promising.

El impacto combinado de la sequía y los cambios en el uso del suelo sobre los recursos hídricos en el Tabular Atlas Medio, Marruecos

The quantitative degradation of water resources in the Tabular Middle Atlas is linked to climate and changes in agricultural practices. The relationship between these variables is identified through the analysis of hydroclimatic data, fieldwork, and the processing of Landsat satellite images in two representative sectors of the Middle Atlas. Interviews with local populations and piezometric measurements performed in the Guigou depression show that the groundwater table has dropped from a few meters deep to over 45 meters in several locations. Additionally, monitoring of the surface water area of Aoua lake between September 1984 and September 2022 from satellite images indicates remarkable variations, with periods of prolonged drying. The critical situation of water resources in this sector of Morocco is explained by the recurrence of drought periods of varying severity, increasing temperatures, and the progressive extension of irrigated areas across the depressions. In three decades, irrigated areas have multiplied by more than five in the Guigou depression and by more than three in the Imouzzer-Aoua depressions. Changes in climatic parameters associated with modifications in agricultural practices have strongly influenced water resources in the Tabular Middle Atlas.

Hydrogeochemical characterization of the areas of exploitation of the CBG sites: cas of the plateaus of N'Dangara and Boundou Wandé, Sangarédi sub-prefecture, Prefecture of Boké, Republic of Guinea

Abstract This work aims to analyze the quality of groundwater in the riparian areas of the bauxitic plateaus of N'Dangara and Boundou Wandé in operation by the CBG (Compagnie des Bauxites de Guinée). The geology of the study area consists mainly of sedimentary formations of the Devonian faro, Neogene and Quaternary. Three water measurement and sampling campaigns on the two plateaus were carried out with determination of piezometric measurements and physic-chemical parameters. This study showed that the general flow direction of groundwater is dispersed. The flows at Boundou Wandé are from the center of the plateau to the north and that at N'Dangara is from the center to the south and southwest. It can be seen that the direction of groundwater flow reflects overall the relief of the deposit conditioned by its geomorphological framework. It emerges from the analysis of physical and chemical parameters that well water is consumable. However, the water from wells MW15, MW16, MW17, MW18 and MW21 with a low pH (4.84 to 5.13) may present a certain nuisance for its consumption and because it can be corrosive. Analysis of the Piper diagram showed two hydrogeochemical facies (calcium and magnesium bicarbonate facies and sodium and potassium carbonate facies). However, this study strongly suggests continuous monitoring of groundwater in and around the study area in order to meet the demand for water supply to communities without compromising the ability of future generations to meet water quality requirements.

Effects of aquitard windows on groundwater fluctuations within a coastal leaky aquifer system: An analytical and experimental study

Low-permeability aquitards are important sedimentary units that protect the underlying confined aquifers from contamination by seawater and anthropogenic sources in coastal leaky aquifer systems. Therefore, the integrity of the aquitard is of crucial importance. However, the aquitard integrity may be vulnerable to horizontal heterogeneities in the form of aquitard windows. In this study, an innovative analytical model was developed to describe groundwater flow in a coastal leaky aquifer system with horizontal heterogeneities in hydraulic properties of either the aquitard or the confined aquifer. Consequently, the effects of aquitard windows, which manifest as horizontally local heterogeneities in hydraulic conductivity and/or specific storage, on the tidal wave propagation can be considered in the analysis. Analytical solutions were derived for tidal-head or constant-flux inland boundary conditions. The derivation process avoided previous methodologies that involved the assembly of large-size matrices. The newly developed analytical model can cover multiple existing analytical models that are associated with the assumptions of homogeneity in hydraulic properties of the aquifer and the aquitard, infinite horizontal extent of the coastal leaky aquifer system, impermeability of the aquitard, or ignorance of aquitard storativity. Analytical investigations revealed that high-permeability aquitard windows acting as preferential-flow conduits tended to dampen the tide-induced head propagation within the underlying confined aquifer. Moreover, an aquitard with a higher storativity (but the same permeability) and of considerable size can result in an apparent propagation bias. The newly developed analytical model in this study was further corroborated through sandbox experiments. Both piezometer measurements and parameter estimates indicated the non-negligible effects of high-permeability aquitard windows on the tidal wave propagation. The sandbox investigation also highlighted the importance of geostatistical inverse modeling in characterizing local heterogeneities within the confined aquifer and in detecting the location and size of aquitard windows, when measurement data of tide-induced aquifer head fluctuations were provided.

Hydrodynamic Characterization of the Water Table of the Upper Dallol Maouri Basin (Niger)

The Dallol Maouri is a valley of an ancient tributary of the Niger River. The groundwater in this area of the upper Dallol Maouri is little known because of the weakness of the data. The purpose of this study is to make a hydrodynamic characterization of the water table of the upper dallol Maouri by piezometric approach. A piezometric monitoring network made up of 65 points (54 wells and 11 piezometers) was set up. Six (6) piezometric measurement campaigns were carried out from June 2018 to June 2021. The piezometric survey is carried out once every six months: in January and June corresponding respectively to the high and low water period. The results show that the water table is multi-layered in places with a combination of alluvial and Continental Terminal 3 (CT3) aquifers, or perched aquifers and inferoflux aquifers around permanent ponds. The flow direction of the Continental Terminal 3 (CT3) aquifer is mainly North-East/South-West. The piezometric levels are around 219 m (in the South-West part) and 281 m (in the North-East part). The hydraulic gradient varies from 0.018‰ to 1.83‰. The recharge zones are located in the outcrop zone of the aquifer and in the valleys. A lack of recharge is observed on the plateaus despite the presence of numerous permanent ponds. The recharge coefficient in 2020 is estimated at 25% of the total rainfall recorded.

Spatiotemporal Analysis of Groundwater Resources in the Saïss Aquifer, Morocco

In recent decades, the Saïss plain, in the northwest of Morocco, has experienced a noticeable increase in water demand due to a very significant population growth and economic development, as well as the climate change effects. With the aim of reaching optimal and dynamic management of these water resources, it is essential to have comprehensive and reliable information on the state of the aquifer systems in the region. To achieve this, we assessed a geostatistical analysis of groundwater level data, and created a multivariate regression model. Indeed, in this study, a spatiotemporal analysis of groundwater depth based on piezometric measurements of 45 wells was carried out for the period from 2005 to 2020. It compares and evaluates eight geostatistical interpolation methods and solves the problem of data gaps of the piezometric measurement by completing the chronological series of the groundwater level between 2005 and 2020 using the ARIMA model. The results demonstrate that the variation in the groundwater level between 2005 and 2020 indicates that the water table level is decreased in certain areas, but it has improved or remained constant in other areas. These results emphasize an urgent need for a dynamic management for the conservation of groundwater resources in certain areas of the region under this study.

What Is the Impact of Leaky Sewers on Groundwater Contamination in Urban Semi-Confined Aquifers? A Test Study Related to Fecal Matter and Personal Care Products (PCPs)

Urban areas exercise numerous and strong pressures on water bodies, implying that different external anthropogenic factors also stress groundwater. Sewerage networks play an important role, being the place of wastewater flow. When sewerage deterioration conditions occur, aquifers can be contaminated by contaminants contained within wastewater. The study aims to verify the impact of sewerage leaks in urban semi-confined aquifers through a multidisciplinary approach. Geological, hydrogeological, hydrochemical, microbiological, and biomolecular investigations are carried out in a test site close to a sewer pipe, from February to October 2022. Microbiological analyses are carried out on a monthly basis, contextually to hydraulic head measurements in purpose-drilled piezometers. The presence of sandy intercalations and the prevalence of silt within the outcropping (about 10 m thick) aquitard makes the aquifer vulnerable to percolation from leaky sewers, therefore causing persistent microbial contamination in groundwater. The presence of fecal indicators (including pathogenic genera), corrosive and human-associated bacteria markers, is detected. The magnitude of microbiological impact varies over time, depending on hydrogeological factors such as dilution, hydrodynamic dispersion, and variation of the groundwater flow pathway at the site scale. As for personal care products, only Disodium EDTA is detected in wastewater, while in groundwater the concentrations of all the analyzed substances are lower than the instrumental detection limit.

Evaluation of groundwater flow through a high rockfill dam foundation in karst area in response to reservoir impoundment

Constructing high dams in karst valleys remains a challenging issue as karst conduits provide preferential channels for flow through the foundations. The uncertainty of the karst system drastically increases the risk of leakage and hence the difficulty in seepage control at the foundations. This study examined the transient flow behaviors through a karst foundation on which a rockfill dam with a height of 219 m had been constructed. During reservoir filling, an abnormal pressure rise occurred in the foundation downstream the grout curtains, typically with a magnitude of 53∼69 m higher than the pore pressure head at the neighboring positions. This phenomenon was comprehensively investigated by site characterization, inverse modelling, numerical simulation and cross-correlation analysis, demonstrating that the abnormal pressure rise is locally induced by eroded fault (left bank) or contact zones between karst formations (right bank). These conduits have an effective permeability value one order of magnitude higher than that of the karst formations, which quickly transmit the reservoir pressure pulse across the grout curtains, as evidenced by a higher cross-correlation and a smaller lag between pool level and piezometer measurements. The grout curtains have sufficiently low permeability in limiting the amount of leakage through the foundation, and hence ensure the safety of the reservoir operation in spite of the pressure rise. This study confirms the applicability of the equivalent continuum model in addressing groundwater flow problems in karst formations, as long as the site conditions are properly characterized.

Effects of solvents on synthesis of piezoelectric polyvinylidene fluoride trifluoroethylene thin films

• Polyvinylidene fluoride thin films were developed with multiple dissolving solvents. • High dipole moment solvents increased piezoelectric properties. • Propylene carbonate used to synthesize polyvinylidene fluoride. Polyvinylidene Fluoride (PVDF) and its co-polymer formulations, such as tri-fluoroethylene (TrFE) have been extensively researched as a thin flexible piezoelectric material for a wide range of applications, and new methods of synthesizing the material are continuously being investigated. Researchers have used various solvents to synthesize the PVDF film, yet the effects of these solvents on the piezoelectric properties have not been systematically investigated. The selection of an optimized solvent for polymer dissolution can affect film properties, which could lead to enhanced device performance for piezoelectric-based microsystems. Herein, several solvents were screened for the dissolution of PVDF-TrFE polymer to investigate the effect of solvents and to determine key properties of the solvents that influence the piezoelectric response, so further enhancements can be made in the future. This study investigated 14 different solvents with varying physicochemical properties. The thin films were characterized via X-ray diffraction and quasi-static piezometer measurements. This paper reports that the piezoelectric coefficient of the thin film was highly dependent on the solvent's dipole moment. Our observation revealed that the solvent with the highest dipole moment that was able to completely dissolve the PVDF-TrFE powder produced the film with the highest piezoelectric coefficient. The spin coated film decreased thickness with increasing spin speed, and the piezoelectric coefficient was not affected by the thickness of the film in the range of 1–5 μm.

ГЕОДЕЗІЯ, КАРТОГРАФІЯ І АЕРОФОТОЗНІМАННЯ

The article presents the aspects of historical development of monitoring of Tereble-Ritska hydroelectric power station (HPP), which led to the need of establishing an automated system of geodetic monitoring (ASGM) of deformations of the water pipeline and other structures. Since 2018, the system has been automated and the instrumental part continues to be expanded. Thus, as of 2022, the instrumental part of ASGM includes 3 main components, namely: linear-angular measurements with the determination of meteorological parameters, satellite GNSS measurements, and piezometric measurements. This article presents the results of ASGM work in order to monitor deformations. There are also some advantages of using ASGM in comparison with classical measurements, which first of all allow determining of coordinates in real-time and increase the accuracy of spatial deformation detection to 2 mm (horizontal) and 3 mm (height) on an area of 2 km2. It is also possible to inform the maintenance services of the monitored object when the received deformation exceeds the established limits. According to the results of the time series of linear-angular measurements, it can be stated that the pipeline undergoes seasonal displacements which are manifested in the horizontal displacement of supports towards the HPP building from winter to summer, and vice versa from summer to winter. To date, the amount of special data for the aggregate analysis of linear-angular measurements with the determination of meteorological parameters, GNSS measurements and piezometric measurements is insufficient. As data accumulates, it will be important to establish relationships between these parameters.

Detection of Outlier Observations in Piezometric Measurements: A Case Study in the Southern Region of Poland

One of the main modes of monitoring the geotechnical conditions of earth dams is piezometric measurement, which measures water levels in an open piezometer or water pressure in a closed piezometer. During piezometric measurements, various types of factors can cause disturbances in these measurements that take the form of systematic, accidental, or obvious mistakes. Before measurements from open or closed piezometers are analyzed, outliers due to coarse errors should be detected and rejected. Such observations may significantly influence the result of the analysis and cause erroneous assessment and interpretation of the phenomenon studied. To do this, statistical tests must be applied so that the doubtful measurement can be accepted or rejected at the assumed significance level. This paper uses five statistical tests for identifying and rejecting outliers: the Q-Dixon test, the Grubbs test, as well as the Hampel test, the Iglewicz and Hoaglin test, and the Rosner test. The aim of this article is to try to identify the most suitable test for periodic piezometric measurements. The scope of the study includes the analysis of piezometric measurements for the Czaniec Dam for the multi-year period 2017–2020.

Initial assessment of the groundwater flow and budget using Geographic Information System, MODFLOW-2005 and the FREEWAT modeling tool in Bouteldja coastal aquifer (Northern East of Algeria)

The Bouteldja coastal aquifer is one of the most important groundwater resources in North eastern of Algeria. The region is under a sub-humid climate with an average rainfall of 600-880 mm/y. The unconfined aquifer is constituted of Quaternary sands formations. The hydrogeological characteristics were determined based on previous reports. A very important inflow recharges the sandy aquifer in the Southeastern boundary, in relation to a fault network system linking the aquifer and the Obeira Lake area. Another inflow is observed at the Southern boundary in relation to the exchanges with the alluvial aquifer of Bouteldja. The purpose of the present study is to provide an initial assessment of the groundwater flow and water budget of this aquifer. To achieve this goal, a one-layer groundwater flow numerical model was developed using the MODFLOW-2005 code and the FREEWAT software, using the available data. The model was run in steady state conditions. Calibration was achieved using the piezometric measurements of May 2018 as calibration target. After several trials of manual calibrations, the model successfully simulated the groundwater flows directions and heads. Calibration efforts lead to an acceptable concordance (for the purpose of this study) between the estimated and calculated hydraulic conductivity and piezometric heads, except at the Eastern border. The analyses of the simulated inflow budget shows that aside the rainfall infiltration, exchanges with surface water bodies, the adjoining alluvial aquifer and the fault system provide a relevant amount of water. This significant recharge needs additional investigations. This numerical modeling exercise using MODFLOW, the FREEWAT software and GIS reached the objective of a preliminary description of the groundwater flow and it represents an acceptable starting point for more thorough hydrodynamic characterization of the Bouteldja coastal aquifer.

Hydroboration of Alkenes Catalysed by a Nickel N-Heterocyclic Carbene Complex: Reaction and Mechanistic Aspects.

The pentamethylcyclopentadienyl N-heterocyclic carbene nickel complex [Ni(η5 -C5 Me5 )Cl(IMes)] (IMes=1,3-dimesitylimidazol-2-ylidene) efficiently catalyses the anti-Markovnikov hydroboration of alkenes with catecholborane in the presence of a catalytic amount of potassium tert-butoxide, and joins the very exclusive club of nickel catalysts for this important transformation. Interestingly, the regioselectivity can be reversed in some cases by using pinacolborane instead of catecholborane. Mechanistic investigations involving control experiments, 1 H and 11 B NMR spectroscopy, cyclic voltammetry, piezometric measurements and DFT calculations suggest an initial reduction of the NiII precursor to a NiI active species with the concomitant release of H2 . The crucial role of the alkoxo-catecholato-borohydride species resulting from the reaction of potassium tert-butoxide with catecholborane in the formation of an intermediate nickel-hydride species that would then be reduced to the NiI active species, is highlighted.

Investigation of groundwater table distribution using borehole piezometer data interpolation: Case study of Singapore

The variation of groundwater table is important information for Civil Engineering and related practices. The most appropriate datasets for the groundwater table mapping are the water level measurements in borehole piezometers. The methods for development of the groundwater table distribution on a continuous surface are affected by the hydrological factors and spatial variability of the soils. In this study, the piezometer data of the groundwater table in soils from four formations in Singapore were used to predict the continuous surface of the groundwater table. The interpolation of groundwater table elevation was performed using geostatistical analyses: inverse distance weighted (IDW) and Ordinary Kriging (OK) interpolations within residual soils from Bukit Timah Granite Formation, Old Alluvium Formation, Jurong Formation, and Kallang Formation. The interpolations were completed based on 80% of dataset (1,282 piezometers for wet season and 2,567 piezometers for dry season). The evaluation of the predicted groundwater table maps was carried out using cross-validation method (CVM) based on 20% of the datasets (256 piezometers for wet season and 512 piezometers for dry season). The results show that the IDW and OK interpolations generated quite similar predictions of the groundwater table distribution ranging between -3.7 m and 58 m elevation with respect to sea level, depending on hydrogeological conditions and soil formation characteristics. The validation method indicated a very good performance of IDW and OK in predicting the groundwater table distribution in Singapore (r2 > 0.8). The proposed procedures and methodologies covering the interpretation of data from piezometers , spatial analyses and evaluation of groundwater table map via geographical information system (GIS) approach presented in this paper will benefit Civil Engineers prior to building construction. The developed groundwater table map will be useful to determine the optimum number of piezometers still required for designs, to design the low cost and effective ground improvement, foundation and retaining wall in order to ensure the stability of the building during and after the completion of the project.

Capabilities of an optical direct push probe for 2D-subsurface imaging

Characterization of hydrological conditions at polluted sites is critical for understanding of contaminant distribution and transport. Standard techniques for site characterization, such as soil coring together with well installation for piezometric measurements and water sampling, allow only some insights into subsurface properties and processes. To obtain additional data, direct-push techniques are often used in soils and unconsolidated formations. The various available techniques provide high resolution information on cm to mm scale. Recently, the Optical Imaging Profiler (OIP) was developed for detection of fluorescent contaminants. Here, we have investigated the applicability of the OIP for groundwater tracing using fluorophores. Our laboratory experiments show that it is possible to qualitatively trace various fluorophores meaning that light emitted by the fluorophores can be detected by a standard digital camera sensor. The measured fluorescence depends on the number of fluorophore molecules present in the pore space adjacent to the OIP and decreases with smaller pore size as well as fluorophore concentration. In a field trial, an injected eosin Y solution could be very clearly detected after the injection within a radius of 0.5 m around the injection point. When the OIP is equipped with a second light source emitting visible light, images of the soil texture and color can be captured. Sediment color can act as a proxy for various soil properties. Tests at a second field site, indicate that detected variation in soil color depend on water saturation and redox processes. Hence, the OIP is a flexible, cost effective and multifunctional tool for characterization of contaminated sites.

Potential effects of climate change on NRCS Wetland Restoration Easements: An ecohydrological assessment

AbstractWater cycles are expected to change globally with predicted climate warming. Yet predicted shifts in hydrological regimes are rarely incorporated into wetland restoration planning, despite large investments in projects very susceptible to hydrological changes. We assessed potential effects of climate change on previously restored wetlands to identify siting and design issues for use in guiding adaptive management or planning future restoration projects. Five United States Department of Agriculture Natural Resources Conservation Service Wetland Reserve Easements in Genesee County, New York, were studied from 2013 through 2014. Elevations of surface water and groundwater were monitored, piezometric measurements made, and water chemistry and plant community data collected. Precipitation, surface water, and groundwater hydrologic data were used to relate each restored wetland to vulnerability of climate change. Although all five sites were functioning as planned, three sites had less vulnerability to climate change due to their connection to more stable sources of groundwater, position within the hydrological landscape, or design features that mimic the natural landscape. Suggestions for adaptive management on already implemented projects include actively managing water‐control structures, enhancing microtopography, and increasing plant diversity by planting or seeding. Potential sites for future restoration projects should be ranked based on location in the watershed, presence of hydric soils, past and potential hydrological connections, and sustainability of hydrology, especially groundwater sourcing. Design options should attempt to mimic natural landscape features, refrain from overengineering, and allow for flexible management of hydroperiods.

Hydrogeology of the Karst Area of the Grassano and Telese Springs

This work deals with the hydraulic phenomenon of the ascendant groundwater flow affecting the karst area of the Grassano and Telese springs (Campania, Southern Italy). It has been investigated through piezometric measurements, discharge and chemical-physical monitoring of springs and measurements of the radon 222Rn activity. The presence of ascendant flows is supported by numerous and different types of evidences in the area: location and topographical position of the springs; amazing density of sinkholes connected to geomorphic processes that develop below the topographic surface and involve the rising of CO2 and H2S rich waters; constancy of the temperature and the electrical conductivity of the spring waters over the time; fluctuation of the radon activity during the hydrological year; increasing of the hydraulic head with depth; presence of artesian conditions in the alluvial plain. Numerical simulations of the groundwater flow also support the general phenomenon of the ascendant flow in the discharge area and represent a useful background to interpret hydrological phenomena in the study area. The results of the simulations are suitable with all the hydrogeological processes observed in the area of the Grassano and Telese springs; this last is thought to belong to the regional groundwater flow system of the Matese massif and represents its discharge zone.

Heat as a Proxy to Image Dynamic Processes with 4D Electrical Resistivity Tomography

Since salt cannot always be used as a geophysical tracer (because it may pollute the aquifer with the mass that is necessary to induce a geophysical contrast), and since in many contaminated aquifer salts (e.g., chloride) already constitute the main contaminants, another geophysical tracer is needed to force a contrast in the subsurface that can be detected from surface geophysical measurements. In this context, we used heat as a proxy to image and monitor groundwater flow and solute transport in a shallow alluvial aquifer (<10 m deep) with the help of electrical resistivity tomography (ERT). The goal of our study is to demonstrate the feasibility of such methodology in the context of the validation of the efficiency of a hydraulic barrier that confines a chloride contamination to its source. To do so, we combined a heat tracer push/pull test with time-lapse 3D ERT and classical hydrogeological measurements in wells and piezometers. Our results show that heat can be an excellent salt substitution tracer for geophysical monitoring studies, both qualitatively and semi-quantitatively. Our methodology, based on 3D surface ERT, allows to visually prove that a hydraulic barrier works efficiently and could be used as an assessment of such installations.

Interpretation of the results of monitoring of the piezometric measurements of the Chańcza dam in 2014–2017

Abstract The occurrence of a hydraulic connection between piezometers is identified based on similar changes in water levels. Some piezometers react to changing upper or lower water levels, some may also react to atmospheric precipitation. If the reaction to variable upper water levels is significant, then leakage of seepage control devices is identified and the dam is subjected to repair works. The aim of this research paper is to present and analyse the dynamics of variability of water levels in open piezometers of the Chańcza dam, located at the 36 km of the Czarna Staszowska River in the town of Korytnica in Świętokrzyskie province (Poland). Before the analysis of the piezometric data was commenced, the Grubbs statistical test was used to identify and reject the outliers. The scope of the research includes the data captured between January 14, 2014 and January 13, 2017. A hypothesis was formulated that the change in the trend occurred after the spring of 2015 when the water level in the reservoir was reduced by approx. 1.5 m. Two trend lines were adapted for the water levels of each piezometer using the least squares method – the first one for the period from January 2014 to May 2015, and the second one from June 2015 to January 2017. In this way, two slopes of the linear function were obtained together with an estimation of their errors. These slopes were compared using a statistical parallelism test.