Improving the method for monitoring the piezometric level of underground water in production wells of the Kamchatka Territory

Приведен опыт в области контроля гидродинамического режима подземных напорных вод при их эксплуатации. Для измерения и корректировки результатов измерений пьезометрического уровня подземных вод в самоизливающихся скважинах использовали автономные автоматизированные измерительные устройства. Экспериментальные исследования проводили на наблюдательной скважине № 1 Мильковского месторождения подземных питьевых вод (Амшарикский участок). Результаты исследований показали, что максимальный уровень подземных вод соответствует периоду таяния снежного покрова (май–июнь). Минимальный уровень подземных вод наблюдали в апреле. Отмечено, что годовой график изменения уровня воды в скважине № 1 не соответствует полностью ни одному из типовых графиков, что свидетельствует о необходимости организации автоматизированного контроля гидродинамического режима данного месторождения подземных вод с целью защиты его от истощения и загрязнения. The experience in monitoring the hydrodynamic regime of underground pressure water in the process of exploitation is presented. To measure and correct the results of measurements of the piezometric level of underground water in blowing wells, self-contained automated measuring devices were used. The experimental studies were carried out at observation well No. 1 of the Mil’kovskoe deposit of underground drinking water (Amsharikski site). The research results showed that the maximum underground water level corresponded to the period of snow cover melting (May – June). The minimum underground water level was observed in April. It is noted that the annual schedule of the water level changes in well No. 1 does not fully comply with any of the standard schedules suggesting the need to establish automated control of the hydrodynamic regime of this underground water deposit in order to protect it from depletion and pollution.

Hydraulic properties calibration by high resolution monitoring data and 1D to 3D groundwater flow modeling of the Carozzo Landslide

<p>A reliable modeling of a landslide activation and reactivation requires a representative geological and engineering geological characterization of the affected materials. Beyond the material strength, landslide reactivation is sensitive to groundwater pressure distributions, that are generated by some external perturbation (recharge) and by the hydraulic properties of the materials. Drainage stabilization works generally involve drilling of a large number of drains and, therefore, minimize the total length is of primary concern to reduce the costs.</p><p>Aim of this work was the calibration of material properties for the optimization of drainage elements to be built for the slope stabilization and the construction of a shallow tunnel crossing a landslide. The case study is represented by the 4.0 · 10<sup>5</sup> m<sup>3</sup> Carozzo landslide (La Spezia, Liguria, Italy) which affects some marly and sandstone formation. During the tunnel excavation a monitoring network consisting of five DMS columns for displacements and piezometric head multilevel measurements was installed. The monitoring provided a series of piezometric head recession curves following some recharge events. The series of data generated in response of a unique perturbation (rainfall recharge event) were chosen to calibrate the material properties through a multi-step approach, starting from a 1D model and progressively approaching a complete 3D model.</p><p>The 1D simplified approach applies the solution by Troch et al. (2003) that considers a homogeneous landslide material, with constant slope and a progressive change in the slope width. In this model a storage function considers the amount of water stored in a slope section. By imposing the continuity equation and the Darcy law a second order of partial differential equation is solved by integration in space and time. By taking the initial conditions from piezometric measurements and assuming a constant rainfall recharge, the piezometric level and the outflow rate were computed and compared with the local piezometric level time history, by changing the hydraulic conductivity and the storage function value.</p><p>Successively, a groundwater flow FEM numerical model (in 2D and 3D) was developed considering the landslide geometry and internal zonation, including the presence of the excavated part of the tunnel. The model domain was divided into sub-zones according to the available geological surveys to account for internal variations of the material properties. The steady-state simulation of the water flow allowed to estimate the equivalent hydrogeological parameters of each subdomain. The hydraulic head distribution obtained under steady-state conditions was used as initial condition for the transient-state simulation. The recharge from precipitation was also included in the water balance by means of daily rainfall time-series. Finally, the model parameters were calibrated in transient state by comparing measured data and simulated results.</p><p>The minimum error between simulated and measured piezometric heads under transient conditions was obtained through the 3D configuration. Calibrated hydraulic conductivities in the 3D solution are up to an order of magnitude lower than the 1D solution because of the homogenous assumption of the model. The internal zonation of the landslide body and the modeling of a low-conductivity shear zone were essential to explain the pressure differences inside the body.</p>

Analysis of Theoretical Concepts for Interpretation the Result of the Experimental Studies of Free Groundwater Level Oscillation in Wells

A number of publications present the results of an experimental study of free oscillations of groundwater piezometric level in wells with their eigenfrequencies. The oscillations were initiated by a pulsed impact on the aquifer through the well. Also in a number of publications a theoretical interpretation was proposed for the established phenomenon. However, the existing theoretical ideas about free oscillations of the groundwater level seem to be incorrect. In the present work, a critical analysis of these available theoretical concepts is performed. The analysis served as an impetus to the development of a consistent theory of relaxation filtration of groundwater.

PEMODELAN PENGARUH PEMOMPAAN SUMUR PRODUKSI PADA AKIFER DENGAN MUKA AIR TANAH MIRING

The main issue in the utilization of ground water is always related to the decrease in water table or piezometric level. The decreasing of groundwater level is often accompanied by number of environmental impacts such as; subsidence, sea water intrusion, or reduced water from residents' wells and surface water bodies. Therefore, an experimental and numerical study was carried out to learn phenomena of cone depression resulted by groundwater production well. The experimental study of physical modeling used the S12-MKII Hydrology Study System equipment, and numerical modeling used Groundwater Modeling Software - Modflow. The modeling results were verified by analytical estimation. The results indicated that the groundwater withdrawn obtained with physical model and numerical simulation is bigger than estimated by analytical equation, particularly in estimating groundwater divide to a well.

Climatic variability in the Sine-Saloum basin and its impacts on water resources: case of the Sob and Diohine watersheds in the region of Niakhar

Local peoples from Niakhar in the Senegalese peanut basin highlight a dramatic increase of water access problems due to marked rainfall deficits and salinization of surface and ground water resources. The chemical quality of groundwaters is often critical because of the salinization process, whereas water surfaces, which should be used in such situations, are up early. More and more, lowlands and rivers beds are pervaded by salt crusts. Then the salinization of wells is increasing, leading to the extension of tans (salty of acidified soils). To study the impacts of climatic pejoration on the agroecosystems and on the living conditions of the populations, we carried out the analysis of the time series of the precipitations with daily and annual time steps from 1950 to 2015 on 6 meteorological stations, in situ measurements on 78 wells for an area of 311 km2, as well as local population interviews and field observation. The results confirm an important climatic break in the region in 1970. The long dry period, from 1970 to 2009, has increased the annual rain variability, decreased the number of rainy days per year. We confirm a real and large extension of well salinization, and salt crusting in the lowlands and the riverbeds. From the local people, it seems the process of degradation of the aquifers continues to progress from a large tidal event in 1984. The rainfall increase noted in the last decade does not seem to be enough to reverse the trend and to ensure both the rise of the piezometric level of the aquifers and the desalinization of surface and ground waters.

Detecting groundwater anthropogenic extraction with cyclicity results of wavelet models

<p>Groundwater is the main water source for irrigation in arid and semi-arid areas. Unfortunately, it has been proven very difficult to prevent unauthorized extractions. The present work studies the application of wavelet analysis to detect and quantify the unfavorable effects of these extractions on the piezometry.</p><p>Wavelets have been widely applied for hydrologic time series analysis since the 1990s, with increasing popularity in recent years. This method can be applied to hydrologic series to reveal complex hydrological processes and evaluate complex latent factors, such as seasonal crop irrigation, controlling groundwater level fluctuations.</p><p>Records of the piezometric level from more than 150 piezometers were studied from 1975 to 2016 in the Almonte-Marismas aquifer (SW Spain). The majority of these time series presented periodicities between 11-12 months, which corresponded to hydrological cycles of recharge and discharge. Nevertheless, in some areas close to crop fields, periodicities of 2-3 and 4-6 months have been detected. In these cases, wavelet analysis could be used as a tool to prevent damage in areas in need of deeper legal control.</p>

Chemical variations in time in a context of climate variability: examples in different hydrogeological settings

<p>Increased variability in precipitation and more extreme weather events caused by climate change can lead to more extended periods of droughts and floods, which directly affects the availability of groundwater. The consequent fluctuation of the water table can also affect groundwater quality. Particularly, a higher recharge, and the resultant increase of the piezometric level, can have, as a positive result, the dilution of the contaminants in aquifers and a decrease of the concentrations. On the other side, water that infiltrates can leach pollutants that are present in the unsaturated zone, with an increase of groundwater pollution. Even, the rise of the piezometric level can have negative consequences on groundwater quality, also due to groundwater that leach the capillary fringe and the previously unsaturated zone; if a contaminant is present in these sectors, it can lead to an increase of the aquifer pollution.</p><p>The increase or decrease in contaminants levels depend on a complex balance between all the described phenomena, and contaminant behaviour. This study wants to analyse the hydrogeochemical variations in time due to climate variability to define the role of different processes.</p><p>Two different hydrogeological environments were chosen as test fields: an alluvial aquifer in the Piedmont Po Plain (NW Italy) and an alluvial-pyroclastic aquifer in the Campanian plain (S Italy).</p><p>Piedmont Po plain shows a diffuse nitrate contamination, due to intensive agricultural and livestock activities. A nickel contamination is locally present, due to natural causes, namely the presence of basic and ultrabasic rocks debris in the supply basins, containing high amount of nickel-bearing femic minerals. Consequently, nitrate and nickel fluctuation were analysed and compared with precipitation and piezometric levels.</p><p>The hydrogeochemistry of the Campanian plain is influenced by the closeness of volcanic active areas (Phlegrean Fields and Vesuvius), bringing high As and F values, and by the presence of reducing conditions, bringing high Fe and Mn values. Moreover, there is a widespread nitrate contamination, prevalently due to intensive agricultural and livestock activities. The fluctuations of these 5 ions (As, F, Fe, Mn and NO<sub>3</sub>) have been observed during almost twenty years and compared with the differences in recharge, sometimes significant due to the climate change.</p><p>The monitoring and analyses of the chemical concentrations of ions of anthropogenic and natural origin in a context of climate variability represent a key element to offer a new and different research perspective in the field of groundwater chemistry.</p>

Meshless method using fundamental solution applied to computational simulation of groundwater flow of real aquifers: study case (Guariroba’s APA and Juazeiro do Norte)

ABSTRACT We investigated the influence of fictitious boundary distance, a parameter of MFS, to determine piezometric levels of two unconfined sedimentary aquifers assuming Dupuit-Forchheimer and steady-state flow hypothesis. Two study areas were modelled: Guariroba’s Environmental Protection Area, in Mato Grosso do Sul State, Brazil, and Juazeiro do Norte City, in Ceará State, Brazil. It was observed that in order to use the MFS as a numerical method in modeling groundwater flow, it is necessary to determine the best distance value of the fictitious boundary. This value can be chosen from the use of field data within the analyzed domain, where the relative error is a parameter to be minimized. Applying this methodology and comparing with the results of the MODFLOW application for the same set of initial data, we concluded that the MSF allows to estimate the piezometric level values within the analyzed domains and that the results of the statistical comparison between them point to the need to investigate the representativeness of both methods to determine which one is most appropriate for modelling the groundwater flow in each region.

Characterization of the mineralization of the Groundwater in high Basin of Guir (Morocco) by geochemical and geostatistical

Due to over-exploitation of water resources, the high basin of Guir posed an alarming risk of elimination in terms of quantity and quality. Therefore, this study intends to evaluate the physical and chemical quality of groundwater in the high Basin of Guir and to identify possible sources of pollution in order to map the quality of the Jurassic groundwater. During May 2018, thirty water points, distributed in the high basin of Guir, were sampled and analysed to determine concentrations of sevenchemical elements: K+, Na+, Ca++, Mg++, Cl-, HCO3-, SO4-. In addition, EC (Electric Conductivity), pH,T° and the piezometric level (PL) weremeasured.To study and compare, we treated statistically all data by Principal Component Analysis (PCA) and SIG.Analysis of the overall quality of water displayed results that range from good to poor quality. The degradation of water quality in the aquifer of the high basin of Guir could be geological and anthropic.