Groundwater Level Monitoring Research Articles

Meteorological and hydrological data from the Alder Creek watershed, SW Ontario

Abstract. Data for small to mid-sized watersheds are seldom publicly available, but may be representative of diverse types of hydrological contexts when assessing patterns. These types of data may also prove valuable for informing numerical experimentation and practical modelling. This paper presents data collected in the Alder Creek watershed, located within the Grand River basin in Ontario, Canada. The Alder Creek watershed provides source water from the aquifers of the Waterloo Moraine for multiple well fields that supply the cities of Kitchener and Waterloo. Recharge rates and human impacts on streamflow are important topics for the watershed, and many numerical models of the area have been constructed. In order to support these types of analyses, field equipment was deployed within the watershed between 2013 and 2018 to monitor groundwater levels, stream stage, soil moisture, soil temperature, rainfall, and other weather parameters. The available data are described, complementary information is presented, and examples of possible analyses are cited and illustrated. The data presented and described in this paper are available at https://doi.org/10.20383/101.0178 (Wiebe et al., 2019).

Groundwater level prediction based on a combined intelligence method for the Sifangbei landslide in the Three Gorges Reservoir Area

The monitoring and prediction of the groundwater level (GWL) significantly influence the landslide kinematics. Based on the long-term fluctuation characteristics of the GWL and the time lag of triggering factors, a dynamic prediction model of the GWL based on the Maximum information coefficient (MIC) algorithm and the long-term short-term memory (LSTM) model was proposed. The Sifangbei landslide in the Three Gorges Reservoir area (TGRA) in China, wherein eight GWL monitoring sensors were installed in different locations, was taken as a case study. The monitoring data represented that the fluctuation of the GWL has a specific time lag concerning the accumulated rainfall (AR) and the reservoir water level (RWL). In addition, there were spatial differences in the fluctuation of the GWL, which was controlled by the elevation and the micro landform. From January 19, 2015, to March 6, 2017, the measured data were used to set up the predicted models. The MIC algorithm was adopted to calculate the lag time of the GWL, the RWL, and the AR. The LSTM model is a time series prediction algorithm that can transmit historical information. The Gray wolf optimization (GWO) algorithm was used to seek the most suitable hyperparameter of the LSTM model under the specific prediction conditions. The single-factor GWO-LSTM model without considering triggering factors and the support vector machine regression (SVR) model were considered to compare the prediction results. The results indicate that the MIC-GWO-LSTM model reached the highest accuracy and improved the prediction accuracy by considering the factor selection process with the learner training process. The proposed MIC-GWO-LSTM model combines the advantages of each algorithm and effectively constructs the response relationship between the GWL fluctuation and triggering factors; it also provides a new exploration for the GWL prediction, monitoring, and early warning system in the TGRA.

Analyses of groundwater storage change using GRACE satellite data in the Usutu-Mhlatuze drainage region, north-eastern South Africa

Study regionThe Usutu-Mhlatuze Water Management Area located in northern KwaZulu-Natal province, South Africa. Study focusRecent studies have indicated a steady decline in groundwater levels in the Usutu-Mhlatuze Water Management Area. However, the absence of representative aquifer storage parameter values including storativity and specific yield, lack of sufficient groundwater monitoring wells and inconsistent and erratic groundwater level observation data from existing limited networks make it difficult to understand groundwater storage changes in the region. Therefore, this study analyses groundwater storage change of the primary and secondary aquifers within the Usutu-Mhlatuze Water Management Area using GRACE satellite derived terrestrial water storage data, Global Land Data Assimilation System (GLDAS) soil moisture data and in-situ measured surface water storage information. New hydrological insights for the regionThe GRACE derived groundwater storage anomalies for the Usutu-Mhlatuze Water Management Area showed good agreement with in-situ groundwater storage anomalies observed from the limited groundwater level monitoring piezometers in the primary and secondary aquifers. The goodness of fit (R2) between the GRACE derived and the observed groundwater storage changes in the primary and secondary aquifers were 0.79 and 0.74, respectively. The GRACE derived groundwater storage change data for the entire study period (between 2002 and 2020) indicated that the primary and secondary aquifers experienced a groundwater storage loss of 925 × 106 m3 and 3614 × 106 m3, respectively.

Hydrogeology of an urban weathered basement aquifer in Kampala, Uganda

Weathered basement aquifers are vital sources of drinking water in Africa. In order to better understand their role in the urban water balance, in a weathered basement aquifer in Kampala, Uganda, this study installed a transect of monitoring piezometers, carried out spring flow and high-frequency groundwater level monitoring, slug tests and hydrochemical analyses, including stable isotopes and groundwater residence time indicators. Findings showed a typical weathered basement aquifer with a 20–50-m thickness. Groundwater recharge was 3–50 mm/year, occurring during sustained rainfall. Recharge to a deep groundwater system within the saprock was slow and prolonged, while recharge to the springs on the valley slopes was quick and episodic, responding rapidly to precipitation. Springs discharged shallow groundwater, mixed with wastewater infiltrating from onsite sanitation practices and contributions from the deeper aquifer and were characterised by low flow rates (< 0.001 m3/s), low pH (<5), high nitrate values (61–190 mg/L as NO3), and residence times of <30 years. The deeper groundwater system occurred in the saprolite/saprock, had low transmissivity (< 1 × 10−5 m2/s), lower nitrate values (<20 mg/L as NO3), pH 6–6.5 and longer residence times (40–60 years). Confined groundwater conditions in the valleys were created by the presence of clay-rich alluvium and gave rise to artesian conditions where groundwater had lower nitrate concentrations. The findings provide new insights into weathered basement aquifers in the urban tropics and show that small-scale abstractions are more sustainable in the deeper groundwater system in the valleys, where confined conditions are present.

Groundwater and Urban Planning Perspective

An analysis of 17 Romanian cities’ Urban General Plans showed that urban planning documents do not satisfactorily rely on groundwater information. The associated hydrogeological supporting studies include only general recommendations. However, they should include specifications to improve water-balance and detail the need to implement monitoring systems to monitor groundwater levels. The studies do not recommend special construction measures to be implemented for future infrastructure elements and do not include maps delimiting the particular geotechnical and hydrogeological characteristics. A study conducted on an urban river corridor using satellite remote sensing and a methodology characterizing the chosen zone clearly shows a major concordance between the groundwater level and vertical displacements. In addition, the presence of urban anthropogenic strata associated with the groundwater level fluctuations showed amplified vertical displacements of the ground when compared to the areas where the natural deposits exist. The methodology combines subsidence occurrence, land-cover changes, hydrogeological, geological, and hydrological characteristics, climatic aspects, the location, the extension of old quarries, and the last 100 years of topographical changes. These observations emphasize the need for accurate studies to properly discriminate between phenomena and processes generating subsidence, which must be used systematically to support the general urban plans of cities as the documentation of future developments.

Evaluation of two linear kriging methods for piezometric levels interpolation and a framework for upgrading groundwater level monitoring network in Ghiss-Nekor plain, north-eastern Morocco

Evaluation of two linear kriging methods for piezometric levels interpolation and a framework for upgrading groundwater level monitoring network in Ghiss-Nekor plain, north-eastern Morocco

Rock Deformation Estimated by Groundwater-Level Monitoring: A Case Study at the Xianshuihe Fault, China

Rock deformations induced by active faults is an important topic in earthquake studies. Such deformations are usually measured with crossfault measurements (CFM), which are time-consuming and labor-intensive. In this study, rock deformations induced by the famous Xianshuihe fault in Xialatuo of China were estimated by groundwater-level monitoring (GLM) and CFM for the period of January 1, 2016 to December 31, 2018. The pattern of the variations in areal strain estimated with GLM matches that from CFM well. The estimated strain by the GLM and CFM both changed from positive to negative with time, indicating that the fault plane switched from tensile to compressive. This indicates that the rate of rock deformation had slowed down during this period, which is consistent with the long-term creep rates obtained by CFM at the site, implying that the fault may have gradually entered the next relock state. The estimated strain changes using the GLM method lag slightly behind those of CFM, which is probably due to the diffusive effects of pore pressure propagation that is caused by the rock deformation under the crustal stress. This study demonstrates that GLM is a more convenient and efficient addition to traditional geophysical techniques and raises the possibility for the characterization of continuous rock deformations. The method may be used to obtain the changing regional strain field with a network of monitoring wells.

Minimizing Errors in the Prediction of Water Levels Using Kriging Technique in Residuals of the Groundwater Model

Groundwater monitoring and water level predictions have been a challenging issue due to the complexity of groundwater movement. Simplified numerical simulation models have been used to represent the groundwater system; these models however only provide the conservative approximation of the system and may not always capture the local variations. Several other efforts such as coupling groundwater models with hydrological models and using geostatistical methods are being practiced to accurately predict the groundwater levels. In this study, we present a novel application of a geostatistical tool on residuals of the groundwater model. The kriging method was applied on the residuals of the numerical model (MODFLOW) generated by the TWDB (Texas Water Development Board) for the Edwards–Trinity (Plateau) aquifer. The study was done for the years 1995 through 2000 where 90% of the observation data was used for model simulation followed by cross-validation with the remaining 10% of the observations. The kriging method reduced the average absolute error of approximately 31 m (for MODFLOW simulation) to less than 5 m. Furthermore, the residuals’ average standard error was reduced from 9.7 to 4.7. This implies that the mean value of residuals over the entire period can be a good estimation for each year separately. The use of the kriging technique thus can provide improved monitoring of groundwater levels resulting in more accurate potentiometric surface maps.

Groundwater Drought Analysis under Data Scarcity: The Case of the Salento Aquifer (Italy)

Salento is a regional coastal karst aquifer located in Southern Italy with a highly complex geological, geomorphological, and hydrogeological structure. High and unruly exploitation of groundwater from licensed and unlicensed wells for irrigation and drinking purposes affects groundwater, with consequent degradation of its qualitative and quantitative status. The increased frequency of meteorological droughts and rising temperatures may only worsen the already compromised situation. The absence of complete and enduring monitoring of groundwater levels prevents the application of some methodologies, which require long time series. The analysis of climate indexes to describe the groundwater level variation is a possible approach under data scarcity. However, this approach may not be obvious for complex aquifers (in terms of scale, intrinsic properties, and boundary conditions) where the response of the groundwater to precipitation is not necessarily linear. Thus, the proposed research deals with the assessment of the response of the Salento aquifer to precipitation variability based on correlations between the Standardized Precipitation Index (SPI) and Standardized Precipitation and Evapotranspiration Index (SPEI) and groundwater levels for nine monitoring wells from July 2007 to December 2011. The study aims at evaluating the ability of the above indicators to explain the behavior of groundwater on complex aquifers. Moreover, it has the general aim to verify their more general reliable application. Results of three different correlation factors outline direct and statistically significant correlations between the time series. They describe the Salento aquifer as a slow filter, with a notable inertial behavior in response to meteorological events. The SPI 18-months demonstrates to be a viable candidate to predict the groundwater response to precipitation variability for the Salento aquifer.

Have forest and land fires been controlled properly?

It is certain that in almost every year forest and land fires in Indonesia will occur, no matter whether it is affected by El-Nino or not. Of course, the negative impacts it causes accompany the fires that occur, such as on health, economic development, social relations, relations between countries, and so on, including the production of greenhouse gas emissions produced during fires, especially on peat land. The results of research and field observations confirm that although the laws and regulations require corporations to construct canal blocks, monitor ground water levels, equip their business areas with fire control facilities and infrastructure, and so on, it turns out that many do not fulfil their obligations. carried out by corporations, including those that often state that they care about the environment the most in the public as well as corporations with investments from abroad. Not to mention what happened on community land where it was proven that the burning was not only a matter of the stomach but had a business nuance, where the fire was no longer 2 ha as legalized for indigenous or traditional communities, but there were already hundreds of ha. This fact confirms that the forest and land fires that occur ensure that not all obligations have been fulfilled and implemented. Not to mention that many district/city or provincial governments are still stuttering in carrying out control activities in the field, as a result of the unavailability of sufficient funds is also not a priority.

PRELIMINARY GEOLOGICAL INVESTIGATION INTO THE CAUSES OF FOUNDATION FAILURE IN JALINGO, NORTHEAST NIGERIA

Post foundation study for the preliminary causes of cracks on buildings at the Central Bank of Nigeria (old site) Jalingo branch, Northeast Nigeria, was carried out using a geophysical approach and groundwater level monitoring. The geophysical survey method employed was the electrical resistivity method. Vertical electrical sounding (VES) was carried out using a Schlumberger electrode array with a maximum half current electrode separation of 20m, vertical electrical sounding (VES) was carried out. The VES results revealed the presence of three (3) geoelectric subsurface layers in the area, namely clayey-sand, fractured/weathered basement, and crystalline basement. The resistivity of the clayey-sand varies from 45-210 Ωm, while that of fractured/weathered basement varies from 305 - 5858 Ωm and that of the crystalline basement varies from 1000-10075 Ω-m with corresponding thicknesses ranging from 0.5 - 2.3 m, 0.2 - 6 m, 2.6 – 4 m to an infinite depth respectively. The study area's field curves were analysed; H and Q-curve types with 35.7% and 64.3%, respectively. Iso-resistivity delineation at 0.5 m, 1.5 m and 3 m showed that the region with high resistivity corresponding to the crystalline basement is found in the northeastern part of the study area and is most suitable for the foundation. The results show that the investigated building was sited within the incompetent clayey-sand layer with resistivity generally less than 200 ῼm.

DEVELOPMENT OF THE GROUNDWATER MONITORING SYSTEM IN THE ZONE OF INFLUENCE OF URANIUM PRODUCTION LEGACY FACILITIES OF THE PRYDNIPROVSKY CHEMICAL PLANT

The results of works on reconstruction and development of the hydrogeological monitoring system at the Prydniprovsky Chemical Plant site, Kamyanske (PChP) and on the groundwater survey using the improved observation wells network are presented (first such survey since 2016). During the works, geology structure of the site was précised, hydraulic testing was carried out, and groundwater was sampled at a number of uranium production legacy objects that have not been previously covered by observations. Automated monitoring of groundwater levels (GWL) has been started. As a result, new information on the seasonal dynamics of GWL was obtained. New sources of serious chemical and radioactive contamination of the geological environment are identified at the Southern PChP site, in particular in the area of settling basins № 220 and 230. Radioactive contamination of groundwater with excess of background levels is also observed also in the zone of “historic” settling pond situated below the “Central Yar” uranium tailings. In addition to previously known chemical toxicants (Mn, Ni, Pb), the monitoring study revealed groundwater contamination by arsenic and mercury in the areas affected by the PChP facilities. Thus, groundwater contamination at the PChP industrial site is formed under the influence of more man-made legacy sources than previously thought. The identified new sources of pollution deserve additional characterization and consideration when predicting the long-term impacts of the PChP site on the surface water system of the Konoplyanka River—Dnieper River.

Design and application of groundwater dynamic online monitoring system in Aeolian desertification area

Populus euphratica, at Tarim Nature Reserve, growing in their natural habitat represents a valuable resource for the surface vegetation on the response mechanism to underground water level. In order to study the distribution of the groundwater level in Aeolian desertification areas, aiming at the current situation of groundwater dynamic online monitoring in Aeolian desertification areas, the network was effectively used to simplify data processing, increase the function of forecast and warning and optimize the power supply system. The results show that the equipment installed in Aeolian desertification areas has completed the remote transmission of data and data analysis. Based on the 25d real-time monitoring data, the groundwater level fluctuates between 0.604 and 1.515 m. Based on the table of groundwater level threshold of populus euphratica growth, the groundwater level at this location is between 0.50 and 4.71 m, and has not crossed the threshold of good growth and stress. Therefore, populus euphratica is growing well, and the equipment does not produce early warning information. Field investigation shows that populus euphratica grows well in this area, and there are many new seedlings germination, which is consistent with the data. Thus, the groundwater monitoring system can be used for dynamic monitoring of groundwater level in Aeolian desertification areas.

Application of machine learning to aquifer analyses：locating hydrogeological boundaries with water table monitoring data

Groundwater level fluctuations in China are being monitored with unprecedented frequency and density, which drives the need for mining such types of data. In a typical aquifer analysis project, groundwater level data is generally applied after the completion of the aquifer conceptual framework. When the temporal and spatial density of groundwater level data gradually increases, the information gain needs to be effectively transformed into conceptual knowledge of the model. In this study, we propose a method to identify hydrological boundaries based on the groundwater level monitoring data. In this method we discretize space into a triangular mesh using monitoring wells as the initial nodes, and a transformation function gradF is defined to calculate the hydraulic gradient at any given location on the mesh. The hydraulic gradient field is subsequently use to drive an array of randomly scattered particles to obtain the streamline representation of the flow field, which will in turn serve as the basis for deducing and refining the recharge and discharge boundaries of a hydrogeological domain. This method is implemented into the geo-environmental scientific computation platform (EnviFusion-CGS), and a detailed work flow is developed to facilitate the development of the aquifer conceptual model. This method is applied to the hydrogeological investigation of the Dagu aquifer located in Qingdao of Shandong Province, where the spatial distributions and dynamic fluctuations of the hydrogeological boundaries are identified.

Holistic Assessment of the Egyptian National Land Reclamation Project from the view of IWRM

Agriculture is the primary sector and central component of the Egyptian economy. The Agriculture economy's early estimates are about 17% of overall GDP and 20% total exports, as well as, accommodating around 30% - 40% of the labor force. Under the 1st Priority Land Reclamation Projects of the New Land development in Egypt, it is planned to reclaim 1.5 million feddans of agricultural land in nine reclamation areas in the Western Desert, mainly irrigated on groundwater. In this paper, the project is assessed in terms of groundwater occurrence, environmental screening, and economic sustainability with the rules of Integrated Resources Management (IWRM) is applied. The review highlights that the literature on groundwater withdrawal and use from all aquifers as a whole is significantly outdated, and might not represent the actual conditions of the groundwater occurrence and regime currently prevailing. Concurrently, updated information on monitoring groundwater levels and quality are not easily accessible, making it difficult for assessing long-term trends on groundwater dynamics, reserves, and quality. Finally, the paper presents an excel based model for optimal crop pattern selection in response to water different water quantities and qualities. The used model is named the Water Allocation Model for computing optimal crop patterns on water or AFWAM. In general, implementing the project is financially feasible, the project is expected to have a direct, positive social impact. Toshka site is the optimal choice for intervention early due to low initial investment costs. Still, the project is feasible in all proposed areas.

Groundwater–surface water interactions in a river estuary and the importance of geomorphology: Insights from hydraulic, thermal and geophysical observations

AbstractThis study presents the groundwater flow and salinity dynamics along a river estuary, the Werribee River in Victoria, Australia, at local and regional scales. Along a single reach, salinity across a transverse section of the channel (~80 m long) with a point bar was monitored using time‐lapse electrical resistivity (ER) through a tidal cycle. Groundwater fluxes were concurrently estimated by monitoring groundwater levels and temperature profiles. Regional porewater salinity distribution was mapped using 6‐km long longitudinal ER surveys during summer and winter. The time‐lapse ER across the channel revealed a static electrically resistive zone on the side of the channel with a pronounced cut bank. Upward groundwater flux and steep vertical temperature gradients with colder temperatures deeper within the sediment suggested a stable zone of fresh groundwater discharge along this cut bank area. Generally, less resistive zones were observed at the shallow portion of the inner meander bank and at the channel center. Subsurface temperatures close to surface water values, vertical head gradients indicating both upward and downward groundwater flux, and higher porewater salinity closer to that of estuary water suggest strong hyporheic circulation in these zones. The longitudinal surveys revealed higher ER values along deep and sinuous segments and low ER values in shallow and straighter reaches in both summer and winter; these patterns are consistent with the local channel‐scale observations. This study highlights the interacting effects of channel morphology, broad groundwater–surface water interaction, and hyporheic exchange on porewater salinity dynamics underneath and adjacent to a river estuary.

Focused groundwater recharge in a tropical dryland: Empirical evidence from central, semi-arid Tanzania

Study regionLittle Kinyasungwe Catchment within the River Wami Basin of central, semi-arid Tanzania. Study focusGroundwater and its replenishment via recharge are critical to sustaining livelihoods and poverty alleviation in tropical drylands yet the processes by which groundwater is replenished remain inadequately observed and resolved. Detailed observations are examined from central Tanzania, where the Makutapora Wellfield supplies freshwater to the rapidly growing, capital city of Dodoma. New hydrological insights for the regionThe prominence of focused recharge from ephemeral stream discharges is shown from: (1) groundwater recharge correlates more strongly with the seasonal duration of ephemeral stream stage exceeding a threshold than seasonal rainfall; (2) hourly monitoring of groundwater-levels and stream stage shows that sustained groundwater-level rises, indicative of groundwater recharge, correspond better to observed pulses of stream discharge from intensive rainfall observed upstream of the wellfield than rainfall recorded proximate to piezometers; and (3) stable isotope ratios of O and H indicate similar compositions of groundwater and ephemeral streamflow; both have undergone evaporative enrichment and are linked to intensive (90th percentile) daily rainfall. This characterisation of focused groundwater recharge from intensive rainfall in this tropical dryland highlights the potential resilience of groundwater resources to climate change amplifying precipitation extremes and informs strategies to augment replenishment of groundwater supplying the city of Dodoma.

Response of Water-Saturated Reservoirs to a Dynamic Impact Based on the Data of Groundwater-Level Monitoring by Precision Measurements

Response of Water-Saturated Reservoirs to a Dynamic Impact Based on the Data of Groundwater-Level Monitoring by Precision Measurements

Design of a Groundwater Level Monitoring System Based on Internet of Things and Image Recognition

This paper designs an intelligent groundwater level monitoring system based on image recognition and Internet of things (IoT). Image recognition technology was employed to process the water level image, and determine the water level line. The IoT was adopted to transmit the collected multimedia data accurately to the monitoring end, thereby realizing the automatic remote monitoring of real-time water level. After analyzing the image recognition technology and the key algorithm of water level recognition, the authors designed the whole process of groundwater level monitoring with two modules: water level monitoring base station, and remote monitoring management center. The water level monitoring base station is embedded with a data acquisition module to periodically collect data, including water level, videos, and images. The collected data were sent to the remote monitoring management center through the cellular network. Then, flood or low water warning could be determined according to the historical data. Finally, the proposed groundwater level monitoring system was tested. The results show that the system not only solves the problem of measurement accuracy, but also improves the work efficiency.

Numerical Groundwater Flow Modeling of Dijil River Catchment, Debre Markos Area, Ethiopia

Dijil River catchment is a sub-catchment of the Abay drainage basin and covers 138.28 km2. This paper presents numerical groundwater flow modeling at steady-state conditions, in a single-layer aquifer system under different stress or scenarios. A numerical groundwater flow models represent the simplification of complex natural systems, different parameters were assembled into a conceptual model to represent the complex natural system in a simplified form. The conceptual model was input into the numeric model to examine the system response. Based on geologic and hydrogeological information, confined subsurface flow condition was considered and simulated using MODFLOW 2000. The model calibration accounts matching of 24 observation points with the simulated head with a permissible residual head of ±10m. The sensitivity of the major parameters of the model was identified during the calibration process. According to the simulated water budget in the model, the simulated inflow is found to be 1.2791870E+05 m3/day which is nearly equal to the simulated outflow of 1.2791755E+05 m3/day with the difference being only 1.1484375E+00 m3/day. Water budget analysis reveals that outflow from river leakage accounts for 92.8 % of the total outflow and 14.1 % of the total inflow comes from the river leakage in the study area. Three scenarios of increased withdrawals and one scenario of altered recharge were used to study the system response. Accordingly, an increase in well withdrawal in scenario-I (existing wells pump simultaneously), scenario-II (existing drilled wells yield withdrawal increased by 30%), and scenario-III (additional eight wells having expected yield of 30 l/s drill and pump) resulted in an average decline of the steady-state water level by 1.06m, 1.68m, and 4.46m, respectively. They also caused the steady-state stream leakage to be reduced by about 2.93%, 4.58%, and 11.23%, and subsurface outflow by 9.41%, 14.67%, and 37.86%, respectively. A decrease in recharge by 25% and 50% results in a decrease of the head by 6.1m and 13.4m respectively, and a stream leakage decrease by 20.3%, and 40.3% respectively as compared to the simulated steady-state value. Therefore, adequate groundwater level monitoring wells should be placed in the catchment to control the total abstraction rates from the aquifer and fluctuations in groundwater levels.