Storage Coefficient Research Articles

Pressure Transient Analysis for Water Injection Wells with Waterflooding-Induced Nonsimultaneously Closed Multistorage Fractures: Semianalytical Model and Case Study

Summary Waterflooding will induce the opening and extension of fractures, which will create some water flow channels. Due to fracture multiclosures, the obtained fracture half-length from conventional finite-conductivity models is less than the actual value, leading to water flow channels that have been formed but not detected by engineers. According to a large number of waterflooding-front matching schematics and interwell connection coefficient analyses, we find that waterflooding usually connects natural fractures to form bi-induced fractures, which will close nonsimultaneously during the falloff test. In this paper, we develop a waterflooding-induced nonsimultaneously closed multistorage fracture model (WNMF) to describe waterflooding-induced fracture characteristics accurately. The bi-induced fractures are separated into multiple segments to calculate their pressure response. The closed induced-fracture conductivities are constant, and the opened induced-fracture conductivities follow the exponential equation measured by the experiments. Induced-fracture interference and multistorage effects are considered. Finally, the Duhamel principle is used to characterize the storage effects of bi-induced fractures and the wellbore. Results show that the type curve of the WNMF model has bi-peaks on the pressure derivative curve, which was regarded as error data in the past. Closed induced-fracture half-length is identified quantitatively. We can obtain an induced-fracture angle by matching the interference flow (an innovative flow regime in this paper), which can guide engineers to prevent and monitor water breakthrough in time. Using the obtained parameters (induced-fracture angle and closed induced-fracture half-length) can guide well pattern encryption and reasonable well location determination. If the induced-fracture angle is 90°, an additional horizontal line will be shown on the pressure derivative curve. When the horizontal line is misidentified as a quasiradial flow regime, the obtained reservoir permeability will be amplified many times. The multistorage coefficient is obtained to correct the magnified storage coefficient. Equation calculation and model matching methods verify each other to improve closed induced-fracture half-length accuracy. In conclusion, the experiment and mathematical model methods work together to describe the pressure response behavior of water injection wells. The WNMF model is compared with the conventional finite-conductivity model to verify its accuracy. A field case demonstrates its practicality.

Semi-analytical solution of single-well push–pull test under transient flow conditions

The single-well push–pull (SWPP) test has been extensively used in parameter estimation models. Numerous analytical solutions to the problem are available, all of which consider solute transport in a non-uniform flow field from steady radial flow created by the SWPP test. However, the non-uniform flow velocity is based on the Thiem equation and varies in a spatial manner, rather than a temporal manner. No analytical solution has been previously described for the solute transport equation of SWPP under fully transient flow. In this study, the generalized integral transform technique (GITT) was used to develop a new semi-analytical solution for solute transport in the SWPP test under fully transient flow. Four phases of the SWPP test were included: injection, chaser, rest, and extraction. With the proposed solution, the differences between a transient flow SWPP model solution and a piecewise steady-state flow SWPP model solution were non-negligible; such differences increased with decreases in the dimensionless parameter related to aquifer flow properties, which is proportional to transmissivity, aquifer thickness, and porosity, but inversely proportional to the storage coefficient and pumping rate. Additionally, long tails of BTCs are characteristic of type curves under the transient flow model. The long tails of BTCs under transient flow could result in overestimation of dispersivity if the SWPP model uses piecewise steady-state flow, rather than transient flow, for parameter estimation. The proposed semi-analytical solution provides a useful tool for curve-fitting during parameter estimation when the effects of transient flow are significant. The proposed solution can also serve as a performance comparison for testing numerical solutions to the SWPP test.

Litter addition as a tool for restoring hydrological processes and controlling erosion in riparian forests disturbed by fine sediment deposition

Riverscape aggradation due to the deposition of fine particles above natural forest litter can change the soil, sediment, and water properties, damage riparian vegetation, and reduce environmental integrity, especially in headwater streams. Litter addition techniques that enhance surface roughness and permeability can decrease the interference of fine particles on the ecosystem, representing a low‐tech alternative to recover disturbed riparian areas. We aimed to evaluate run‐off, percolation, storage coefficients, run‐off volume, and sediment yield using a rainfall simulator and the mitigation potential provided by the addition of forest litter to limnological variables—turbidity, total suspended solids (TSS), electrical conductivity, pH, nitrogen—which are indicators of integrity that can reflect streams' aggradation. Fifteen soil samples from a disturbed area (silt and clay deposits aboveground), five from an undisturbed area (sandy soil), and superficial forest litter were obtained from riparian areas adjacent to two small streams in Carajás National Forest, Brazil. The addition of litter showed great potential to mitigate erosive processes and to reestablish hydrological processes in the disturbed soil. The run‐off volume and sediment yield were 2–4 times lower in litter addition treatments compared to non‐litter addition. Litter addition also improved run‐off water quality, especially turbidity and TSS, which were 12–16 times and 3–13 times lower, respectively. The experimental addition of litter has shown encouraging results to be applied in situ as a sustainable, low‐cost, and simplified nature‐based solution to contribute to the restoration of degraded riparian forests and reduce in‐stream silt and clay aggradation.

Parameter‐robust mixed element method for poroelasticity with Darcy‐Forchheimer flow

AbstractIn this paper, the Biot's consolidation model is considered, and Darcy‐Forchheimer equation is used to describe the relationship between the fluid velocity and pressure. The model is nonlinear and the unknown variables are the solid displacement, the fluid velocity and pressure. The Bernardi‐Raugel element is used for displacement and the RT mixed element is used for the fluid velocity and pressure. The parameter‐robust BR‐RT0‐P0 method presented here is uniformly stable not only with respect to the Lamé constant , but also with respect to the constrained specific storage coefficient . We demonstrate the well‐posedness of the BR‐RT0‐P0 finite element solutions, and give the error estimates of the finite element approximations using the monotonicity of the nonlinear Forchheimer term. The error estimates are divided into two cases, that is, is positive and is nonnegative. Numerical experiments are presented to verify theoretical analysis. Moreover we focus on the variation of pressure by several poroelasticity problems.

Hygrothermal performance of a self-insulated exterior wall with various exterior/interior insulation thicknesses in two climate zones in China: A novel moisture-energy-environment-economic (M3E) method in insulation thickness optimization

The accumulation of moisture inside the envelope under high-humid climates can strongly affect the hygrothermal properties and can lead to moisture-related damage / moulds to the materials, especially in severe weather conditions. However, the optimal insulation thickness of the exterior envelope is typically determined by factors such as overall heat transfer performance, carbon dioxide production and economic cost. The effect of insulation thickness on the annual average moisture content (AAMC) of a self-insulated exterior envelope is often neglected and seldom considered in the optimization process. In this study, a coupled heat, air and moisture transfer (HAM) model was derived and validated. Theoretical indices for water vapour transfer were implemented, such as moisture storage coefficient and moisture inertia factor. A simplified model for liquid water penetration and evaporation was also implemented. A novel four-dimensional moisture-energy-environment-economic (M3E) method that incorporates moisture content analysis was proposed for insulation thickness optimization. A case study was conducted on a self-insulated aerated concrete wall in two climate zones: the hot summer and cold winter (HSCW) zone and the cold zone. The insulation thickness interval investigated were 0–50 mm for interior thermal insulation (ITI) and 0–60 mm for exterior thermal insulation (ETI). The results of the case study showed that the AAMC of the entire envelope varied up to 15.2% (HSCW zone) and 10.0% (cold zone) for different insulation thicknesses. In the HSCW zone, the lowest AAMC of the outer part of the envelope adjacent to the atmosphere was found at 30 mm (ITI) or 20 mm (ETI), indicating the presence of turning thicknesses; while in the cold zones, the lowest AAMC was found at 50 mm (ITI) or 10 mm (ETI) with no turning thickness. The proposed theoretical implementations accounted for changes of AAMC in different interior/exterior insulation thicknesses and were verified with the results of numerical calculation. The proposed theoretical indices revealed an opposite effect of water vapour transfer and liquid water transfer on the AAMC for different insulation thicknesses, which can explain the presence of turning thickness. Furthermore, the selected optimal insulation thicknesses from Pareto fronts were found around 25–29 mm for ITI and 36–38 mm for ETI in two climate zones. The results from the M3E method showed a reduction in moisture risks (up to 62.91%) and mould growth risks (up to 4.84%) in the case study, successfully meeting the acceptable range of moisture risk and mould growth risk. The findings of this paper can help generate a new understanding of moisture transfer, and the proposed M3E method can be applied in all cases to reduce the moisture/mould growth risks in the design stage.

Calibration and validation of models to estimate the hydraulic parameters of a confined aquifer in a tropical region

This article deals with the calibration and validation of models for water yield from a confined aquifer in a tropical region. From 2015 to 2019, 20 variable flow pumping tests were carried out. The average pumping flows varied between 0.07 and 17.4 L/s; the average drawdown of the water levels, between 5.99 and 50.94 m; the values of transmissivity and storage coefficient were lower than 77 m 2 /day and 6 x 10 -5, for probability of non-exceedance of 85%. In the calibration stage, the mean values of the coefficients of the proposed models a and b were in the order of 10 1 and 10 3. The determination coefficients obtained in the statistical adjustment of the proposed models are satisfactory, they varied between 76 and 85%. The validation stage revealed that the models need to be tested with a larger number of data.

A multi-field model for growth and dissipation of excess pore water pressure induced by slurry shield tunneling in semi-confined aquifer

This study focuses on the mechanism of slurry infiltration in front of the tunnel face during the construction of a slurry shield machine. A multi-field transient model is proposed to describe the growth and dissipation of the excess pore water pressure and the deposition of bentonite particles for slurry shield tunneling in the saturated semi-confined aquifer. Based on the conservation principle, the governing equations for the mass continuity of bentonite particles and volume continuity of slurry are derived with consideration of particle deposition and the elastic storage of the aquifer. The proposed model is validated by field measurements. The results indicate that the excess pore water pressure drops steeply close to the tunnel face and then gradually decreases to a stable value over several tunnel diameters due to the retardation of the infiltration zone. The retardation effect is positively correlated with the permeability coefficient of the soil and the filtration coefficient, while it is negatively correlated with the specific storage coefficient. The penetration distance of bentonite particles decreases with smaller soil pores and a higher slurry concentration. Besides, a quantitative equation is proposed to evaluate the influence of slurry concentration, filtration coefficient, and storability of the soil on slurry support efficiency.

Mechanical and Thermal Properties of Phase Change Aerated Concrete with Paraffin Microcapsule

In this paper, phase change paraffin microcapsule and aerated concrete are combined to construct a new type phase change aerated concrete. Four groups of specimens with 0%, 2.5%, 5%, and 7.5% of microcapsule phase change material (MPCM) were manufactured. Comprehensive tests, including microstructure characterization, dry density, compressive strength, and thermal parameter tests were conducted to evaluate the influence of MPCM on mechanical and thermal properties of the phase change aerated concrete. Scanning electron microscope diagrams show that the structure of MPCM is complete in the cement substrate without damage. The test results show that with the increase of the content of MPCM: (1) density, peak strain, specific heat capacity, and heat storage coefficient increase; (2) elastic modulus and thermal conductivity decrease; and (3) the cubic compressive strength and the ultimate prismatic strength increase first and then decrease. Based on this study, the optimal content of MPCM is 2.5%, which performs better than non-autoclaved aerated concrete without MPCM in terms of both mechanical and thermal properties.

Comparative study of novel backfill coupled heat exchangers using different waste materials in underground stopes

Underground mines in China are rich in geothermal resources. Based on backfill mining technology, the collaborative development of deep mineral resources and geothermal resources can be realized. The key of this approach is to form artificial thermal reservoirs by heat storage backfill body and to extract geothermal energy as much as possible through the built-in pipe. It is important to investigate the backfill material and system parameter design to improve the heat storage and release performance of backfill body and enhance the extraction efficiency of geothermal energy in mine. In this paper, experimental and simulation studies of backfill coupled heat exchanger system with different backfill materials are carried out to make a comparative study. The backfill materials involved include traditional backfill material, natural flake graphite backfill material and paraffin RT28 backfill material. After comparing the heat storage and heat release behavior, liquid fraction variation and efficiency of different systems, the natural flake graphite backfill body which has better engineering value is selected to further conduct experiments to study the influence of surrounding rock temperature, initial temperature of backfill body and inlet water temperature on the thermal performance of the system. The results show that with the increase of surrounding rock temperature, initial temperature of backfill body, or the decrease of inlet water temperature, the total heat storage, heat release and energy utilization coefficient of the system all increase. When the initial temperature of backfill is 26 °C, surrounding rock temperature is 45 °C, inlet velocity and temperature are respectively 0.7 m/s and 18 °C, the energy utilization coefficient of the system is the highest, which is 81.4%. The research results are helpful to the design of heat storage backfill body and the improvement of thermal performance of the system.

Semianalytical Model for Monitoring Fracture Liquid-Loading in Vertical Fractured Gas Wells

Summary Liquid loading seriously affects gas wells production and even causes gas wells abandonment. Many researchers still focus on correcting a critical liquid-loading flow rate to alleviate these problems. However, they still cannot reasonably be explained. Gas flow rate is higher than the critical liquid-loading flow rate, but liquid loading can still occur. Therefore, until an accurate critical fluid-loading flow rate is discovered, we should monitor the fluid-loading phenomenon to prevent it from affecting production gas wells’ performance. In this work, a fracture liquid-loading monitoring (FLLM) model is proposed and solved for the timely monitoring of fracture liquid-loading (FLL) positions and volume. The Newman product and Green function methods are used to develop and solve the FLLM model. The fracture is discretized into 2nxnz grids to describe an FLL volume and position. The numerical simulation method is used to verify the accuracy of the FLLM model. As a result, four innovative flow regimes, including fracture cavity liquid-loading flow, fracture root liquid-loading flow, transitional flow considering fracture cavity liquid-loading flow, and transitional flow considering fracture root liquid-loading flow, are identified on the pressure response curves. The pressure response of the same gas well at different times is well matched by the model in this paper, and the obtained parameters are more reasonable. The FLLM model can correct for magnified permeability, shortened half-length, and magnified wellbore storage coefficient. In conclusion, the FLLM model is established to monitor FLL, and alert engineers to remove liquid loading on time to prevent water from suddenly rushing into a wellbore and causing gas wells abandonment.

Evaluation of Subsurface Hydraulic Conditions, between Ajeel and Al-Shari Basins

This research work aims to recognize the contact between Ajeel and Shari ground water basins on the South west limb of the Northern hemrien Anticline, depending on the hydraulic Conditions and Pumping test which carried out on three Wells in the Study area.
 According to the result, it is found that the Transmissivity(T) = 1177.605 m2/day, hydraulic conductivity (K)= 52.754 m/day, and Storage coefficient (Sc)= 0.00053, East the contact.
 While west of the contact T= 717.10 m2/day, K= 24.34 m/day, and Sc = 0.0001 .

Hydrogeological Conditions of Groundwater Aquifers/ West Makhul, North Iraq

The lithological description of drilled wells and pumping test analysis used to determine the hydrogeological conditions of the west Makhul area, the main ground water aquifer in the area represented by unconfined aquifer within the sediments of Injana Formation, the hydraulic properties of this aquifer (Transmissivity, Storage coefficient, Hydraulic conductivity) were estimated by pumping test, the flow net of ground water was plotted, it reflected that the ground water flow direction from the northeastern to the southwestern which compatible with the general direction of surface drainage system and general slope

Gravity estimation of groundwater mass balance of sandy aquifers in the land subsidence-hit region of Yunlin County, Taiwan

Land subsidence will decrease the safety factor of bridges and structures. Many highways and railways constructed decades ago are experiencing damage due to continual land subsidence in several alluvial fans of Taiwan. Groundwater over-pumping for industrial and agricultural uses leads to severe (>3 cm/year) land subsidence in the middle to distal Choushui River Alluvial Fan (CRAF), the largest alluvial fan in Taiwan. The Taiwan High Speed Rail passes through CRAF and land subsidence is now a major concern. Replenishing groundwater with artificial recharge lakes is a potential solution to mitigate land subsidence impacts. Using gravimetry, we examined two undetermined regional unconfined aquifers (RUAs) in the land subsidence-hit region that could host potential artificial recharge lakes to replenish groundwater. We established seven absolute gravity sites and measured time-lapsed gravity values in Yunlin in southern CRAF in 2021, including five sites in the subsidence-hit region and over two unconfined aquifers in the proximal fan. A consistent pattern of residual gravity changes associated with water storage changes at all the gravity sites confirms the recharge potential of the two RUAs in the land subsidence-hit region. Here we estimated groundwater storage changes by residual gravity changes around gravity sites without using prior hydrology information such as groundwater levels and storage coefficients. Of all the gravity sites in the land subsidence-hit region, the most significant March-to-September residual gravity change (26.6 μgal) and vertical displacement (−4.2 cm) were observed at Siutan elementary school (STES). The estimated groundwater storage change around STES is significantly large to increase the water balance in Yunlin, despite the site's severe land subsidence in 2021. We used electrical resistivity imaging (ERI) to aid the identification of the RUA near STES and discussed a potential joint gravimetry-ERI study of the RUAs for subsidence-mitigation engineering works such as constructions of recharge lakes.

Quantitative evaluation of reservoir quality of tight oil sandstones in chang 7 member of Ordos Basin

In order to establish a quantitative evaluation system for reservoir quality suitable for tight oil sandstones, in this study, taking the Chang 7 Member in the Maling area of the Ordos Basin as an example, the nuclear magnetic resonance, clay mineral analysis, high pressure mercury injection analysis and logging interpretation technology have been used to carry out a comprehensive evaluation of the pore structures, sand body structures and oil-bearing properties of tight oil sandstone reservoirs. The results show that the pseudo-capillary pressure curves transformed by the NMR T2 spectra are consistent with the capillary pressure curves measured by the core experiments. This method can be used for accurate characterization of the pore structures of the reservoir. The pore structure parameters calculated based on the pseudo-capillary pressure curves can accurately reflect the pore structures of the reservoirs such as micropores-thin throats and complex tortuosity. At the same time, the smoothness feature of conventional logging curves is used to evaluate the sand body structures and heterogeneity of the reservoir, and the apparent energy storage coefficient is introduced to quantitatively evaluate the oil-bearing properties of tight oil reservoirs. The evaluation results are in good agreement with the actual production situation. The larger the apparent energy storage coefficient, the higher the initial output of the oil wells. The evaluation results of the reservoir quality of the tight oil sandstones constructed in this paper are highly consistent with the production status, so the method has broad application prospects.

Determination of the Storage or Porosity Coefficient Using the Natural Logarithm Curve by Means of <i>in Situ</i> Measurements

The relevance of studying the storage coefficient variable brings with it the updating of this value in the hydraulic characteristics as part of the hydrogeological parameters applied to each country, where recommended values for the storage coefficient to be used in hydrogeological studies are presented. And the application of a methodology adapted to the conditions of each country, is done under current conditions resulting in reference values. For this research work, an adequate methodology was sought for calculating the storage coefficient with a natural logarithm (LN) arrangement. To achieve this, first, the variables that affect the storage coefficient were identified, then the model was described with the natural logarithm (LN) arrangement, and as a third point the storage coefficient was calculated. In conclusion, in points 1 and 2 it was possible to calculate the storage coefficient from the Natural Logarithm arrangement model, with a correlation equal to R2 = 0.99, and R2 = 0.97 respectively, indicating that this method can be applied as long as there is free aquifer conditions and that manipulation of data alteration is not frequent.

Rainfall-Runoff Time Lags from Saltwater Interface Interactions in Atlantic Coastal Plain Basins

The dynamic behavior of the freshwater-saltwater interface (FSI) in coastal aquifers can introduce unexpected lags between recharge and stream discharge, especially when recharge is forced by long-term cyclical precipitation patterns. This work seeks to assess these FSI impacts at the watershed scale. Recharge-discharge time lags were evaluated in 68 watersheds overlying the Floridan Aquifer System in the coastal region of the southeastern United States (Florida, Georgia, and South Carolina). Utilizing the strength of the Atlantic multidecadal oscillation (AMO) signal in this region, 10–20 year averaged recharge and discharge time series were used for the selected watersheds. Lags of 10–25 years between recharge and discharge were found in 16% of the basins considered, possibly induced by a dynamic FSI which responded slowly to the AMO-scale recharge signal. Freshwater storage coefficients (S) were estimated from time series of change-in-storage and groundwater level, with 11 basins showing S>1.5 indicating water storage well above that expected for unconfined aquifers. These 11 basins with both multidecadal recharge-discharge time lags and high S values showed a positive linear relationship between time lag and FSI depth with slope 0.016 yr/m (R-squared = 0.30). These large time lags may be directly impacting the management of these basins as they obscure water and solute mass balances in the southeastern US.

Simulasi Termodinamika Pengaruh Temperatur Subcooling di Kondensor Terhadap Kinerja Cold Storage

The subcooling temperature in the condenser can affect the overall performance of the refrigeration system. One of the refrigeration systems that plays an important role in the cold chain of fishery products is cold storage. This paper discusses thermodynamic study of the effect of condenser subcooling temperatures on the performance of cold storage that operates based on a vapor compression refrigeration cycle based on the CoolPack software. The subcooling temperatures varied was 5 – 10 Kelvin and the system performance parameters analyzed were refrigerant mass flow rate, heat rejected in the condenser, compressor power and coefficient of performance. The results of this study indicate that as the subcooling temperature increases, the refrigerant mass flow rate decreases so that the compressor power and the rate of heat release in the condenser also decrease. Thus, the performance coefficient of cold storage will increase as the subcooling temperature increases.

Evaluation of Potential Seawater Intrusion in the Coastal Aquifers System of Benin and Effect of Countermeasures Considering Future Sea Level Rise

In the present study, a three-dimensional SEAWAT model was developed to generally simulate the impact of climate change and anthropogenic activities on seawater intrusion (SWI) in the coastal region of Benin by the end of 2050. The model was calibrated and validated from 2015 to 2020, considering groundwater head and salt concentration measured in 30 wells. After calibration, a sensitivity analysis was performed with the model parameters (hydraulic conductivity, recharge, storage coefficient and boundary conditions). For the calibration, model computed and observed values displayed good correlation, approximatively 0.82 with a root mean square error (RMSE) of 0.97 m and 13.38 mg/L for groundwater head and salt concentration, respectively. The simulation results indicate that freshwater head had declined by 1.65 m from 2015 to 2020 (taking reference from the average groundwater head in 2015: 27.08 m), while the seawater intrusion area increased in the same period by an average of 1.92 km2 (taking reference from the seawater intrusion area in 2015: 20.03 km2). The model is therefore used to predict groundwater level decline and seawater intrusion area increase by the end of 2050, considering the predicted sea level rise (SLR) and estimated groundwater pumping rate. Furthermore, the interface fresh groundwater–saltwater change was studied using the SHARP interface developed by USGS in 1990. The interface variation was found to be influenced by the distance from shoreline, sea level, groundwater level and geological formation hydraulic conductivity. Finally, the 3D model was used to simulate the effect of a managed aquifer recharge system on reducing SWI rate in the study region.

Research on Rheological Energy Characteristics of Fractured Sandstone Strengthened with CFRP

The rheological energy characteristics and evolution law of fractured sandstone strengthened with CFRP (carbon fiber reinforced plastic) were studied to solve the problem of rheological failure of rock after engineering excavation disturbance. In this paper, the graded loading rheological tests of fractured sandstone after reinforcement are carried out. The results show that the failure rheological stress of sandstone increases with the increase of the area strengthened by CFRP. When the reinforcement area is from 3140 mm2 to 4710 mm2, the failure rheological stress of rock mass is increased from 65 MPa to 75 MPa, approximately 15.4%. Except for the initial rheological stage, the elastic energy is decreasing and the dissipative energy is increasing. The elastic energy is fully released, and the dissipative energy is provided by the total energy when the rock is destroyed. The energy dissipation ratio (Ud/U) of sandstone under the two reinforcement areas reached the minimum value at the stable rheological stage, which was 0.26 (A = 3140 mm2) and 0.42 (A = 4710 mm2) respectively. The energy mechanism of CFRP is that CFRP stores energy mainly and consumes energy secondly before the energy inflexion. However, CFRP switches to consuming energy mainly and storing energy secondly after the energy inflexion. The energy storage coefficient of CFRP can directly describe the function of elastic energy or dissipative energy of CFRP under arbitrary stress. When the energy storage coefficient T > 1, the damage of CFRP is small. Further, the energy storage coefficient reaches the maximum value of 5 at the energy inflection point (55 MPa). When the energy storage coefficient T < 1, the damage of CFRP is large, and the energy storage coefficient reaches the minimum value of 0.005 at the stress of 40 MPa. During the rheological process of fractured sandstone strengthened with CFRP, the energy evolution shows the relationship between elastic energy and dissipated energy. The energy mechanism of CFRP explains the working mechanism of the reinforced structure in the rheological process and plays a guiding role in the analysis of the rheological failure of the reinforced rock in the practical engineering.

Characterization of Changes in Groundwater Storage in the Lachlan Catchment, Australia, Derived From Observations of Surface Deformation and Groundwater Level Data

AbstractGlobal Positioning System (GPS) deformation measurements were combined with groundwater level data to examine the spatiotemporal variability of groundwater storage in the Lachlan catchment located in central New South Wales (Australia). After correcting for effects of glacial isostatic adjustment, non‐tidal oceanic and atmospheric loading as well as hydrologic loading using existing models, we show that the seasonal and interannual variability of ground deformation and hydraulic head level data, extracted using wavelet time‐frequency analysis, exhibits an in‐phase behavior, indicating that the observed surface deformation is the poroelastic response to groundwater pressure change in aquifer system. Combination of GPS displacement and groundwater level change enables the estimation of elastic skeletal specific storage coefficients, which were then used for estimating groundwater storage changes. The estimated groundwater storage changes clearly reflect the four climate events of the Lachlan catchment since 1996: (a) the Millennium drought over 1996–2009, (b) the 2011–2012 La Nina and two significant floods in 2012 and 2016, (c) the drought conditions from mid‐2017 to late‐2019, and (d) the return of La Nina conditions since early 2020. We also found annual and long‐term groundwater storage variations of respectively and over the period 2012–2021. Moreover, we show that groundwater level fluctuations can be predicted from GPS displacement measurements and storage coefficients with sufficient accuracy (80% correlation and 70% RMS reduction when compared in terms of seasonal cycle). This study provides essential information that can contribute to future groundwater planning, management, and control over the Australian continent.