Subsurface Systems Research Articles

An Empirical Model for Aeolian Sandy Soil Wetting Front Estimation with Subsurface Drip Irrigation

In subsurface irrigation systems in desert areas, the wetting front transport pattern allows the determination of irrigation flow and timing. In this study, an indoor subsurface irrigation experiment on aeolian sandy soil is designed, and the vertical and horizontal wetting front movement distances under different irrigation flows are obtained. The dimensional analysis method was used to perform a dimensional analysis on the experimental data. An empirical setting front distance estimation model, which only considers three parameters, saturated hydraulic conductivity Ks, irrigation flow Q, and total irrigation volume V, was proposed. The model’s accuracy was statistically evaluated with the observed data and verified by a numerical simulation using HYDRUS-2D/3D. The mean absolute error (MAE) and root mean square error (RMSE) of the proposed model in the horizontal and downward directions were 0.80 and 0.95 cm, respectively, with a percentage bias (PBIAS) of −3.47 ≤ ±10 and a Nash–Sutcliffe efficiency (NSE) of 0.98, which is close to 1. Thus, this model can contribute to the selection of the appropriate depth and spacing of subsurface laterals.

Gravity Modeling to Understand the Subsurface Geology of the Central Part of West Bandung Regency (Citatah Karst Area, Cipatat-Padalarang)

Understanding the subsurface system of the central part of West Bandung Regency (including Karst Area), Indonesia, is an important undertaking carried out by geological and geophysical investigations. This research aims to identify geological subsurface features, especially faults,that have an impact on geohazards in the area. To achieve this goal, deep analysis of geology, geomorphology, and geophysical data is conducted. The central part of West Bandung regency is crossed by the Cimandiri Fault, which is located east of the transitional zone between the frontal subduction of Java and the oblique subduction of Sumatra. The preliminary result shows that the active fault has an impact on geohazards (earthquakes and landslides) in the area. Gravity reduction, regional and residual separation, as well as forward modeling with the Pluoff Equation, are all parts of the examination of the gravity data. A second-order polynomial trend surface was subtracted from the entire Bouguer gravity grid to create the residual gravity anomaly map. The amplitudes of the anomalies range from −12 to 8 mGal. The density distribution from the inverse calculation using 4 horizontal line sections (AB, CD, EF, and GH) was set up in the range of −0.3 to +0.3 g/cc. Geological surface markers for the model can be correlated with the information from the Cianjur Sheet geological map. Regional structure is also interpreted in the model to show the main structure of the reverse fault in the study area. HIGHLIGHTS The gravity method using density properties can provide good information about the subsurface karst system Modeling data gravity contributes to an understanding of geological subsurface interpretation Identifying geological subsurface features, especially faults that cause earthquakes and trigger landslides, is part of geohazard mitigation GRAPHICAL ABSTRACT

Numerical verification on the feasibility of compressed carbon dioxide energy storage in two aquifers

Compressed carbon dioxide energy storage in aquifers (CCESA) is a new large-scale energy storage technology derived from geological carbon dioxide sequestration, compressed air energy storage in aquifers, and compressed carbon dioxide energy storage. However, there have been no practical applications so far. In this study, we present a numerical model that simulates the whole process of gas filling period and daily cyclic period of the subsurface system of CCESA with two wellbores and two aquifers, and reveal the hydrodynamic and thermodynamic properties, energy efficiency, and the influences of wellbore and aquifer locations, injection temperature and injection rate on system performance. The results show that the fluctuation ranges of pressure and temperature in the wellbores and aquifers increase with time, especially in the high-pressure aquifer where the maximum and minimum pressures are 15.96 and 9.78 MPa after 200 days of cycles. The maximum energy efficiency of the system can reach 1.022. Within 100 days of cushion gas filling and 200 days of cycles, the maximum horizontal CO2 transportation distance in aquifers is 198.1 m, indicating a strong sealing effect of the system. The system energy efficiencies of the two target aquifers are very similar for different vertical intervals, while the variations in wellbore pressure and temperature differ significantly, which affects the energy efficiency and stability of the surface plant. Low-temperature CO2 injection is beneficial to improving the energy efficiency of the system. Increasing injection-production rate can directly improve power generation rate, and energy efficiency is also higher for higher flow rates.

Break-up and mobilization of DNAPL by acoustic excitation: Experimental evidence and pore network modeling

Dense non-aqueous phase liquids (DNAPLs) are long-term groundwater contaminants due to their high toxicity and slight solubility in water. The use of acoustic waves to remobilize trapped ganglia in subsurface porous systems have some advantages over pre-existing solutions including eliminating the bypassing effect and new environmental hazards. Designing an effective acoustically assisted remediation method for such purposes relies on understanding the underlying mechanisms and developing validated models. In this work, pore-scale microfluidic experiments were run to investigate the interplay between break-up and remobilization under sonication at different levels of flow rate and wettability conditions. Based on the experimental observation and pore-scale physical characteristics, a pore network model was developed and verified against the experimental results. Such a model was developed based on a two-dimensional network and scaled up to three-dimensional networks. In the experiments, processing of two-dimensional images showed that acoustic waves can remobilize trapped ganglia. The other observed effect of vibration is to break up blobs and reduce the mean ganglia size. Recovery enhancements were greater in hydrophilic micromodels as compared to hydrophobic system. A strong correlation was found between the remobilization and breakup indicating that the trapped ganglia are breaking up due to acoustic stimulation firstly and then a background viscous force may get them flowing under the new generated fluid distribution. In modeling, the simulation results of residual saturation reasonably matched with experimental observations. The differences between the prediction by the model and the experimental data at verification points is less than 2% for data before and after the acoustic excitation. The transitions from three-dimensional simulations were used to propose a modified capillary number. This study gives a better understanding of the mechanisms behind the effect of acoustic waves in porous media and provides a predictive tool for evaluating enhancement in fluid displacement.

Nano-scale synchrotron imaging of shale swelling in the presence of water

Swelling of shale in response to interaction with water is an important consideration within subsurface energy systems. In the case of waste disposal, swelling can provide important barriers around the waste and enhance the sealing ability of rocks. For shale gas exploration purpose, however, swelling may cause wellbore instability. Therefore, a careful study of shale swelling is critical for subsurface energy related applications. Here, the swelling effects of shale were imaged at nanoscale using an advanced synchrotron Transmission X-ray Microscopy (TXM) imaging technique for the first time, with a spatial resolution down to 40.9 nm. Organic matter and clays within the analysed sample were observed to display large swelling effects which resulted in a 50% reduction in porosity. Strain maps generated using Digital Volume Correlation (DVC) show deformation and significant strain were mostly localized to between the contact boundaries of sharp brittle minerals and softer organic matter and clays. This is the first study, to our knowledge, to directly image the swelling deformation of shale at the tens of nanometer scale and provide local information on the strain evolution.

Quantifying the impacts of a proposed hydraulic dam on groundwater flow behaviors and its eco-environmental implications in the large Poyang Lake-floodplain system

Dam-induced hydrological alterations and eco-environmental impacts have significant implications, however, these concern issues in large floodplain systems are less well understood. The present study shows a first attempt to adopt a quasi-three-dimensional groundwater flow modeling FEFLOW (Finite Element subsurface FLOW system) to investigate the influences of a proposed hydraulic dam on groundwater dynamics in the largest floodplain lake of the Yangtze River basin (Poyang Lake, China). The FEFLOW model was successfully constructed and has the ability to represent the hydrodynamics of floodplain groundwater flow. Model simulations indicate that, in general, the dam is likely to increase the groundwater levels across the floodplain during different hydrological phases. The responses of floodplain groundwater levels to the dam during the dry and recession phases are stronger (∼2–3 m) than the rising and flooding phases (<2 m). Under the natural condition, the floodplain groundwater may recharge the lake during the dry and recession phases, and discharge the lake during the rising and flooding phases. However, the dam regulation may alter the natural recharge-discharge patterns, forming a generally gaining condition of the floodplain groundwater. The proposed dam is most likely to reduce the groundwater flow velocity (∼<1 m/d) relative to the natural condition (up to 2 m/d) during different hydrological phases, and it may also alter the floodplain groundwater flow direction during the dry and recession phases. Additionally, the floodplain groundwater system is mainly characterized by losing state (−4.5 × 106 m3/yr) under the natural condition, while the dam-induced groundwater system exhibits an overall gaining state (9.8 × 106 m3/yr). The current research findings contribute to future water resources assessment and management by providing a foundation for assessing associated eco-environmental changes of the large lake-floodplain system.

Effect of increased carbon load on denitrification efficiency and nitrate isotope enrichment factors in subsurface wastewater infiltration system.

Denitrification plays a dominant role in nitrate removal in subsurface wastewater infiltration system (SWIS). However, the effect of increased carbon (C) load on denitrification efficiency in the SWIS remain unclear. In this study, we used analyses of stable isotopes of nitrogen (N) and oxygen (O) in nitrate to investigate the N and O isotope enrichment factors (15 ε and 18 ε) and quantified N losses via denitrification in SWIS. The results demonstrated that an increase in C loads positively affected the pollutant removal performance of SWIS. The natural abundance of 15 N and 18 O increased with decreasing nitrate concentration from 12.5 to 7.3 mg/L, accompanied by increased 15 ε and 18 ε from -8.7‰ to -10.6‰ and -5.9‰ to -8.2‰, respectively, as the C load increased from 18 to 36 g/(m2 d). The contribution of denitrification to nitrate removal was 62%, 71%, and 77% when C loads were 18, 27, and 36 g/(m2 d), respectively, indicating that increased C loads could improve the nitrate removal through denitrification in SWIS. PRACTITIONER POINTS: Increasing C loads positively affected the nitrate removal performance of SWIS. N and O isotope enrichment factors of nitrate increased with the enhancement of influent C load. A C load of 36 g/(m2 d) is recommended in SWIS to improve the N removal performance and denitrification efficiency.

Geomechanical assessment of a large-scale CO2 storage and insights from uncertainty analysis

Geological storage of CO2 provides a feasible solution to curb CO2 emissions to the atmosphere and relieve climate change. However, as CO2 is injected into the reservoir, the increased pore pressure may result in fault reactivations or damaging geomechanical changes to the caprock, which could be detrimental to the containment of injected CO2. On the other hand, uncertainty is inevitable due to the limited information of the complex subsurface system. In this study, we develop a workflow to assess the geomechanical impact of CO2 geological storage and include management of sources of uncertainties associated with the subsurface system. We utilize the hypothetical large-scale carbon sequestration situated in the Southern San Joaquin Valley in California, USA as a case study. We firstly set up a three-dimensional (3D) geomechanical model using a non-linear quasi-static finite element method. The applied workflow has features including: (1) Coulomb friction behavior to model fault slippage, (2) CAD representation of land surface and faults, (3) non-uniform pressure increase based on dynamic reservoir simulations, and (4) variable rock properties for formation layers. We perform uncertainty analyses using a response surface methodology and a Box-Behnken design to assess the significance of subsurface uncertainties to geomechanical responses. We find that the intact caprock will not have a shear failure even considering the subsurface uncertainties. However, the faults can reactivate and give potential flow pathways in the caprock. The presented workflow integrates advanced geomechanical models and uncertainty analysis, which can be readily applied to other CO2 storage projects to mitigate geomechanical sources of risk.

A Novel Multipurpose Self-Irrigated Green Roof with Innovative Drainage Layer

Climate change is a significant problem that many countries are currently facing, and green roofs (GRs) are one of the suitable choices to confront it and decrease its impacts. The advantages of GRs are numerous, such as stormwater management, thermal need reduction, runoff quality, and life quality improvement. However, there are some limitations, including the weight, limits in water retention, irrigation in the drought period, suitability of harvested water for building usages, installation on sloped roofs, and high cost. Therefore, developing a novel system and design for GRs with higher efficiency and fewer negative points seems necessary and is the main scope of this research. In this regard, a novel multipurpose self-irrigated green roof with an innovative drainage layer combined with specific multilayer filters has been developed. The application of the proposed system in terms of water retention capacity, water storage volume, runoff treatment performance, irrigation system, drainage layer, application of the harvested water for domestic purposes, and some other aspects has been analyzed and compared with the conventional systems with a focus on extensive green roofs. The results demonstrate that this novel green roof would have many advantages including less weight due to the replacement of the gravel drainage layer with a pipeline network for water storage, higher water retention capacity due to the specific design, higher impacts on runoff treatment due to the existence of multilayer filters that can be changed periodically, easier installation on flat and sloped roofs, the possibility of using the collected rainfall for domestic use, and fewer irrigation water demands due to the sub-surface self-irrigation system.

Nitrogen removal in improved subsurface wastewater infiltration system: Mechanism, microbial indicators and the limitation of phosphorus

To enhance the nitrogen removal capacity, scrap iron filings and Si–Al porous clay mineral material (PCMW) was used to improve a subsurface wastewater infiltration system (SWIS). The results showed TN and NH4+-N removal efficiencies of improved SWIS were 20.72% and 5.49% higher than those of the control SWIS, respectively. Based on the response of the removal performance, microbial community and function analysis of 16s rRNA amplicon sequencing results, the amending soil matrix substantially enriched the nitrogen removal bacteria (Rhizobiales_Incertae_Sedis and Gemmatimonadaceae), and significantly improved the activities of key enzymes (Hao, NasAB, NarGHI, NirK, NorBC, NirA and NirBD), particularly at co-occurrence zone of nitrification and denitrification (70–130 cm depth). The amending soil matrix not only extended the growth space of microbes, but also provided additional electrons and carbon sources for denitrifying bacteria by regulating the structure and function of the microbial community. In addition, amending soil matrix could enhance phosphate metabolism genes and phosphate solubilizing microbes in the denitrification zone by increasing the phosphorus source, thus strengthening nitrogen metabolism. Nitrospiraceae, Rhizobiales_Incertae_Sedis and Gemmatimonadaceae related to nitrogen removal and Bacillaceae with phosphate-solubilizing ability could be used as microbial indicators of nitrogen removal in SWISs. The reciprocal action of environmental on microbial characteristics exhibited microbial functional were related to DO, Fe2+, TOC, TP, TN, NH4+-N and NO3−-N. Those could be used as physicochemical and biological indicators for application and monitoring of SWIS. In conclusion, this study provided a low-cost and efficient enhancement approach for the application of SWIS in decentralized domestic sewage treatment, and furnished theoretical support for subsequent applications.

Simultaneous removal of typical antibiotics and nitrogen by SWIS assisted by iron carbon micro-electrolysis

In this study, a combination of subsurface wastewater infiltration system (SWIS) with iron carbon micro-electrolysis (namely ICMESWIS) was used to enhance the simultaneous removal of nitrogen and typical antibiotics (SMX, OTC and HCl-Lev was selected). The results indicated that assisted by 10 % dopant amount of ICME, SMX, OTC, Lev-HCl, NH4+-N, NO3--N and NO2--N removal rates increased by 26.6 %, 19.7 %, 10.2 %, 33.7 %, 28.5 % and 19.3 %, respectively via ICMESWIS than SWIS. The higher TFe release rate, organic matter content and richer microbial populations encouraged ICMESWIS to resist the impact of antibiotics. High-throughput sequencing revealed that electrochemical effect enhanced the microbial community structure, which was the main pathway for nitrogen and antibiotics removal. The total proportions of nitrogen and antibiotics removal relating bacteria were 18.38 % and 46.67 %, 5.49 % and 4.72 % higher than those of SWIS, respectively. Anammox became an additional N removal way in ICMESWIS.

Design of an active subsurface system thermal energy supply to the bio-vegetation complex

The efficiency of vegetable production in closed ground structures is directly dependent on the costs associated with creating artificial, controlled conditions for growing plants during the period when cultivation of them in open ground due to climatic conditions is impossible. One of the indicators of the economic efficiency of vegetable production in protected soil structures is labor costs and funds per 1 hundredweight, per 100 rubles of gross production, as well as energy costs, including thermal energy. Usually, solar, biological, electric and other types of heating are used to supply thermal energy to cultivation facilities, each of which has its own disadvantages. The bio-vegetation complexes structurally distinguished by the fact that cultivation beds are located on various foundations make it possible to create an active underground heating system. The paper presents the development of a design for an active subsurface system for thermal energy supply to the bio-vegetation complex and calculations of the main parameters of the system for autonomous operation of the object at negative outside air temperatures. The design of the active subsurface system for thermal energy supply to the bio-vegetation complex is proposed in the form of a heat-accumulating sand-gravel mass, inside of which there are heat supply circuits with a heat carrier closed with a concrete screed on top. The calculation of energy consumed by the active sub-ground thermal system providing optimal parameters of the growing medium corresponding to biological rhythms of plant development at low outside air temperatures is also presented. The study determines the area of the photovoltaic unit and the number of photovoltaic modules for generating electric energy in order to cover the spent thermal energy and the effective functioning of the active subsurface system for thermal energy supply to the bio-vegetation complex.

Effect of Soil Aeration and Root Morphology on Yield under Aerated Irrigation

Soil compaction easily causes root hypoxia stress, resulting in poor root growth and the absorption of soil water and nutrients. We hypothesized that aerated irrigation (AI) could enhance nutrient uptake and utilization, thus unlocking the high yield potential by increasing soil aeration and root morphology indicators compared with that in the non-aeration treatment. A greenhouse experiment was conducted to investigate the effect of soil aeration and root morphology on the yield of greenhouse cucumbers. The dissolved oxygen (DO) in irrigation water at 10 mg L−1 (A1), 20 mg L−1 (A2), and non-aeration treatment (A0) were applied via a subsurface drip irrigation system. The soil respiration rates, DO in soil water, root morphology, and crop yield were measured. The results showed that AI could significantly improve the soil respiration rate, DO in soil water, and root morphology compared with non-aeration treatment. The A2 significantly increased soil respiration rate by 11.63% and 11.93%, respectively, compared with the A1 and A0 treatments. Under A1 and A2, the DO in soil water increased by 20.01% and 18.02%, respectively, compared with the A0. Moreover, during the flowering and fruit set, the mature, and the late stages, the root surface area, root volume, root tip number, root forks, and root dry weight in the A2 treatment significantly increased than that in the A0 treatment. The soil respiration rate, DO in soil water, root length, and root forks were the main indexes correlated to the yield, respectively. The DO in soil water and root forks number significantly influenced the yield. The cucumber yield and economic benefits in A2 peaked at 53.04 t ha−1 and 3.95 × 104 USD ha−1, increased by 7.86% and 7.30% compared with that in the A0 treatment, respectively (p &lt; 0.05). The results could provide technical support and scientific knowledge for regulating greenhouse cucumbers under AI.

Deep reinforcement learning for optimal well control in subsurface systems with uncertain geology

A general control policy framework based on deep reinforcement learning (DRL) is introduced for closed-loop decision making in subsurface flow settings. Traditional closed-loop modeling workflows in this context involve the repeated application of data assimilation/history matching and robust optimization steps. Data assimilation can be particularly challenging in cases where both the geological style (scenario) and individual model realizations are uncertain. The closed-loop reservoir management (CLRM) problem is formulated here as a partially observable Markov decision process (POMDP), with the associated optimization problem solved using a proximal policy optimization algorithm. This provides a control policy that instantaneously maps flow data observed at wells (as are available in practice) to optimal well pressure settings. The policy is represented by a temporal convolution and gated transformer blocks. Training is performed in a preprocessing step with an ensemble of prior geological models, which can be drawn from multiple geological scenarios. Example cases involving the production of oil via water injection, with both 2D and 3D geological models, are presented. The DRL-based methodology is shown to result in an increase in NPV of 15% (for the 2D cases) and 33% (3D cases) relative to robust optimization over prior models, and to an improvement of 2 - 7% in NPV relative to traditional CLRM. The solutions from the control policy are found to be comparable to those from deterministic optimization, in which the geological model is assumed to be known, even when multiple geological scenarios are considered. The control policy approach results in a 76% decrease in computational cost relative to traditional CLRM with the algorithms and parameter settings considered in this work.

Centrifugal radial drainages and their geological significance in southern Kerala, India

The drainage fabric is the reflection of the surface and sub-surface geological systems and processes of the Earth. In this context, the State of Kerala, has prolific network of drainages due to the unique physiographic conditions and it was studied to map the drainage fabric and the anomalies using IRS FCC wrapped DEM of SRTM data of the Southern parts of Kerala. The study revealed the occurrence of larger centrifugal radial drainages conspicuously in a number of places. Such drainages seem to indicate the phenomenon of doming due to the still prevalent northerly directed compressive force related to the post collision tectonics and the east north easterly compressive force due to the rising of the Carlsberg ridge in the Arabian Sea. These both forces in combination might have resulted in the phenomenon of simultaneous cross folding leading to the formation of the domes. The active tectonics have serious implications on the natural disasters in general and the tectonically vibrant Kerala State in particular, therefore the drainage anomalies of Kerala warrant demanding studies.

Prediction and uncertainty quantification of shale well performance using multifidelity Monte Carlo

Uncertainty quantification is an integral component of reservoir management, especially considering the inherent uncertainty in subsurface systems. While a standard practice to estimate the uncertainty, Monte Carlo (MC) simulation is computationally intense when the sampling population comprises high-fidelity simulations. Alternatively, the Multi-fidelity Monte Carlo (MFMC) simulation overcomes this computational intensity by integrating low- and high-fidelity simulations. Our goal is to minimize the number of expensive high-fidelity simulations while maintaining accuracy and using numerous fast and cheap low-fidelity simulations to efficiently sample to input parameter space of interest. We selected gas production from unconventional wells to demonstrate the potential speedups and accuracy of the MFMC approach. The model fidelity usually determines the trade-off between accuracy and efficiency. While the high-fidelity model is more accurate, the low-fidelity model is more efficient. Our high-fidelity simulation includes reservoir simulations of a hydraulically fractured well. On the other hand, our low-fidelity model comprises the parallel-plate flow model. We used differential programming to efficiently solve the 1D flow model, where automatic differentiation is used to efficiently compute the gradients. We matched the production profile of high-fidelity simulations with our low-fidelity simulations. Then, we used a support vector regression to map the high- and low-fidelity input parameters. The mapping function is essential to tune the low-dimensional parameter space of the low-fidelity model to the high-dimensional parameter space of the high-fidelity model. We found that we can use a combination of 9 high fidelity and 10,000 low fidelity simulations to efficiently and accurately simulate pressure management. This method is at least two orders of magnitude faster than only using high-fidelity simulations. From a broader perspective, MFMC could efficiently estimate the uncertainty of various systems and models, integrating low- and high-fidelity models.

Yield, dry matter and water productivity simulation for surface and subsurface drip-irrigated bell pepper using the SALTMED model

AbstractSALTMED model performance was evaluated by comparing simulated and observed soil water content, dry matter (DM) yield, yield and water productivity (WP) data of field-grown bell pepper (Capsicum annuum L.) under Mediterranean climatic conditions irrigated with surface and subsurface drip systems. Simulation data were obtained from field experiments performed in 2016 and 2017. Treatments were full irrigation (I100), conventional deficit irrigation at 75 and 50% actual crop evapotranspiration (ETa; I75 and I50), regulated-deficit irrigation (RDI) and partial root-zone drying (PRD) at 50% ETa using surface (SfDI) and subsurface drip systems (SbDI) on a clay-loam soil, in a split-plot with four replications. Results showed that 56 and 29 mm less irrigation water was applied to SdDI100 in 2016 and 2017, respectively, than SfDI100; RDI used 27 and 77 mm less irrigation water than SfDI100 in experimental years, respectively. SbDI and SfDI performed similarly for bell pepper yield, DM and WP. However, the effect of irrigation treatments on yield, DM and WP was significant. I100 showed the highest yield (74.9 and 71.1 t/ha in 2016 and 2017, respectively), followed by RDI in 2016; I100, RDI and I75 produced greater yield than other treatments in 2017. PRD50 and I50 produced the least yield (49.8 and 45.9 t/ha in 2016 and 2017, respectively). SbPRD50 and SbI50 had the greatest WP value under SbDI in the experimental years. Results showed that the SALTMED model simulated yield, DM, soil water content and WP reasonably well (R2 = 0.95, 0.97, 0.98 and 0.74, respectively).

Integrated thermo-poro-mechanical characterization for CO2 Sequestration at deep aquifer conditions

Modelling and forecasting of injected CO2 plume behaviour is an essential step in the baseline, monitoring, and verification [BMV] process in the CO2 sequestration lifecycle. The goal of reduction of uncertainty through forecasting models, can be better realized by accounting for the thermo-poro-mechanical nature of the deep subsurface reservoir systems. The current study focusses on developing and refining a laboratory workflow which will help in generating representative static and dynamic datasets at ambient and deep aquifer conditions. The workflow involves characterizing the poroelastic Biot coefficient and mechanical properties at ambient, high temperatures and at reservoir representative stress conditions. This information will be combined with the dataset from a CO2 flood experiment which replicates the displacement of brine by super critical CO2 at ambient and high temperatures and at reservoir representative stresses. Resistivity and acoustic signals will be monitored throughout the flood experiment. Existing analytical models for fluid substitution such as the Biot-Gassmann-Brie populated with representative data will be evaluated for finding the best description of the experimental observations. The integrated results of the workflow are meant to help develop better informed static and dynamic models improving the confidence in the BMV process of CCUS.

Pressure drop analysis of subsurface irrigation dripper system and its flow rate uniformity

Recently, water scarcity has become a serious social problem caused by global climate change. In agricultural water usage, subsurface irrigation techniques can be an alternative method to save water and improve the productivity and quality of crops. The technique supplies water by burying an irrigation hose 30 cm underground rather than placing it on the ground (topsoil), effectively preventing evaporation loss at the soil surface. In this study, we numerically calculated the pressure drop using a dripper installed inside an underground irrigation hose developed in Korea. The pumping load of the domestic product was evaluated in terms of momentum loss and compared with the most widely used Netafim products. The lower the pressure drop in the dripper, the higher the performance of the irrigation system in terms of stable water supply. Using computational fluid dynamics and experiments, we provide a meaningful evaluation of the domestic product in the irrigation system.

A Depth-Adaptive Filtering Method for Effective GPR Tree Roots Detection in Tropical Area

This study presents a technique for processing Step-frequency continuous wave (SFCW) ground penetrating radar (GPR) data to detect tree roots. SFCW GPR is portable and enables precise control of energy levels, balancing depth and resolution trade-offs. However, the high-frequency components of the transmission band suffers from poor penetrating capability and generates noise that interferes with root detection. The proposed time-frequency filtering technique uses a short-time Fourier transform (STFT) to track changes in frequency spectrum density over time. To obtain the filter window, a weighted linear regression (WLR) method is used. By adopting a conversion method that is a variant of the chirp Z-Transform (CZT), the time-frequency window filters out frequency samples that are not of interest when doing the frequency-to-time domain data conversion. The proposed depth-adaptive filter window can self-adjust to different scenarios, making it independent of soil information and effectively determines subsurface tree roots. The technique is successfully validated using SFCW GPR data from actual sites in a tropical area with different soil moisture levels, and the two-dimensional (2D) radar map of subsurface root systems is highly improved compared to existing methods.