Subsidence Features Research Articles

Long-Term SAR Data Analysis for Subsidence Monitoring and Correlation Study at Beijing Capital Airport

Land subsidence, resulting from natural or human activities, is a global environmental geological disaster. The Interferometric Synthetic Aperture Radar (InSAR) time-series analysis technique offers high spatial and continuous temporal resolution, providing data and a foundation for investigating regional land subsidence and its evolution mechanism. Beijing Capital International Airport (BCIA) has experienced uneven land subsidence since 1935, together with severe fissures significantly affecting its normal operations. In this study, the time-series InSAR method was successfully applied to monitor the gradual increase in uneven local subsidence and ground fissures activity at BCIA from June 2003 to March 2023. Initially, ENVISAT-ASAR, Cosmo-SkyMed, and Sentinel-1 data were processed by time-series InSAR techniques to generate deformation rate maps and time series for the airport area. Subsequently, a comparison was made between the displacement time series from InSAR and ground leveling measurements to assess the accuracy of InSAR-derived measurements. Through a comprehensive analysis of the distribution characteristics of land subsidence at the airport, a long-standing ground fault was located within the airport was identified. A preliminary discussion on the development status of this ground fissure was carried out based on the visual interpretation of optical images. Lastly, the inducing factors and evolutionary conditions of land subsidence were discussed. This case demonstrates the applicability of InSAR technology in identifying and monitoring geological processes such as land subsidence and ground fissure activities. It provides a scientific approach to exploring and studying the causes and formation mechanisms of land subsidence and ground fissures in the Beijing Capital Airport area.

Seismic performance of soft rock tunnel under composite support conditions

In order to effectively improve the seismic and impact resistance performance of soft rock tunnels, a composite support method was proposed and validated in the paper. The UDEC (Universal Distinct Element Code) model of soft rock layers was established, and the movement and subsidence characteristics of the roof and floor of the rock layers under impact loads was simulated and calculated. As a result, a composite support scheme with good cushioning performance was proposed. The top and sides of the tunnel were supported by a combination of anchor rods of different lengths and metal mesh, reinforced by steel beams and vibration absorbing filler around. The anchor rod was designed as a segmented loading structure, and can be set to different preloading forces based on the internal deformation of the rock layer. The dynamic response testing scheme was designed, and the results indicate that the segmented loading anchor rod has a significant buffering effect on the response to impact load, and can provide reasonable tension feedback at different stages. Research has found that when the water cement ratio is 0.5-1.5, the curing efficiency and strength are both higher. In order to compare the seismic performance of composite support and traditional constant resistance anchor rod support, local blasting experiments were conducted. Based on a blasting vibration tester, a data detection and transmission system were designed to obtain the vibration speed of the tunnel roof during the vibration process. The research results show that composite support can reduce the maximum vibration by more than 40 %, stabilize the fragmentation coefficient at 1.38, and have a very significant vibration reduction effect.

InSAR time series analysis of natural and anthropogenic coastal plain subsidence: A case of Hangjiahu plain

The early excessive groundwater exploitation caused extensive land subsidence in the Hangjiahu Plain (HJHP), threatening geological stability and infrastructure. Government restrictions on groundwater exploitation led to considerable changes in surface subsidence. To explore the distribution and causes of surface deformation after restrictions on groundwater exploitation, we used 46 Sentinel-1A TOPS images to detect the spatiotemporal distribution of surface deformation in the HJHP area from January 2019 to October 2022 by SBAS-InSAR technique and verified it with leveling results. Results indicated the following: (1) The uneven surface subsidence in the HJHP was relatively apparent, with the localized subsidence concentrated in a few areas. During InSAR monitoring, the maximum subsidence velocity reached −21.0 mm/yr. The most severe subsidence area was in the Shengze town industrial park, with remarkable subsidence bowls and a maximum subsidence of −85.8 mm. (2) Results were verified by comparing the InSAR results with leveling, and the results were in good agreement, indicating the reliability of the InSAR results. (3) Comprehensive analysis of the spatial distribution characteristics of surface subsidence, geological data and rainfall changes revealed that fault activity and rainfall changes had varying degrees of effect on surface subsidence in the HJHP area. (4) The comparison with land use data indicated that the built area was the dominant mechanism of surface subsidence in the study area. In addition, the effect of industrial activities on the surface cannot be ignored. The study results provide scientific data support for emergency disaster prevention work in the HJHP.

Analysis of the Subsidence Evolution Characteristics of Existing Railway Lines Due to Surface Subsidence from Salt Cavern Gas Storage Facilities

The railway subgrade is a crucial component of the railway transportation system and serves as the foundation for the normal operation of the railway. Uneven subsidence of the railway subgrade is an important factor affecting the safety of train operations. In areas surrounding salt cavern gas storage facilities, subsidence caused by underground engineering can pose a threat to the safe operation of nearby railways. Through finite element numerical simulations, this study reveals the dynamic characteristics of cavity contraction and surface subsidence in salt cavern gas storage facilities under long-term operational conditions. These conclusions emphasize the complexity and long-term impacts of surface subsidence during the operation of salt cavern gas storage, providing important references for the safe operation of these facilities.

Field test of compactability of soaked subsidence soil using heavy tamper

Dynamic compaction, including heavy compaction, is a widespread method throughout the world for improving the physical and mechanical characteristics of subsidence and low-density soils. The results of theoretical and experimental studies have established that the depth of compaction and the density of compacted soils depend on the weight, shape of the bottom, the height of the tamper and humidity, the type of structural connection, and the granulometric composition of the compacted soil. This article discusses the results of compaction with a heavy tamper when soaking loess-like subsidence soil, widespread in the city of Darkhan, Mongolia, to optimal moisture.

Surface Subsidence over a Coastal City Using SBAS-InSAR with Sentinel-1A Data: A Case of Nansha District, China

The loss of life and property in economically developed areas due to geological hazards caused by intense ground subsidence is incalculable. As one of the fastest growing areas in the Guangdong-Hong Kong-Macao Greater Bay Area, the study of ground subsidence in Nansha will help to provide a scientific basis for urban planning and improve the capacity of monitoring and prevention of ground subsidence. The combination of coastal soft soil foundation and urbanization conditions creates a certain risk of land subsidence. We chose Nansha District, the geographical center of the Greater Bay Area, as the study area to analyze its surface subsidence characteristics in recent years. The 20-view Sentinel-1A data and SBAS-InSAR technique were used to monitor the ground subsidence in Nansha from 2017 to 2023. The main rate of ground subsidence in Nansha ranges from −19.4 to 7.7 mm/yr and is distributed in the urban area, along the rivers, in the construction area, and in the reclamation area. As of 4 May 2023, the average ground settlement in Nansha is 10.05 mm and the maximum settlement can be up to 142.45 mm. The 6-year total settlement at all four settlement intensities is greater than 60 mm, with the highest value exceeding 110 mm. The cumulative settlement increases with time, but inverse settlement and no settlement also occur at points where settlement is severe. For settlement caused by soft soil consolidation, it is recommended that drainage pipes be installed to accelerate drainage as a means of stabilizing settlement. For settlement caused by groundwater extraction and additional loads on the road surface, it is recommended to rationally extract groundwater and reinforce the foundation of the road surface with severe settlement.

LAND SUBSIDENCE IN WUHAN REVEALED USING A MULTI-SENSOR INSAR TIME SERIES FUSION APPROACH

Abstract. Satellite Interferometric Synthetic Aperture Radar (InSAR) is widely utilized for topographic, geological, and natural resource investigations. However, many existing InSAR studies on ground deformation are limited to relatively short observation periods and single sensors. This paper introduces a novel method for fusing multi-sensor InSAR time series data, specifically designed to address scenarios involving partial overlaps and temporal gaps. The method employs a new Power Exponential Knothe Model (PEKM) to fit and fuse overlaps in the deformation curves, while a Long Short-Term Memory (LSTM) neural network predicts and fuses data during temporal gaps in the series. In this study, the city of Wuhan in China was selected as the experimental area. SAR datasets from COSMO-SkyMed (2011–2015), TerraSAR-X (2015–2019), and Sentinel-1 (2019–2021) were fused to map long-term surface deformation over the past decade. An independent InSAR time series analysis from 2011 to 2020, based on 230 COSMO-SkyMed scenes, was used as a reference for comparison. The correlation coefficient between the fusion algorithm’s results and the reference data is 0.87 in the time overlapping region and 0.97 in the time-interval dataset. The overall correlation coefficient of 0.78 demonstrates that the proposed algorithm achieves a similar trend as the reference deformation curve. Based on the long time series settlement results obtained through fusion, a detailed analysis of the causes of settlement was conducted for several subsidence zones. The subsidence in the Houhu area is primarily attributed to the consolidation and compression of soft soil. Soil mechanics were employed to estimate the expected completion time of subsidence and calculate the degree of consolidation for each year. The COSMO-SkyMed PSInSAR results indicate that the area has entered the late stage of consolidation and compression, gradually stabilizing over time. Furthermore, the subsidence curve observed in the area around Xinrong reveals that the construction of an underground section of subway Line 21 has caused significant settlement in that particular region. The high temporal granularity of the PSInSAR time series also enables precise detection of a rebound phase following a major flooding event in 2016. The experimental results demonstrate the accuracy of the proposed fusion method in providing robust time series for analyzing long-term land subsidence mechanisms. Additionally, these findings unveil previously unknown characteristics of land subsidence in Wuhan, thus clarifying the relationship with urban causative factors.

Subsurface deformation monitoring with InSAR and elastic inversion modeling in west Texas

Recent Interferometric Synthetic Aperture Radar (InSAR) observations depict centimeter-level surface uplift/subsidence signals in west Texas that correlate spatially and temporally with increased fluid extraction and injection activities over the past decade. Linear subsidence features from InSAR data near the Pecos area, that align well with maximum horizontal stress orientations and recent clusters of seismic events, suggest fault motion is also associated with this deformation. In this study, we investigate the relationship between observed surface displacement and inferred subsurface fault slip and reservoir compaction/inflation by inversely solving a combined model of elastic dislocation (Okada, 1985, 1992) and poroelastic reservoir compaction/inflation model (Geertsma, 1973).Our geomechanical analysis coupled with InSAR observations are consistent with the idea that both fault slip and reservoir inflation/compaction are occurring associated with fluid injection and withdrawal in the Pecos area. Numerical results show that the linear surface displacement patterns can be accurately reproduced using clusters of finite slip on multiple elastic dislocations in the subsurface, but also matching the broader areal subsidence and uplift signals requires the addition of poroelastic subsurface inflation and depletion. The inverted areal reservoir pressure distribution correlates well with known injection and withdrawal operations in the area. The best-fit surface deformation locates most fault slips patches at depths of 1–3 km, which is shallower than most reported earthquakes in this area. The difference in the estimation of depth suggests there could be aseismic fault slippages.

Integrating SBAS-InSAR and LSTM for subsidence monitoring and prediction at Hong Kong international airport

Hong Kong International Airport (HKIA) is one of the busiest airports in the world, and much of its land is reclaimed from the sea, making it prone to uneven subsidence of the ground. Monitoring and predicting the subsidence of its surface are crucial for ensuring the operational safety of the airport. This paper firstly obtained the surface subsidence characteristics of the HKIA through applying the Small Baseline Subset Interferometry Synthetic Aperture Radar (SBAS-InSAR) technology, and then the spatial–temporal evolution was analyzed by using the Standard Deviational Ellipse (SDE) method. Moreover, the Long Short-Term Memory (LSTM) was employed to perform surface trend prediction of HKIA. The results show that the HKIA presents different levels of subsidence and uplift, with a maximum average subsidence rate of −64 mm/year and a maximum cumulative subsidence of −199 mm. The comparison between predicted curves and the actual subsidence revealed by InSAR from 2019 to 2023 is highly consistent, with the average absolute error and root mean square error less than 5 mm, and a coefficient of determination greater than 0.99. The LSTM model utilized in this paper can achieve reliable results in subsidence prediction based on time-series InSAR, and provide alternative means for geohazard prediction.

Mapping and Analyses of Land Subsidence in Hengshui, China, Based on InSAR Observations

In this paper, we use interferometric synthetic aperture radar (InSAR) annual and time-series analysis of RADARSAT-2 SAR data, spanning from September 2011 to October 2022, to study the temporal–spatial characteristics of land subsidence in Hengshui, North China Plain. The data reveal two large-scale subsidence areas in Hengshui, individually located to the north of Hengshui city around the Hutuo River and to the east or south along the Fuyang, Suolu and Qingliang Rivers. The fastest subsidence arises after 2017, with the maximum rate exceeding 11 cm/year. We correlate the observed subsidence with the central table variation of groundwater depression, groundwater table variation of three confined aquifers, hydraulic head declines of three confined aquifers and the time-dependent total hydraulic head variation. We find a spatial consistency between land subsidence and groundwater depression or hydraulic head declines of three confined aquifers, and subsidence displacement and total hydraulic heads both manifest clear seasonal variability. This suggests that the subsidence is primarily caused by groundwater extraction for agricultural use. We also observe that the subsidence rates in Hengshui did not decrease but rather increased when the groundwater table significantly rose after September 2019. It is very likely that as a result of the occurrence of thick and widespread continuity of clay layers with high compressibility in the Quaternary deposit of Hengshui, a new preconsolidation head could be generated due to groundwater table drop, leading to the effective hydraulic head still existing in the aquitards even if the groundwater table rises in the aquifer systems.

Reconstruction of spatially continuous time-series land subsidence based on PS-InSAR and improved MLS-SVR in Beijing Plain area

ABSTRACT Beijing has undergone severe settlement in recent years. Persistent Scatterers Interferometric Synthetic Aperture Radar (PS-InSAR) technique has been widely used to derive time-series land deformation. However, existing studies have faced two challenges: (1) the nonlinear characteristics of time-series subsidence has not been fully investigated; (2) since PS points are normally distributed in urban areas with high building density, measurement gaps usually exist in nonurban areas. To address the challenges, we presented a new method to reconstruct spatially continuous time-series deformation. First, PS-InSAR was used to retrieve the deformation based on 135 scenes of Envisat ASAR and Radarsat-2 images from 2003 to 2020. Polynomial Curve Fitting (PCF) was then used to model nonlinear time-series deformation for the PS points. In the PS measurement gaps, Iterative Self-Organizing Data Analysis Technique (ISODATA) and Multi-output Least Squares Support Vector Regression (MLS-SVR) were used to estimate the PCF coefficients and then time-series deformation considering 40 features including thickness of the compressible layers, annual groundwater level, etc. The major results showed that (1) compared to linear, quadratic, and quartic models, cubic polynomial model generated better fit for the time-series deformation (R2 ≈0.99), suggesting obvious nonlinear temporal pattern of deformation; (2) the time-series deformation over measurement gaps reconstructed by ISODATA and MLS-SVR had satisfactory accuracy (R2 = 0.92, MAPE < 15%) and yielded higher accuracy (R2 = 0.947) than IDW (R2 = 0.687) and Ordinary Kriging (R2 = 0.688) interpolation methods. The reconstructed results maintain the nonlinear characteristics and ensure the high spatial resolution (120 m) of time-series deformation. Among the 40 predictor variables, ground water level datasets are the most influential predictors of time-series deformation.

Study of the Overlying Strata Movement Law for Paste-Filling Longwall Fully Mechanized in Gaohe Coal Mine

Green mining plays a vital role in achieving environmentally friendly and ecologically sound mining practices. In domestic mining areas, the coal mining method is gradually transitioning from collapse mining to filling mining. Paste filling has been proven effective in controlling surface deformation, although the understanding of its underlying control mechanisms remains incomplete. This study focuses on the E1302 paste-filling working face at Shanxi Gaohe Energy Co., Ltd. and conducts a comprehensive investigation into the movement patterns of overlying strata in longwall fully mechanized mining with paste filling. Through mathematical analysis, a mechanical model for overburden movement in paste-filling faces is established, and the movement behavior of overburden is studied through numerical simulations. Field measurements are conducted to analyze the primary influencing factors of overburden movement, while surface subsidence monitoring is employed to analyze the subsidence characteristics of paste-filling faces. The research reveals that the deflection formula for the roof behind the paste-filling face follows a unitary quartic equation. The key factors influencing significant roof subsidence in filling faces include the filling step distance, filling body strength, and filling rate. Compared to traditional caving mining, filling mining exhibits reduced stress concentration, a smaller range of stress influence, and less deformation in the surrounding rock. The coefficient of gentle subsidence for the overlying rock in filling mining is approximately one-tenth of that in caving mining. The development of cracks in filling mining can be divided into three stages: initial crack propagation, crack recompaction, and stable maintenance of cracks. Notably, the progression of advanced cracks assumes a “sail-shaped” pattern, and the area of crack recompaction is located above the rear side of the excavation. Cracks behind the working face only appear in the basal roof rock layer. When the filling rate in longwall fully mechanized mining with paste filling exceeds 94%, the top plate of the filling working face remains intact but exhibits bending and sinking. The sinking of the top plate increases exponentially with the filling step distance, and approximately 80% of the filling body’s deformation occurs within 20 m after filling. Following backfilling mining, the stability period of the overlying rock is significantly shortened compared to caving mining, resulting in a relatively gentle movement without an active surface movement phase. After six months of backfilling, the overlying rock settles steadily and consistently. The subsidence coefficient for backfilling mining is 0.065, with a maximum surface subsidence of 215 mm. These findings highlight the successful control of surface subsidence. The research outcomes provide an effective theoretical foundation and research direction for predicting overburden movement and surface subsidence in paste-filling faces.

An Extraction Method for Large Gradient Three-Dimensional Displacements of Mining Areas Using Single-Track InSAR, Boltzmann Function, and Subsidence Characteristics

This paper presents an extraction method for large gradient three-dimensional (3-D) displacements of mining areas using single-track interferometric synthetic aperture radar (InSAR), Boltzmann function, and subsidence characteristics. This is mainly aimed at overcoming the limitations of surface deformation monitoring in mining areas by using single-track InSAR technology. One is that the rapid and large gradient deformation of the mine surface usually leads to image decoherence, which makes it difficult to obtain correct deformation information. Second, the surface deformation monitored by InSAR is only one-dimensional line of sight (LOS) displacement, and thus it is difficult to reflect the real 3-D displacements of the surface. Firstly, the Boltzmann function prediction model (BPM) is introduced to assist InSAR phase unwrapping; thus the missing large gradient deformation phase of InSAR is recovered. Then, the subsidence characteristics in mining horizontal (or near-horizontal) coal seams are used as prior knowledge for theoretical derivation, and a 3-D displacement extraction model of coal seam mining with single-track InSAR is constructed. The feasibility of the method is verified by simulating LOS displacements with random noise and underestimation phenomenon caused by the large gradient deformation as InSAR observations. The results show that the root mean square error (RMSE) of 3-D displacements on the observation line calculated by the proposed method is 21.5 mm, 19.0 mm, and 32.9 mm, respectively. Based on the single-track Sentinel-1 images, the method in this paper was applied to the extraction of surface 3-D displacements in the Huaibei coal mine, and the experimental results show that the extracted 3-D displacements are in good agreement with that of measurement by the surface observation station. The proposed method can adapt to limited InSAR acquisitions and complex monitoring environments.

Study on the Characteristics of Strata Movement and Surface Subsidence Induced by Multiseam Mining

Multiseam mining generates enhanced characteristics of strata movement and surface subsidence (CSMSS) than single seam mining, which strongly increases the possibility of mine water disasters and surface deformation. In this study, the effect of seam separation distances and key stratum (KS) configurations on CSMSS is evaluated using the discrete-element method. The results of the analyses indicated that control function loss of the KS aggravated the failure of the overlying strata and expanded the original water-flowing fractured zone, which grew by 91.49% and 23.40% in short-distance and medium-distance multiseam mining. In addition, the subsidence was higher in the first two cases and also in the tilts and strains. The separation and penetrating tensile cracks determined the upper boundary of the caved and fractured zones in the discrete-element method simulation analysis supported by field data. Finally, this study provides a method for identifying the multiseam category according to the CSMSS resulting from multiseam mining operations, which is the first step toward effective disaster prevention and management.

Surface Subsidence Characteristics of Mining Panel Layout Configuration with Multi-Seam Longwall Mining

Mining-induced subsidence is critical for ecological environment reconstruction and damage prevention in coal mining areas. Understanding the characteristics of surface subsidence with multi-seam mining is the first step. Surface subsidence of different mining panel layout configurations was investigated by means of UDEC numerical simulation. Based on the simulation results, it was indicated that mining panel layout configuration had a significant impact on surface subsidence, including ground surface subsidence, horizontal displacement, crack propagation, and ground surface fissure development. The overlapped region of the upper panel and the lower panel is the key region, where existing bedding separations and strata cracks close and activate, the integrity and strength of the interburden layer are reduced, and the subsidence magnitude is enhanced. The subsidence profile of the overlapped region for the stacked configuration, external staggered, the edge of the lower panel internal staggered, two edges of the lower panel internal staggered are steeper and deeper, and the corresponding values of ground surface subsidence and horizontal displacement are greater than other regions. The ground surface fissures with the types of stepped, slided, and graben developed on the ground surface above the edge of the mining panel, and the development location is closely related to the strata movement edge. Because of the support activities of the reserved coal pillar, the ground subsidence of the external staggered (internal staggered) of the upper panel with the coal pillar is slight. The external staggered (internal staggered) and external staggered (internal staggered) of the upper panel with the coal pillar can be selected as the preferred layout configuration. The proposed description of surface subsidence of different mining panel layout configurations can be applied in subsidence prediction.

A New Method of Regional Mining Subsidence Control for Sustainable Development in Coal Areas

Coordinated and sustainable development of production-living-ecological space (PLES) is directly related to the global energy security and quality of life in coal areas. However, the current surface subsidence control methods have some problems, such as low resource recovery rate, high cost, insufficient materials, which are difficult to meet the requirements for the PLES sustainable development in coal areas. Under this background, based on characteristics of surface subsidence and deformation due to sub-critical extraction, the large protection area, and high deformation tolerance in PLES of mining areas, the new method of regional mining subsidence control was proposed, with the combination of source control and ground rehabilitation. The effectiveness of the method was verified by numerical simulation results and practical applications, and the application principles and implementation methods were proposed. The research results could provide technical support for the sustainable development of coal areas in major coal producing countries of the world.

Policymaking and the spatial characteristics of land subsidence in North Jakarta

The narrative of “Jakarta is sinking!” has grown louder following the seasonal flood events over the past few years. What makes the case interesting is that the actual shape of land subsidence is growing fastest at around 20 cm per year in the northwest area, which is dominated by housing and settlements rather than commercial buildings and industries. This study aims to provide an academic explanation of the land subsidence phenomenon from the perspective of historical institutionalism. Applying spatial analysis and documentary reviews, we discussed the relationship between policy directions and land subsidence forms over decades. This paper found that spatial policy which have been pushed the urbanization in north Jakarta has contributed a more significant impact on land subsidence. The inability of government policy to address groundwater utilization both from the settlements and industries with the provisioning of access to safe water, emerged as one of the most significant factors triggering land subsidence.

Cenozoic Subsidence History of the Northern South China Sea: Examples from the Qiongdongnan and Yinggehai Basins

The Qiongdongnan and Yinggehai Basins are important petroliferous basins. To study the Cenozoic subsidence characteristics of these two basins, their controlling factors, and their implications, we studied the basins’ subsidence characteristics via one-dimensional, two-dimensional, and holistic subsidence. Then, we compared the basins’ subsidence characteristics based on the evolution of several particular geological processes that occurred in the South China Sea (SCS) and adjacent areas. The results indicated that the change in the holistic subsidence of both basins occurred episodically. In addition, the subsidence in these two basins differed, including their subsidence rates, the migration of the depocenters, and the changes in the holistic subsidence. The dynamic differences between the two basins were the main factors controlling the differences in the subsidence in the two basins. In the Qiongdongnan Basin, the subsidence characteristics were primarily controlled by the mantle material flowing under the South China Block in the Eocene and the spreading of the SCS from the Oligocene to the Miocene. In the Yinggehai Basin, the subsidence characteristics were primarily controlled by the coupling between the uplift of the Tibetan Plateau and the strike-slip motion of the Red River Fault before the Early Miocene and by only the effect of the strike-slip motion of the Red River Fault from the Middle Miocene to the Late Miocene. Since the Pliocene, the subsidence characteristics of both basins have been principally controlled by the dextral strike-slip motion of the Red River Fault. The major faults contributed to the spaciotemporal variations in the subsidence within each basin.

Prediction and Experimental Study of Tire Slip Rate Based on Chassis Sinkage Amount

In view of the problems that the fuselage inclines and the driving straightness is difficult to guarantee due to the sinking and sliding of the wheels when the high-clearance plant protection machine is working in the paddy field, this paper takes high-clearance wheels as the research object, based on the paddy field driving environment, establishes a prediction model of the wheel subsidence through derivation, and explores the influence of different wheel parameters on the subsidence characteristics through experiments, so as to improve the chassis trafficability. At the same time, using the test data under different wheel parameters, the prediction model of the settlement of the working chassis with high clearance is correspondingly modified. Finally, the paddy field trafficability of the working chassis is compared and analyzed based on different tire parameters. The results show that when the wheel slip rate is 0.5, the traction force of the solid tire is 37% higher than that of the pneumatic tire; when the height of the wheel spike increases, the traction force increases, and the settlement decreases obviously; proper increase of the wheel diameter can improve the passing performance of the chassis; with the increase of the tire width, the angle of soil penetration decreases while the tire is driving, and the angle of the slope climbing increases; and when the load changes, the driving coefficient is proportional to the traction coefficient, and the tire resistance coefficient is inversely proportional to the traction coefficient. Through the research on the settlement mechanism of the high-clearance operation chassis and the analysis of the paddy field trafficability, the stability of the high-clearance plant protection machine in the paddy field has been improved, providing a platform and guarantee for subsequent precision operation.

Improving the Resolution of GRACE/InSAR Groundwater Storage Estimations Using a New Subsidence Feature Weighted Combination Scheme

GRACE observations and land subsidence data derived from InSAR both assess groundwater storage changes. However, GRACE data at local scales are restricted by the coarser spatial resolution of satellite systems, and inversion of Groundwater Storage Anomalies (GWSA) by InSAR requires extensive and unavailable lithological data. Here, we propose a New Subsidence Feature Weighted Combination (NSFWC) scheme to enhance the spatial resolution of GRACE-derived GWSA from 0.5° to 0.05°. This method can not only retain the spatial distribution of groundwater changes but also reflect local details related to surface subsidence. A case study was executed to evaluate the performance of the NSFWC scheme in the Beijing Plain, which has seriously overexploited groundwater. Results showed that the simulated GWSA were consistent with in situ measurements in most regions, with a correlation coefficient of 0.85 and an RMSE of 4.41 mm/year. Additionally, there were 22 overexploited wells in the Beijing Plain, although groundwater levels generally recovered after the South to North Water Diversion Project. Simultaneously, four cones of depression were detected by the InSAR technology, where the maximum cumulative subsidence and subsidence rate achieved −198.52 mm and −53.09 mm/year, respectively. This paper provides data support and technical guarantees for small-scale groundwater resources management.