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Search Results (445)

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18 pages, 31612 KiB  
Article
Land Subsidence Velocity and High-Speed Railway Risks in the Coastal Cities of Beijing–Tianjin–Hebei, China, with 2015–2021 ALOS PALSAR-2 Multi-Temporal InSAR Analysis
by Qingli Luo, Mengli Li, Zhiyuan Yin, Peifeng Ma, Daniele Perissin and Yuanzhi Zhang
Remote Sens. 2024, 16(24), 4774; https://doi.org/10.3390/rs16244774 - 21 Dec 2024
Viewed by 191
Abstract
Sea-level rise has important implications for the economic and infrastructure security of coastal cities. Land subsidence further exacerbates relative sea-level rise. The Beijing–Tianjin–Hebei region (BTHR) along the Bohai Bay is one of the areas most severely affected by ground subsidence in the world. [...] Read more.
Sea-level rise has important implications for the economic and infrastructure security of coastal cities. Land subsidence further exacerbates relative sea-level rise. The Beijing–Tianjin–Hebei region (BTHR) along the Bohai Bay is one of the areas most severely affected by ground subsidence in the world. This study applies the Small Baseline Subset Interferometric Synthetic Aperture Radar (SBAS InSAR) method to analyze 47 ALOS PALSAR-2 images with five frames, mapping subsidence across 21,677.7 km2 and revealing spatial patterns and trends over time from 2015 to 2021. This is one of the few published research studies for large-scale and long-term analysis of its kind using ALOS-2 data in this region. The results reveal the existence of six major areas affected by severe subsidence in the study area, with the most pronounced in Jinzhan Town, Beijing, with the maximum subsiding velocity of −94.42 mm/y. Except for the two subsidence areas located in Chaoyang District of Beijing and Guangyang District of Langfang City, the other areas with serious subsidence detected are all located in suburban areas; this means that the strict regulations of controlling urban subsidence for downtown areas in the BTHR have worked. The accumulated subsidence is highly correlated with the time in the time series. Moreover, the subsidence of 161.4 km of the Beijing–Tianjin Inter-City High-Speed Railway (HSR) and 194.5 km of the Beijing–Shanghai HSR (out of a total length of 1318 km) were analyzed. It is the first time that PALSAR-2 data have been used to simultaneously investigate the subsidence along two important HSR lines in China and to analyze relatively long sections of the routes. The above two railways intersect five and seven subsiding areas, respectively. Within the range of the monitored railway line, the percentage of the section with subsidence velocity below −10 mm/y in the monitoring length range is 11.2% and 27.9%; this indicates that the Beijing–Shanghai HSR has suffered more serious subsidence than the Beijing–Tianjin Inter-City HSR within the monitoring period. This research is also beneficial for assessing the subsidence risk associated with different railways. In addition, this study further analyzed the potential reasons for the serious land subsidence of the identified areas. The results of the geological interpretation still indicate that the main cause of subsidence in the area is due to hydrogeological characteristics and underground water withdrawal. Full article
(This article belongs to the Special Issue Synthetic Aperture Radar Interferometry Symposium 2024)
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<p>Study area and coverage of the datasets: (<b>a</b>) the location of the study area in China; (<b>b</b>) the spatial coverage of the ALOS PALSAR-2 data in the study area; (<b>c</b>) the coverage of ALOS PALSAR-2 data overlapped with Tianditu maps; the blue rectangles in (<b>b</b>,<b>c</b>) are the spatial coverage of the ALOS PALSAR-2 data; and the orange and red lines in (<b>c</b>) highlight the Beijing–Tianjin Inter-City HSR and the Beijing–Shanghai HSR, respectively.</p>
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<p>Differential interference results of Frame 770A between 9 May 2019 and 6 May 2021: (<b>a</b>) topographic information; (<b>b</b>) the ALOS PALSAR-2 image from 9 May 2019; (<b>c</b>) the differential interferogram; and (<b>d</b>) the coherence.</p>
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<p>Processing for PALSAR-2 imagery by SBAS.</p>
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<p>The overall average subsidence velocity in the BTHR. Stable areas are indicated in green, while orange and red represent subsiding areas with the velocity of −30 and -90 mm/y, respectively. The main subsidence centers are identified as follows: (<b>A</b>) Jinzhan Town, (<b>B</b>) Wenjing Sub-District, (<b>C</b>) Guangyang District, (<b>D</b>) Wangqingtuo Town, (<b>E</b>) Shengfang Town, and (<b>F</b>) Tuanbo Town.</p>
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<p>Subsidence history of ground points in subsidence funnel.</p>
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<p>The partially enlarged average deformation map of Beijing–Tianjin Inter-City HSR. A1–A5 are the main five serious subsiding centers along the Beijing–Tianjin Inter-City HSR.</p>
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<p>The partially enlarged average deformation map of Beijing–Shanghai HSR. B1–B7 are the main seven subsiding centers along the Beijing–Shanghai HSR.</p>
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<p>Comparisons of SBAS InSAR results and leveling data: (<b>a</b>) the Beijing–Tianjin Inter-City HSR; (<b>b</b>) the Beijing–Shanghai HSR; (<b>c</b>) scatterplot for correlation analysis along the Beijing–Tianjin Inter-City HSR; and (<b>d</b>) scatterplot along the Beijing–Shanghai HSR.</p>
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<p>Land resources distribution and groundwater extraction in the BTHR: (<b>a</b>) groundwater exploitation situation; and (<b>b</b>) geological map. These two maps are from the 2015 China Geological Survey conducted by the Ministry of Land and Resources. A, B, C, D, E, and F are the main six subsiding centers marked in <a href="#remotesensing-16-04774-f004" class="html-fig">Figure 4</a>.</p>
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<p>Profiles of average subsidence velocity along railways from SBAS InSAR results: (<b>a</b>) the profile of Beijing–Tianjin Inter-City HSR; (<b>b</b>) the profile of Beijing–Shanghai HSR. A1–A5 and B1–B7 are the sections affected by relatively serious subsidence along the Beijing–Tianjin Inter-City HSR and the Beijing–Shanghai HSR, respectively.</p>
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<p>The histograms of the distances between the point pairs from the HSRs and the SBAS InSAR results: (<b>a</b>) the histogram of the distances along Beijing–Tianjin Inter-City HSR; and (<b>b</b>) the histogram of the distances along Beijing–Shanghai HSR.</p>
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35 pages, 19129 KiB  
Article
Mapping Lithology with Hybrid Attention Mechanism–Long Short-Term Memory: A Hybrid Neural Network Approach Using Remote Sensing and Geophysical Data
by Michael Appiah-Twum, Wenbo Xu and Emmanuel Daanoba Sunkari
Remote Sens. 2024, 16(23), 4613; https://doi.org/10.3390/rs16234613 - 9 Dec 2024
Viewed by 668
Abstract
Remote sensing provides an efficient roadmap in geological analysis and interpretation. However, some challenges arise when remote sensing techniques are integrated with machine learning in geological surveys. Factors including irregular spatial distribution, sample imbalance, interclass resemblances, regolith, and geochemical similarities impede geological feature [...] Read more.
Remote sensing provides an efficient roadmap in geological analysis and interpretation. However, some challenges arise when remote sensing techniques are integrated with machine learning in geological surveys. Factors including irregular spatial distribution, sample imbalance, interclass resemblances, regolith, and geochemical similarities impede geological feature diagnosis, interpretation, and identification across varied remote sensing datasets. To address these limitations, a hybrid-attention-integrated long short-term memory (LSTM) network is employed to diagnose, interpret, and identify lithological feature representations in a remote sensing-based geological analysis using multisource data fusion. The experimental design integrates varied datasets including Sentinel-2A, Landsat-9, ASTER, ALOS PALSAR DEM, and Bouguer anomaly gravity data. The proposed model incorporates a hybrid attention mechanism (HAM) comprising channel and spatial attention submodules. HAM utilizes an adaptive technique that merges global-average-pooled features with max-pooled features, enhancing the model’s accuracy in identifying lithological units. Additionally, a channel separation operation is employed to allot refined channel features into clusters based on channel attention maps along the channel dimension. The comprehensive analysis of results from comparative extensive experiments demonstrates HAM-LSTM’s state-of-the-art performance, outperforming existing attention modules and attention-based models (ViT, SE-LSTM, and CBAM-LSTM). Comparing HAM-LSTM to baseline LSTM, the HAM module’s integrated configurations equip the proposed model to better diagnose and identify lithological units, thereby increasing the accuracy by 3.69%. Full article
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<p>An overview of this study’s workflow: The multisource data fusion technique is employed to fuse the gravity anomaly data and remote sensing data. Channel and spatial attention mechanisms are modeled to learn the spatial and spectral information of pixels in the fused data and the resultant attention features, fed into the LSTM network for sequential iterative processing to map lithology.</p>
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<p>Location of study area and regional geological setting. (<b>a</b>) Administrative map of Burkina Faso; (<b>b</b>) administrative map of Bougouriba and Ioba Provinces within which the study area is located; (<b>c</b>) geological overview of Burkina Faso (modified from [<a href="#B44-remotesensing-16-04613" class="html-bibr">44</a>]) indicating the study area; (<b>d</b>) color composite image of Landsat-9 covering the study area.</p>
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<p>False color composite imagery of remote sensing data used: (<b>a</b>) Sentinel-2A (bands 4-3-2); (<b>b</b>) Landsat-9 (bands 4-3-2); (<b>c</b>) ASTER (bands 3-2-1); and (<b>d</b>) 12.5 m spatial resolution high-precision ALOS PALSAR DEM.</p>
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<p>Vegetation masking workflow.</p>
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<p>The HAM structure. It comprises three sequential components: channel attention submodule, feature separation chamber, and spatial attention submodule. One-dimensional and two-dimensional feature maps are produced by the channel and spatial attention submodules, respectively.</p>
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<p>Framework of HAM’s channel attention submodule. Dimensional feature information is generated by both max-pooling and average-pooling operations. The resultant features are then fed through a one-dimensional convolution with a sigmoid activation to deduce the definitive channel feature.</p>
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<p>Framework of HAM’s spatial attention. Two feature clusters of partitioned refined channel features from the separation chamber are fed into the submodule. Average-pooling and max-pooling functions subsequently synthesize two pairs of 2D maps into a shared convolution layer to synthesize spatial attention maps.</p>
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<p>The structural framework of the proposed HAM-LSTM model.</p>
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<p>Gravity anomaly maps of the terrane used: (<b>a</b>) complete Bouguer anomaly; (<b>b</b>) residual gravity.</p>
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<p>Band imagery: (<b>a</b>) Landsat-9 band 5; (<b>b</b>) Sentinel-2A band 5; (<b>c</b>) ASTER band 5; (<b>d</b>) fused image; (<b>e</b>) partial magnification of (<b>a</b>) (<math display="inline"><semantics> <mrow> <mn>279</mn> <mo>×</mo> <mn>235</mn> </mrow> </semantics></math> pixels); (<b>f</b>) partial magnification of (<b>b</b>) (<math display="inline"><semantics> <mrow> <mn>279</mn> <mo>×</mo> <mn>235</mn> </mrow> </semantics></math> pixels); (<b>g</b>) partial magnification of (<b>c</b>) (<math display="inline"><semantics> <mrow> <mn>279</mn> <mo>×</mo> <mn>235</mn> </mrow> </semantics></math> pixels); and (<b>h</b>) partial magnification of (<b>d</b>) (<math display="inline"><semantics> <mrow> <mn>279</mn> <mo>×</mo> <mn>235</mn> </mrow> </semantics></math> pixels).</p>
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<p>Resultant multisource fusion imagery.</p>
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<p>Annotation map of the study area.</p>
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<p>An illustration of the sliding window method implementation.</p>
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<p>Graphs of training performance of the varied model implementations in this study: (<b>a</b>) accuracy and (<b>b</b>) loss.</p>
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<p>Classification maps derived from implementing (<b>a</b>) HAM-LSTM, (<b>b</b>) CBAM-LSTM, (<b>c</b>) SE-LSTM, (<b>d</b>) ViT, and (<b>e</b>) LSTM on the multisource fusion dataset.</p>
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<p>Confusion matrices of (<b>a</b>) HAM-LSTM, (<b>b</b>) CBAM-LSTM, (<b>c</b>) SE-LSTM, (<b>d</b>) LSTM, and (<b>e</b>) ViT implementation.</p>
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20 pages, 10429 KiB  
Article
Dynamic Geo-Visualization of Urban Land Subsidence and Land Cover Data Using PS-InSAR and Google Earth Engine (GEE) for Spatial Planning Assessment
by Joko Widodo, Edy Trihatmoko, Muhammad Rokhis Khomarudin, Mohammad Ardha, Udhi Catur Nugroho, Nugraheni Setyaningrum, Galih Prasetya Dinanta, Rahmat Arief, Andie Setiyoko, Dandy Aditya Novresiandi, Rendi Handika, Muhammad Priyatna, Shinichi Sobue, Dwi Sarah and Wawan Hermawan
Urban Sci. 2024, 8(4), 234; https://doi.org/10.3390/urbansci8040234 - 1 Dec 2024
Viewed by 1108
Abstract
The North Java coastal area, known as the Pantura region, is experiencing significant land subsidence, with certain areas sinking up to 10 cm per year. Pekalongan is among the most affected, with subsidence rates between 10 and 19 cm annually, mainly due to [...] Read more.
The North Java coastal area, known as the Pantura region, is experiencing significant land subsidence, with certain areas sinking up to 10 cm per year. Pekalongan is among the most affected, with subsidence rates between 10 and 19 cm annually, mainly due to groundwater extraction, sediment compaction, and coastal erosion. Other coastal cities, like Semarang and Demak, show rates averaging 4 to 10 cm per year. This rapid subsidence is due to favorable geological conditions and ongoing urban development. This study investigates land subsidence in Pekalongan using the PS-InSAR method and dynamic visualization of time-series land cover data. PS-InSAR was applied to 45 scenes from ALOS-2 PALSAR-2 to monitor subsidence from 2014 to 2022. The results were validated with in situ subsidence benchmarks. Urban development dynamics were analyzed through land cover and land use change (LULC) and population density over the same period, using the GLC_FCS30D dataset in the GEE to detect non-natural LULC. The PS-InSAR results indicated that over 60.9% of investigation points experienced subsidence, up to 100 cm between 2014 and 2022. Ground validation showed an 83% agreement with PS-InSAR results. A statistical analysis of LULC from 2014 to 2022 did not show significant built-up area development, but the extension of salt marshes and water bodies indicated subsidence expansion. The population density reached 6873 people per square km by 2022, causing extensive groundwater use for domestic and industrial purposes, further aggravating the subsidence. Full article
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<p>An example of urban change in Pekalongan City is derived from LANDSAT data comparing 1993 (<b>a</b>) and 2019 (<b>b</b>).</p>
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<p>Research location (land area clipped from the ALOS-2 scene utilized in the study).</p>
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<p>PS-InSAR records distribution and its velocity (in cm) during 2014–2022.</p>
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<p>The velocity of the land subsidence within the research period using 17,121 records.</p>
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<p>A graph of the accuracy test results for ALOS-2 data and field observations shows an <span class="html-italic">NSE</span> value of 0.83.</p>
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<p>LULC within the research period (2014–2022) in the research location.</p>
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<p>The LULC comparison in 2014 and 2022.</p>
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<p>Pixel number changes for LULC in 2014 and 2022.</p>
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<p>Pekalongan city’s spatial plan.</p>
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24 pages, 3621 KiB  
Article
Improving Forest Above-Ground Biomass Estimation Accuracy Using Multi-Source Remote Sensing and Optimized Least Absolute Shrinkage and Selection Operator Variable Selection Method
by Er Wang, Tianbao Huang, Zhi Liu, Lei Bao, Binbing Guo, Zhibo Yu, Zihang Feng, Hongbin Luo and Guanglong Ou
Remote Sens. 2024, 16(23), 4497; https://doi.org/10.3390/rs16234497 - 30 Nov 2024
Viewed by 643
Abstract
Estimation of forest above-ground biomass (AGB) using multi-source remote sensing data is an important method to improve the accuracy of the estimate. However, selecting remote sensing factors that can effectively improve the accuracy of forest AGB estimation from a large amount of data [...] Read more.
Estimation of forest above-ground biomass (AGB) using multi-source remote sensing data is an important method to improve the accuracy of the estimate. However, selecting remote sensing factors that can effectively improve the accuracy of forest AGB estimation from a large amount of data is a challenge when the sample size is small. In this regard, the Least Absolute Shrinkage and Selection Operator (Lasso) has advantages for extensive redundant variables but still has some drawbacks. To address this, the study introduces two Least Absolute Shrinkage and Selection Operator Lasso-based variable selection methods: Least Absolute Shrinkage and Selection Operator Genetic Algorithm (Lasso-GA) and Variance Inflation Factor Least Absolute Shrinkage and Selection Operator (VIF-Lasso). Sentinel 2, Sentinel 1, Landsat 8 OLI, ALOS-2 PALSAR-2, Light Detection and Ranging, and Digital Elevation Model (DEM) data were used in this study. In order to explore the variable selection capabilities of Lasso-GA and VIF-Lasso for remote sensing estimation of forest AGB. It compares Lasso-GA and VIF-Lasso with Boruta, Random Forest Importance Selection, Pearson Correlation, and Lasso for selecting remote sensing factors. Additionally, it employs eight machine learning models—Random Forest (RF), Extreme Gradient Boosting (XGBoost), Support Vector Machine (SVM), Bayesian Regression Neural Network (BRNN), Elastic Net (EN), K-Nearest Neighbors (KNN), Extremely Randomized Trees (ETR), and Stochastic Gradient Boosting (SGBoost)—to estimate forest AGB in Wuyi Village, Zhenyuan County. The results showed that the optimized Lasso variable selection could improve the accuracy of forest biomass estimation. The VIF-Lasso method results in a BRNN model with an R2 of 0.75 and an RMSE of 16.48 Mg/ha. The Lasso-GA method results in an ETR model with an R2 of 0.73 and an RMSE of 16.70 Mg/ha. Compared to the optimal SGBoost model with the Lasso variable selection method (R2 of 0.69, RMSE of 18.63 Mg/ha), the VIF-Lasso method improves R2 by 0.06 and reduces RMSE by 2.15 Mg/ha, while the Lasso-GA method improves R2 by 0.04 and reduces RMSE by 1.93 Mg/ha. From another perspective, they also demonstrated that the RX sample count and sensitivity provided by LiDAR, as well as the Horizontal Transmit, Vertical Receive provided by Microwave Radar, along with the feature variables (Mean, Contrast, and Correlation) calculated from the Green, Red, and NIR bands of optical remote sensing in 7 × 7 and 5 × 5 windows, play an important role in forest AGB estimation. Therefore, the optimized Lasso variable selection method shows strong potential for forest AGB estimation using multi-source remote sensing data. Full article
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<p>Technology roadmap for this study.</p>
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<p>The study area and sample plot distribution: (<b>a</b>) The location of Zhenyuan in Yunnan Province; (<b>b</b>) Six Types of Remote Sensing Imagery; (<b>c</b>) Remote sensing image data of Wuyi Village.</p>
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<p>Data distribution for the original dataset (60 samples), training set (42 samples), and test set (18 samples).</p>
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<p>Results of variable selection: (<b>a</b>) Boruta’s variable selection results by comparing the shaded features with the original feature evaluation; (<b>b</b>) Lasso regularized compression of the eigenvectors obtained from the; (<b>c</b>) Lasso Variable Selection Results with GA variable selection Re-used in the Lasso variable selection case; (<b>d</b>) Results of variable selection with correlation coefficients greater than 0.5 between remote sensing factors and forest AGBs; (<b>e</b>) RFIS variable importance value selection results for each remote sensing factor; (<b>f</b>) Lasso variable selection results in the case of removing multicollinear remote sensing factors using VIF.</p>
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<p>Scatterplots of forest AGB model test set fit using 8 algorithms for 6 variable choices.</p>
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<p>The results of 6 variable selection results in 8 machine learning in the test set R<sup>2</sup> fitting results.</p>
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<p>AGB inversion plot using 8 algorithms with 6 types of variable selection.</p>
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20 pages, 4507 KiB  
Article
Enhanced Polarimetric Radar Vegetation Index and Integration with Optical Index for Biomass Estimation in Grazing Lands Across the Contiguous United States
by Jisung Geba Chang, Simon Kraatz, Martha Anderson and Feng Gao
Remote Sens. 2024, 16(23), 4476; https://doi.org/10.3390/rs16234476 - 28 Nov 2024
Viewed by 488
Abstract
Grazing lands are crucial for agricultural productivity, ecological stability, and carbon sequestration, underscoring the importance of monitoring vegetation biomass for the effective management of these ecosystems. Remote sensing data, including optical vegetation indices (VIs) like the Normalized Difference Vegetation Index (NDVI), are widely [...] Read more.
Grazing lands are crucial for agricultural productivity, ecological stability, and carbon sequestration, underscoring the importance of monitoring vegetation biomass for the effective management of these ecosystems. Remote sensing data, including optical vegetation indices (VIs) like the Normalized Difference Vegetation Index (NDVI), are widely used to monitor vegetation dynamics due to their simplicity and high sensitivity. In contrast, radar-based VIs, such as the Polarimetric Radar Vegetation Index (PRVI), offer additional advantages, including all-weather imaging capabilities, a wider saturation range, and sensitivity to the vegetation structure information. This study introduces an enhanced form of the PRVI, termed the Normalized PRVI (NPRVI), which is calibrated to a 0 to 1 range, constraining the minimum value to reduce the background effects. The calibration and range factor were derived from statistical analysis of PRVI components across vegetated regions in the Contiguous United States (CONUS), using dual-polarization C-band Sentinel-1 and L-band ALOS-PALSAR data on the Google Earth Engine (GEE) platform. Machine learning models using NPRVI and NDVI demonstrated their complementarity with annual herbaceous biomass data from the Rangeland Analysis Platform. The results showed that the Random Forest Model outperformed the other machine learning models tested, achieving R2 ≈ 0.51 and MAE ≈ 498 kg/ha (relative MAE ≈ 32.1%). Integrating NPRVI with NDVI improved biomass estimation accuracy by approximately 10% compared to using NDVI alone, highlighting the added value of incorporating radar-based vegetation indices. NPRVI may enhance the monitoring of grazing lands with relatively low biomass compared to other vegetation types, while also demonstrating applicability across a broad range of biomass levels and in diverse vegetation covers. Full article
(This article belongs to the Section Remote Sensing in Agriculture and Vegetation)
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<p>Distribution of vegetated regions across the CONUS from NLCD2021 (<b>upper</b>) and annual herbaceous above-ground biomass from RAP for the year 2022 (<b>lower</b>).</p>
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<p>Distribution of Degree of Polarization (DOP) and cross-polarization backscattering coefficient (<math display="inline"><semantics> <mrow> <msubsup> <mrow> <mi mathvariant="sans-serif">σ</mi> </mrow> <mrow> <mn>0</mn> </mrow> <mrow> <mi mathvariant="normal">h</mi> <mi mathvariant="normal">v</mi> </mrow> </msubsup> </mrow> </semantics></math> or <math display="inline"><semantics> <mrow> <msubsup> <mrow> <mi mathvariant="sans-serif">σ</mi> </mrow> <mrow> <mn>0</mn> </mrow> <mrow> <mi mathvariant="normal">v</mi> <mi mathvariant="normal">h</mi> </mrow> </msubsup> </mrow> </semantics></math>) for Sentinel-1 (C-band) and PALSAR (L-band) across different vegetation types.</p>
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<p>Correlation (Pearson R) heatmap illustrating the relationships between NPRVI, NDVI indices, and reference annual biomass across various seasons for 2022.</p>
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<p>Density plots of NPRVI derived from Sentinel-1 and NDVI derived from HLS data against annual herbaceous AGB (kg/ha) across grazing lands of the CONUS, along with corresponding histograms. The biomass range of herbaceous AGB is 0–5000 kg/ha, with low biomass defined as 0–400 kg/ha (12.66%), medium biomass as 400–1800 kg/ha (57.87%), and high biomass as 1800–5000 kg/ha (29.47%). The data were randomly sampled from 10,000 pixels.</p>
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<p>Comparison of machine learning models (MLR, RFM, XGBoost, DNN) for biomass estimation using all vegetation indices. Metrics include mean R<sup>2</sup> (<b>red</b>) and mean MAE (<b>blue</b>).</p>
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<p>NPRVI difference (NPRVI<sub>C</sub> − NPRVI<sub>L</sub>) ranges from −0.3 (indicating higher L-band values, shown in red) to 0.3 (indicating lower L-band values than C-band value, shown in blue). White strip regions in the mosaic figure indicate missing images from SAR data, primarily from PALSAR imagery.</p>
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<p>Range of NPRVIs and their differences (NPRVI<sub>C</sub> − NPRVI<sub>L</sub>) for each vegetation type based on the NLCD dataset. The violin plots show the distribution and density of NPRVI values, while the box plots indicate the median and interquartile range (IQR), with whiskers extending to 95% of the data. These plots capture both the central tendency and variability for each vegetation type.</p>
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<p>Multi-temporal trends of NDVI from HLS and NPRVI from Sentinel-1 at the upper part, and cross-ratio (VH/VV) and (1-DOP) at the lower part, between 1 January 2022 and 31 July 2024, with data points every 16 days: averages from 100 randomly selected regions in the grazing lands of the CONUS, with the dotted line representing the average values and the light shading indicating ±0.2 standard deviations.</p>
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21 pages, 8795 KiB  
Article
Morphometric Characterization and Dual Analysis for Flash Flood Hazard Assessment of Wadi Al-Lith Watershed, Saudi Arabia
by Bashar Bashir and Abdullah Alsalman
Water 2024, 16(22), 3333; https://doi.org/10.3390/w16223333 - 20 Nov 2024
Viewed by 563
Abstract
Flash floods are one of the most hazardous natural events globally, characterized by their rapid onset and unpredictability, often overwhelming emergency preparedness and response systems. In the arid environment of Saudi Arabia, Wadi Al-Lith watershed is particularly prone to flash floods, exacerbated by [...] Read more.
Flash floods are one of the most hazardous natural events globally, characterized by their rapid onset and unpredictability, often overwhelming emergency preparedness and response systems. In the arid environment of Saudi Arabia, Wadi Al-Lith watershed is particularly prone to flash floods, exacerbated by sudden storms and the region’s distinct topographical features. This study focuses on the morphometric characterization and comparative analysis of flash flood risk within the Wadi Al-Lith basin. To assess flood susceptibility, two widely adopted methodologies were employed: the morphometric ranking approach and El-Shamy’s method. A 12.5-m resolution ALOS PALSAR digital elevation model (DEM) was used to delineate the watershed and generate a detailed drainage network via Arc-Hydro tools in the ArcGIS 10.4 software. Fifteen morphometric parameters were analyzed to determine their influence on flood potential and hazard prioritization. The findings of this study provide crucial insights for regional flood risk management, offering an improved understanding of flash flood dynamics and assisting in developing effective mitigation strategies for Wadi Al-Lith and similar environments. The findings reveal that Wadi Al-Lith comprises multiple sub-catchments with varying degrees of vulnerability to flash flooding. According to the morphometric hazard analysis (MHA), certain sub-catchments, including sc-2, sc-4, sc-5, sc-6, sc-10, sc-12, sc-13, and sc-15, emerge as highly susceptible to flood hazards, while others (sc-1 and sc-9) fall into moderate risk categories. In contrast, the application of El-Shamy’s method provides a different ranking of flood risks across the watershed’s sub-catchments, offering a comparative view of flood susceptibility. The insights gained from this dual-analysis approach are expected to support the development of targeted flood prevention and mitigation strategies, which are essential for minimizing the future impacts of flash flooding in the Wadi Al-Lith watershed and ensuring better preparedness for local communities. Full article
(This article belongs to the Special Issue Use of Remote Sensing Technologies for Water Resources Management)
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<p>(<b>a</b>) Regional map of Saudi Arabia and (<b>b</b>) hillshade map showing location of the Wadi Al-Lith watershed.</p>
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<p>(<b>a</b>) A digital elevation model map and (<b>b</b>) the geomorphological zones of the Wadi Al-Lith watershed.</p>
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<p>Chart illustrating the drainage systems and morphometric parameters analysis of the Wadi Al-Lith watershed.</p>
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<p>(<b>a</b>) sub-catchments (1–15) and (<b>b</b>) different stream orders of the Wadi Al-Lith watershed.</p>
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<p>Distribution of the morphometric parameter values for the 15 sub-catchments. Lb: basin length; Wb: basin width; Rlw: length width ratio; Os: stream order; Ns: stream number; Ls: stream length; Rb: bifurcation ratio; A: total area; P: perimeter; Re: elongation ratio; Rc: circulation ratio; sh-f: shape factor; Dd: drainage density; F: stream factor; Dt: stream texture.</p>
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<p>Distribution of the morphometric parameter values for the 15 sub-catchments. Lb: basin length; Wb: basin width; Rlw: length width ratio; Os: stream order; Ns: stream number; Ls: stream length; Rb: bifurcation ratio; A: total area; P: perimeter; Re: elongation ratio; Rc: circulation ratio; sh-f: shape factor; Dd: drainage density; F: stream factor; Dt: stream texture.</p>
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<p>Flood susceptibility levels based on the ranking hazard approach.</p>
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<p>El-Shamy method diagrams for assigning flash flood susceptibility classes. (<b>a</b>) Bifurcation ratio (Rb) against drainage density (Dd) and (<b>b</b>) bifurcation ratio (Rb) against stream frequency (Fs).</p>
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<p>Flood susceptibility levels according to the El-Shamy method. (<b>a</b>) Rb ve Dd and (<b>b</b>) Rb ve Fs.</p>
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27 pages, 21954 KiB  
Article
Long-Term Ground Deformation Monitoring and Quantitative Interpretation in Shanghai Using Multi-Platform TS-InSAR, PCA, and K-Means Clustering
by Yahui Chong and Qiming Zeng
Remote Sens. 2024, 16(22), 4188; https://doi.org/10.3390/rs16224188 - 10 Nov 2024
Viewed by 835
Abstract
Ground subsidence in urban areas is mainly due to natural or anthropogenic activities, and it seriously threatens the healthy and sustainable development of the city and the security of individuals’ lives and assets. Shanghai is a megacity of China, and it has a [...] Read more.
Ground subsidence in urban areas is mainly due to natural or anthropogenic activities, and it seriously threatens the healthy and sustainable development of the city and the security of individuals’ lives and assets. Shanghai is a megacity of China, and it has a long history of ground subsidence due to the overexploitation of groundwater and urban expansion. Time Series Synthetic Aperture Radar Interferometry (TS-InSAR) is a highly effective and widely used approach for monitoring urban ground deformation. However, it is difficult to obtain long-term (such as over 10 years) deformation results using single-platform SAR satellite in general. To acquire long-term surface deformation monitoring results, it is necessary to integrate data from multi-platform SAR satellites. Furthermore, the deformations are the result of multiple factors that are superimposed, and relevant studies that quantitatively separate the contributions from different driving factors to subsidence are rare. Moreover, the time series cumulative deformation results of massive measurement points also bring difficulties to the deformation interpretation. In this study, we have proposed a long-term surface deformation monitoring and quantitative interpretation method that integrates multi-platform TS-InSAR, PCA, and K-means clustering. SAR images from three SAR datasets, i.e., 19 L-band ALOS-1 PALSAR, 22 C-band ENVISAT ASAR, and 20 C-band Sentinel-1A, were used to retrieve annual deformation rates and time series deformations in Shanghai from 2007 to 2018. The monitoring results indicate that there is serious uneven settlement in Shanghai, with a spatial pattern of stability in the northwest and settlement in the southeast of the study area. Then, we selected Pudong International Airport as the area of interest and quantitatively analyzed the driving factors of land subsidence in this area by using PCA results, combining groundwater exploitation and groundwater level change, precipitation, temperature, and engineering geological and human activities. Finally, the study area was divided into four sub-regions with similar time series deformation patterns using the K-means clustering. This study helps to understand the spatiotemporal evolution of surface deformation and its driving factors in Shanghai, and provides a scientific basis for the formulation and implementation of precise prevention and control strategies for land subsidence disasters, and it can also provide reference for monitoring in other urban areas. Full article
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<p>The geographic location of Shanghai and spatial coverage of SAR datasets.</p>
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<p>SAR image acquisition dates and the spatial baselines of three SAR sensors with respect to the reference image for each sensor. The star represents the reference image of each sensor.</p>
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<p>The data processing flowchart of this study.</p>
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<p>Spatial–temporal baseline configurations of SAR datasets: (<b>a</b>) ALOS-1 PALSAR, (<b>b</b>) ENVISAT ASAR, and (<b>c</b>) Sentinel-1A.</p>
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<p>Annual LOS deformation rates obtained from three SAR datasets: (<b>a</b>) ALOS-1 PALSAR, (<b>b</b>) ENVISAT ASAR, and (<b>c</b>) Sentinel-1A.</p>
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<p>(<b>a</b>) Average vertical deformation rate and (<b>b</b>) time series cumulative surface deformation obtained from ALOS-ENVISAT-S1A fusion results for Shanghai from 2007 to 2018.</p>
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<p>Comparisons of long-term time series cumulative deformation obtained by ALOS-ENVISAT-S1A and self-weight consolidation settlement model: (<b>a</b>) P1, (<b>b</b>) P2, (<b>c</b>) P3, and (<b>d</b>) P4.</p>
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<p>(<b>a</b>) Scatterplot and (<b>b</b>) correlation coefficient graph of TS-InSAR deformation rate and field measurements.</p>
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<p>Landsat TM/ETM optical images of Pudong International Airport for the following years: (<b>a</b>) 2007, (<b>b</b>) 2010, (<b>c</b>) 2015, and (<b>d</b>) 2018.</p>
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<p>Vertical annual deformation rates of Pudong International Airport during (<b>a</b>) 2007–2010 and (<b>b</b>) 2015–2018 (base image is from Google Map).</p>
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<p>PCA result derived from ALOS-ENVISAT: (<b>a</b>) variance explained by the PC 1–4 and (<b>b</b>) eigenvectors obtained from PC 1–4.</p>
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<p>PCA result derived from Sentinel-1A: (<b>a</b>) variance explained by the PC 1–4 and (<b>b</b>) eigenvectors obtained from PC 1–4.</p>
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<p>Correlation map between eigenvectors of PC 1–3 obtained from ALOS-ENVISAT and temperature, groundwater level, precipitation, groundwater extraction volume, and impervious surface area: (<b>a</b>) PC1, (<b>b</b>) PC2, and (<b>c</b>) PC3.</p>
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<p>Correlation map between eigenvectors of PC 1–2 obtained from Sentinel-1A and temperature, groundwater level, precipitation, groundwater extraction volume, and impervious surface area: (<b>a</b>) PC and (<b>b</b>) PC2.</p>
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<p>The deformation rate of Pudong International Airport on the east–west profile line: (<b>a</b>) AB profile and (<b>b</b>) CD profile.</p>
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<p>P1–P7 time series cumulative deformation acquired by ALOS-ENVISAT in the runway and terminal areas.</p>
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<p>Q1–Q7 time series cumulative deformation acquired by Sentinel-1A in the runway and terminal areas.</p>
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<p>K-means clustering results of the long-term time series deformation obtained from ALOS-ENVISAT-S1A: (<b>a</b>) spatial distribution of each cluster, (<b>b</b>) percentage of each cluster, (<b>c</b>) time series of cumulative deformation of the cluster center, and (<b>d</b>) violin map of the annual deformation velocity for each cluster.</p>
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31 pages, 7836 KiB  
Article
Estimation of Forest Growing Stock Volume with Synthetic Aperture Radar: A Comparison of Model-Fitting Methods
by Maurizio Santoro, Oliver Cartus, Oleg Antropov and Jukka Miettinen
Remote Sens. 2024, 16(21), 4079; https://doi.org/10.3390/rs16214079 - 31 Oct 2024
Viewed by 573
Abstract
Satellite-based estimation of forest variables including forest biomass relies on model-based approaches since forest biomass cannot be directly measured from space. Such models require ground reference data to adapt to the local forest structure and acquired satellite data. For wide-area mapping, such reference [...] Read more.
Satellite-based estimation of forest variables including forest biomass relies on model-based approaches since forest biomass cannot be directly measured from space. Such models require ground reference data to adapt to the local forest structure and acquired satellite data. For wide-area mapping, such reference data are too sparse to train the biomass retrieval model and approaches for calibrating that are independent from training data are sought. In this study, we compare the performance of one such calibration approach with the traditional regression modelling using reference measurements. The performance was evaluated at four sites representative of the major forest biomes in Europe focusing on growing stock volume (GSV) prediction from time series of C-band Sentinel-1 and Advanced Land Observing Satellite Phased Array L-band Synthetic Aperture Radar (ALOS-2 PALSAR-2) backscatter measurements. The retrieval model was based on a Water Cloud Model (WCM) and integrated two forest structural functions. The WCM trained with plot inventory GSV values or calibrated with the aid of auxiliary data products correctly reproduced the trend between SAR backscatter and GSV measurements across all sites. The WCM-predicted backscatter was within the range of measurements for a given GSV level with average model residuals being smaller than the range of the observations. The accuracy of the GSV estimated with the calibrated WCM was close to the accuracy obtained with the trained WCM. The difference in terms of root mean square error (RMSE) was less than 5% units. This study demonstrates that it is possible to predict biomass without providing reference measurements for model training provided that the modelling scheme is physically based and the calibration is well set and understood. Full article
(This article belongs to the Special Issue SAR for Forest Mapping III)
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<p>The location of the study sites. Each site is illustrated with a colour composite of Sentinel-1 imagery (Red: VV-polarized backscatter; Green: VH-polarized backscatter; Blue: difference in the VV- and VH-polarized backscatter).</p>
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<p>Canopy height from ICESat-2 data averaged at the level of sub-national units and corresponding average GSV values together with the fit of Equation (5) after stratifying by forest biome. Estimates of the coefficients a and b in Equation (5) and the standard error of the regression are visualized in the upper left corner of each panel.</p>
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<p>Measured and modelled Sentinel-1 VV- and VH-polarized backscatter over the Catalonian site stratified by the local incidence angle and illustrated as a function of the canopy density level (circles: average value; vertical bars: two-sided one standard deviation). The Sentinel-1 image was acquired on 17 July 2016. The asterisks at the canopy densities of 0% and 100% represent the estimates of <span class="html-italic">σ</span><sup>0</sup><span class="html-italic"><sub>gr</sub></span> and <math display="inline"><semantics> <mrow> <msubsup> <mrow> <mover accent="true"> <mrow> <mi>σ</mi> </mrow> <mo>^</mo> </mover> </mrow> <mrow> <mi>v</mi> <mi>e</mi> <mi>g</mi> </mrow> <mrow> <mn>0</mn> </mrow> </msubsup> </mrow> </semantics></math> obtained by regressing Equation (1) to the observations. The diamond and cross symbols at 100% canopy density represent the estimate of <span class="html-italic">σ</span><sup>0</sup><span class="html-italic"><sub>veg</sub></span> obtained by compensating for <math display="inline"><semantics> <mrow> <msubsup> <mrow> <mover accent="true"> <mrow> <mi>σ</mi> </mrow> <mo>^</mo> </mover> </mrow> <mrow> <mi>v</mi> <mi>e</mi> <mi>g</mi> </mrow> <mrow> <mn>0</mn> </mrow> </msubsup> </mrow> </semantics></math> for the standard deviation of the observations and the backscatter of dense forests, respectively (see also <a href="#remotesensing-16-04079-f005" class="html-fig">Figure 5</a>).</p>
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<p>Measured and modelled Sentinel-1 VV- and VH-polarized backscatter over the Finland N site as a function of canopy density. The Sentinel-1 image was acquired on 12 July 2018. Plot notations are the same as in <a href="#remotesensing-16-04079-f003" class="html-fig">Figure 3</a>.</p>
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<p>The standard deviation of the VV- and VH-polarized backscatter observations per canopy density level (circles) and linear regression (solid line) for the Sentinel-1 image acquired over the Catalonian site on 17 July 2016.</p>
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<p>The standard deviation of the VV- and VH-polarized backscatter observations for the Sentinel-1 image acquired over the Finland N site on 12 July 2018 at VV and VH polarization. Plot notations follow <a href="#remotesensing-16-04079-f005" class="html-fig">Figure 5</a>.</p>
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<p>Measured and modelled ALOS-2 PALSAR-2 HH- and HV-polarized backscatter over the Finland N site stratified by the local incidence angle and illustrated as a function of the canopy density level (circles: average value; vertical bars: two-sided one standard deviation). The asterisks at canopy densities of 0% and 100% represent the estimates of <span class="html-italic">σ</span><sup>0</sup><span class="html-italic"><sub>gr</sub></span> and <math display="inline"><semantics> <mrow> <msubsup> <mrow> <mover accent="true"> <mrow> <mi>σ</mi> </mrow> <mo>^</mo> </mover> </mrow> <mrow> <mi>v</mi> <mi>e</mi> <mi>g</mi> </mrow> <mrow> <mn>0</mn> </mrow> </msubsup> </mrow> </semantics></math> obtained by fitting Equation (1) to the observations. The diamond and cross symbols at 100% canopy density represent the estimate of <span class="html-italic">σ</span><sup>0</sup><span class="html-italic"><sub>veg</sub></span> obtained by compensating for <math display="inline"><semantics> <mrow> <msubsup> <mrow> <mover accent="true"> <mrow> <mi>σ</mi> </mrow> <mo>^</mo> </mover> </mrow> <mrow> <mi>v</mi> <mi>e</mi> <mi>g</mi> </mrow> <mrow> <mn>0</mn> </mrow> </msubsup> </mrow> </semantics></math> for the standard deviation of the observations and the backscatter of dense forests, respectively.</p>
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<p>The standard deviation of the backscatter observations per canopy density level (circles) and linear regression (solid line) for the ALOS-2 PALSAR-2 HH- and HV-polarized backscatter acquired over the Finland N site.</p>
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<p>Measured and modelled VV- and VH-pol. backscatter as a function of GSV for the sites of Catalonia (<b>left panels</b>) and Finland N (<b>right panels</b>) for the Sentinel-1 dataset used in <a href="#remotesensing-16-04079-f003" class="html-fig">Figure 3</a> and <a href="#remotesensing-16-04079-f004" class="html-fig">Figure 4</a>.</p>
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<p>Scatter plots illustrating the estimates of <span class="html-italic">σ</span><sup>0</sup><span class="html-italic"><sub>gr</sub></span> and <span class="html-italic">σ</span><sup>0</sup><span class="html-italic"><sub>veg</sub></span> from training (<span class="html-italic">x</span> axis) and calibration (<span class="html-italic">y</span> axis) for VV- and VH-polarized Sentinel-1 images over the sites of Catalonia and Finland N. The dashed line represents the identity line.</p>
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<p>Measured and modelled ALOS-2 PALSAR-2 HH- and HV-pol. backscatter as a function of GSV grouped for the sites of Catalonia, Finland N, and Finland S.</p>
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<p>Scatter plots illustrating the estimates of <span class="html-italic">σ</span><sup>0</sup><span class="html-italic"><sub>gr</sub></span> and <span class="html-italic">σ</span><sup>0</sup><span class="html-italic"><sub>veg</sub></span> from training (<span class="html-italic">x</span> axis) and calibration (<span class="html-italic">y</span> axis) for HH- and HV-polarized ALOS-2 PALSAR-2 mosaics acquired between 2015 and 2020 over the sites of Catalonia, Finland N, and Finland S. The dashed line represents the identity line.</p>
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<p>The comparison of GSV values estimated from the Sentinel-1 dataset and from field inventory for the sites of Catalonia and Finland N. Crosses refer to individual field plots. Circles represent the median value of the estimated GSV for 10 m<sup>3</sup>/ha large bins of reference GSV. The dashed line represents the identity line.</p>
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<p>GSV estimates from the ALOS-2 PALSAR-2 mosaic of 2018 and the mosaics of 2015–2021 compared to the field inventory values for the site of Finland S. Plot arrangement and notations follow <a href="#remotesensing-16-04079-f013" class="html-fig">Figure 13</a>.</p>
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<p>The comparison of GSV values estimated from three years of ALOS-2 PALSAR-2 mosaics and from field inventory for the sites of Catalonia, Finland N, and Finland S. Plot arrangement and notations follow <a href="#remotesensing-16-04079-f013" class="html-fig">Figure 13</a>.</p>
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<p>Scatter plots comparing the SAR-based and the field-measured GSV for all study sites. Plot arrangement and notations follow <a href="#remotesensing-16-04079-f013" class="html-fig">Figure 13</a>.</p>
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30 pages, 11775 KiB  
Article
Predictive Modelling of Land Cover Changes in the Greater Amanzule Peatlands Using Multi-Source Remote Sensing and Machine Learning Techniques
by Alex Owusu Amoakoh, Paul Aplin, Pedro Rodríguez-Veiga, Cherith Moses, Carolina Peña Alonso, Joaquín A. Cortés, Irene Delgado-Fernandez, Stephen Kankam, Justice Camillus Mensah and Daniel Doku Nii Nortey
Remote Sens. 2024, 16(21), 4013; https://doi.org/10.3390/rs16214013 - 29 Oct 2024
Viewed by 1265
Abstract
The Greater Amanzule Peatlands (GAP) in Ghana is an important biodiversity hotspot facing increasing pressure from anthropogenic land-use activities driven by rapid agricultural plantation expansion, urbanisation, and the burgeoning oil and gas industry. Accurate measurement of how these pressures alter land cover over [...] Read more.
The Greater Amanzule Peatlands (GAP) in Ghana is an important biodiversity hotspot facing increasing pressure from anthropogenic land-use activities driven by rapid agricultural plantation expansion, urbanisation, and the burgeoning oil and gas industry. Accurate measurement of how these pressures alter land cover over time, along with the projection of future changes, is crucial for sustainable management. This study aims to analyse these changes from 2010 to 2020 and predict future scenarios up to 2040 using multi-source remote sensing and machine learning techniques. Optical, radar, and topographical remote sensing data from Landsat-7, Landsat-8, ALOS/PALSAR, and Shuttle Radar Topography Mission derived digital elevation models (DEMs) were integrated to perform land cover change analysis using Random Forest (RF), while Cellular Automata Artificial Neural Networks (CA-ANNs) were employed for predictive modelling. The classification model achieved overall accuracies of 93% in 2010 and 94% in both 2015 and 2020, with weighted F1 scores of 80.0%, 75.8%, and 75.7%, respectively. Validation of the predictive model yielded a Kappa value of 0.70, with an overall accuracy rate of 80%, ensuring reliable spatial predictions of future land cover dynamics. Findings reveal a 12% expansion in peatland cover, equivalent to approximately 6570 ± 308.59 hectares, despite declines in specific peatland types. Concurrently, anthropogenic land uses have increased, evidenced by an 85% rise in rubber plantations (from 30,530 ± 110.96 hectares to 56,617 ± 220.90 hectares) and a 6% reduction in natural forest cover (5965 ± 353.72 hectares). Sparse vegetation, including smallholder farms, decreased by 35% from 45,064 ± 163.79 hectares to 29,424 ± 114.81 hectares. Projections for 2030 and 2040 indicate minimal changes based on current trends; however, they do not consider potential impacts from climate change, large-scale development projects, and demographic shifts, necessitating cautious interpretation. The results highlight areas of stability and vulnerability within the understudied GAP region, offering critical insights for developing targeted conservation strategies. Additionally, the methodological framework, which combines optical, radar, and topographical data with machine learning, provides a robust approach for accurate and detailed landscape-scale monitoring of tropical peatlands that is applicable to other regions facing similar environmental challenges. Full article
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<p>Study area map: (<b>a</b>) agro-ecological zones and the regional administrative boundaries of Ghana; (<b>b</b>) identified patchy peatlands and communities fringing them, as well as the district administrative boundaries in the GAP. Peatland information was obtained from Hen Mpoano’s data repository and is based on participatory GIS and ground truthing approach. Basemap: Google Hybrid, Map data (© 2023 Google).</p>
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<p>Digital elevation model (DEM) of the study area showing the Amanzule, Tano, and Ankobra rivers. The colour gradients represent variations in terrain elevation, with the scale indicating relative heights in meters above sea level (Source: authors’ own creation using SRTM-derived DEM data accessed via Google Earth Engine).</p>
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<p>Workflow for land cover change analysis using multi-sensor data, featuring model building with Random Forest (RF) classification, feature optimisation through Recursive Feature Elimination (RFE), and GIS-based land cover projection.</p>
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<p>Plot of accuracy vs. number of image features.</p>
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<p>Feature importance scores of selected image features following RFE. Original bands, texture, spectral indices, and terrain features were chosen based on the number of features that retained optimal accuracy.</p>
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<p>Land cover changes in the GAP between 2010, 2015, and 2020.</p>
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<p>Land cover maps for GAP from (<b>a</b>) 2010, (<b>b</b>) 2015, and (<b>c</b>) 2020.</p>
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<p>Sankey diagram showing dynamic land cover transitions in the GAP: (<b>a</b>) represents transitions from 2010 to 2015 and (<b>b</b>) depicts changes from 2015 to 2020.</p>
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<p>Early growth stages of replanted mangroves in GAP (Source: Hen Mpoano, [<a href="#B20-remotesensing-16-04013" class="html-bibr">20</a>]).</p>
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18 pages, 4741 KiB  
Article
Estimation of Glacier Outline and Volume Changes in the Vilcanota Range Snow-Capped Mountains, Peru, Using Temporal Series of Landsat and a Combination of Satellite Radar and Aerial LIDAR Images
by Nilton Montoya-Jara, Hildo Loayza, Raymundo Oscar Gutiérrez-Rosales, Marcelo Bueno and Roberto Quiroz
Remote Sens. 2024, 16(20), 3901; https://doi.org/10.3390/rs16203901 - 20 Oct 2024
Viewed by 859
Abstract
The Vilcanota is the second-largest snow-capped mountain range in Peru, featuring 380 individual glaciers, each with its own unique characteristics that must be studied independently. However, few studies have been conducted in the Vilcanota range to monitor and track the area and volume [...] Read more.
The Vilcanota is the second-largest snow-capped mountain range in Peru, featuring 380 individual glaciers, each with its own unique characteristics that must be studied independently. However, few studies have been conducted in the Vilcanota range to monitor and track the area and volume changes of the Suyuparina and Quisoquipina glaciers. Notably, there are only a few studies that have approached this issue using LIDAR technology. Our methodology is based on a combination of optical, radar and LIDAR data sources, which allowed for constructing coherent temporal series for the both the perimeter and volume changes of the Suyuparina and Quisoquipina glaciers while accounting for the uncertainty in the perimeter detection procedure. Our results indicated that, from 1990 to 2013, there was a reduction in snow cover of 12,694.35 m2 per year for Quisoquipina and 16,599.2 m2 per year for Suyuparina. This represents a loss of 12.18% for Quisoquipina and 22.45% for Suyuparina. From 2006 to 2013, the volume of the Quisoquipina glacier decreased from 11.73 km3 in 2006 to 11.04 km3 in 2010, while the Suyuparina glacier decreased from 6.26 km3 to 5.93 km3. Likewise, when analyzing the correlation between glacier area and precipitation, a moderate inverse correlation (R = −0.52, p < 0.05) was found for Quisoquipina. In contrast, the correlation for Suyuparina was low and nonsignificant, showing inconsistency in the effect of precipitation. Additionally, the correlation between the snow cover area and the annual mean air temperature (R = −0.34, p > 0.05) and annual minimum air temperature (R = −0.36, p > 0.05) was low, inverse, and not significant for Quisoquipina. Meanwhile, snow cover on Suyuparina had a low nonsignificant correlation (R = −0.31, p > 0.05) with the annual maximum air temperature, indicating a minimal influence of the measured climatic variables near this glacier on its retreat. In general, it was possible to establish a reduction in both the area and volume of the Suyuparina and Quisoquipina glaciers based on freely accessible remote sensing data. Full article
(This article belongs to the Section Remote Sensing for Geospatial Science)
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<p>An Airborne LIDAR point cloud of 3.2 m spatial resolution was acquired on the Suyuparina and Quisoquipina glaciers in the province of Canchis, Cusco.</p>
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<p>Binarized NDSI images recovered from Landsat 5 images from May 1990 (<b>A</b>) and Landsat 7 from April 2013 (<b>B</b>) for the Suyuparina and Quisoquipina glaciers. In orange and red, the shapefiles of the Suyuparina and Quisoquipina glaciers are delimited by expert criteria.</p>
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<p>Processing scheme. Blue represents inputs, green represents processing, yellow represents intermedium processing, and purple represents outputs.</p>
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<p>(<b>A</b>) Glacierized area of Quisoquipina, and (<b>B</b>) Suyuparina glaciers. In gray is the uncertainty band of the estimated glacier area.</p>
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<p>(<b>Up</b>) Glaciated area of Quisoquipina, and Suyuparina glaciers (<b>Down</b>) analyzed from 1990 to 1999 and from 2000 to 2013.</p>
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<p>(<b>A</b>) Volume changes of the Quisoquipina and (<b>B</b>) Suyuparina glaciers. Confidence intervales to the linear fitted model, shown in gray.</p>
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<p>(<b>A</b>) Glacierized outlines of Suyuparina and Quisoquipina glaciers. (<b>B</b>) Elevation change based on ALOS and LIDAR DEM analysis. Snow glaciological stakes installed between 2014 to 2016 are shown as reference. The background image corresponds to Google Earth 2019.</p>
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<p>Scatterplots of climatic and glacier surface changes. MeanAPE: Mean annual potential evapotranspiration (mm/day), MeanAP: Annual mean precipitation (mm/day), MaxAAT: Max. annual air temperature (°C), MinAAT: Min. annual air temperature (°C), MeanAMAT: Mean annual mean air temperature (°C).</p>
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19 pages, 17901 KiB  
Article
Evaluating ICESat-2 and GEDI with Integrated Landsat-8 and PALSAR-2 for Mapping Tropical Forest Canopy Height
by Aobo Liu, Yating Chen and Xiao Cheng
Remote Sens. 2024, 16(20), 3798; https://doi.org/10.3390/rs16203798 - 12 Oct 2024
Viewed by 1248
Abstract
Mapping forest canopy height is critical for climate modeling and forest management, and tropical forests present unique challenges for remote sensing due to their dense vegetation and complex structure. The advent of ICESat-2 and GEDI, two advanced lidar datasets, offers new opportunities for [...] Read more.
Mapping forest canopy height is critical for climate modeling and forest management, and tropical forests present unique challenges for remote sensing due to their dense vegetation and complex structure. The advent of ICESat-2 and GEDI, two advanced lidar datasets, offers new opportunities for improving canopy height estimation. In this study, we used footprint-level canopy height products from ICESat-2 and GEDI, combined with features extracted from Landsat-8, PALSAR-2, and FABDEM products. The AutoGluon stacking ensemble learning algorithm was employed to construct inversion models, generating 30 m resolution continuous canopy height maps for the tropical forests of Puerto Rico. Accuracy validation was performed using the high-resolution G-LiHT airborne lidar products. Results show that tropical forest canopy height inversion remains challenging, with all models yielding relative root mean square errors (rRMSE) exceeding 0.30. The stacking ensemble model outperformed all base learners, and the GEDI-based map had slightly higher accuracy than the ICESat-2-based map, with RMSE values of 4.81 and 4.99 m, respectively. Both models showed systematic biases, but the GEDI-based model exhibited less underestimation for taller canopies, making it more suitable for biomass estimation. The proposed approach can be applied to other forest ecosystems, enabling fine-resolution canopy height mapping and enhancing forest conservation efforts. Full article
(This article belongs to the Special Issue Machine Learning in Global Change Ecology: Methods and Applications)
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<p>Location and land cover types of the study area.</p>
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<p>Flowchart illustrating the process of generating spatially continuous canopy height maps using publicly accessible data products and the Google Earth Engine cloud platform.</p>
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<p>Comparison of three lidar detection technologies. Adapted from [<a href="#B29-remotesensing-16-03798" class="html-bibr">29</a>].</p>
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<p>Spatial coverage of GEDI, ICESat-2, and G-LiHT data.</p>
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<p>Diagram of the AutoGluon stacking ensemble learning model.</p>
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<p>Accuracy comparison of seven base models and the stacking ensemble model for canopy height inversion using ICESat-2 ATL08 data. (<b>A</b>) random forests, (<b>B</b>) extremely randomized trees, (<b>C</b>) neural networks, (<b>D</b>) XGBoost, (<b>E</b>) LightGBM, (<b>F</b>) CatBoost, (<b>G</b>) k-nearest neighbors, and (<b>H</b>) the stacking ensemble model.</p>
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<p>Accuracy comparison of seven base models and the stacking ensemble model for canopy height inversion using GEDI L2A data. (<b>A</b>) random forests, (<b>B</b>) extremely randomized trees, (<b>C</b>) neural networks, (<b>D</b>) XGBoost, (<b>E</b>) LightGBM, (<b>F</b>) CatBoost, (<b>G</b>) k-nearest neighbors, and (<b>H</b>) the stacking ensemble model.</p>
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<p>Performance comparison of stacking ensemble models based on (<b>A</b>) ICESat-2 and (<b>B</b>) GEDI data, showing predicted vs. observed canopy height, and the corresponding residual distributions for (<b>C</b>) ICESat-2 and (<b>D</b>) GEDI.</p>
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<p>Top ten most important variables for canopy height prediction in stacking ensemble models based on (<b>A</b>) ICESat-2 and (<b>B</b>) GEDI data.</p>
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<p>Three-dimensional terrain and canopy height maps. (<b>A</b>) Terrain elevation map of Puerto Rico; (<b>B</b>) canopy height map based on ICESat-2 data; (<b>C</b>) canopy height map based on GEDI data.</p>
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<p>Residual distribution of predicted canopy heights based on (<b>A</b>) ICESat-2 and (<b>B</b>) GEDI data. The population size of each bin is indicated next to the corresponding box plot.</p>
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<p>Comparison of canopy height distributions estimated from G-LiHT, ICESat-2, and GEDI footprint-level data.</p>
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17 pages, 8248 KiB  
Article
Mapping of Soil Erosion Vulnerability in Wadi Bin Abdullah, Saudi Arabia through RUSLE and Remote Sensing
by Majed Alsaihani and Raied Alharbi
Water 2024, 16(18), 2663; https://doi.org/10.3390/w16182663 - 19 Sep 2024
Cited by 2 | Viewed by 1166
Abstract
This study investigates soil loss in the Wadi Bin Abdullah watershed using the Revised Universal Soil Loss Equation (RUSLE) combined with advanced tools, such as remote sensing and the Geographic Information System (GIS). By leveraging the ALOS PALSAR Digital Elevation Model (DEM), Climate [...] Read more.
This study investigates soil loss in the Wadi Bin Abdullah watershed using the Revised Universal Soil Loss Equation (RUSLE) combined with advanced tools, such as remote sensing and the Geographic Information System (GIS). By leveraging the ALOS PALSAR Digital Elevation Model (DEM), Climate Hazards Group InfraRed Precipitation with Station data (CHIRPS) rainfall data, and the Digital Soil Map of the World (DSMW), the research accurately evaluates soil loss loads. The methodology identifies significant variations in soil loss rates across the entire watershed, with values ranging from 1 to 1189 tons per hectare per year. The classification of soil loss into four stages—very low (0–15 t/ha/yr), low (15–45 t/ha/yr), moderate (45–75 t/ha/yr), and high (>75 t/ha/yr)—provides a nuanced perspective on soil loss dynamics. Notably, 20% of the basin exhibited a soil loss rate of 36 tons per hectare per year. These high rates of soil erosion are attributed to certain factors, such as steep slopes, sparse vegetation cover, and intense rainfall events. These results align with regional and global studies and highlight the impact of topography, land use, and soil properties on soil loss. Moreover, the research emphasizes the importance of integrating empirical soil loss models with modern technological approaches to identify soil loss-prone locations and precisely quantify soil loss rates. These findings provide valuable insights for developing environmental management strategies aimed at mitigating the impacts of soil loss, promoting sustainable land use practices, and supporting resource conservation efforts in arid and semi-arid regions. Full article
(This article belongs to the Section Water Erosion and Sediment Transport)
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<p>Geographic location of the Wadi Bin Abdullah watershed.</p>
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<p>Flowchart depicting the conceptual framework for assessing soil loss retention using the RUSLE Model.</p>
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<p>Illustrates the four maps of Wadi Bin Abdullah. (<b>A</b>) shows the LS factor, (<b>B</b>) shows the R factor, (<b>C</b>) is the K factor map, and (<b>D</b>) shows the land cover land use.</p>
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<p>Illustrates the Total soil loss of Wadi Bin Abdullah.</p>
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<p>Illustrates the soil loss classification.</p>
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22 pages, 12863 KiB  
Article
Remote and Proximal Sensors Data Fusion: Digital Twins in Irrigation Management Zoning
by Hugo Rodrigues, Marcos B. Ceddia, Wagner Tassinari, Gustavo M. Vasques, Ziany N. Brandão, João P. S. Morais, Ronaldo P. Oliveira, Matheus L. Neves and Sílvio R. L. Tavares
Sensors 2024, 24(17), 5742; https://doi.org/10.3390/s24175742 - 4 Sep 2024
Viewed by 737
Abstract
The scientific field of precision agriculture employs increasingly innovative techniques to optimize inputs, maximize profitability, and reduce environmental impact. However, obtaining a high number of soil samples is challenging in order to make precision agriculture viable. There is a trade-off between the amount [...] Read more.
The scientific field of precision agriculture employs increasingly innovative techniques to optimize inputs, maximize profitability, and reduce environmental impact. However, obtaining a high number of soil samples is challenging in order to make precision agriculture viable. There is a trade-off between the amount of data needed and the time and resources spent to obtain these data compared to the accuracy of the maps produced with more or fewer points. In the present study, the research was based on an exhaustive dataset of apparent electrical conductivity (aEC) containing 3906 points distributed along 26 transects with spacing between each of up to 40 m, measured by the proximal soil sensor EM38-MK2, for a grain-producing area of 72 ha in São Paulo, Brazil. A second sparse dataset was simulated, showing only four transects with a 400 m distance and, in the end, only 162 aEC points. The aEC map via ordinary kriging (OK) from the grid with 26 transects was considered the reference, and two other mapping approaches were used to map aEC via sparse grid: kriging with external drift (KED) and geographically weighted regression (GWR). These last two methods allow the increment of auxiliary variables, such as those obtained by remote sensors that present spatial resolution compatible with the pivot scale, such as data from the Landsat-8, Aster, and Sentinel-2 satellites, as well as ten terrain covariates derived from the Alos Palsar digital elevation model. The KED method, when used with the sparse dataset, showed a relatively good fit to the aEC data (R2 = 0.78), with moderate prediction accuracy (MAE = 1.26, RMSE = 1.62) and reasonable predictability (RPD = 1.76), outperforming the GWR method, which had the weakest performance (R2 = 0.57, MAE = 1.78, RMSE = 2.30, RPD = 0.81). The reference aEC map using the exhaustive dataset and OK showed the highest accuracy with an R2 of 0.97, no systematic bias (ME = 0), and excellent precision (RMSE = 0.56, RPD = 5.86). Management zones (MZs) derived from these maps were validated using soil texture data from clay samples measured at 0–10 cm depth in a grid of 72 points. The KED method demonstrated the highest potential for accurately defining MZs for irrigation, producing a map that closely resembled the reference MZ map, thereby providing reliable guidance for irrigation management. Full article
(This article belongs to the Special Issue Sensors and Artificial Intelligence in Smart Agriculture)
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<p>Flowchart of the methodology of simulation of the aEC dataset with sparse sampling and the mapping methods followed by the management zones approach.</p>
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<p>Location of the study area with the height gradient and digital elevation model.</p>
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<p>(<b>A</b>) EM38-MK2 being calibrated to the specific magnetic scenario of the field; (<b>B</b>) the sensor is paired with the handheld controller to set the timing acquisition.</p>
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<p>Study area with digital elevation model in the background; Exhaustive Grid and Sparse Grid showing the distance between sampling lines; external validation dataset.</p>
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<p>Remote sensing covariates used as predictors in the kriging with external drift and geographically weighted regression.</p>
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<p>(<b>A</b>) Soil sampling of 0–10 cm using soil sampler ring; (<b>B</b>) planting area covered by beans and irrigated by a central pivot on the background.</p>
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<p>Electrical conductivity data in mS/m (millisiemens per meter); (<b>A</b>) original format; (<b>B</b>) transformed to Neperian logarithm.</p>
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<p>Predicted versus experimental aEC values of proximal sensor data as a function of remote sensor data using the training dataset. The continuous black lines adjust the intercept and slope for the models, while the dashed lines are intercepted and idealized as 1 and 0, respectively. R<sup>2</sup> adj: R<sup>2</sup> adjusted value; aEC: apparent electrical conductivity in mS/m (millisiemens per meter).</p>
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<p>Empirical (circles) and adjusted (lines) semivariograms of apparent electrical conductivity (aEC) in mS/m. (<b>A</b>) Using ordinary kriging with 26 lines (reference); (<b>B</b>) using ordinary kriging with four rows (sparse); (<b>C</b>) using kriging with external drift of aEC data with sparse data as a function of remote sensor data defined in <a href="#sec3dot5-sensors-24-05742" class="html-sec">Section 3.5</a>; (<b>D</b>) using geographically weighted regression with sparse data as a function of remote sensor data defined in <a href="#sec3dot5-sensors-24-05742" class="html-sec">Section 3.5</a>; (<b>E</b>) semivariogram of the R<sup>2</sup> indices obtained by calculating the GWR for spatialization.</p>
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<p>Maps of apparent electrical conductivity (aEC) in mS/m. (<b>A</b>) Using ordinary kriging with 26 lines (reference); (<b>B</b>) using ordinary kriging with four rows (sparse); (<b>C</b>) using kriging with external drift of the sparse data as a function of the remote sensing data defined in <a href="#sec3dot5-sensors-24-05742" class="html-sec">Section 3.5</a>; (<b>D</b>) using geographically weighted regression with sparse data as a function of remote sensor data defined in <a href="#sec3dot5-sensors-24-05742" class="html-sec">Section 3.5</a>; (<b>E</b>) map of the adjusted R<sup>2</sup> obtained by calculating the GWR for the aEC sparse dataset.</p>
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<p>Maps of apparent electrical conductivity (aEC) in mS/m. (<b>A</b>) Using ordinary kriging with 26 lines (reference); (<b>B</b>) using ordinary kriging with four rows (sparse); (<b>C</b>) using kriging with external drift of the sparse data as a function of the remote sensing data defined in <a href="#sec3dot5-sensors-24-05742" class="html-sec">Section 3.5</a>; (<b>D</b>) using geographically weighted regression with sparse data as a function of remote sensor data defined in <a href="#sec3dot5-sensors-24-05742" class="html-sec">Section 3.5</a>; (<b>E</b>) map of the adjusted R<sup>2</sup> obtained by calculating the GWR for the aEC sparse dataset.</p>
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<p>Maps of management zones for soil types. (<b>A</b>) Using ordinary kriging with 26 lines (reference); (<b>B</b>) using ordinary kriging with four rows (sparse); (<b>C</b>) using kriging with external drift of the sparse aEC data as a function of the remote sensing data defined in <a href="#sec2dot6dot2-sensors-24-05742" class="html-sec">Section 2.6.2</a>; (<b>D</b>) using geographically weighted regression with sparse data as a function of remote sensor data defined in <a href="#sec2dot6dot3-sensors-24-05742" class="html-sec">Section 2.6.3</a>.</p>
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29 pages, 38452 KiB  
Article
Integration of Multi-Source Datasets for Assessing Ground Swelling/Shrinking Risk in Cyprus: The Case Studies of Pyrgos–Parekklisia and Moni
by Athanasios V. Argyriou, Maria Prodromou, Christos Theocharidis, Kyriaki Fotiou, Stavroula Alatza, Constantinos Loupasakis, Zampela Pittaki-Chrysodonta, Charalampos Kontoes, Diofantos G. Hadjimitsis and Marios Tzouvaras
Remote Sens. 2024, 16(17), 3185; https://doi.org/10.3390/rs16173185 - 28 Aug 2024
Viewed by 1056
Abstract
The determination of swelling/shrinking phenomena, from natural and anthropogenic activity, is examined in this study through the synergy of various remote sensing methodologies. For the period of 2016–2022, a time-series InSAR analysis of Sentinel-1 satellite images, with a Coherent Change Detection procedure, was [...] Read more.
The determination of swelling/shrinking phenomena, from natural and anthropogenic activity, is examined in this study through the synergy of various remote sensing methodologies. For the period of 2016–2022, a time-series InSAR analysis of Sentinel-1 satellite images, with a Coherent Change Detection procedure, was conducted to calculate the Normalized Coherence Difference. These were combined with Sentinel-2 multispectral data by exploiting the Normalized Difference Vegetation Index to create multi-temporal image composites. In addition, ALOS-Palsar DEM derivatives highlighted the geomorphological characteristics, which, in conjunction with the satellite imagery outcomes and other auxiliary spatial datasets, were embedded within a Multi-Criteria Decision Analysis (MCDA) model. The synergy of the remote sensing and GIS techniques’ applicability within the MCDA model highlighted the zones undergoing seasonal swelling/shrinking processes in Pyrgos–Parekklisia and Moni regions in Cyprus. The accuracy assessment of the produced final MCDA outcome provided an overall accuracy of 72.4%, with the Kappa statistic being 0.66, indicating substantial agreement of the MCDA outcome with the results from a Persistent Scatterer Interferometry analysis and ground-truth observations. Thus, this study offers decision-makers a powerful procedure to monitor longer- and shorter-term swelling/shrinking phenomena. Full article
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Graphical abstract
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<p>The Pyrgos–Parekklisia, Moni, and Monagroulli deforming sites in Limassol, Cyprus.</p>
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<p>The Pyrgos Lemesou–Parekklisia and Moni–Monagroulli geology.</p>
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<p>Sentinel-1 satellite passes in ascending and descending tracks and satellite image details.</p>
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<p>The Coherent Change Detection workflow methodology. The step that provides the coherence values is marked in red.</p>
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<p>Pyrgos–Parekklisia area. (<b>a</b>) Coherence difference and (<b>b</b>) Normalized Coherence difference from descending Sentinel-1 satellite images during 12 February 2021–8 March 2021. (<b>c</b>) Coherence difference and (<b>d</b>) Normalized Coherence difference from ascending Sentinel-1 satellite images during 23 February 2021–7 March 2021.</p>
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<p>Moni–Monagroulli area. (<b>a</b>) Coherence difference and (<b>b</b>) Normalized Coherence difference from descending Sentinel-1 satellite images during 12 February 2021–8 March 2021. (<b>c</b>) Coherence difference and (<b>d</b>) Normalized Coherence difference from ascending Sentinel-1 satellite images during 23 February 2021–7 March 2021.</p>
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<p>Annual NDVI variations and corresponding masked areas excluded from further analysis.</p>
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<p>CCD of the Area of Interest showing the changes that occurred between 2016 and 2022.</p>
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<p>The TWI with dark bluish hues highlighting the high moisture accumulation.</p>
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<p>Landform type classification, showing valleys, semi-mountainous, and mountainous zones.</p>
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<p>The determined precipitation derived from the weather stations.</p>
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<p>The soil texture map of the AoI.</p>
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<p>The reclassified soil texture map, highlighting the degree of the swelling/shrinking effect.</p>
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<p>The reclassified hydrogeological map highlights the swelling degree.</p>
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<p>The GIS-based MCDA swelling and shrinking effect outcome based on the acknowledged variables of CCD, soil texture, hydrogeology, TWI, landforms, and rainfall. High-risk zones are presented in orange and very high-risk zones in red.</p>
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<p>(<b>a</b>) Sentinel-1 LoS displacements in Pyrgos–Parekklisia for descending satellite pass and (<b>b</b>) interpolated Sentinel-1 LOS displacements in Pyrgos–Parekklisia for descending satellite pass.</p>
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<p>The MCDA swelling and shrinking effect outcome with the overlaid ground-truth locations with verified deformed structures, indicated with red arrows, from ground-truth surveys.</p>
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<p>The distribution of the accuracy assessment points across the final MCDA swelling/shrinking effect outcome.</p>
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19 pages, 9326 KiB  
Article
Retrospect on the Ground Deformation Process and Potential Triggering Mechanism of the Traditional Steel Production Base in Laiwu with ALOS PALSAR and Sentinel-1 SAR Sensors
by Chao Ding, Guangcai Feng, Lu Zhang and Wenxin Wang
Sensors 2024, 24(15), 4872; https://doi.org/10.3390/s24154872 - 26 Jul 2024
Cited by 1 | Viewed by 874
Abstract
The realization of a harmonious relationship between the natural environment and economic development has always been the unremitting pursuit of traditional mineral resource-based cities. With rich reserves of iron and coal ore resources, Laiwu has become an important steel production base in Shandong [...] Read more.
The realization of a harmonious relationship between the natural environment and economic development has always been the unremitting pursuit of traditional mineral resource-based cities. With rich reserves of iron and coal ore resources, Laiwu has become an important steel production base in Shandong Province in China, after several decades of industrial development. However, some serious environmental problems have occurred with the quick development of local steel industries, with ground subsidence and consequent secondary disasters as the most representative ones. To better evaluate possible ground collapse risk, comprehensive approaches incorporating the common deformation monitoring with small-baseline subset (SBAS)-synthetic aperture radar interferometry (InSAR) technique, environmental factors analysis, and risk evaluation are designed here with ALOS PALSAR and Sentinel-1 SAR observations. A retrospect on the ground deformation process indicates that ground deformation has largely decreased by around 51.57% in area but increased on average by around −5.4 mm/year in magnitude over the observation period of Sentinel-1 (30 July 2015 to 22 August 2022), compared to that of ALOS PALSAR (17 January 2007 to 28 October 2010). To better reveal the potential triggering mechanism, environmental factors are also utilized and conjointly analyzed with the ground deformation time series. These analysis results indicate that the ground deformation signals are highly correlated with human industrial activities, such underground mining, and the operation of manual infrastructures (landfill, tailing pond, and so on). In addition, the evaluation demonstrates that the area with potential collapse risk (levels of medium, high, and extremely high) occupies around 8.19 km2, approximately 0.86% of the whole study region. This study sheds a bright light on the safety guarantee for the industrial operation and the ecologically friendly urban development of traditional steel production industrial cities in China. Full article
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<p>The geographical background of the study area in Laiwu, in which the image coverages for ALOS PALSAR and Sentinel-1 are contoured with blue and cyan polylines, respectively. The background image of this study region is the topographic map. Notably, indicated by the magenta dots, 15 test points coded from A to O are located at Yujiaquan tailing pond (A, B, C, D), the iron ore mining region (E, F, G, H, I), the banksides of the Dawen River (J, K, L), and the coal mining region (M, N, O).</p>
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<p>Diagram of the methodology utilized for retrieving the ground deformation process, analyzing the potential triggering mechanisms, and evaluating the possible subsidence risks.</p>
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<p>(<b>a</b>) ALOS PALSAR (17 January 2007~28 October 2010) and (<b>b</b>) Sentinel-1 (30 July 2015~22 August 2022) derived light-of-sight (LOS) deformation velocities (mm/year).</p>
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<p>The identified LOS deformation region covered by green points for (<b>a</b>) ALOS PALSAR observations from 17 January 2007 to 28 October 2010, and (<b>b</b>) Sentinel-1 observations from 30 July 2015 to 22 August 2022.</p>
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<p>The LOS deformation velocities of the region near the banksides of the Dawen River derived from (<b>a</b>) ALOS PALSAR observations (17 January 2007~28 October 2010) and (<b>b</b>) Sentinel-1 observations (30 July 2015~22 August 2022). Notably, indicated by the magenta dots, 4 test points coded from J, K, L and M are located at the banksides of the Dawen River (J, K, L) and the coal mining region (M).</p>
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<p>The LOS deformation velocities of the Yujiaquan tailing pond derived from (<b>a</b>) ALOS PALSAR observations (17 January 2007~28 October 2010) and (<b>b</b>) Sentinel-1 observations (30 July 2015~22 August 2022). Notably, indicated by the magenta dots, 4 test points coded from A, B, C and D are located at Yujiaquan tailing pond.</p>
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<p>The LOS deformation velocities of the Yaojialing iron ore-mining region derived from (<b>a</b>) ALOS PALSAR observations (17 January 2007~28 October 2010) and (<b>b</b>) Sentinel-1 observations (30 July 2015~22 August 2022). Notably, the magenta point of I indicates the location of Yaojialing iron ore-mining region.</p>
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<p>The LOS deformation velocities of the newly constructed landfill for industrial wastes derived from (<b>a</b>) ALOS PALSAR observations (17 January 2007~28 October 2010) and (<b>b</b>) Sentinel-1 observations (30 July 2015~22 August 2022). Notably, with the location indicated by the magenta point of H, this landfill was constructed from July 2019 to December 2019.</p>
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<p>The time-series LOS deformation for test points of (<b>a</b>–<b>i</b>), in which A, B, C, and D are located on the banksides of the Yujiaquan tailing pond; E, F, and G are located in the traditional Luzhong iron ore-mining region; H is located in a newly constructed landfill for industrial wastes; I is located in the Yaojialing iron ore-mining region. In addition, the LOS deformation time series of J, K, L, M, N, and O can be found in <a href="#app1-sensors-24-04872" class="html-app">Figures S1–S6</a>. The environmental factors incorporating the daily precipitation, the cumulative precipitation, and the earthquake events, are cross-compared to the deformation time series derived from ALOS PALSAR and Sentinel-1 SAR observations.</p>
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<p>The time-series LOS deformation for test points of (<b>a</b>–<b>i</b>), in which A, B, C, and D are located on the banksides of the Yujiaquan tailing pond; E, F, and G are located in the traditional Luzhong iron ore-mining region; H is located in a newly constructed landfill for industrial wastes; I is located in the Yaojialing iron ore-mining region. In addition, the LOS deformation time series of J, K, L, M, N, and O can be found in <a href="#app1-sensors-24-04872" class="html-app">Figures S1–S6</a>. The environmental factors incorporating the daily precipitation, the cumulative precipitation, and the earthquake events, are cross-compared to the deformation time series derived from ALOS PALSAR and Sentinel-1 SAR observations.</p>
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<p>The time-series LOS deformation for test points of (<b>a</b>–<b>i</b>), in which A, B, C, and D are located on the banksides of the Yujiaquan tailing pond; E, F, and G are located in the traditional Luzhong iron ore-mining region; H is located in a newly constructed landfill for industrial wastes; I is located in the Yaojialing iron ore-mining region. In addition, the LOS deformation time series of J, K, L, M, N, and O can be found in <a href="#app1-sensors-24-04872" class="html-app">Figures S1–S6</a>. The environmental factors incorporating the daily precipitation, the cumulative precipitation, and the earthquake events, are cross-compared to the deformation time series derived from ALOS PALSAR and Sentinel-1 SAR observations.</p>
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<p>The time-series LOS deformation for test points of (<b>a</b>–<b>i</b>), in which A, B, C, and D are located on the banksides of the Yujiaquan tailing pond; E, F, and G are located in the traditional Luzhong iron ore-mining region; H is located in a newly constructed landfill for industrial wastes; I is located in the Yaojialing iron ore-mining region. In addition, the LOS deformation time series of J, K, L, M, N, and O can be found in <a href="#app1-sensors-24-04872" class="html-app">Figures S1–S6</a>. The environmental factors incorporating the daily precipitation, the cumulative precipitation, and the earthquake events, are cross-compared to the deformation time series derived from ALOS PALSAR and Sentinel-1 SAR observations.</p>
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<p>(<b>a</b>) The risk level map and (<b>b</b>) corresponding statistical pie chart of the traditional steel production base in Laiwu.</p>
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<p>(<b>a</b>) The risk level map and (<b>b</b>) corresponding statistical pie chart of the traditional steel production base in Laiwu.</p>
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