Topographic Analysis of Intertidal Polychaete Reefs (Sabellaria alveolata) at a Very High Spatial Resolution

In temperate coastal regions of Western Europe, the polychaete Sabellaria alveolata (Linné) builds large intertidal reefs of several hectares on soft-bottom substrates. These reefs are protected by the European Habitat Directive EEC/92/43 under the status of biogenic structures hosting a high biodiversity and providing ecological functions such as protection against coastal erosion. As an alternative to time-consuming field campaigns, a UAV-based Structure-from-Motion photogrammetric survey was carried out in October 2020 over Noirmoutier Island (France) where the second-largest known European reef is located in a tidal delta. A DJI Phantom 4 Multispectral UAV provided a topographic dataset at very high resolutions of 5 cm/pixel for the Digital Surface Model (DSM) and 2.63 cm/pixel for the multispectral orthomosaic images. The reef footprint was mapped using a combination of two topographic indices: the Topographic Openness Index and the Topographic Position Index. The reef structures covered an area of 8.15 ha, with 89% corresponding to the main reef composed of connected and continuous biogenic structures, 7.6% of large isolated structures (<60 m2), and 4.4% of small isolated reef clumps (<2 m2). To further describe the topographic complexity of the reef, the Geomorphon landform classification was used. The spatial distribution of tabular platforms considered as a healthy stage of the reef in contrast to a degraded stage was mapped with a proxy that consists in comparing the reef volume to a theoretical tabular-shaped reef volume. Epibionts colonizing the reef (macroalgae, mussels, and oysters) were also mapped by combining multispectral indices such as the Normalised Difference Vegetation Index and simple band ratios with topographic indices. A confusion matrix showed that macroalgae and mussels were satisfactorily identified but that oysters could not be detected by an automated procedure due to their spectral complexity. The topographic indices used in this work should now be further exploited to propose a health index for these large intertidal reefs.

Evolution of Surface Drainage Network for Spoil Heaps under Simulated Rainfall

Spoil heaps laid from the infrastructure building sites or the mining sites are confoundedly prone to accelerated soil erosion and inducing debris flows on extreme rainfall occasion, thus threatening water quality and personal safety. In present study, the roughness and drainage network evolution of the loess spoil heap (a 33° slope gradient) were investigated via indoor simulation experiment under three rainfall intensities (60, 90, and 120 mm/h). A detailed scan of the slope using laser scanner, topographic analysis based on ArcGIS software, and statistical analyses were the main methods utilized in the study. The results showed that surface roughness increased with cumulative rainfall. For three rainfall intensity treatments, the proneness of shallow landslide under 90 mm/h intensity resulted in the largest roughness. The drainage density and stream frequency of the spoil heap slope both decreased with cumulative rainfall and negatively correlated with surface roughness, which indicated the convergence of the drainage network. Meanwhile, the individual flow paths presented an increasing sinuosity and a decreasing gradient with cumulative rainfall. However, drainage network features varied in a less marked degree during different rainfall intensities, showing comparable fractal dimensions of 1.350–1.454, 1.305–1.459, and 1.292–1.455 for the three rainfall intensities. Evaluating the response of four hydrodynamic characteristics of runoff to the drainage network evolution, stream power was found to be most sensitive. The linearity of the relationships between stream power and drainage density and that between stream sinuosity and gradient were estimated to have R2 between 0.961 and 0.979.

The Spatiotemporal Relationship between Landslides and Mechanisms at the Heifangtai Terrace, Northwest China

Landslide disasters have occurred frequently in the Chinese Loess Plateau (CLP) due to increased agricultural irrigation. To explore the spatiotemporal relationship between landslides and mechanisms at the Heifangtai terrace, the HFT irrigated area was selected as a typical case study to investigate the fundamental mechanism of the irrigation-induced landslide in the CLP. Multi-temporal remote sensing images, topographic maps, and unmanned aerial vehicle (UAV) photogrammetry data were used to investigate the evolution progress of landslides. Moreover, the evolution mechanism was discussed through topographic analysis, field monitoring, and laboratory testing. The results showed that erosion, collapse, and sliding had occurred at different scales and at different locations in the past 50 years. With an average retrogressive speed of 9.6 × 103 m2 per year, the tableland decreased by 4.9 × 105 m2 from 1967 to 2018, accounting for about 4.5% of its total area. Over 20 landslides and collapses were extracted in the Dangchuan section in the past four years. More than 5.48 × 105 m3 of loess slipped with an average volume of 381 m3 per day. The evolutionary process of the irrigation-induced landslide, which features retrogression, lateral extension, and clustering, began with local failure and ended in a series of slidings. The increase of groundwater level was a slow process, which is the reason for the lagged occurrence of the landslide. The influence of rainfall and irrigation on slope stability was greater than that of the periodic change of the groundwater level. The triggering effect of irrigation and rainfall on the landslide had a time lag due to slow loess infiltration, and the time response among irrigation, rainfall, and groundwater level was 4–6 months. Our findings provide guidance, concerning the planning and controlling of landslide disasters, which is of critical value for human and construction safety.

Topographic Analysis of Low-Grade Myeloid Neoplasms By Multiparametric in Situ Imaging of Human Bone Marrow Core Biopsy Tissues

Diagnosis of low-grade myelodysplastic syndromes (LG-MDS) is one of the most challenging in hematopathology as it relies predominantly on morphologic assessment of dysplasia. Prior studies have demonstrated poor interobserver agreement among pathologists. Histomorphological evaluation of bone marrow core biopsy samples remains the gold standard for diagnostic workup of LG-MDS, including myelodysplastic syndromes (MDS) and other myeloid neoplasms. However, this approach may be subjective, and cannot quantitatively assess subtle differences in marrow topography and the cellular microenvironment. Multiparametric in situ imaging (MISI) through various techniques enables multiple biomarker detection in a single tissue. BostonGene has developed an AI-based image analysis platform to reveal spatial information and subtle histomorphologic features in an objective, quantitative fashion. Here, we demonstrate the potential for automated AI-based imaging analysis of MISI to assist in the differentiation of LG-MDS samples from normal marrow tissues (NBM). Decalcified human bone marrow core biopsy tissues from LG-MDS (n=6) and uninvolved staging marrows (NBM, n=4) were first prepared by immunofluorescence-based MISI via staining with DAPI and CD34, CD38, CD117, CD71, CD15, and CD61 antibodies. BostonGene analyzed the resulting images (fig.1) using a proprietary AI-based imaging platform to identify cells by segmentation performed with the pre-trained instance segmentation neural network. Cell types were identified with mean marker expression values using an accelerated version of BostonGene's phenograph clustering algorithm. Pathologists manually masked fat and bone trabeculae. Using a combination of cell size/shape parameters and antigen expression levels, the following unique cell types were identified: myeloblasts, proerythroblasts, erythroid normoblasts, maturing granulocytes, megakaryocytes, mast cells, plasma cells, and B-cell precursors (hematogones). Data revealed differences in the cellular content of NBM and LG-MDS samples, and separation of LG-MDS samples with the del(5q) subtype (n=2). While linear slender islet-like small clusters of erythroid normoblasts were detected in NBM, we observed a chaotic arrangement of them in LG-MDS samples. In LG-MDS samples, we found an increase in the total number of erythroid normoblasts from 17% to 31%, LG-MDS-del(5q) had 14%. The ratio of maturing granulocytes to erythroid normoblasts (M:E ratio) was significantly lower in LG-MDS (0.63) than in NBM (1.95). The M:E ratio generated by MISI strongly correlated to the M:E ratio produced by manual differential count of bone marrow aspirate samples (R=0.83, p &lt; 0.003). Additionally, fewer hematogones were identified in LG-MDS marrows compared to NBM samples, as reported by others using orthogonal methods. Topographic analysis showed the fat to cellular tissue area ratio was higher in NBM (0.73) than LG-MDS (0.41), but the ratio of trabecular area to total tissue area was higher in LG-MDS (1.67) than NMB (0.74). Spatially, myeloblasts and megakaryocytes were found closer to trabeculae in NBM than LG-MDS;12 different cell communities were identified;2 of them (cluster 3 - erythroid normoblasts enriched, cluster 5 - erythroid normoblasts contacting proerythroblasts) were distributed statistically significantly differently in NBM and LG-MDS samples, indicating the use of MISI with AI-based imaging to distinguish LG-MDS from NBM. Patients of MDS-del(5q) subtype differ significantly from other MDS samples and are more similar to NBM. AI-based image analysis applied to MISI of bone marrow tissue revealed multiple cell types in single tissue sections, along with histologically subtle differences in topography between NBM and LG-MDS samples. These results highlight the importance of integrating in situ tissue analysis with techniques that examine single cell characteristics for a more comprehensive picture of the differences between normal tissue and tumor samples. Coupling sophisticated imaging analytics with this imaging method may provide a more powerful tool for novel biomarker discovery of prognostic and therapeutic significance in the management of MDS and other marrow-based disorders. Figure 1 Figure 1. Disclosures Svekolkin: BostonGene Corp.: Current Employment, Current holder of stock options in a privately-held company, Patents & Royalties. Varlamova: BostonGene Corp.: Current Employment, Current holder of stock options in a privately-held company, Patents & Royalties. Galkin: BostonGene Corp.: Current Employment, Current holder of stock options in a privately-held company, Patents & Royalties. Akaeva: BostonGene Corp.: Current Employment, Current holder of stock options in a privately-held company, Patents & Royalties. Smirnova: BostonGene Corp.: Current Employment, Current holder of stock options in a privately-held company, Patents & Royalties. Ovcharov: BostonGene Corp.: Current Employment, Current holder of stock options in a privately-held company, Patents & Royalties. Polyakova: BostonGene Corp.: Current Employment, Current holder of stock options in a privately-held company, Patents & Royalties. Tabakov: BostonGene Corp.: Current Employment, Current holder of stock options in a privately-held company. Postovalova: BostonGene Corp.: Current Employment, Current holder of stock options in a privately-held company, Patents & Royalties: BostonGene. Koltakova: BostonGene Corp.: Current Employment, Current holder of stock options in a privately-held company. Gunn: BostonGene Corp.: Current Employment, Current holder of stock options in a privately-held company. Bagaev: BostonGene Corp.: Current Employment, Current holder of stock options in a privately-held company, Patents & Royalties: BostonGene.

Spatiotemporal dynamics of encroaching tall vegetation in timberline ecotone of the Polar Urals region, Russia

Previous studies discovered a spatially heterogeneous expansion of Siberian larch into the tundra of the Polar Urals (Russia). This study reveals that the spatial pattern of encroachment of tree stands is related to environmental factors including topography and snow cover. Structural and allometric characteristics of trees, along with terrain elevation and snow depth were collected along a transect 860 m long and 80 m wide. Terrain curvature indices, as representative properties, were derived across a range of scales in order to characterize microtopography. A density-based clustering method was used here to analyze the spatial and temporal patterns of tree stems distribution. Results of the topographic analysis suggest that trees tend to cluster in areas with convex surface. The clustering analysis also indicates that the patterns of tree locations are linked to snow distribution. Records from the earliest campaign in 1960 show that trees lived mainly at the middle and bottom of the transect across the areas of high snow depth. As trees expanded uphill with a warming climate in recent decades, the high snow depth areas also shifted upward creating favorable conditions for recent trees growth at locations that were previously covered with heavy snow. The identified landscape signatures of increasing above-ground Arctic biomass in terms of tall vegetation can facilitate scaling to larger area regions.

Spatiotemporal Rates of Tectonic Deformation and Landscape Evolution above a Laterally Propagating Thrust Fault: Wheeler Ridge Anticline, California, USA

The Wheeler Ridge anticline, located in the southern San Joaquin Valley of California, USA, is a well-studied and classic example of a laterally growing fault propagation fold. New high-resolution lidar elevation data combined with nine infrared stimulated luminescence (IRSL) ages of discrete geomorphic surfaces that are bounded by prominent transverse wind and river gaps allow for investigation of tectonic topography through time. Luminescence ages from four of the six surfaces yield depositional ages that range from 32 ka to 153 ka, which are broadly consistent with a previously published soil chronosequence. Our graphical modeling indicates an average surface uplift rate of ~2.1 mm/yr and an average along-strike fold propagation rate of ~20 mm/yr. However, our probabilistic modelling and topographic analysis suggest a rate decrease of both uplift and lateral propagation toward the fault tip from ~2.4 to 0.7 mm/yr and from ~49 to 14 mm/yr, respectively. Rate decreases are not progressive but rather occur in punctuated deformational intervals across previously documented structural barriers (tear faults) resulting in a fold that is characterized by discrete segments that exhibit a systematic deformational decrease toward the east. The punctuated tectonic growth of Wheeler Ridge has also locally controlled the topographic evolution of the anticline by effecting the formational timing and position of at least seven wind and river gaps that result from multiple north-flowing antecedent streams that traverse the growing structure. We quantify the timing of wind and river gap formation, based on IRSL results and inferred incision rates, and present a model for the spatiotemporal evolution of transverse drainages and the topographic development of Wheeler Ridge. Our chronology of gap formation broadly correlates with regional Late Pleistocene dry climate intervals suggesting that both tectonics and climate were integral to the geomorphic development of the Wheeler Ridge anticline.

Beyond Vertical Point Accuracy: Assessing Inter-pixel Consistency in 30 m Global DEMs for the Arid Central Andes

Quantitative geomorphic research depends on accurate topographic data often collected via remote sensing. Lidar, and photogrammetric methods like structure-from-motion, provide the highest quality data for generating digital elevation models (DEMs). Unfortunately, these data are restricted to relatively small areas, and may be expensive or time-consuming to collect. Global and near-global DEMs with 1 arcsec (∼30 m) ground sampling from spaceborne radar and optical sensors offer an alternative gridded, continuous surface at the cost of resolution and accuracy. Accuracy is typically defined with respect to external datasets, often, but not always, in the form of point or profile measurements from sources like differential Global Navigation Satellite System (GNSS), spaceborne lidar (e.g., ICESat), and other geodetic measurements. Vertical point or profile accuracy metrics can miss the pixel-to-pixel variability (sometimes called DEM noise) that is unrelated to true topographic signal, but rather sensor-, orbital-, and/or processing-related artifacts. This is most concerning in selecting a DEM for geomorphic analysis, as this variability can affect derivatives of elevation (e.g., slope and curvature) and impact flow routing. We use (near) global DEMs at 1 arcsec resolution (SRTM, ASTER, ALOS, TanDEM-X, and the recently released Copernicus) and develop new internal accuracy metrics to assess inter-pixel variability without reference data. Our study area is in the arid, steep Central Andes, and is nearly vegetation-free, creating ideal conditions for remote sensing of the bare-earth surface. We use a novel hillshade-filtering approach to detrend long-wavelength topographic signals and accentuate short-wavelength variability. Fourier transformations of the spatial signal to the frequency domain allows us to quantify: 1) artifacts in the un-projected 1 arcsec DEMs at wavelengths greater than the Nyquist (twice the nominal resolution, so &gt; 2 arcsec); and 2) the relative variance of adjacent pixels in DEMs resampled to 30-m resolution (UTM projected). We translate results into their impact on hillslope and channel slope calculations, and we highlight the quality of the five DEMs. We find that the Copernicus DEM, which is based on a carefully edited commercial version of the TanDEM-X, provides the highest quality landscape representation, and should become the preferred DEM for topographic analysis in areas without sufficient coverage of higher-quality local DEMs.

The Seat of the Roman Governor at Carnuntum (Pannonia Superior)

The Roman site of Carnuntum was once a flourishing center on the frontiers of the Roman Empire. In its heyday as the capital of the province of Pannonia superior, Carnuntum probably covered an area of almost 9 km². The whole site was divided into a military settlement (castra and canabae legionis) and a civil town (municipium/colonia). Through a large-scale archaeological prospection project, this huge area could be investigated and analyzed in great detail using a wide variety of nondestructive prospection methods. One of the main discoveries of the project was observed in the military settlement, where it was possible to identify a previously unknown military camp, interpreted as the garrison of the governor’s guard, the castra singularium. Through the topographic analysis of the immediate surroundings, the Roman fort was determined to be embedded in a large administrative complex related to the governor’s seat in Carnuntum. This article presents these new discoveries and shows what an important part they formed in the administration of the Roman province of Upper Pannonia.

Agricultural suitability assessment and rehabilitation of subsided coal mines: a case study of the Dawu coal mine in Jiangsu, Eastern China

Land-use suitability assessment crucial is for coal mine rehabilitation planning, especially for the coal mines that have undergone varying degrees of mining subsidence. In this study, we present an assessment on the suitability of crop cultivation in the Dawu coal mining district in NW Jiangsu province, Eastern China. Distribution of local land subsidence is delineated with topographic analysis, and the weight-of-evidence (WoE) suitability assessment has encompassed various factors including the conditions of soil (e.g., acidity and porosity), groundwater level, irrigation and drainage, terrain slope, and land pollution. Consequently, the Dawu district is divided into four categories (high, moderate, low, very-low) of agricultural suitability. Collaborating with the local government agencies (e.g., Land and Resources Bureau and Agriculture Bureau), a land-use plan is proposed. In the plan, the highly suitable areas for agriculture (and the surrounding moderately suitable areas) are allocated as farmlands, whilst the other moderately to lowly suitable areas are allocated as ecological zones for restoring the ecosystem and ecological diversity. The barely suitable areas with severe subsidence are allocated as artificial lakes, which also serve as reservoirs for farmland irrigation and drainage. To protect these new farmlands from soil erosion, infrastructure such as embankment and windbreak are also included in our rehabilitation plan. Our study highlights the necessity of forward planning in coal mine rehabilitation.