LiDAR Surveys Research Articles

COMPARISON ASSESSMENT OF DIGITAL 3D MODELS OBTAINED BY DRONE-BASED LIDAR AND DRONE IMAGERY

Abstract. The purpose of this study is to assess the potential of drone airborne LiDAR technology in Morocco in comparison with drone photogrammetry. The cost and complexity of the equipment which includes a laser scanner, an inertial measurement unit, a positioning system and a platform are among the causes limiting its use. Furthermore, this study was motivated by the following reasons: (1) Limited number of studies in Morocco on drone-based LiDAR technology applications, (2) Lack of study on the parameters that influence the quality of drone-based LiDAR surveys as well as on the evaluation of the accuracy of derived products. In this study, the evaluation of LiDAR technology was carried out by an analysis of the geometric accuracy of the 3D products generated: Digital Terrain Model (DTM), Digital Surface Model (DSM) and Digital Canopy Model (DCM). We conduct a comparison with the products generated by drone photogrammetry and GNSS surveys. Several tests were carried out to analyse the parameters that influence the mission results namely height, overlap, drone speed and laser pulse frequency. After data collection, the processing phase was carried out. It includes: the cleaning, the consolidation then the classification of point clouds and the generation of the various digital models. This project also made it possible to propose and validate a workflow for the processing, the classification of point clouds and the generation of 3D digital products derived from the processing of LiDAR data acquired by drone.

UAV LiDAR Survey for Archaeological Documentation in Chiapas, Mexico

Airborne laser scanning has proven useful for rapid and extensive documentation of historic cultural landscapes after years of applications mapping natural landscapes and the built environment. The recent integration of unoccupied aerial vehicles (UAVs) with LiDAR systems is potentially transformative and offers complementary data for mapping targeted areas with high precision and systematic study of coupled natural and human systems. We report the results of data capture, analysis, and processing of UAV LiDAR data collected in the Maya Lowlands of Chiapas, Mexico in 2019 for a comparative landscape study. Six areas of archaeological settlement and long-term land-use reflecting a diversity of environments, land cover, and archaeological features were studied. These missions were characterized by areas that were variably forested, rugged, or flat, and included pre-Hispanic settlements and agrarian landscapes. Our study confirms that UAV LiDAR systems have great potential for broader application in high-precision archaeological mapping applications. We also conclude that these studies offer an important opportunity for multi-disciplinary collaboration. UAV LiDAR offers high-precision information that is not only useful for mapping archaeological features, but also provides critical information about long-term land use and landscape change in the context of archaeological resources.

Four-Dimensional Investigation of Gravel Beach Ridge Accretion and 50 Years of Beach Recharge at Dungeness, UK, Using Historic Images, GPR and Lidar (HIGL)

Dungeness is a cuspate foreland on the south coast of England that is the largest shingle feature in Europe and includes hundreds of beach ridges. It is also the location of two nuclear power stations that were constructed in the 1960s. The dominant southwest waves cause longshore drift from west to east, eroding the southwest side of Dungeness, accompanied by accretion on the east side. A record of this eastward movement and sediment accretion is preserved by the shingle beach ridges. The power stations are located on the eroding southwestern side of the ness, and a system of beach recharge has been used to move shingle from the downdrift, east-facing shore to the updrift, southwest-facing shore to protect the power stations from coastal erosion. We use a novel combination of historic images, ground-penetrating radar (GPR), and Lidar (HIGL) to investigate accretion and beach ridges at Dungeness during the past 80 years. We report changes in accretion along the coast and use GPR to determine the thickness of beach gravels. The amount of accretion, represented by the width of the backshore, decreases downdrift from south to north. The number of beach ridges preserved also decreases from south to north. By combining the shingle thickness from GPR with elevation data from Lidar surveys and records of beach accretion measured from aerial images, we estimate the volume and mass of gravel that has accumulated at Dungeness. Historic rates of beach accretion are similar to recent rates, suggesting that the 55 years of beach recharge have had little impact on the longer-term accretion downdrift.

Origins and spread of formal ceremonial complexes in the Olmec and Maya regions revealed by airborne lidar.

City plans symbolizing cosmologies have long been recognized as a defining element of Mesoamerican civilizations. The origins of formal spatial configurations are thus the key to understanding early civilizations in the region. Assessment of this issue, however, has been hindered by the lack of systematic studies of site plans over broad areas. Here, we report the identification of 478 formal rectangular and square complexes, probably dating from 1,050 to 400 BC, through a lidar (laser imaging, detection and ranging) survey across the Olmec region and the western Maya lowlands. Our analysis of lidar data also revealed that the earlier Olmec centre of San Lorenzo had a central rectangular space, which possibly provided the spatial template for later sites. This format was probably formalized and spread after the decline of San Lorenzo through intensive interaction across various regions. These observations highlight the legacy of San Lorenzo and the critical role of inter-regional interaction.

Review of Remote Sensing for Land Administration: Origins, Debates, and Selected Cases

Conventionally, land administration—incorporating cadastres and land registration—uses ground-based survey methods. This approach can be traced over millennia. The application of photogrammetry and remote sensing is understood to be far more contemporary, only commencing deeper into the 20th century. This paper seeks to counter this view, contending that these methods are far from recent additions to land administration: successful application dates back much earlier, often complementing ground-based methods. Using now more accessible historical works, made available through archive digitisation, this paper presents an enriched and more complete synthesis of the developments of photogrammetric methods and remote sensing applied to the domain of land administration. Developments from early phototopography and aerial surveys, through to analytical photogrammetric methods, the emergence of satellite remote sensing, digital cameras, and latterly lidar surveys, UAVs, and feature extraction are covered. The synthesis illustrates how debates over the benefits of the technique are hardly new. Neither are well-meaning, although oft-flawed, comparative analyses on criteria relating to time, cost, coverage, and quality. Apart from providing this more holistic view and a timely reminder of previous work, this paper brings contemporary practical value in further demonstrating to land administration practitioners that remote sensing for data capture, and subsequent map production, are an entirely legitimate, if not essential, part of the domain. Contemporary arguments that the tools and approaches do not bring adequate accuracy for land administration purposes are easily countered by the weight of evidence. Indeed, these arguments may be considered to undermine the pragmatism inherent to the surveying discipline, traditionally an essential characteristic of the profession. That said, it is left to land administration practitioners to determine the relevance of these methods for any specific country context.

Utilising Lidar Survey to Locate and Evaluate Offa’s Dyke

The enigmatic and gigantic Offa’s Dyke has long been understood as a demonstration of the power of the Mercian state in the long eighth century. Despite this, rarely have previous studies involved anything more than the visual observations of the earthwork. Moreover, ground-level perspectives cannot possibly contextualise its total breadth and character. The shortcomings in the resulting quality of data on the Dyke has led to uncertainties and debate over its route, extent, and placement in the landscape. With the application of lidar and other digital technologies, my ongoing doctoral research is providing a fresh understanding of the nature and original extent of Offa’s Dyke’s route by the creation of an accurate and empirical dataset. This digital dataset for Offa’s Dyke is identifying hitherto unknown sections of the monument. Furthermore, it is providing the foundation for new investigations of the nature of the frontier in the eighth century by creating the basis for new investigations into the placement and landscape context of the monument. This article presents interim results on the investigation of the Herefordshire section of Offa’s Dyke, a stretch that has been among the most problematic and poorly understood from all sections of the earthwork. This study thus provides fresh perspectives utilising digital heritage tools and data sources to examine and re-evaluate evidence of the nature and extent of the monument and the wider Mercian frontier.

Airborne Lidar Survey, Density-Based Clustering, and Ancient Maya Settlement in the Upper Usumacinta River Region of Mexico and Guatemala

We present results from the archaeological analysis of 331 km2 of high-resolution airborne lidar data collected in the Upper Usumacinta River basin of Mexico and Guatemala. Multiple visualizations of the DEM and multi-spectral data from four lidar transects crossing the Classic period (AD 350–900) Maya kingdoms centered on the sites of Piedras Negras, La Mar, and Lacanja Tzeltal permitted the identification of ancient settlement and associated features of agricultural infrastructure. HDBSCAN (hierarchical density-based clustering of applications with noise) cluster analysis was applied to the distribution of ancient structures to define urban, peri-urban, sub-urban, and rural settlement zones. Interpretations of these remotely sensed data are informed by decades of ground-based archaeological survey and excavations, as well as a rich historical record drawn from inscribed stone monuments. Our results demonstrate that these neighboring kingdoms in three adjacent valleys exhibit divergent patterns of structure clustering and low-density urbanism, distributions of agricultural infrastructure, and economic practices during the Classic period. Beyond meeting basic subsistence needs, agricultural production in multiple areas permitted surpluses likely for the purposes of tribute, taxation, and marketing. More broadly, this research highlights the strengths of HDBSCAN to the archaeological study of settlement distributions when compared to more commonly applied methods of density-based cluster analysis.

Leaf-Off and Leaf-On UAV LiDAR Surveys for Single-Tree Inventory in Forest Plantations

LiDAR technology has been proven to be an effective remote sensing technique for forest inventory and management. Among existing remote sensing platforms, unmanned aerial vehicles (UAV) are rapidly gaining popularity for their capability to provide high-resolution and accurate point clouds. However, the ability of a UAV LiDAR survey to map under canopy features is determined by the degree of penetration, which in turn depends on the percentage of canopy cover. In this study, a custom-built UAV-based mobile mapping system is used for simultaneously collecting LiDAR and imagery data under different leaf cover scenarios in a forest plantation. Bare earth point cloud, digital terrain model (DTM), normalized height point cloud, and quantitative measures for single-tree inventory are derived from UAV LiDAR data. The impact of different leaf cover scenarios (leaf-off, partial leaf cover, and full leaf cover) on the quality of the products from UAV surveys is investigated. Moreover, a bottom-up individual tree localization and segmentation approach based on 2D peak detection and Voronoi diagram is proposed and compared against an existing density-based clustering algorithm. Experimental results show that point clouds from different leaf cover scenarios are in good agreement within a 1-to-10 cm range. Despite the point density of bare earth point cloud under leaf-on conditions being substantially lower than that under leaf-off conditions, the terrain models derived from the three scenarios are comparable. Once the quality of the DTMs is verified, normalized height point clouds that characterize the vertical forest structure can be generated by removing the terrain effect. Individual tree detection with an overall accuracy of 0.98 and 0.88 is achieved under leaf-off and partial leaf cover conditions, respectively. Both the proposed tree localization approach and the density-based clustering algorithm cannot detect tree trunks under full leaf cover conditions. Overall, the proposed approach outperforms the existing clustering algorithm owing to its low false positive rate, especially under leaf-on conditions. These findings suggest that the high-quality data from UAV LiDAR can effectively map the terrain and derive forest structural measures for single-tree inventories even under a partial leaf cover scenario.

The formation and morphodynamics of complex multi‐hooked spits and the contribution of swash bars

AbstractNumerous studies have been devoted to recurved and hooked spits in micro‐ and meso‐tidal environments, but none have really focused on the peculiar right‐angle plan shape exhibited by some spit hooks. The morphodynamics of a complex multi‐hooked spit in a macrotidal inlet in Normandy, France, have been investigated using aerial photographs and 12 topographic LiDAR surveys from 2000 to 2017, complemented by hydrodynamic data. Merville Spit is a 2.5 km‐long hooked spit, composed of four ‘nested’ ridges each with a right‐angle hook at its tip, that has developed in the vicinity of the sand‐rich outlet of the Orne River. Monitoring of the two last ridges shows that ridge formation starts with the attachment of the tip of a swash bar to the fulcrum point of the previous ridge, and ends following its westward elongation and counter‐clockwise rotation when its hook impinges on the Orne outlet. The main factor controlling ridge plan‐view shape is swash bar dynamics in the vicinity of the spit. The offshore wave direction has no significant impact on ridge and hook behaviour due to the large number of swash bars on the ebb‐tidal delta. Over the study period, between 5 and 10 swash bars massively assured sand supply to the upper foreshore, favouring the growth of existing ridges, but also enabling the building of a new ridge. The bars contribute to imparting hook right angles at the tips of the ridges by creating local wave refraction or by providing a sheltering effect. Strong tidal currents in the Orne channel act as a hydrodynamic barrier that stops hook elongation at the edge of the river's outlet. The similar behaviour of the two studied ridges has been synthesized into a new and original conceptual model of complex multi‐hooked spit formation and evolution under the influence of swash bars.

Reduced sediment export to the Pennsylvania Lake Erie littoral zone during an era of average lake levels

This paper analyzes high-resolution lidar data to estimate sediment export to the Pennsylvania Lake Erie littoral zone from lakefront bluff retreat under relatively unique lake-level conditions: approximately a decade of average lake level transitioning into a mild transgression. Analysis identifies bluff-failure patterns important to coastal hazard planning, possible feeder-bluff conservation areas to preserve sediment supply, and data pertinent to sand management in the western Erie County littoral cell (WECLC) and at Presque Isle State Park in the next-downdrift cell.Based on 2007–2015 bluff-face mapping, there were net losses of 318,250 m3 of total-sediment and 105,700 m3 of sand+ (sand-boulders) to the littoral zone. On an average annual basis, bluffs thus exported 39,800 m3 of total-sediment and 13,300 m3 of sand+ to the WECLC. Exports of sand+ by six HUC-12 watersheds ranged from ~0 to 4600 m3/yr, with ~ 30% supplied by Crooked Creek watershed bluffs that occupy only 18% of the coast. Sand+ export volumes reported here were ~65% lower than prior research covering different lake-level phases. Understanding sediment export during periods of average lake level is important because such lake-level phases occur in the record and will likely recur. Incorporating a decade-scale low sediment-supply scenario for sand management in the Presque Isle littoral cell would permit fine-tuning of estimates of sand nourishment needed to mitigate ongoing beach erosion. Uncertainty in bluff-face change can be minimized by expanding data-comparison windows; future tracking of sediment export from Pennsylvania bluffs may not need lidar surveys any more frequently than once every 10–15 years.

Rapid lake Michigan shoreline changes revealed by UAV LiDAR surveys

The recent record-breaking Laurentian Great Lakes water levels have led to severe erosion along many shorelines, but quantification of this erosion has not yet been widely reported. In this paper, novel shoreline measurements of Lake Michigan erosion, using a LiDAR-equipped unmanned aerial vehicle (UAV). The vehicle surveyed two beaches, Dune Acres and Beverly Shores, along the Indiana shoreline of southern Lake Michigan over the period 2018–2019, which are compared to existing aircraft-based LiDAR surveys. The UAV surveys reveal extensive shoreline erosion and recession at both beaches since the low water conditions of 2012–2013, with both beaches losing 70.7 and 64.8 m3/m of dry beach volume. Shoreline recession over this period was nearly 35 m for both beaches. In the period 2018–2019, the UAV measurements reveal continued beach erosion and the transition of beach topography to a steep, actively eroding foredune. Storm erosion resolved by short-interval surveys highlight the episodic nature of shoreline erosion, with 8 m3/m of material lost over a stormy two-week period at Dune Acres. While large, the erosion and recession observed at both beaches is in keeping with limited historical observations of shoreline change during high water episodes. However, the observed overall shoreline recession slopes of 1:29 (water level rise : recession) are much less than historical slopes, suggesting that the beaches are not yet in equilibrium with the high water levels and that erosion will continue in the foreseeable future while lake levels remain high.

Impacts of selective logging on Amazon forest canopy structure and biomass with a LiDAR and photogrammetric survey sequence

Sustainable forest management relies on good knowledge of forest structure obtained from ground surveys combined with remote sensing. Capable of detecting both the forest floor and canopy elements, airborne LiDAR can estimate forest structure parameters with accuracy and precision, but is still difficult to acquire due to the lake of service provider in remote regions of developing countries. Alternatively if ground surface elevations are known (e.g., from LiDAR), they can be tied to a canopy surface model derived from stereo photogrammetry using RGB images from unmanned aerial vehicles (UAV). Here we assessed whether such photogrammetric canopy measurements offer aboveground biomass (AGB) and disturbance impact estimates from logging that are comparable to LiDAR, and whether the use of both in sequence can provide an efficient post-harvest monitoring system. Specifically, through a combination of forest inventory ground plots, airborne LiDAR data, and a UAV-RGB camera system we (i) automatically located and measured canopy disturbance caused by logging, (ii) compared AGB models produced by LiDAR alone and the combination of LiDAR (for terrain elevation model) and RGB-photogrammetry (for forest surface model), and (iii) estimated the AGB stock loss from logging. The study was carried out in the Antimary State forest located in the southwestern Brazilian Amazon. Our results demonstrate that the use of RGB-photogrammetry in regions where the terrain elevation has already been estimated can be an effective way to rapidly identify selective logging and to accurately monitor its impact.

Hydrogeochemistry Studies in the Oil Sands Region to Investigate the Role of Terrain Connectivity in Nitrogen Critical Loads

Hydrology and geochemistry studies were conducted in the Athabasca Oil Sands region to better understand the water and nitrogen cycles at two selected sites in order to assess the potential for nitrogen transport between adjacent terrain units. A bog—poor fen—upland system was instrumented near Mariana Lakes (ML) (55.899° N, 112.090° W) and a rich fen—upland system was instrumented at JPH (57.122° N, 111.444° W), 100 km south and 45 km north of Fort McMurray, Alberta respectively. LiDAR surveys were initially conducted to delineate the watershed boundaries and topography and to select a range of specific locations for the installation of water table wells and groundwater piezometers. Field work, which included a range of physical measurements as well as water sampling for geochemical and isotopic characterization, was carried out mainly during the thaw seasons of 2011 to 2015. From analysis of the runoff response and nitrogen species abundances we estimate that nitrogen exchange between the wetlands and adjacent terrain units ranged between 2.2 and −3.1 kg/ha/year for rich fens, 0.6 to −1.1 kg/ha/year for poor fens, and between 0.6 and −2.5 kg/ha/year for bogs, predominantly via surface pathways and in the form of dissolved nitrate. A significant storage of dissolved ammonium (and also dissolved organic nitrogen) was found within the pore water of the bog-fen complex at Mariana Lakes, which we attribute to decomposition, although it is likely immobile under current hydrologic conditions, as suggested by tritium distributions. In comparison with the experimental loads of between 5 and 25 kg/ha/year, the potential nitrogen exchange with adjacent terrain units is expected to have only a minor or negligible influence, and is therefore of secondary importance for defining critical loads across the regional landscape. Climate change and development impacts may lead to significant mobilization of nitrogen storages, although more research is required to quantify the potential effects on local ecosystems.

ABSOLUTE 3D ACCURACY ASSESSMENT OF UAS LIDAR SURVEYING

Abstract. Surveying an area with small, unoccupied aerial systems (UAS) equipped with a lidar mapping payload—absent permanent, stable, geometrical reference surfaces—demands accurate, repeatable data collection procedures. While relative error within a single UAS lidar dataset may reveal itself in strip misalignment, absolute error (particularly horizontal error) can prove more difficult to detect, casting doubt upon the quality of both individual surveys and time change analyses of multiple surveys of the area. To gain insight on the UAS lidar error budget, this study presents an analysis of multiple UAS lidar surveys over a set of accurately surveyed geometric checkpoints. Each flight’s trajectory was processed multiple times using multiple static GNSS base observations, both autonomous and set over surveyed monuments, at varying distances from the study site. Custom algorithms were used to mensurate the geometric targets detected in each UAS lidar survey's point cloud, allowing for precise comparison of both absolute horizontal and vertical accuracy of each survey against the rigorous ground survey. The results of the analysis suggest that high horizontal accuracy can be achieved under a variety of conditions, whereas vertical accuracy is sensitive to the quality of ground control. and a discussion of the results explores the ultimate goal of isolating and understanding the sources and magnitudes of error in the UAS lidar error budget.

Long‐term shifts in feedbacks among glacier surface change, melt generation and runoff, McMurdo Dry Valleys, Antarctica

AbstractGlaciers of the McMurdo dry valleys (MDVs) Antarctica are the main source of streamflow in this polar desert. Because summer air temperatures hover near 0°C small changes in the energy balance strongly affect meltwater generation. Here we demonstrate that increased surface roughness, which alters the turbulent transfer of energy between the ice surface and atmosphere, yields a detectable increase in meltwater runoff. At low elevations on the glaciers, basin‐like topography became significantly rougher over 13 years between repeat lidar surveys, yielding greater melt. In contrast, the smoother ice at higher elevation exhibited no detectable change in roughness. We pose a conceptual model of the cycle of glacier surface change as a result of climate forcing whereby glacier surfaces transition from being dominated by sublimation to becoming increasingly melt‐dominated, which is reversible under prolonged cool periods. This research advances our understanding of warm season effects on polar glaciers.

UNHIDING FORESTED LANDSCAPES. THE ARCHAEOLOGICAL INDEX OF SOUTH-EASTERN CARPATHIANS

Starting with late 2018, a new archaeological research project has been unfolding in the framework funded by the Romanian Governmental Unit for Research and Development (UEFISCDI) dedicated to top fundamental research, as one of the few winners of 2016 edition (the single to date) of ‘Complex Projects for Frontier Research’ competition. The Project, whose aims and methods will be shortly presented further, is entitled ‘Hidden Landscapes: Exploratory Remote-sensing for the Archaeology of the Lost Roads, Borders and Battlefields of South-Eastern Carpathians’ (HiLands). It implements a systematic and diachronic investigation of the historic strategic circulation corridors crossing the South-Eastern part of the Carpathian Mountains – the main gate used along ages by people transiting between Transylvania and the Danube or the Black Sea. In order to achieve such aims we have been exploring, starting from large scale LiDAR surveys, the circulation corridors’ diachronic archaeological fingerprint, preserved in the shape of repeatedly fortified landscapes. LiDAR surveys have been carried on continuously since 2018, by airplane, but also with portable sensors based on SLAM technology. The results of the LiDAR explorations were enhanced by field surveys, geophysical prospections and pin-pointed excavations, in order to elucidate the nature of anomalies or better contextualize the significance and layout of the roads’ routes. The results of these activities are resumed in a constantly updated, open access, online data base of archaeological sites - The archaeological index of South-Eastern Carpathians (AISEC). The current contribution details the essentials of HiLands research (aims, concepts, methods), in order to introduce in the scientific circuit the AISEC’s functions and instruments, ready to be used as citable work.

Removing residual airborne sensor motion for measuring seismic signals from a drone

Acquiring seismic data using drones requires excellent knowledge of the drone’s motion since positional measurements made from an airborne sensor represent a combination of sensor and ground motion. Recent advancements in laser Doppler vibrometry and repeat lidar surveys show that the frequency and resolution of non-contact motion measurements is increasing to the point necessary for measuring seismic signals. We explore the conditions under which separation of sensor motion from ground motion can be accomplished in practice. We assume (i) that the translation and rotation of a stabilized airborne sensor follows an analytic form in time that is either known or can be estimated from the sensor’s measurements, (ii) that the seismic signal we observe has compact support contained within the measurement window, and (iii) that the ground motion can be described by a rigid translation. We analyze the effectiveness of our signal separation problem as a function of peak signal, sensor noise level, sensor rotation angle, and sensor point sampling density by defining a boundary where SNR = 0 dB for various combinations of these parameters. We find that under the set of assumptions, lower rotation angles, lower sensor noise, and denser point samplings on the ground provide better signal separation using our method.

Rapid shrub expansion in a subarctic mountain basin revealed by repeat airborne LiDAR

As a consequence of increasing temperatures, a rapid increase in shrub vegetation has occurred throughout the circumpolar North and is expected to continue. Rates of shrub expansion are highly variable, both at the regional scale and within local study areas. This study uses repeat airborne LiDAR and field surveys to measure changes in shrub vegetation cover along with landscape-scale variations in a well-studied subarctic headwater catchment in Yukon Territory, Canada. Airborne LiDAR surveys were conducted in August 2007 and 2018, whereas vegetation surveys were conducted in summer 2019. Machine learning classification algorithms were used to predict shrub presence/absence in 2018 based on rasterized LiDAR metrics, with the best-performing model applied to the 2007 LiDAR to create binary shrub cover layers to compare between survey years. Results show a 63.3% total increase in detectable shrub cover >= 0.45 m in height between 2007 and 2018, with an average yearly expansion of 5.8%. These changes were compared across terrain derivatives to quantify the influence of topography on shrub expansion. Terrain comparisons show that shrubs are located in and are preferentially expanding into lower and flatter areas near stream networks, at lower slope positions and with a higher potential for topographic wetness. Overall, the findings from this research reinforce the documented increase in pan-Arctic shrub vegetation in recent years, quantify the variation in shrub expansion over terrain derivatives at the landscape scale, and demonstrate the feasibility of using LiDAR to compare changes in shrub properties over time.

Coastal Remote Sensing: Merging Physical, Chemical, and Biological Data as Tailings Drift onto Buffalo Reef, Lake Superior

On the Keweenaw Peninsula of Lake Superior, two stamp mills (Mohawk and Wolverine) discharged 22.7 million metric tonnes (MMT) of tailings (1901–1932) into the coastal zone off the town of Gay. Migrating along the shoreline, ca. 10 MMT of the tailings dammed stream and river outlets, encroached upon wetlands, and contaminated recreational beaches. A nearly equal amount of tailings moved across bay benthic environments into critical commercial fish spawning and rearing grounds. In the middle of the bay, Buffalo Reef is important for commercial and recreational lake trout and lake whitefish production (ca. 32% of the commercial catch in Keweenaw Bay, 22% along southern Lake Superior). Aerial photographs (1938–2016) and five LiDAR and multispectral over-flights (2008–2016) emphasize: (1) the enormous amounts of tailings moving along the beach; and (2) the bathymetric complexities of an equal amount migrating underwater across the shelf. However, remote sensing studies encounter numerous specific challenges in coastal environments. Here, we utilize a combination of elevation data (LiDAR digital elevation/bathymetry models) and in situ studies to generate a series of physical, chemical, and biological geospatial maps. The maps are designed to help assess the impacts of historical mining on Buffalo Reef. Underwater, sand mixtures have complicated multispectral bottom reflectance substrate classifications. An alternative approach, in situ simple particle classification, keying off distinct sand end members: (1) allows calculation of tailings (stamp sand) percentages; (2) aids indirect and direct assays of copper concentrations; and (3) permits determinations of density effects on benthic macro-invertebrates. The geospatial mapping shows how tailings are moving onto Buffalo Reef, the copper concentrations associated with the tailings, and how both strongly influence the density of benthic communities, providing an excellent example for the International Maritime Organization on how mining may influence coastal reefs. We demonstrate that when large amounts of mine tailings are discharged into coastal environments, temporal and spatial impacts are progressive, and strongly influence resident organisms. Next steps are to utilize a combination of hi-resolution LiDAR and sonar surveys, a fish-monitoring array, and neural network analysis to characterize the geometry of cobble fields where fish are successful or unsuccessful at producing young.

Hydrometeorological, glaciological and geospatial research data from the Peyto Glacier Research Basin in the Canadian Rockies

Abstract. This paper presents hydrometeorological, glaciological and geospatial data from the Peyto Glacier Research Basin (PGRB) in the Canadian Rockies. Peyto Glacier has been of interest to glaciological and hydrological researchers since the 1960s, when it was chosen as one of five glacier basins in Canada for the study of mass and water balance during the International Hydrological Decade (IHD, 1965–1974). Intensive studies of the glacier and observations of the glacier mass balance continued after the IHD, when the initial seasonal meteorological stations were discontinued, then restarted as continuous stations in the late 1980s. The corresponding hydrometric observations were discontinued in 1977 and restarted in 2013. Datasets presented in this paper include high-resolution, co-registered digital elevation models (DEMs) derived from original air photos and lidar surveys; hourly off-glacier meteorological data recorded from 1987 to the present; precipitation data from the nearby Bow Summit weather station; and long-term hydrological and glaciological model forcing datasets derived from bias-corrected reanalysis products. These data are crucial for studying climate change and variability in the basin and understanding the hydrological responses of the basin to both glacier and climate change. The comprehensive dataset for the PGRB is a valuable and exceptionally long-standing testament to the impacts of climate change on the cryosphere in the high-mountain environment. The dataset is publicly available from Federated Research Data Repository at https://doi.org/10.20383/101.0259 (Pradhananga et al., 2020).