Geology topics

Jessica D. DeWitt

Publications and source records attributed to Jessica D. DeWitt.

14 recordsLinked to original sources

USGS2026

Creating 3D point clouds, digital elevation models, and orthomosaics from historical aerial imagery through structure from motion aided photogrammetry

Detailed and accurate historical data are crucial to characterizing landscape change, whether it is caused by natural phenomena or of anthropogenic origin. Aerial imagery has been periodically collected by government and nongovernment agencies, for a broad range of purposes, since the early 20th century. The acquisition of aerial images involves using standardized equipment with large-format, carefully calibrated cameras and lens assemblies. Historical archives of aerial images preserve a record of the landscape and are invaluable sources of information that predate satellite and lidar. Structure from motion (SfM) aided photogrammetry provides an efficient means for creating digital three-dimensional data from the vast archives of historical aerial imagery. This report presents techniques, methods, best practices, and a standard workflow for creating point clouds, digital elevation models, and orthomosaic digital scans of overlapping (stereographic) vertical aerial photographs using photogrammetry software. A list of critical issues relevant to SfM-aided photogrammetry of historical aerial imagery is provided, along with potential contingencies and solutions. The workflow was tested in many geographic study areas and with historical imagery datasets of different scales and sources. Three case studies are included. By integrating known SfM methods, these procedures enable the consistent and optimal extraction of historical quantitative data from archives like the U.S. Geological Survey (USGS) Aerial Photo Single Frame archive in the USGS EarthExplorer data portal.

Techniques and Methods↗

USGS2026

Sediment response to stream restoration in an agricultural watershed

Despite widespread implementation of stream restoration there is limited research of its effectiveness in impaired agricultural settings. To quantify the effects of stream restoration on sediment load, we investigated erosion and deposition along 9 stream reach sites (4 restored, 4 unrestored, and 1 downstream) in Turtle Creek, Pennsylvania, United States - a representative agricultural subbasin of the Chesapeake Bay. These stream restoration projects had the goal of reducing sediment load primarily by installing log structures and regrading streambanks in order to stabilize streambanks and reconnect floodplains. Floodplain and streambank sediment fluxes were quantified over a 3-year period through repeated measurement of clay pads and pins and measurement of sediment bulk density. Uncrewed aerial imagery was collected at 3 of the sites, then processed using structure from motion (SfM) to create high-resolution digital elevation models. Terrain analysis enabled three-dimensional understanding of the generality of the specific field flux measurement locations to the larger stream reach. Restored sites on average had deposition on streambanks compared to streambank erosion along unrestored sites, and approximately two times greater floodplain deposition than unrestored sites. Overall, restored stream had an average seven-fold increase in the net balance (sum of streambank and floodplain) of sediment flux, a 81.2 kg/m/yr increase in retention, compared to unrestored stream. The measured larger streambed particle size distribution (D 50 ) in restored streams also suggests additional improvements to instream habitat quality. Terrain analysis confirmed that the field-based measurements were representative of the larger reach. These results indicate that stream restoration in agricultural watersheds using less-engineered designs can reduce sediment loading and improve stream habitat and health goals.

Pennsylvania↗

USGS2023

Investigating geomorphic change using a structure from motion elevation model created from historical aerial imagery: A case study in northern Lake Michigan, USA

South Manitou Island, part of Sleeping Bear Dunes National Lakeshore in northern Lake Michigan, is a post-glacial lacustrine landscape with substantial geomorphic changes including landslides, shoreline and bluff retreat, and sand dune movement. These changes involve interrelated processes, and are influenced to different extents by lake level, climate change, and land use patterns, among other factors. The utility of DEM of Difference (DoD) and other terrain analyses were investigated as a means of understanding interrelated geomorphologic changes and processes across multiple decades and at multiple scales. A 1m DEM was developed from 1955 historical aerial imagery using Structure from Motion Multi-View Stereo (SfM-MVS) and compared to a 2016 lidar-based DEM to quantify change. Landslides, shoreline erosion, bluff retreat, and sand dune movement were investigated throughout South Manitou Island. While the DoD indicates net loss or gain, interpretation of change must take into consideration the SfM-MVS source of the historical DEM. In the case of landslides, where additional understanding may be gleaned through review of the timing of lake high- and lowstands together with DoD values. Landscape-scale findings quantified cumulative feedbacks between interrelated processes. These findings could be upscaled to assess changes across the entire park, informing future change investigations and land management decisions.

Michigan↗

USGS2022

Quantifying and visualizing 32 years of agricultural land use change in Kabul, Afghanistan

Agriculture is a key element of Afghanistan’s economy and plays an essential role supporting the expanding population and urban development of Kabul, the country’s capital. Over the past decades the urban landscape has changed substantially and agricultural land use has shifted in its extent, location, and density. Identifying trends in the amount of agricultural area, as an indication of food production, is important for city planning and humanitarian efforts. While many studies have investigated Afghanistan's agriculture, most are conducted at scales that preclude their use for local-scale decision-making. This study quantifies agricultural extent across 32 years from 1988 to 2020 at local scale using simple and repeatable Landsat multispectral image analysis. The volume of data in time-series analysis complicatesvisualization of key findings and long-term trends. This study also explored visualization methods such as zonal mapping, animations, and the isolation of key themes in a 2D static map.

Kabul↗

USGS2021

Borehole sampling of surficial sediments in Northern Virginia and Southern Maryland

From 2014 to 2017, the U.S. Geological Survey’s Florence Bascom Geoscience Center (FBGC) entered into an inter-agency agreement with the Federal Highway Administration’s Turner-Fairbank Highway Research Center (TFHRC) to assist in field site selection and auger drilling fieldwork. The TFHRC was developing a device to measure the erosional properties of clay-rich sediments to be used for in situ testing at locations of bridge pier construction. FBGC scientists selected 15 drilling locations at 14 different field sites across Northern Virginia and Southern Maryland for the investigation of near-surface sediment properties and the development and testing of the TFHRC’s in situ scour testing device (ISTD). This report provides information about the project and summarizes the data collected during fieldwork including sediment descriptions of the borehole cores and the methods used during fieldwork.

Maryland, Virginia↗

USGS2021

Remote sensing inventory and geospatial analysis of brick kilns and clay quarrying in Kabul, Afghanistan

Reconstruction and urban development in Kabul, Afghanistan, has prompted vast expansion of the clay quarrying and brick making industry. This study identified the extent and distribution of clay quarrying and brick kilns in the greater Kabul area between 1965 and 2018. Very high-resolution satellite imagery was interpreted to quantify and characterize the type, number, and location of brick kilns for 1965, 2004, 2011, and 2018. Geospatial analysis of kilns together with geologic data and the results of hyperspectral image analysis yielded information regarding the extent of relevant mineral resources. Finally, kernel density analysis of kiln locations for each date called attention to their shifting spatial distribution. The study found that the clay quarrying and brick making industry has expanded exponentially. The type of kilns has transitioned from artisanal style clamp kilns to small-scale Bull’s Trench Kilns (BTK), and ultimately to Fixed Chimney Bull’s Trench Kilns (FCBTK). While quarrying has occurred entirely within quaternary windblown loess and clay deposits, artisanal clamp kilns were located in fine sediments containing montmorillonite and FCBTKs have developed in sediments containing calcite and muscovite. The study’s inventory of kilns was then used to estimate kiln workforce at 27,500 workers and production at 1.579 billion bricks per year.

Kabul↗

USGS2021

Afghanistan artisanal and small-scale mining sector

For millennia, extractive activity in Afghanistan (officially the Islamic Republic of Afghanistan, or IRA) has been entirely artisanal or small-scale in scope. Various international governments, organizations, and companies have supported the growth of the sector, and the Government of the Islamic Republic of Afghanistan (GoIRA) views its mineral wealth as vital to the country’s stability and prosperity moving forward (Ministry of Mines and Petroleum 2019a). The development of the sector has been prioritized in multiple national plans, strategies, and roadmaps. Of particular importance is the formalization of the artisanal and small-scale mining (ASM) sector to improve working conditions and enable the government to earn royalties from mineral production.

Report↗

USGS2020

Investigation of suitable habitat for the endangered plant Ptilimnium nodosum (Rose) Mathias (harperella) using remote sensing and field analysis—Documentation of methods and results

Ptilimnium nodosum (Rose) Mathias (harperella) is an endangered plant species found in Maryland, Virginia, and West Virginia, as well as in other locations throughout the southeastern United States. The narrow range of habitat characteristics for areas in which harperella has been found makes locating potential occurrence sites difficult and attempts at reintroduction of the plant relatively unsuccessful. Sightings of harperella have been made along the banks and in-channel bars of the Potomac River, along the Chesapeake and Ohio Canal National Historic Park, and within the Sideling Hill Wildlife Refuge near Hancock, Md. The large area covered by these sightings presents logistical challenges for repeat studies of harperella growth within the Park and in nearby areas. This study developed a geospatial method for characterizing harperella habitat through remote sensing, geospatial analysis, and field investigation. A geospatial prediction model was developed to model the habitat characteristics discussed in literature and found at harperella field observation sites in order to narrow the potential area for observation of the plant and its habitat. Analysis of historical aerial imagery was conducted within the space of the Potomac River to observe the persistence and flooding conditions of in-channel bars. The products of the geospatial prediction model and the historical aerial image analysis are a geospatial description of where harperella habitat is most likely to be found, as well as a map of in-channel bar locations and their persistence through time. From these two analyses, areas were identified that merited detailed observation. Very high resolution, unmanned aerial systems imagery was collected for 10 sites within this area in the Potomac River in June 2019. Unmanned aerial systems imagery has the potential to greatly improve detailed study of the harperella plant, as it provides the spatial resolution necessary to catalog detailed vegetation conditions (and potentially species identification). More importantly, the timing of imagery collection can be aligned carefully with the plant’s phenological patterns and local weather conditions to maximize cost-effectiveness of repeated imaging for specific areas.

Maryland, Virginia↗

USGS2020

Evaluating elevation change thresholds between structure-from-motion DEMs derived from historical aerial photos and 3DEP LiDAR data

This study created digital terrain models (DTMs) from historical aerial images using Structure from Motion (SfM) for a variety of image dates, resolutions, and photo scales. Accuracy assessments were performed on the SfM DTMs, and they were compared to the United States Geological Survey’s three-dimensional digital elevation program (3DEP) light detection and ranging (LiDAR) DTMs to evaluate geomorphic change thresholds based on vertical accuracy assessments and elevation change methodologies. The results of this study document a relationship between historical aerial photo scales and predicted vertical accuracy of the resultant DTMs. The results may be used to assess geomorphic change thresholds over multi-decadal timescales depending on spatial scale, resolution, and accuracy requirements. This study shows that if elevation changes of approximately ±1 m are to be mapped, historical aerial photography collected at 1:20,000 scale or larger would be required for comparison to contemporary LiDAR derived DTMs.

Virginia↗

USGS2020

Geomorphological mapping and anthropogenic landform change in an urbanizing watershed using structure-from-motion photogrammetry and geospatial modeling techniques

Increasing urbanization and suburban growth in cities globally has highlighted the importance of land planning using detailed geomorphologic maps that depict anthropogenic landform changes. Such mapping provides information crucial for land management, hazard identification, and the management of the challenges arising from urbanization. The development and use of quantitative and repeatable methods to map anthropogenic and natural processes are required to advance the science of urban geomorphological mapping. This study investigated the application of geospatial modeling, structure-from-motion (SfM) photogrammetric methods and DEM differencing as means of quantifying anthropogenic landform changes from archival aerial imagery. Anthropogenic landforms were incorporated into a detailed geomorphologic map in an urbanizing watershed located in the Washington, D.C. metropolitan suburb of Vienna, Virginia.

Virginia↗

USGS2020

Mapping the extent and methods of small-scale emerald mining in the Panjshir Valley, Afghanistan

Emerald mining in the Panjshir Valley, Afghanistan, has occurred for thousands of years, yet few records exist documenting the detailed spatial extent, techniques, or productivity of small-scale miners. This study proposes new methods to map and monitor the extent and changes in small-scale mining in remote and inaccessible terrain by integrating multispectral remote sensing analysis with archival geologic data and three-dimensional topographic change detection to examine emerald deposit zones and mining activity in the Panjshir Valley. Specifically, previously mapped geologic units known to host emeralds were re-analyzed using Landsat multispectral analysis to investigate the potential distribution of mining activity. Interpretation of very fine-resolution satellite imagery showed that mining activity is becoming more concentrated and transitioning from traditional tunneling methods to mechanized surface excavation. Finally, topographic change analysis of mechanized mine sites was combined with archival grade data to estimate production and consider improved recovery methods by small-scale miners.

Panjshir Valley↗

USGS2018

The Central African Republic Diamond Database—A geodatabase of archival diamond occurrences and areas of recent artisanal and small-scale diamond mining

The alluvial diamond deposits of the Central African Republic (CAR) are mined almost exclusively by way of informal artisanal and small-scale mining (ASM) methods. ASM sites range in diameter from a few meters to 30 meters or more, and are typically excavated by crews of diggers using hand tools, sieves, and jigs. CAR’s reported annual production has ranged from 300,000 to 470,000 carats over the past decade. This production is significant for CAR because it accounts for a large portion of the country’s export income and employs an estimated 60,000 to 90,000 miners nationally. Diamond production has also been linked to the violent conflict and political instability which have plagued the country for decades. The most recent conflict began in 2012 and resulted in an international embargo on the export of rough diamonds from CAR. This embargo was followed by a ceasefire and a return of peace in certain zones of the country in 2015; however, political and economic instability continues to afflict many areas of the country. International efforts to restore peace in CAR have included United Nations support as well as international technical assistance in tracking, assessing, and monitoring diamond production. In 2015, the Kimberley Process (KP) developed an operational framework allowing for legitimate exports from five subprefectures in CAR that were deemed to be compliant with KP internal controls and which were also considered to be free from systematic violence or control of armed groups. The goal of this study was to address information gaps regarding the location and extent of diamond occurrences and mining activity through the integration of geologic research with remote sensing, geographic information systems analysis, and fieldwork. Effective and efficient monitoring of diamond mining activity using satellite imagery requires detailed understanding of the geographic distribution of diamond sources and mining activities. A two-phase methodology was developed to address the knowledge gaps. The first phase consisted of the creation of a comprehensive geospatial catalogue of diamond mining and occurrence locations from archival records such as historical maps, mining reports, academic publications, and field data. Building upon this locational database, the second phase consisted of the creation of a geospatial dataset cataloguing current mining activity locations through manual interpretation of recently acquired satellite imagery. The accuracy of this second geospatial dataset was then assessed using field observations made between 2016 and 2017 by the U.S. Agency for International Development’s Property Rights and Artisanal Diamond Development II project. This report presents a two-part geodatabase: part 1 contains the locations of diamond mine sites and occurrences from archival sources, and part 2 indicates areas of current or recent mining activity. This geodatabase is unique in its temporal and spatial extent and may be used to analyze the geographic distribution of CAR’s known diamond resources, to assess the effect of recent violent conflicts and KP actions on diamond produc-tion, to provide decision makers with information regarding small-scale diamond mining, and to improve the monitoring of mining in regions of the country prone to conflict.

Open-File Report↗

USGS2017

Creating high-resolution bare-earth digital elevation models (DEMs) from stereo imagery in an area of densely vegetated deciduous forest using combinations of procedures designed for lidar point cloud filtering

For areas of the world that do not have access to lidar, fine-scale digital elevation models (DEMs) can be photogrammetrically created using globally available high-spatial resolution stereo satellite imagery. The resultant DEM is best termed a digital surface model (DSM) because it includes heights of surface features. In densely vegetated conditions, this inclusion can limit its usefulness in applications requiring a bare-earth DEM. This study explores the use of techniques designed for filtering lidar point clouds to mitigate the elevation artifacts caused by above ground features, within the context of a case study of Prince William Forest Park, Virginia, USA. The influences of land cover and leaf-on vs. leaf-off conditions are investigated, and the accuracy of the raw photogrammetric DSM extracted from leaf-on imagery was between that of a lidar bare-earth DEM and the Shuttle Radar Topography Mission DEM. Although the filtered leaf-on photogrammetric DEM retains some artifacts of the vegetation canopy and may not be useful for some applications, filtering procedures significantly improved the accuracy of the modeled terrain. The accuracy of the DSM extracted in leaf-off conditions was comparable in most areas to the lidar bare-earth DEM and filtering procedures resulted in accuracy comparable of that to the lidar DEM.

GIScience and Remote Sensing↗

USGS2015

Topographic and Hydrographic GIS Datasets for the Afghanistan Geological Survey and U.S. Geological Survey 2014 Mineral Areas of Interest

Mineral extraction and associated industries play an important role in the Afghan economy, particularly in the “transitional era” of declining foreign aid and withdrawal of foreign troops post 2014. In addition to providing a substantial source of government revenue, other potential benefits of natural resource development include boosted exports, employment opportunities, and strengthened industrialization (Joya, 2012). Continued exploration and investment in these industries has resulted in large economic improvements since 2007, when this series of studies was initiated. At that time, the “Preliminary Non-Fuel Mineral Resource Assessment of Afghanistan” was completed by members of the U.S. Geological Survey and Afghanistan Geological Survey (Peters and others, 2007). The assessment published a series of country-wide datasets, including a digital elevation model (DEM), elevation contours, hydrography, transportation routes, geophysics, and cultural datasets (Peters and others, 2007). It also delineated 20 mineralized areas for further study using a geologic-based methodology. A second data product, “Summaries of Important Areas for Mineral Investment and Production Opportunities of Nonfuel Minerals in Afghanistan,” was released by Peters and others in 2011. This work highlighted geologic, geohydrologic, and hyperspectral studies that were carried out in specific Areas of Interest (AOIs) to assess the location and characteristics of mineral resources. Also included in the 2011 publication is a collection of appendixes and inventories of Geographic Information System (GIS) datasets for each of the 24 identified AOIs. A third data product was released in 2013 (Casey and Chirico, 2013), publishing datasets for five different AOIs, two subareas, and one AOI extension. Each dataset contains vector shapefiles of the AOI boundary, streams, roads, and contours at 25-, 50-, and 100-meter (m) intervals, as well as raster files of the AOI’s DEM and hillshade. This work represents the fourth installment of the series, and publishes a dataset of eight new AOIs and one subarea within Afghanistan. These areas include Dasht-e-Nawar, Farah, North Ghazni, South Ghazni, Chakhansur, Godzareh East, Godzareh West, and Namaksar-e-Herat AOIs and the Central Bamyan subarea of the South Bamyan AOI (datasets for South Bamyan were published previously in Casey and Chirico, 2013). For each AOI and subarea, this dataset collection consists of the areal extent boundaries, elevation contours at 25-, 50-, and 100-m intervals, and an enhanced DEM. Hydrographic datasets covering the extent of four AOIs and one subarea are also included in the collection. The resulting raster and vector layers are intended for use by government agencies, developmental organizations, and private companies in Afghanistan to support mineral assessments, monitoring, management, and investment.

Open-File Report↗