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USGS1977

National Cartographic Information Center Newsletter No. 6

As a rule we don't carry personnel information additions, subtractions, etc., in the newsletter. This is a technical publication, not a forum for office baseball league scores. Now, having got that disclaimer out of the way, we wanted to note that Dick Swinnerton, Chief of NCIC since the Center's inception in 1974, has left us. Dick was recently chosen as Chief of the Topographic Divisions's Western Mapping Center (a move up and, geographically at least, to the left). When Dick arrived NCIC consisted of 4 briefing books and an interesting concept. 3 years later we have 10 books and a thriving organization. We shall miss him. This issue contains what we hope is an interesting collection of cartographic news, including articles about recent Federal mapping agreements, new publication announcements, notes on the second NCIC coordinating conference, and a cumulative index for the spring 1975 to summer 1977 issues.

Newsletter↗
USGS2006

Land-based lidar mapping: a new surveying technique to shed light on rapid topographic change

The rate of natural change in such dynamic environments as rivers and coastlines can sometimes overwhelm the monitoring capacity of conventional surveying methods. In response to this limitation, U.S. Geological Survey (USGS) scientists are pioneering new applications of light detection and ranging (lidar), a laser-based scanning technology that promises to greatly increase our ability to track rapid topographic changes and manage their impact on affected communities.

Fact Sheet↗
USGS1991

Surficial geologic map of the Walden 30' x 60' quadrangle, Jackson, Larimer, and Routt counties, Colorado

This map is one of a series of four 30' x 60' surficial geologic maps (1:100,000 scale) intended to provide basic geologic information for planning for energy resource development and growth in northwestern Colorado. An effort is made to characterize all surficial materials, regardless of origin. Hence, residuum is given much more emphasis than is customary, and this results in several departures from conventional geologic maps: bedrock geology is deemphasized; the part of the map symbol denoting geologic age is omitted for surficial units because all surficial units shown are believed to be of Quaternary age; and faults are not shown because none in this map area was observed to displace surficial materials. Few exposures of most map units exist, except in manmade excavations, such as gravel pits and road cuts. Consequently, thicknesses usually are estimated, and data on stratification, clast size, and relative proportions of matrix and framework clasts are limited to a few localities for each map unit. The Wentworth scale is used to describe grain sizes. Mapping was done chiefly on aerial photographs taken in 1953. Hence, landslides and modifications resulting from gravel mining since 1953 may not show on this map. The scales of the aerial photographs (about 1:60,000) and the map (1:100,000) governed the minimum size of the deposits mapped. The minimum thickness of the depostis mapped is about 1.5m in most places. Deposit thickness, although not a mapping criterion, influences the topographic expression of many landforms, and landform is the basis for delineating the surficial deposits shown.

Colorado↗
USGS1991

Surficial geologic map of the Steamboat Springs 30' x 60' quadrangle, Grand, Jackson, and Routt counties, Colorado

This map is one of a series of four 30' x 60' surficial geologic maps (1:100,000 scale) intended to provide basic geologic information for planning for energy resource development and growth in northwestern Colorado. An effort is made to characterize all surficial materials, regardless of origin. Hence, residuum is given much more emphasis than is customary, and this results in several departures from conventional geologic maps: bedrock geology is deemphasized; the part of the map symbol denoting geologic age is omitted for surficial units because all surficial units shown are believed to be of Quaternary age; and faults are not shown because none in this map area was observed to displace surficial materials. Few exposures of most map units exist, except in manmade excavations, such as gravel pits and road cuts. Consequently, thicknesses usually are estimated, and data on stratification, clast size, and relative proportions of matrix and framework clasts are limited to a few localities for each map unit. The Wentworth scale is used to describe grain sizes. Mapping was done chiefly on aerial photographs taken in 1953. Hence, landslides and modifications resulting from gravel mining since 1953 may not show on this map. The scales of the aerial photographs (about 1:60,000) and the map (1:100,000) governed the minimum size of the deposits mapped. The minimum thickness of the depostis mapped is about 1.5m in most places. Deposit thickness, although not a mapping criterion, influences the topographic expression of many landforms, and landform is the basis for delineating the surficial deposits shown.

Colorado↗
USGS1980

Seismic hazard study of the western portion of the Garlock fault [California]

Investigations of the western segment of the Garlock fault were conducted at Castac Lake, Twin Lakes and Oak Creek Canyon. Studies were concentrated on the youngest fault trace as delineated by Clark (1973). Seismic refraction surveys, topographic surveys and geologic mapping provided positive evidence for fault offsets in Quaternary deposits at Twin Lakes and Oak Creek Canyon. Investigations at Castac Lake were concentrated on the fault segment north of the lake. Previous investigations south of the lake and across the dry lake bottom exposed unbroken strata dating back 8050 +300 years B.P. No evidence of offset of young deposits was found north of the lake from surface investigations or seismic refraction data. Trenching of sag pond deposits at Twin Lakes revealed fault traces representing 2 events confined to a zone 3 meters wide. The stratigraphy at Twin Lakes consists of alternating units of clay and sand allowing measurements of vertical offsets. Based on radiocarbon dates of detrital charcoal, the most recent movement occurred less than 890 +195 years B.P. and the proceeding event occurred greater than 2,800 +165 years B.P. Total vertical offset was 80 to 100 cm for the most recent movement and 55-60 cm for the proceeding event. Geomorphic analysis of offset alluvial stream channels at Oak Creek Canyon provided an estimate of 1.6 to 3.3 mm per year of left lateral movement during Holocene and late Pleistocene times. This estimate is based on correlation of soil profile development with dated soil stratigraphy in the San Joaquin Valley. Scarp heights and lack of definitive evidence for recent left-lateral offset in Oak Creek Canyon indicates a significant and perhaps predominant vertical component of movement with: 1) a comparatively long recurrence interval and/or 2) a small component of left-lateral movement. Arching of late Pleistocene deposits in Oak Creek Canyon is consistent with right-lateral rather than left-lateral wrench faulting, suggesting a fluctuation in stresses along this part of the fault since late Pleistocene time.

Open-File Report↗
USGS1988

Aggradation and degradation of alluvial sand deposits, 1965 to 1986, Colorado River, Grand Canyon National Park, Arizona

High discharges occurring between 1983-1985 resulted in redistribution of sand stored in zones of recirculating current in the Colorado River in Grand Canyon National Park. Redistribution resulted in net loss in the number of reattachment deposits in narrow reaches and aggradation of some separation deposits. Separation deposits were more stable than other types of deposits. Alluvial sand deposits that are large enough and of sufficient size for use as campsites were more stable than smaller lower-elevation deposits. Fluctuating flows between October 1985 and January 1986 caused erosion throughout the Grand Canyon, and caused erosion of some deposits created by the high flows of 1983-1985. Data collected for this study included measurements of flow velocity, scour-and-fill of sand deposits, topographic and bathymetric surveys, mapping of surface-flow patterns, water-surface slope surveys, sedimentological analysis, and replication of photographs. A classification system of alluvial sand deposits was developed on the basis of morphometric characteristics and the location of these deposits in relation to parts of recirculation zones. (Author 's abstract)

Open-File Report↗
USGS2008

Estimated Flood Discharges and Map of Flood-Inundated Areas for Omaha Creek, near Homer, Nebraska, 2005

Repeated flooding of Omaha Creek has caused damage in the Village of Homer. Long-term degradation and bridge scouring have changed substantially the channel characteristics of Omaha Creek. Flood-plain managers, planners, homeowners, and others rely on maps to identify areas at risk of being inundated. To identify areas at risk for inundation by a flood having a 1-percent annual probability, maps were created using topographic data and water-surface elevations resulting from hydrologic and hydraulic analyses. The hydrologic analysis for the Omaha Creek study area was performed using historical peak flows obtained from the U.S. Geological Survey streamflow gage (station number 06601000). Flood frequency and magnitude were estimated using the PEAKFQ Log-Pearson Type III analysis software. The U.S. Army Corps of Engineers' Hydrologic Engineering Center River Analysis System, version 3.1.3, software was used to simulate the water-surface elevation for flood events. The calibrated model was used to compute streamflow-gage stages and inundation elevations for the discharges corresponding to floods of selected probabilities. Results of the hydrologic and hydraulic analyses indicated that flood inundation elevations are substantially lower than from a previous study.

Scientific Investigations Report↗
USGS2011

Geologic map of the Montoso Peak quadrangle, Santa Fe and Sandoval Counties, New Mexico

The Montoso Peak quadrangle is underlain by volcanic rocks and associated sediments of the Cerros del Rio volcanic field in the southern part of the Española Basin that record volcanic, faulting, alluvial, colluvial, and eolian processes over the past three million years. The geology was mapped from 1997 to 1999 and modified in 2004 to 2008. The geologic mapping was carried out in support of the U.S. Geological Survey (USGS) Rio Grande Basin Project, funded by the USGS National Cooperative Geologic mapping Program. The mapped distribution of units is based primarily on interpretation of 1:16,000-scale, color aerial photographs taken in 1992, and 1:40,000-scale, black-and-white, aerial photographs taken in 1996. Most of the contacts on the map were transferred from the aerial photographs using a photogrammetric stereoplotter and subsequently field checked for accuracy and revised based on field determination of allostratigraphic and lithostratigraphic units. Determination of lithostratigraphic units in volcanic deposits was aided by geochemical data, 40 Ar/ 39 Ar geochronology, aeromagnetic and paleomagnetic data. Supplemental revision of mapped contacts was based on interpretation of USGS 1-meter orthoimagery. This version of the Montoso Peak quadrangle geologic map uses a traditional USGS topographic base overlain on a shaded relief base generated from 10-m digital elevation model (DEM) data from the USGS National Elevation Dataset (NED). Faults are identified with varying confidence levels in the map area. Recognizing and mapping faults developed near the surface in young, brittle volcanic rocks is difficult because (1) they tend to form fractured zones tens of meters wide rather than discrete fault planes, (2) the youth of the deposits has allowed only modest displacements to accumulate for most faults, and (3) many may have significant strike-slip components that do not result in large vertical offsets that are readily apparent in offset of sub-horizontal contacts. Those faults characterized as "certain" either have distinct offset of map units or had slip planes that were directly observed in the field. Faults classed as "inferred" were traced based on linear alignments of geologic, topographic and aerial photo features such as vents, lava flow edges, and drainages inferred to preferentially develop on fractured rock. Lineaments defined from magnetic anomalies form an additional constraint on potential fault locations.

New Mexico↗
USGS2014

Plenary: Progress in Regional Landslide Hazard Assessment—Examples from the USA

Landslide hazard assessment at local and regional scales contributes to mitigation of landslides in developing and densely populated areas by providing information for (1) land development and redevelopment plans and regulations, (2) emergency preparedness plans, and (3) economic analysis to (a) set priorities for engineered mitigation projects and (b) define areas of similar levels of hazard for insurance purposes. US Geological Survey (USGS) research on landslide hazard assessment has explored a range of methods that can be used to estimate temporal and spatial landslide potential and probability for various scales and purposes. Cases taken primarily from our work in the U.S. Pacific Northwest illustrate and compare a sampling of methods, approaches, and progress. For example, landform mapping using high-resolution topographic data resulted in identification of about four times more landslides in Seattle, Washington, than previous efforts using aerial photography. Susceptibility classes based on the landforms captured 93 % of all historical landslides (all types) throughout the city. A deterministic model for rainfall infiltration and shallow landslide initiation, TRIGRS, was able to identify locations of 92 % of historical shallow landslides in southwest Seattle. The potentially unstable areas identified by TRIGRS occupied only 26 % of the slope areas steeper than 20°. Addition of an unsaturated infiltration model to TRIGRS expands the applicability of the model to areas of highly permeable soils. Replacement of the single cell, 1D factor of safety with a simple 3D method of columns improves accuracy of factor of safety predictions for both saturated and unsaturated infiltration models. A 3D deterministic model for large, deep landslides, SCOOPS, combined with a three-dimensional model for groundwater flow, successfully predicted instability in steep areas of permeable outwash sand and topographic reentrants. These locations are consistent with locations of large, deep, historically active landslides. For an area in Seattle, a composite of the three maps illustrates how maps produced by different approaches might be combined to assess overall landslide potential. Examples from Oregon, USA, illustrate how landform mapping and deterministic analysis for shallow landslide potential have been adapted into standardized methods for efficiently producing detailed landslide inventory and shallow landslide susceptibility maps that have consistent content and format statewide.

Conference Paper↗
USGS2008

Landslides Mapped from LIDAR Imagery, Kitsap County, Washington

Landslides are a recurring problem on hillslopes throughout the Puget Lowland, Washington, but can be difficult to identify in the densely forested terrain. However, digital terrain models of the bare-earth surface derived from LIght Detection And Ranging (LIDAR) data express topographic details sufficiently well to identify landslides. Landslides and escarpments were mapped using LIDAR imagery and field checked (when permissible and accessible) throughout Kitsap County. We relied almost entirely on derivatives of LIDAR data for our mapping, including topographic-contour, slope, and hill-shaded relief maps. Each mapped landslide was assigned a level of 'high' or 'moderate' confidence based on the LIDAR characteristics and on field observations. A total of 231 landslides were identified representing 0.8 percent of the land area of Kitsap County. Shallow debris topples along the coastal bluffs and large (>10,000 m2) landslide complexes are the most common types of landslides. The smallest deposit mapped covers an area of 252 m2, while the largest covers 0.5 km2. Previous mapping efforts that relied solely on field and photogrammetric methods identified only 57 percent of the landslides mapped by LIDAR (61 percent high confidence and 39 percent moderate confidence), although nine landslides previously identified were not mapped during this study. The remaining 43 percent identified using LIDAR have 13 percent high confidence and 87 percent moderate confidence. Coastal areas are especially susceptible to landsliding; 67 percent of the landslide area that we mapped lies within 500 meters of the present coastline. The remaining 33 percent are located along drainages farther inland. The LIDAR data we used for mapping have some limitations including (1) rounding of the interface area between low slope surfaces and vertical faces (that is, along the edges of steep escarpments) which results in scarps being mapped too far headward (one or two meters), (2) incorrect laser-distance measurements resulting in inaccurate elevation values, (3) removal of valid ground elevations, (4) false ground roughness, and (5) faceted surface texture. Several of these limitations are introduced by algorithms in the processing software that are designed to remove non-ground elevations from LIDAR data. Despite these limitations, the algorithm-enhanced LIDAR imagery does effectively 'remove' vegetation that obscures many landslides, and is therefore a valuable tool for landslide inventories and investigations in heavily vegetated regions such as the Puget Lowland.

Open-File Report↗
USGS2021

Elevation and elevation-change maps of Fountain Creek, southeastern Colorado, 2015-20

The U.S. Geological Survey, in cooperation with Colorado Springs Utilities, has collected topographic data annually since 2012 at 10 study areas along Fountain Creek, southeastern Colorado. The 10 study areas were located between Colorado Springs and the terminus of Fountain Creek at the Arkansas River in Pueblo. The purpose of this report is to present elevation maps based on topographic surveys collected in 2020 and to present maps of elevation change that occurred between 2015 and 2020 at all 10 study areas. Elevation and elevation-change maps were developed in Global Mapper, R, and ArcGIS from topographic surveys collected at each study area during the winters of 2015 and 2020. Topographic surveys in 2015 were completed using real-time kinematic Global Navigation Satellite Systems. Topographic surveys in 2020 were completed using both real-time kinematic Global Navigation Satellite Systems and light detection and ranging. Elevation-change maps were created using propagated uncertainties associated with the 95-percent confidence limit. Study areas along Fountain Creek underwent a range of geomorphic responses between 2015 and 2020 that were often related to the dominant channel planform pattern of the study area. The results of this ongoing monitoring effort can be used to assess long-term changes in land-surface elevation and to advance understanding of the geomorphic response to possible changes in flow conditions on Fountain Creek.

Colorado↗
USGS2018

Streams do work: Measuring the work of low-order streams on the landscape using point clouds

The mutable nature of low-order streams makes regular updating of surface water maps necessary for accurate representation. Low-order streams make up roughly half the streams in the conterminous United States by length, and small inaccuracies in stream head location can result in significant error in stream reach, order, and density. Reliable maps of stream features are vital for hydrologic modeling, ecosystem research, and boundary monitoring. High resolution digital elevation models derived from lidar data have shown promise in low order stream modeling yet forested high relief landscapes and low relief agricultural areas remain challenging. Here we present early results from research analyzing lidar point clouds to identify features and patterns that may be used in low-order stream identification and classification in challenging geographic conditions. This work has identified characteristics derived from point clouds that correlate with the presence of streams and stream heads and show promise for mapping small streams. In low topographic relief agricultural areas, cross sections collected at regular intervals along drainage channels extracted as 3D lines show a significant jump in value and variance of profile curvature standard deviation at stream heads. In high relief areas, observations show potential for stream mapping by identifying trends in riparian zone structure. Lidar return point density from riparian vegetation under 30 feet tall dips in the vicinity of intermittent stream heads. Also seen is an increase in point density above 60 feet downstream of stream heads. The trends found here likely reflect a change in vegetation structure relative to the presence of streams.

Illinois, Iowa, North Carolina↗
USGS2009

Surficial geologic map of the Evansville, Indiana, and Henderson, Kentucky, area

The geologic map of the Evansville, Indiana, and Henderson, Kentucky, area depicts and describes surficial deposits according to their origin and age. Unconsolidated alluvium and outwash fill the Ohio River bedrock valley and attain maximum thickness of 33-39 m under Diamond Island, Kentucky, and Griffith Slough, south of Newburgh, Indiana. The fill is chiefly unconsolidated, fine- to medium-grained, lithic quartz sand, interbedded with clay, clayey silt, silt, coarse sand, granules, and gravel. Generally, the valley fill fines upward from the buried bedrock surface: a lower part being gravelly sand to sandy gravel, a middle part mostly of sand, and a surficial veneer of silt and clay interspersed with sandy, natural levee deposits at river's edge. Beneath the unconsolidated fill are buried and discontinuous, lesser amounts of consolidated fill unconformably overlying the buried bedrock surface. Most of the glaciofluvial valley fill accumulated during the Wisconsin Episode (late Pleistocene). Other units depicted on the map include creek alluvium, slackwater lake (lacustrine) deposits, colluvium, dune sand, loess, and sparse bedrock outcrops. Creek alluvium underlies creek floodplains and consists of silt, clayey silt, and subordinate interbedded fine sand, granules, and pebbles. Lenses and beds of clay are present locally. Silty and clayey slackwater lake (lacustrine) deposits extensively underlie broad flats northeast of Evansville and around Henderson and are as thick as 28 m. Fossil wood collected from an auger hole in the lake and alluvial deposits of Little Creek, at depths of 10.6 m and 6.4 m, are dated 16,650+-50 and 11,120+-40 radiocarbon years, respectively. Fossil wood collected from lake sediment 16 m below the surface in lake sediment was dated 33,100+-590 radiocarbon years. Covering the hilly bedrock upland is loess (Qel), 3-7.5 m thick in Indiana and 9-15 m thick in Kentucky, deposited about 22,000-12,000 years before present. Most mapped surficial deposits in the quadrangle are probably no older than about 55,000 years. Lithologic logs, shear-wave velocities, and other cone penetrometer data are used to interpret depositional environments and geologic history of the surficial deposits. This map, which includes an area of slightly more than seven 7.5-minute quadrangles, serves several purposes. It is a tool for assessing seismic and flood hazards of a major urban area; aids urban planning; conveys geologic history; and locates aggregate resources. The map was produced concurrently with research by seismologists to determine places where the surficial deposits may tend to liquefy and (or) to amplify ground motions during strong earthquakes. Such hazardous responses to shaking are related to the characteristics of the geologic materials and topographic position, which the geologic map depicts. The geologic map is an element in the cooperative seismic hazard assessment program among the States of Indiana, Kentucky, and Illinois and the U.S. Geological Survey, funded by the National Earthquake Hazards Reduction Program and National Cooperative Geologic Mapping Program of the U.S. Geological Survey.

Indiana, Kentucky↗
USGS2020

Elevation and elevation-change maps of Fountain Creek, southeastern Colorado, 2015–19

The U.S. Geological Survey, in cooperation with Colorado Springs Utilities, has been collecting topographic data at 10 study areas along Fountain Creek, Colorado, annually since 2012. The 10 study areas are located between Colorado Springs and the terminus of Fountain Creek at the Arkansas River in Pueblo. The purpose of this report is to present elevation maps based on topographic surveys collected in 2015 and 2019 and to present maps of elevation change that occurred between 2015 and 2019 at all 10 study areas. Elevation and elevation-change maps were developed in ArcGIS from topographic surveys collected at each study area using real-time kinematic Global Navigation Satellite Systems during the winter months (January through April) of 2015 and 2019. Elevation-change maps were created using statistically defined minimum levels of change detection asso-ciated with the 68-percent confidence limit and the 95-percent confidence limit. Study areas along Fountain Creek underwent a range of geomorphic responses between 2015 and 2019 that often depended on the dominant channel pattern of the study area. The results of this ongoing monitoring effort can be used to assess long-term changes in land-surface elevation and to advance understanding of the geomorphic response to possible alterations in flow conditions on Fountain Creek.

Colorado↗
USGS2011

A new strategy for developing Vs 30 maps

Despite obvious limitations as a proxy for site amplification, the use of time-averaged shear-wave velocity over the top 30m (Vs 30 ) is useful and widely practiced, most notably through its use as an explanatory variable in ground motion prediction equations (and thus hazard maps and ShakeMaps, among other applications). Local, regional, and global Vs 30 maps thus have diverse and fundamental uses in earthquake and engineering seismology. As such, we are developing an improved strategy for producing Vs 30 maps given the common observational constraints available in any region for various spatial scales. We investigate a hierarchical approach to mapping Vs 30 , where the baseline model is derived from topographic slope because it is available globally, but geological maps and Vs 30 observations contribute, where available. Using the abundant measured Vs 30 values in Taiwan as an example, we analyze Vs 30 versus slope per geologic unit and observe minor trends that indicate potential interaction of geologic and slope terms. We then regress Vs 30 for the geologic Vs 30 medians, topographic-slope, and cross-term coefficients for a hybrid model. The residuals of this hybrid model still exhibit a strong spatial correlation structure, so we use the kriging-with-a-trend method (the trend is the hybrid model) to further refine the Vs 30 map so as to honor the Vs 30 observations. Unlike the geology or slope models alone, this strategytakes advantage of the predictive capabilities of the two models, yet effectively defaults to ordinary kriging in the vicinity of the observed data, thereby achieving consistency with the observed data.

Book↗
USGS2019

Assessing the hydrologic impact of historical railroad embankments on wetland vegetation response in Canaan Valley, WV (USA): The value of high-resolution data

The recovery of natural ecological processes after disturbance is poorly understood. Some disturbances may be so severe as to set ecosystems onto a new trajectory. The Canaan Valley National Wildlife Refuge in West Virginia protects a unique high-altitude wetland that was heavily disturbed by logging 100 years BP and has since transitioned to a new ecological state (shrub wetland). Refuge managers interested in preserving and restoring ecosystem states expressed concerned about lingering impacts of previous disturbances (logging, railroads, beaver, deer, fire). Available data suggested hydrologic impacts from the remnant rail grade but managers had insufficient quantitative data to assess these impacts. We initiated a fine scale assessment of topography, vegetation distribution, and hydrology to assess impacts from the remnant rail grade using lidar data, vegetation surveys, and piezometers. We developed topographic models, hydrological models, and mapped vegetation distribution. We developed statistical models to assess relationships between vegetation communities, hydrology, and distance to the rail grade. Surprisingly, we found that hydrologic flow paths did not conform to expectation and were not restricted by remnant land use features. For the most part, vegetation communities are responding to topographic and environmental gradients that existed prior to disturbance. Use of highly detailed topographic data (lidar), field hydrology, and vegetation studies allowed us to more accurately assess hydrologic and vegetation regimes, eliminating the need for mitigation, saving significant resources.

West Virginia↗
USGS2003

Mapping the seabed and habitats in National Marine Sanctuaries - Examples from the East, Gulf and West Coasts

The National Marine Sanctuary System requires seabed and habitat maps to serve as a basis for managing sanctuary resources and for conducting research. NOAA, the agency that manages the sanctuaries, and the USGS have conducted mapping projects in three sanctuaries (Stellwagen Bank NMS, Flower Garden Banks NMS, and Channel Islands NMS) with an emphasis on collaboration of geologists and biologists from the two agencies and from academic institutions. Mapping of seabed habitats is a developing field that requires the integration of geologic and biologic studies and the use of swath imaging techniques such as multibeam and sidescan sonar. Major products of swath mapping are shaded-relief topographic imagery which shows seabed features in great detail, and backscatter imagery which provides an indication of the types of materials that constitute the seabed. Sea floor images provide an excellent basis for conducting the groundtruthing studies (using video, photo, and sampling techniques) that are required to collect the data necessary for making meaningful interpretative maps of the seabed. The compilation of interpretive maps showing seabed environments and habitats also requires the development of a sea floor classification system that will be a basis for comparing, managing, and researching characteristic areas of the seabed. Seabed maps of the sanctuaries are proving useful for management and research decisions that address commercial and recreational fishing, habitat disturbance, engineering projects, tourism, and cultural resources.

Marine Technology Society Journal↗
USGS2014

Tracking geomorphic signatures of watershed suburbanization with multi-temporal LiDAR

Urban development practices redistribute surface materials through filling, grading, and terracing, causing drastic changes to the geomorphic organization of the landscape. Many studies document the hydrologic, biologic, or geomorphic consequences of urbanization using space-for-time comparisons of disparate urban and rural landscapes. However, no previous studies have documented geomorphic changes from development using multiple dates of high-resolution topographic data at the watershed scale. This study utilized a time series of five sequential light detection and ranging (LiDAR) derived digital elevation models (DEMs) to track watershed geomorphic changes within two watersheds throughout development (2002–2008) and across multiple spatial scales (0.01–1 km 2 ). Development-induced changes were compared against an undeveloped forested watershed during the same time period. Changes in elevations, slopes, hypsometry, and surface flow pathways were tracked throughout the development process to assess watershed geomorphic alterations. Results suggest that development produced an increase in sharp topographic breaks between relatively flat surfaces and steep slopes, replacing smoothly varying hillslopes and leading to greater variation in slopes. Examinations of flowpath distributions highlight systematic modifications that favor rapid convergence in unchanneled upland areas. Evidence of channel additions in the form of engineered surface conduits is apparent in comparisons of pre- and post-development stream maps. These results suggest that topographic modification, in addition to impervious surfaces, contributes to altered hydrologic dynamics observed in urban systems. This work highlights important considerations for the use of repeat LiDAR flights in analyzing watershed change through time. Novel methods introduced here may allow improved understanding and targeted mitigation of the processes driving geomorphic changes during development and help guide future research directions for development-based watershed studies.

Geomorphology↗