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At least 1,693 records · Page 94Linked to original sources

Multi-temporal surface water mapping with high-resolution elevation and image data through weakly supervised deep learning

Monitoring the extent of surface water features (hydrography), accurately storing them in databases, and representing them on topographic maps are essential for various applications such as navigation and policy-making for legislative boundaries and permitting. In this context, hydrographic data includes features that generally have water present or image data showing signs that water is forming a terrain channel, and which would be included in 1:24,000 or larger scale topographic maps. In addition, reliable hydrographic data play a critical role to help manage environmental risks such as droughts, floods, fires, and landslides, as well as monitoring biological resources and pollutants. Inaccuracies in hydrography data can lead to modelling inaccuracies, resulting in economic, social, and environmental risks. However, generating sufficiently accurate high-resolution (HR) hydrography and terrain data for these purposes remains a substantial challenge primarily because of complex surface water dynamics and data handling limitations.

Alaska↗

InSAR detects possible thaw settlement in the Alaskan Arctic Coastal Plain

Satellite interferometric synthetic aperture radar (InSAR) has proven to be an effective tool for monitoring surface deformation from volcanoes, earthquakes, landslides, and groundwater withdrawal. This paper seeks to expand the list of applications of InSAR data to include monitoring subsidence possibly associated with thaw settlement over the Alaskan Arctic Coastal Plain. To test our hypothesis that InSAR data are sufficiently sensitive to detect subsidence associated with thaw settlement, we acquired all Japanese Earth Resources Satellite-1 (JERS-1) L-band data available for the summers of 1996, 1997, and 1998 over two sites on the Alaska North Slope. The least amount of subsidence for both study sites was detected in the interferograms covering the summer of 1996 (2-3 cm), interferograms from 1997 and 1998 revealed that about 3 cm of subsidence occurred at the northern Cache One Lake site, and about 5 cm of subsidence was detected at the southern Kaparuk River site. These preliminary results illustrate the capacity of the L-band (24 cm) wavelength JERS-1 radar data to penetrate the short Arctic vegetation to monitor subsidence possibly associated with thaw settlement of the active layer and (or) other hydrologic changes over relatively large areas.

Canadian Journal of Remote Sensing↗

Windows to the deep 2018: Exploration of the southeast US Continental margin

Windows to the Deep 2018: Exploration of the Southeast US Continental Margin was a 36-day expedition aboard NOAA Ship Okeanos Explorer to acquire data on priority exploration areas identified by the ocean management and scientific communities. This expedition involved high-resolution multibeam sonar mapping and ROV dives, ranging from 340 m to 3,400 m depth, across the southeast US continental margin. Operations primarily targeted areas with potential to host deep-sea coral and sponge communities, including mounds, ridges, and terraced features on the continental slope. Dive sites also included maritime heritage sites, a submarine landslide feature, and several submarine canyon slopes, some of which exhibited evidence of active cold seeps. High biological abundance was noted at six of 17 dive sites, three of which also had high biological diversity. Additionally, deep-sea corals or sponges were observed on every dive except one, which was dedicated to gas seep exploration.

Atlantic Ocean, Blake Plateau, Stetson Mesa↗

Measurement and modeling of unsaturated hydraulic conductivity

The unsaturated zone plays an extremely important hydrologic role that influences water quality and quantity, ecosystem function and health, the connection between atmospheric and terrestrial processes, nutrient cycling, soil development, and natural hazards such as flooding and landslides. Unsaturated hydraulic conductivity is one of the main properties considered to govern flow; however it is very difficult to measure accurately. Knowledge of the highly nonlinear relationship between unsaturated hydraulic conductivity (K) and volumetric water content () is required for widely-used models of water flow and solute transport processes in the unsaturated zone. Measurement of unsaturated hydraulic conductivity of sediments is costly and time consuming, therefore use of models that estimate this property from more easily measured bulk-physical properties is common. In hydrologic studies, calculations based on property-transfer models informed by hydraulic property databases are often used in lieu of measured data from the site of interest. Reliance on database-informed predicted values with the use of neural networks has become increasingly common. Hydraulic properties predicted using databases may be adequate in some applications, but not others. This chapter will discuss, by way of examples, various techniques used to measure and model hydraulic conductivity as a function of water content, K(). The parameters that describe the K() curve obtained by different methods are used directly in Richards’ equation-based numerical models, which have some degree of sensitivity to those parameters. This chapter will explore the complications of using laboratory measured or estimated properties for field scale investigations to shed light on how adequately the processes are represented. Additionally, some more recent concepts for representing unsaturated-zone flow processes will be discussed.

Book chapter↗

A large submarine sand-rubble flow on kilauea volcano, hawaii

Papa'u seamount on the south submarine slope of Kilauea volcano is a large landslide about 19 km long, 6 km wide, and up to 1 km thick with a volume of about 39 km3. Dredge hauls, remote camera photographs, and submersible observations indicate that it is composed primarily of unconsolidated angular glassy basalt sand with scattered basalt blocks up to 1 m in size; no lava flows were seen. Sulfur contents of basalt glass from several places on the sand-rubble flow and nearby areas are low (< 240 ppm), indicating that the clastic basaltic material was all erupted on land. The Papa'u sandrubble flow was emplaced during a single flow event fed from a large near-shore bank of clastic basaltic material which in turn was formed as lava flows from the summit area of Kilauea volcano disintegrated when they entered the sea. The current eruptive output of the volcano suggests that the material in the submarine sand-rubble flow represents about 6000 years of accumulation, and that the flow event occurred several thousand years ago. ?? 1979.

Journal of Volcanology and Geothermal Research↗

Earthquake hazards to domestic water distribution systems in Salt Lake County, Utah

A magnitude-7. 5 earthquake occurring along the central portion of the Wasatch Fault, Utah, may cause significant damage to Salt Lake County's domestic water system. This system is composed of water treatment plants, aqueducts, distribution mains, and other facilities that are vulnerable to ground shaking, liquefaction, fault movement, and slope failures. Recent investigations into surface faulting, landslide potential, and earthquake intensity provide basic data for evaluating the potential earthquake hazards to water-distribution systems in the event of a large earthquake. Water supply system components may be vulnerable to one or more earthquake-related effects, depending on site geology and topography. Case studies of water-system damage by recent large earthquakes in Utah and in other regions of the United States offer valuable insights in evaluating water system vulnerability to earthquakes.

Conference Paper↗

Geological hazards: programs and research in the USA

Geological hazards have been studied for centuries, but government support of research to lessen their effects is relatively new. This article briefly describes government programs and research under way in the U.S.A. that are directed towards reducing losses of life and property from earthquakes, volcanic eruptions and landslides. -Author

Episodes↗

APPALACHIAN FOLDS, LATERAL RAMPS, AND BASEMENT FAULTS: A MODERN ENGINEERING PROBLEM?

Field studies and analysis of radar data have shown that cross-strike faulting in the central and southern Appalachians has affected geologic structures at the surface. These basement faults appear to have been active through much of geologic time. Indeed, more than 45 percent of modern earthquakes occur along these narrow zones here termed 'lateral ramps. ' Because of this seismic activity, these lateral ramps are likely to be zones that are prone to slope failure. The engineer should be aware of the presence of such zones and the higher landslide potential along them.

Transportation Research Record↗

Geological hazards programs and research in the USA

Geological hazards have been studied for centuries, but government support of research to lessen their effects is relatively new. This article briefly describes government programs and research underway in the USA that are directed towards reducing losses of life and property from earthquakes, volcanic eruptions and landslides. -from Author

Earthquakes & Volcanoes (USGS)↗

Natural hazard zonation

This paper presents the basic scientific principles underpinning the professional practice of zonation for natural hazards such as floods, severe storms, earthquakes, volcanic eruptions, landslides, wildfires, tsunamis, and droughts. Zonation is the scientific process of identifying those parts of a geographic area which are best and least suited for community development in terms of their exposure to the physical effects of recurring, rapid onset, natural hazards.

Conference Paper↗

Rates and processes of bluff recession along the Lake Michigan shoreline in Illinois

Examined bluffs along 30 km of the Lake Michigan shoreline from Wilmette to Waukegan, Illinois, to measure amounts and variation in retreat rates and to determine what factors control rates and processes of retreat. The predominant bluff-retreat process is shallow- to intermediate-depth translational landsliding triggered by heavy rainfall and wave erosion at the base of the bluff; rotational slumping and shallow creep and earth flow also are common. Using historical maps and airphotos, we measured amounts of bluff-top retreat at 300 locations. For two time periods, 1872-1937 and 1937-1987, rates of retreat vary from 10 to 75 cm/yr between discrete segments of bluffs (defined by lithology) and between time periods for a given bluff segment. The average retreat rates for the entire area, however, do not vary significantly between the two time periods and are approximately 20-25 cm/yr. Longterm average and short-term extreme lake levels and precipitation also do not vary significantly between the two periods, and thus local temporal variations in retreat rate cannot be attributed to these factors. Shore protection built to date may have altered the spatial distribution of retreat rates in the area but has had little overall effect on the average regional retreat rates. -from Authors

Journal of Great Lakes Research↗

The susceptibility of rock slopes to earthquake-induced failure

Faulure of rock slopes is a major cause of damage and casualties during moderate and strong earthquakes. This article presents a method for assessing the seismic stability of rock slopes, which can be applied on a regional scale, using data from existing maps, reports, aerial photographs, and reconnaissance-level field observations. The method is based on observed associations between landslide concentrations and slope characteristics in 24 earthquakes that occurred in various parts of the world.

Bulletin of the Association of Engineering Geologi↗

Debris-flow hazard map units from gridded probabilities

The common statistical practice of dividing a range of probabilities into equal probability intervals may not result in useful landslide-hazard map units for areas populated by equal-area cells, each of which has a unique probability. Most hazard map areas contain very large numbers of cells having low probability of failure, and as probability increases, the number of cells decreases in a non-linear fashion. Exploration of this distribution suggests that the spatial frequency of expected failures may be used to identify probability intervals that define map units. From a spatial database of gridded probabilities, map units that address the different objectives of land-use planners and emergency response officials can be defined.

Conference Paper↗

Volcanic debris flows in developing countries - The extreme need for public education and awareness of debris-flow hazards

In many developing countries, volcanic debris flows pose a significant societal risk owing to the distribution of dense populations that commonly live on or near a volcano. At many volcanoes, modest volume (up to 500,000 m 3) debris flows are relatively common (multiple times per century) and typically flow at least 5 km along established drainages. Owing to typical debris-flow velocities there is little time for authorities to provide effective warning of the occurrence of a debris flow to populations within 10 km of a source area. Therefore, people living, working, or recreating along channels that drain volcanoes must learn to recognize potentially hazardous conditions, be aware of the extent of debris-flow hazard zones, and be prepared to evacuate to safer ground when hazardous conditions develop rather than await official warnings or intervention. Debris-flow-modeling and hazard-assessment studies must be augmented with public education programs that emphasize recognizing conditions favorable for triggering landslides and debris flows if effective hazard mitigation is to succeed. ?? 2003 Millpress,.

Conference Paper↗

Enlisting the support of land-use planners to reduce debris-flow hazards in the United States

Land-use planners have an important role in reducing losses from debris-flow hazards. For that reason, the U.S. Geological Survey (USGS) and the American Planning Association (APA) have developed a strategy to make information about landslide and debris-flow hazards available to local planners so that they can incorporate this information into the planning process. A guidebook for planners and active training and technical support are the centerpieces of this strategy. The strategy that the USGS is using, which enlists the support of a professional society such as the APA to develop the guidebook and communicate with its members, may be a useful example for other countries to follow. ?? 2003 Millpress.

Conference Paper↗

Geomedia: Mapping Colorado at a fine scale

Currently, only 24 percent of Colorado's spectacular geology has been mapped at the fine scale of 1:24,000. At the same time, the state hosts many geologic hazards. Most maps of Colorado are at much broader scales, failing to show detail of basic geology crucial to safe engineering and building practices in a state that had the third-fastest-growing population during the 1990s. And the 2000 Census showed that the state, despite some economic woes, remains one of the fastest growing. Detailed geologic maps also aid the mineral industries that help fuel such growth. Since 1992, the Colorado Geological Survey (CGS) has mapped 1:24,000-scale quadrangles in high-impact areas under the STATEMAP component of the National Cooperative Geologic Mapping Program. In 2002, CGS completed its 43rd geologic quadrangle map. The long-range plan for the state is to complete 116 high-priority quadrangles in the next 15 years. The survey's approach is to select rapidly growing areas with relatively high potential for hazards and map contiguous quadrangles. In addition to mapping bedrock, CGS geologists have mapped the Quaternary deposits at the surface. Understanding these deposits is extremely important for implementing sound engineering practices because of potential for subsidence and landslides. The CGS mapping has not only yielded information about potential hazards, but also advanced scientific understanding of the state.

Geotimes↗

Issues of scale, location and geologic terrain related to Salt Lake City and Baltimore-Washington metropolitan areas

Planning and development of expanding metropolitan regions require consideration of earth science issues related to issues involving scale, space (location), geologic terrain and physiographic units, and information transfer. This paper explores these matters with examples from the Salt Lake City, Utah area and Mid-Atlantic region of Baltimore-Washington that include water supply and natural hazards (earthquakes, landslides, and sinkholes.) Information transfer methods using physiographic units at national, regional, local and site scales serve to communicate relevant geologic constraint and natural resource information.

Conference Paper↗

Geomorphic effects of large debris flows and flash floods, northern Venezuela, 1999

A rare, high-magnitude storm in northern Venezuela in December 1999 triggered debris flows and flash floods, and caused one of the worst natural disasters in the recorded history of the Americas. Some 15,000 people were killed. The debris flows and floods inundated coastal communities on alluvial fans at the mouths of a coastal mountain drainage network and destroyed property estimated at more than $2 billion. Landslides were abundant and widespread on steep slopes within areas underlain by schist and gneiss from near the coast to slightly over the crest of the mountain range. Some hillsides were entirely denuded by single or coalescing failures, which formed massive debris flows in river channels flowing out onto densely populated alluvial fans at the coast. The massive amount of sediment derived from 24 watersheds along 50 km of the coast during the storm and deposited on alluvial fans and beaches has been estimated at 15 to 20 million m3. Sediment yield for the 1999 storm from the approximately 200 km2 drainage area of watersheds upstream of the alluvial fans was as much as 100,000 m3/km2. Rapid economic development in this dynamic geomorphic environment close to the capital city of Caracas, in combination with a severe rain storm, resulted in the death of approximately 5% of the population (300,000 total prior to the storm) in the northern Venezuelan state of Vargas. ?? 2006 Gebru??der Borntraeger.

Zeitschrift fur Geomorphologie, Supplementband↗