5,238 research outputs found
Site Characterization Using Integrated Imaging Analysis Methods on Satellite Data of the Islamabad, Pakistan, Region
We develop an integrated digital imaging analysis approach to produce a first-approximation site characterization map for Islamabad, Pakistan, based on remote-sensing data. We apply both pixel-based and object-oriented digital imaging analysis methods to characterize detailed (1:50,000) geomorphology and geology from Advanced Spaceborne Thermal Emission and Reflection Radiometer (ASTER) satellite imagery. We use stereo-correlated relative digital elevation models (rDEMs) derived from ASTER data, as well as spectra in the visible near-infrared (VNIR) to thermal infrared (TIR) domains. The resulting geomorphic units in the study area are classified as mountain (including the Margala Hills and the Khairi Murat Ridge), piedmont, and basin terrain units. The local geologic units are classified as limestone in the Margala Hills and the Khairi Murat Ridge and sandstone rock types for the piedmonts and basins. Shear-wave velocities for these units are assigned in ranges based on established correlations in California. These ranges include Vs30-values to be greater than 500 m/sec for mountain units, 200â600 m/sec for piedmont units, and less than 300 m/sec for basin units. While the resulting map provides the basis for incorporating site response in an assessment of seismic hazard for Islamabad, it also demonstrates the potential use of remote-sensing data for site characterization in regions where only limited conventional mapping has been done
Toward an imminent extinction of Colombian glaciers?
This study documents the current state of glacier coverage in the Colombian Andes, the glacier shrinkage over the twentieth century and discusses indication of their disappearance in the coming decades. Satellite images have been used to update the glacier inventory of Colombia reflecting an overall glacier extent of about 42.4â±â0.71â
km2 in 2016 distributed in four glacierized mountain ranges. Combining these data with older inventories, we show that the current extent is 36% less than in the mid-1990s, 62% less than in the mid-twentieth century and almost 90% less than the Little Ice Age maximum extent. Focusing on Nevado Santa Isabel (Los Nevados National Park), aerial photographs from 1987 and 2005 combined with a terrestrial LiDAR survey show that the mass loss of the former ice cap, which is nowadays parceled into several small glaciers, was about â2.5 m w.e. yrâ1 during the last three decades. Radar measurements performed on one of the remnant glaciers, La Conejeras glacier, show that the ice thickness is limited (about 22 m in average in 2014) and that with such a mass loss rate, the glacier should disappear in the coming years. Considering their imbalance with the current climate conditions, their limited altitudinal extent and reduced accumulation areas, and in view of temperature increase expected in future climate scenarios, most of the Colombian glaciers will likely disappear in the coming decades. Only the largest ones located on the highest summits will probably persist until the second half of the twenty-first century although very reducedThis study was conducted in the context of the project Capacity Building and Twinning for Climate Observing Systems (CATCOS) supported by the Federal Office of Meteorology and Climatology MeteoSwiss [contract no. 7F-08114.1], between the Swiss Agency for Development and Cooperation (SDC) and MeteoSwiss, by the Swiss State Secretariat for Economic Affairs (SECO). This work was also supported by SNO GLACIOCLIM; LMI GREAT ICE (IRD); Labex OSUG@2020, Investissements dâavenir: [Grant Number ANR10 LABX56]. M. MĂ©nĂ©goz is supported by the project VOLCADEC funded by the Spanish programme Retos (MINECO/FEDER, ref. CGL2015â70177-R).Peer ReviewedPostprint (author's final draft
GMES-service for assessing and monitoring subsidence hazards in coastal lowland areas around Europe. SubCoast D3.5.1
This document is version two of the user requirements for SubCoast work package 3.5, it is
SubCoast deliverable 3.5.1. Work package 3.5 aims to provide a European integrated GIS
product on subsidence and relative sea level rise. The first step of this process was to
contact the European Environment Agency as the main user to discover their user
requirements.
This document presents these requirments, the outline methodology that will be used to carry
out the integration and the datasets that will be used. In outline the main user requirements
of the EEA are:
1. Gridded approach using an Inspire compliant grid
2. The grid would hold data on:
a. Likely rate of subsidence
b. RSLR
c. Impact (Vulnerability)
d. Certainty (confidence map)
e. Contribution of ground motion to RSLR
f. A measure of certainty in the data provided
g. Metadata
3. Spatial Coverage - Ideally entire coastline of all 37 member states
a. Spatial resolution - 1km
4. Provide a measure of the degree of contribution of ground motion to RSLR
The European integration will be based around a GIS methodology. Datasets will be
integrated and interpreted to provide information on data vlues above. The main value being
a likelyhood of Subsidence. This product will initially be developed at itâs lowest level of detail
for the London area. BGS have a wealth of data for london this will enable this less detialed
product to be validated and also enable the generation of a more detailed product usig the
best data availible. One the methodology has been developed it will be pushed out to other
areas of the ewuropean coastline.
The initial input data that have been reviewed for their suitability for the European integration
are listed below. Thesea re the datasets that have European wide availibility, It is expected
that more detailed datasets will be used in areas where they are avaiilble.
1. Terrafirma Data
2. One Geology
3. One Geology Europe
4. Population Density (Geoland2)
5. The Urban Atlas (Geoland2)
6. Elevation Data
a. SRTM
b. GDEM
c. GTOPO 30
d. NextMap Europe
7. MyOceans Sea Level Data
8. Storm Surge Locations
9. European Environment Agencya.
Elevation breakdown 1km
b. Corine Land Cover 2000 (CLC2000) coastline
c. Sediment Discharges
d. Shoreline
e. Maritime Boundaries
f. Hydrodynamics and Sea Level Rise
g. Geomorphology, Geology, Erosion Trends and Coastal Defence Works
h. Corine land cover 1990
i. Five metre elevation contour line
10. FutureCoas
Perspectives on open access high resolution digital elevation models to produce global flood hazard layers
Global flood hazard models have recently become a reality thanks to the release of open access global digital elevation models, the development of simplified and highly efficient flow algorithms, and the steady increase in computational power. In this commentary we argue that although the availability of open access global terrain data has been critical in enabling the development of such models, the relatively poor resolution and precision of these data now limit significantly our ability to estimate flood inundation and risk for the majority of the planetâs surface. The difficulty of deriving an accurate âbare-earthâ terrain model due to the interaction of vegetation and urban structures with the satellite-based remote sensors means that global terrain data are often poorest in the areas where people, property (and thus vulnerability) are most concentrated. Furthermore, the current generation of open access global terrain models are over a decade old and many large floodplains, particularly those in developing countries, have undergone significant change in this time. There is therefore a pressing need for a new generation of high resolution and high vertical precision open access global digital elevation models to allow significantly improved global flood hazard models to be developed
\u27How To\u27 Guide for Synthesizing NERRs Marsh Monitoring Data
The purpose of this guide is to provide a user-friendly and informative guide on âHow toâ synthesize salt marsh data from theNational Estuarine Research Reserve System (NERRs). In this guide, we outline and detail the steps taken from requesting/cataloguing data to summarizing these data through visual and statistical analysis. These methods can be used at a single or multiple site(s) as well as over multiple years. Though this guide is specific to NERRs and focuses on plant community data, it may also be useful for other monitoring parameters and programs to guide protocol design and analyses. Here, we conduct a synthesis of New England salt marshes using NERRs data collected from the past decade
Automated Satellite-Based Landslide Identification Product for Nepal
Landslide event inventories are a vital resource for landslide susceptibility and forecasting applications. However, landslide inventories can vary in accuracy, availability, and timeliness as a result of varying detection methods, reporting, and data availability. This study presents an approach to use publicly available satellite data and open source software to automate a landslide detection process called the Sudden Landslide Identification Product (SLIP). SLIP utilizes optical data from the Landsat 8 OLI sensor, elevation data from the Shuttle Radar Topography Mission (SRTM), and precipitation data from the Global Precipitation Measurement (GPM) mission to create a reproducible and spatially customizable landslide identification product. The SLIP software applies change detection algorithms to identify areas of new bare-earth exposures that may be landslide events. The study also presents a precipitation monitoring tool that runs alongside SLIP called the Detecting Real-time Increased Precipitation (DRIP) model that helps identify the timing of potential landslide events detected by SLIP. Using SLIP and DRIP together, landslide detection is improved by reducing problems related to accuracy, availability, and timeliness that are prevalent in the state-of-the-art of landslide detection. A case study and validation exercise was performed in Nepal for images acquired between 2014 and 2015. Preliminary validation results suggest 56% model accuracy, with errors of commission often resulting from newly cleared agricultural areas. These results suggest that SLIP is an important first attempt in an automated framework that can be used for medium resolution regional landslide detection, although it requires refinement before being fully realized as an operational tool
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Evaluating river cross section geometry for a hydraulic river routing model : Guadalupe and San Antonio river basins
textA new methodology is presented to construct reliable river channel cross section approximations. These approximations are based on the idea of downstream hydraulic geometry as well as supported by the information collected by the USGS streamflow measurement stations across the study area. A hydraulic river routing model (SPRNT) is run with the newly constructed cross section approximations. Initial conditions for the simulation are estimated based on the steady state solution for the model. Boundary conditions or lateral inflows for the river network are estimated based on the outputs of a Land Surface model: Noah, which provides surface and sub-surface runoff for every catchment area in the San Antonio and Guadalupe river basins. Simulations are compared with observed measurements from the USGS stations.Civil, Architectural, and Environmental Engineerin
Mapping of the Geological Structures Using Digital Elevation Model (DEM)-Derived Flow Direction: A Case Study of Rungwe Volcanic Province, Southwest Tanzania
This study aimed to assess the potentiality of Digital Elevation Model (DEM)-derived flow direction in mapping geologic structures, specifically in areas with thick overburden of soil or volcanic materials such as in the Rungwe Volcanic Province, SW Tanzania. Clustering of flow directions based on trends of structure sets found in the study area was applied and it successfully revealed a large number of geological structures through demarcated tectonic blocks from patterns created by flow directions. Northwestâsouthwest (NW-SE) and NE-SW- trending lineaments are the dominant structural sets in the area whereas N-S and E-W-trending lineaments constitute the minor sets. Moreover, the approach has also unveiled the NW-SE-trending faults that control most of the volcanic centers. The extracted lineaments by the method presented in this research are consistent with the known geological structures and structure surface manifestations such as volcanic centers, hot springs and earthquake epicenters. Findings of this study has revealed that the method can be applied as a robust technique to map crustal structures mostly in early phases of exploration, and has shown good results in delineating faults in areas with thick overburden such as soils and volcanic materials.
Keywords: Applied Remote Sensing; Flow Direction; Geological Structures; Rungwe Volcanic Province
Surface temperatures in New York City: Geospatial data enables the accurate prediction of radiative heat transfer
Three decades into the research seeking to derive the urban energy budget,
the dynamics of the thermal exchange between the densely built infrastructure
and the environment are still not well understood. We present a novel hybrid
experimental-numerical approach for the analysis of the radiative heat transfer
in New York City. The aim of this work is to contribute to the calculation of
the urban energy budget, in particular the stored energy. Improved
understanding of urban thermodynamics incorporating the interaction of the
various bodies will have implications on energy conservation at the building
scale, as well as human health and comfort at the urban scale. The platform
presented is based on longwave hyperspectral imaging of nearly 100 blocks of
Manhattan, and a geospatial radiosity model that describes the collective
radiative heat exchange between multiple buildings. The close comparison of
temperature values derived from measurements and the computed surface
temperatures (including streets and roads) implies that this geospatial,
thermodynamic numerical model applied to urban structures, is promising for
accurate and high resolution analysis of urban surface temperatures.Comment: 11 pages, 5 figure
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