10.4 Geographic information systems (GIS) and spatial data analysis

Geographic Information Systems (GIS) are powerful tools for managing and analyzing spatial data. They combine hardware, software, and data to capture, store, and visualize geographic information. GIS helps geoscientists make sense of complex spatial relationships and patterns in Earth systems.

GIS integrates various data sources, including remote sensing imagery, to create comprehensive maps and models. It enables spatial analysis techniques like overlay, proximity, and network analysis. These tools support decision-making in fields like urban planning, resource management, and natural hazard assessment.

Geographic Information Systems: Concepts and Components

Key Components of GIS

Top images from around the web for Key Components of GIS

• 

  GIS - EESC 3750 - Geographic Information Systems - Brooklyn College Library LibGuides Home at ... View original

  Is this image relevant?

• 

  GIS - EESC 3750 - Geographic Information Systems - Brooklyn College Library LibGuides Home at ... View original

  Is this image relevant?

• 

  Introduction to GIS – EO4GEO View original

  Is this image relevant?

• 

  GIS - EESC 3750 - Geographic Information Systems - Brooklyn College Library LibGuides Home at ... View original

  Is this image relevant?

• 

  GIS - EESC 3750 - Geographic Information Systems - Brooklyn College Library LibGuides Home at ... View original

  Is this image relevant?

1 of 3

Top images from around the web for Key Components of GIS

• 

  GIS - EESC 3750 - Geographic Information Systems - Brooklyn College Library LibGuides Home at ... View original

  Is this image relevant?

• 

  GIS - EESC 3750 - Geographic Information Systems - Brooklyn College Library LibGuides Home at ... View original

  Is this image relevant?

• 

  Introduction to GIS – EO4GEO View original

  Is this image relevant?

• 

  GIS - EESC 3750 - Geographic Information Systems - Brooklyn College Library LibGuides Home at ... View original

  Is this image relevant?

• 

  GIS - EESC 3750 - Geographic Information Systems - Brooklyn College Library LibGuides Home at ... View original

  Is this image relevant?

1 of 3

• Geographic information systems (GIS) are computer-based systems designed to capture, store, manipulate, analyze, manage, and present spatial or geographic data
• The main components of a GIS include:
  • Hardware: the physical components of a computer system, such as the computer, monitor, keyboard, mouse, and printer
  • Software: the programs and applications used to manipulate, analyze, and display geospatial data
  • Data: the information that is used and analyzed in a GIS, including both spatial data (maps, satellite imagery) and attribute data (tables, databases)
  • People: the individuals who design, manage, and use the GIS
  • Methods: the procedures and techniques used to apply GIS to real-world problems and decision-making processes

Data Organization and Coordinate Systems

• GIS data is typically organized into layers, with each layer representing a specific theme or dataset (roads, land use, elevation)
  • This layered approach allows for efficient data management and analysis, as users can selectively display and combine layers based on their needs
• GIS uses a coordinate system, such as latitude and longitude or Universal Transverse Mercator (UTM), to define the location of features on the Earth's surface
  • Latitude and longitude are angular measurements that specify a location on the Earth's surface relative to the equator and prime meridian
  • UTM is a grid-based coordinate system that divides the Earth into 60 zones and provides a standardized way of representing locations within each zone

GIS for Geospatial Data Management

Efficient Data Storage and Retrieval

• GIS allows users to efficiently store, manage, and retrieve large volumes of geospatial data
  • Geospatial databases, such as PostgreSQL with PostGIS extension, provide optimized storage and indexing of spatial data
  • Metadata, or data about data, is often used to document the characteristics and provenance of geospatial datasets, facilitating data discovery and sharing
• GIS provides tools for querying and filtering geospatial data based on spatial and attribute criteria
  • For example, a user could retrieve all parcels within a specified distance of a river or all roads with a certain surface type

Geospatial Data Analysis and Visualization

• GIS provides tools for analyzing geospatial data, such as:
  • Overlay analysis: combining multiple layers of geospatial data to identify relationships and patterns (land use and soil type to determine agricultural suitability)
  • Proximity analysis: identifying features that are within a specified distance of other features (schools within 1 km of a proposed development)
  • Network analysis: analyzing the flow of resources or information through a network (finding the shortest route between two locations on a road network)
• GIS enables users to create maps, charts, and other visualizations to communicate geospatial information effectively
  • Thematic maps can be used to display the spatial distribution of a particular attribute or phenomenon (population density, soil pH levels)
  • 3D visualizations can be used to represent terrain, buildings, and subsurface features (digital elevation models, geological cross-sections)
• GIS supports decision-making processes by allowing users to model and analyze different scenarios and outcomes based on geospatial data
  • For example, a city planner could use GIS to evaluate the potential impacts of different zoning policies on traffic congestion and air quality

Integrating Remote Sensing in GIS

Incorporating Remote Sensing Data

• Remote sensing data, such as satellite imagery and aerial photographs, can be integrated into a GIS to provide additional layers of information
  • Multispectral satellite imagery can be used to map land cover, monitor vegetation health, and detect changes over time (Landsat, Sentinel-2)
  • High-resolution aerial photographs can be used to create detailed base maps and identify small-scale features (buildings, trees, roads)
• GIS can be used to georeference remote sensing data, which involves assigning geographic coordinates to the data so that it can be accurately overlaid with other geospatial datasets
  • Ground control points (GCPs) are often used to establish the relationship between image coordinates and real-world coordinates
  • Georeferencing allows remote sensing data to be integrated with other GIS layers, such as land use maps or digital elevation models

Image Classification and Feature Extraction

• GIS allows users to perform image classification on remote sensing data, which involves categorizing pixels into different land cover or land use classes based on their spectral signatures
  • Supervised classification involves training the classifier using known samples of each class (training sites) and then applying the trained classifier to the entire image
  • Unsupervised classification involves grouping pixels into clusters based on their spectral similarity, without prior knowledge of the land cover classes
• GIS can be used to extract features, such as roads, buildings, and water bodies, from remote sensing data using techniques such as:
  • Edge detection: identifying sharp changes in pixel values that correspond to the boundaries of features
  • Object-based image analysis (OBIA): segmenting the image into homogeneous regions and classifying those regions based on their spectral, spatial, and contextual properties
• By integrating remote sensing data with other geophysical datasets, such as digital elevation models and geologic maps, GIS can provide a more comprehensive understanding of the Earth's surface and subsurface
  • For example, combining high-resolution satellite imagery with LiDAR-derived elevation data can enable detailed mapping of landforms, vegetation structure, and infrastructure

Spatial Data Analysis in Geophysics

Spatial Analysis Techniques

• GIS provides a range of tools for performing spatial data analysis, including:
  • Spatial statistics: analyzing the distribution and patterns of geospatial data (clustering of earthquakes, spatial autocorrelation of soil properties)
  • Geostatistics: interpolating values at unsampled locations based on the values at sampled locations (creating a continuous surface of groundwater levels from well measurements)
  • Terrain analysis: analyzing the topography of the Earth's surface (calculating slope, aspect, and hillshade from a digital elevation model)
• Spatial analysis techniques can be used to identify patterns, trends, and anomalies in geophysical data
  • Hot spot analysis can be used to identify areas with statistically significant clustering of high or low values (seismic activity, mineral concentrations)
  • Trend surface analysis can be used to model the overall spatial trend of a variable across a region (regional groundwater flow direction)

Geophysical Modeling and Site Suitability Analysis

• GIS can be used to create models that simulate geophysical processes, such as:
  • Groundwater flow: modeling the movement of water through aquifers and the impact of pumping or recharge on water levels
  • Seismic wave propagation: modeling the transmission of seismic waves through the Earth's crust and the potential for ground shaking during earthquakes
  • Volcanic eruptions: modeling the flow of lava and the dispersion of volcanic ash based on topography and wind patterns
• GIS allows users to perform site suitability analysis, which involves identifying the best locations for a particular activity or development based on multiple geospatial criteria
  • For example, a geothermal energy company could use GIS to identify areas with high heat flow, favorable geology, and proximity to infrastructure for potential geothermal power plant sites
• By integrating geophysical data and models within a GIS, users can gain insights into complex Earth systems and make informed decisions about resource management, hazard assessment, and environmental monitoring
  • For example, combining seismic data, geologic maps, and land use information in a GIS can help assess the risk of earthquakes to critical infrastructure and guide urban planning decisions