Geographical Information Systems Overview

Geographical Information System (GIS)

• A system designed to capture, store, manage, analyze, and visualize geographically referenced data.
• The core function of GIS is to use location-based data to understand relationships, patterns, and trends.
• History: Began with early mapping and surveying techniques, evolved into computer-based systems in the 1960s, and has since become a powerful tool across various fields.
• Components:
  • Hardware: Computers, scanners, GPS receivers, and other equipment.
  • Software: Applications used to manage, analyze, and visualize GIS data.
  • Data: Geospatial data, including maps, imagery, and attribute information.
  • People: Individuals trained in GIS to collect, analyze, and interpret data.
• Data Structure and Formats:
  • Raster: Data represented as a grid of cells, each cell representing a specific value (e.g., elevation, temperature).
  • Vector: Data represented as points, lines, and polygons, each with attribute information attached.
  • Data formats: Popular formats for storing geographic data are shapefiles, geodatabases, and raster images.
• Spatial Data Models:
  • Raster: Useful for continuous data like elevation or temperature, easy to manipulate and analyze for change detection or surface modeling.
  • Vector: More suitable for discrete features like roads, buildings, or boundaries, allows for precise representation and detailed analysis.
• Database Design in GIS:
  • Editing and Topology Creation: Maintaining data integrity and consistency using tools to control data relationships and spatial constraints (e.g., lines connecting to form closed polygons, ensuring that boundaries are valid).
• Linkage Between Spatial and Non-Spatial Data:
  • Spatial data: Information about location and geometry.
  • Non-spatial data: Attributes associated with geographic features (e.g., population, rainfall data, soil type).
  • Linking spatial and non-spatial data: Allows for powerful analyses by combining location-based data with descriptive information, leading to comprehensive insights.

QGIS - An Open Source Geographic Information System

• Free and open-source software: Accessible to a wide audience.
• Powerful capabilities: Provides tools for spatial analysis, data visualization, map creation, and many other GIS functions.
• Community support: Large active community contributing to its continual development.

Applications of GIS

• Geological Investigations:
  • Mapping geological formations, investigating mineral resources.
  • Assessing geological risks like landslides or earthquakes.
• Water Resources Management
  • Monitoring water quality, managing water supply and irrigation.
  • Assessing groundwater availability and flood risk.
• Environmental Studies
  • Mapping pollution levels, analyzing ecosystem changes, monitoring deforestation.
  • Predicting environmental impacts of development projects.
• EIA (Environmental Impact Assessment) Based Studies
  • Assessing the likely environmental impacts of proposed developments.
  • Identifying potential environmental risks and mitigation strategies.
• Land Use Planning
  • Mapping land use patterns, planning for urban development, land resource management.
• Soil Studies:
  • Analyzing soil composition and fertility, mapping soil types.
  • Supporting agricultural practices and land management.
• Transportation Planning
  • Designing transportation infrastructure, analyzing traffic flow, planning efficient routes.