GIS
About this Space
Address: Opposite University of Juba
How to get started with GIS using QGIS Email: Kerejo.Tech.Space24@gmail.com
Tel: +211 921 704 079 /+211 988 888 224
Facebook: @K-Tech Space
By: Lodu B. John WhatsApp: +211 920 063 323
Course Content
1. Introduction to GIS Software
2. Working with Spatial Data
3. Basic Mapping and Visualization
4. Data Editing and Digitization
5. Geospatial Analysis Basics
6. Working with GPS Data
7. Creating Maps and Reports
8. Plugins
9. Project Work
Geospatial Analysis Basics
❖ Understanding spatial relationships
❖ Performing common GIS analysis techniques
❖ Practical applications in real-world scenarios
Introduction to Geospatial Analysis
❖ What is Geospatial Analysis?
o The process of analyzing spatial data to find patterns and relationships.
❖ Why is it Important?
o Supports decision-making in urban planning, healthcare, environment, and
more.
Buffer Analysis
❖ What is Buffer Analysis?
✓ "Buffer Analysis" is a spatial analysis technique that creates a designated zone (called a buffer)
around a geographic feature, allowing you to identify locations that fall within a specified distance
from that feature.
o Creates zones around features at a specified distance.
o NB: To set up a Buffer Analysis in QGIS, navigate to the "Vector" menu, then "Geoprocessing Tools," and
select "Buffer"; choose your input layer, specify the desired buffer distance, and click "Run" to generate the
buffer zone around your selected features.
o Buffering usually create two areas: within a specified distance to selected real world feature and area that is
beyond.
❖ Use Cases
o Defining areas around hospitals (e.g., 500m buffer for emergency response).
o Determining proximity to hazardous sites.
❖ Steps to Perform Buffer Analysis
o Select input feature (e.g., hospitals layer).
o Set buffer distance (e.g., 500m).
o Generate buffer zone and analyze results.
Spatial Joins
❖ What is a Spatial Join?
o Merges attributes from one layer to another based on spatial relationships.
❖ Types of Spatial Joins
o Point-to-Polygon: Assigning neighborhood names to customer locations.
o Point-to-Point: Finding nearest fire stations to buildings.
❖ Steps to Perform a Spatial Join
o Choose target and join layers.
o Define spatial relationship (e.g., intersects, contains).
o Merge attribute tables and analyze results.
Clipping and Merging
Clipping
❖ What is Clipping?
✓ “Clipping" refers to a geospatial processing tool that allows you to extract a specific portion of a data
layer (like a shapefile or raster) by "cutting out" the area defined by another layer.
o Extracts features within a defined boundary.
✓ Open your layers, navigate to the "Raster" menu, select "Extraction," then choose "Clip by Mask
Layer" (for raster data), specify the input layer you want to clip, select the mask layer (the layer
defining the clipping area), and click "Run" to generate the clipped result; for vector data, the process
is similar, but you would access the "Clip" tool within the processing toolbox.
❖ Use Cases ❖ Steps to Perform Clipping
o Extracting city roads from a national dataset. o Select input layer and clip boundary.
o Isolating forests within a protected area. o Run the clip tool.
o Analyze extracted features.
Clipping and Merging
Merging
❖ What is Merging?
o Combines multiple layers into one dataset.
o Navigate to the "Processing" tab, search for the "Merge Vector Layers" tool, select the
layers you want to combine, set the output file location, and click "Run" to merge them
into a single layer; for raster data, go to "Raster" > "Miscellaneous" > "Merge" to access
the merging tool.
❖ Use Cases
o Merging road networks from different regions.
o Combining administrative boundaries.
❖ Steps to Perform Merging
o Select layers to merge.
o Ensure matching attributes.
o Run merge tool and save output.
Hands-on Practice
❖ Create a buffer around hospitals.
❖ Perform a spatial join between schools and districts.
❖ Clip a land-use map to a city boundary.
Summary & Next Steps
❖ Key Takeaways
o Buffer analysis helps define spatial influence zones.
o Spatial joins integrate data from different layers.
o Clipping and merging refine and combine spatial datasets.
❖ Next Steps
o Explore advanced geoprocessing tools.
o Apply spatial analysis in real-world projects.
o Learn automation with GIS scripting
Q&A
Any Questions?
