Marine GIS Applications (using QGIS)
- Course Summary
- Introduction to Marine GIS
- Introduction to QGIS
- View data in QGIS
- Map Projections and Coordinate Systems
- Create Base Map in QGIS
- Creating Data Collection from the World Ocean Database
- Introduction to Ocean Data View
- Working with Spreadsheet Data
- Edit Data in QGIS
- Edit Data: Area of Interest and Analysis Mask
- Interpolating surfaces
- Rendering Raster Data
- Raster Calculator
- Working with NetCDF
- Plotting Vector Arrows from U and V Component Grids
- Downloading species observations from the Ocean Biogeographic Information System (OBIS)
- Creating KML files for Google Earth
- Publication Quality Maps
- Topic 1
This course provides an in depth overview of the application of Geographic Information Systems (GIS) to the marine environment using QGIS.
Aims and Objectives:
- Provide an introduction to GIS for marine applications
- Focus on some publicly available marine datasets
- Show the potential applications of GIS for the marine environment
- Knowledge and understanding of GIS, spatial data, raster and vector models
- Core tasks involved in the GIS analysis process including data acquisition, management, manipulation and analysis, and presentation and output
- Core functionality of QGIS Desktop and QGIS Browser
- Creating and editing spatial data
- Appreciation of coastal and marine GIS data applications
- Topic 2
Introduction to Marine GIS
A Geographic Information System (GIS) is a technology for managing geographic, or spatial, data. It is an integrated set of hardware and software tools used for the capture, storage, analysis and display of geographic data. GIS technology integrates common database operations such as query and statistical analysis with the visualisation and geographic analysis benefits offered by maps and charts.
GIS Components. There are five primary components of a GIS which are critical to its success.
GIS Data Models. A data model in geographic information systems is a mathematical construct for representing geographic objects or surfaces as data. In this course you will use both vector and raster data.
Marine GIS Applications. Marine GIS plays an important role in our understanding of the environment, and in particular, the marine environment. Marine GIS can be adapted and utilized to assist researchers and organizations in managing spatial applications related to oceanographic and coastal problems by facilitating the process of creating and producing geospatial data including coastal shorelines and bottom sea bathymetric (Oceanteacher Digital Library). An excellent publication that focuses on the potential and progress of GIS research in the marine and coastal realm is Marine and Coastal Geographical Information Systems edited by Dawn Wright and Darius Bartlett. Marine GIS can cover a wide range of of applications and can be categorized, for example, as coastal, oceanographic or fisheries (OceanTeacher Digital LIbrary). See also Geospatial Technology for Coastal Environments from ESRI.
- Topic 3
Introduction to QGIS
As information becomes increasingly spatially aware, there is no shortage of tools able to fulfill some or all commonly used GIS functions. Why should anyone be using QGIS over some other GIS software package?
Here are only some of the reasons:
- It’s free, as in lunch. Installing and using the QGIS program costs you a grand total of zero money. No initial fee, no recurring fee, nothing.
- It’s free, as in liberty. If you need extra functionality in QGIS, you can do more than just hope it will be included in the next release. You can sponsor the development of a feature, or add it yourself if you are familiar with programming.
- It’s constantly developing. Because anyone can add new features and improve on existing ones, QGIS never stagnates. The development of a new tool can happen as quickly as you need it to.
- Extensive help and documentation is available. If you’re stuck with anything, you can turn to the extensive documentation, your fellow QGIS users, or even the developers.
- Cross-platform. QGIS can be installed on MacOS, Windows and Linux.
Now that you know why you want to use QGIS.
- Topic 4
View data in QGIS Desktop
QGIS provides several windows, convenient for the user. Main windows of QGIS include:
- Data displaying and managing Windows; in these windows there are subwindows as follows:
ü Window for managing data layers (layers)
ü Window for data browser (Browser)
ü Window for displaying attribute (Attribute Table)
ü Print window
- Topic 5
Map Projections and Coordinate Systems
A geographic coordinate system defines locations on the earth using a three-dimensional spherical surface. A coordinate system includes an angular unit of measure, a prime meridian, and a datum (based on a spheroid). A feature is referenced by its longitude and latitude values. Longitude and latitude are angles measured from the earth’s centre to a point on the earth’s surface measured in degrees. See Geolocation by Latitiude and Longitude (OceanTeacher Digital Library).
In a GIS every dataset has a coordinate system which is used to integrate it with other geographic data layers within a common coordinate framework. Coordinate systems enable you to perform various analytical operations such as overlaying data layers from disparate sources and coordinate systems. There are two common types of coordinate systems used in GIS:
- A global or spherical coordinate system such as latitude-longitude, often referred to as a geographic coordinate system.
- A projected coordinate system which project a map of the earth's spherical surface onto a two-dimensional Cartesian coordinate plane. Projected coordinate systems are referred to as map projections.
Geographic Coordinate Systems.
A geographic coordinate system is a coordinate system that enables every location on the Earth to be specified by a set of numbers (Wikipedia). The exercises in this course will be using geographic (or unprojected) coordinate system using a rectangular latitude and longitude grid.
Map Projections, USGS
Understanding Map Projections, ESRI
- Topic 6
Create Base Map in QGIS
As a first step to developing a national marine data collection it is necessary to define the Area of Interest (AOI). There are a number of resources where you can download base map data. Some examples are high resolution country data (including administrative boundaries, roads, railways, land cover and population density), global bathymetry contours and coastline, and global EEZ boundaries. These data layers are available as shapefiles and can be used directly in ArcMap.
All exercises in this course will be based around the West African country of Liberia. The methods used here, however, can be used for your own area of interest.
- Topic 7
Creating Data Collection from the World Ocean Database
The World Ocean Database Project, or WOD, is a project established by the Intergovernmental Oceanographic Commission (IOC). WOD represents the world’s largest collection of ocean profile-plankton data available internationally without restriction with data coming from the National Oceanographic Data Centres (NODCs) of IODE as well as other international programmes such as World Ocean Circulation Experiment (WOCE) and Joint Global Ocean Flux Study (JGOFS), CLIVAR , Argo, Global Temperature-Salinity Profile Project (GTSPP). See World Ocean Database and World Ocean Atlas (OceanTeacher Digital Library).
The data in the World Ocean Database are made available through the online search and retrieval system known as WODselect. The WODselect retrieval system allows a user to search World Ocean Database 2009 and new data added since its release using a user-specified search criteria. A distribution map and cast count of these search criteria will give the user the option to have the data extracted and placed on the NODC FTP site in the WOD09 native and ".csv" data format.
- Topic 8
Introduction to Ocean Data View
Ocean Data View (ODV) is a software package for the interactive exploration, analysis and visualization of oceanographic and other geo-referenced profile or sequence data. ODV can display original data points or gridded fields based on the original data. ODV can be downloaded here. You will need to register as a member of the ODV users group first.
This exercise will briefly introduce ODV to create an ODV collection from the World Ocean Database and then export the data from ODV so it can be used in ArcGIS.
You can learn more about ODV watching this video.
Correction for Exercise: Exporting Marine Data from ODV : Data Subsets
Step no 9. Select EXPORT>STATION DATA>ODV SPREADSHEET FILE.
Note: Liberia has two distinct seasons: a wet season (referred to as the West African Monsoon) between May and November where the dominant wind direction is south‐westerly, blowing moist air from the Atlantic onto the continent. In the winter, the dominant wind direction is reversed, when the winds blow from the Sahara desert. For these exercises you will select data for the wet season (June, July, August) and the dry season (January, February, March).
In step 6 select Season:
i) from Jan/01 to Mar/31
ii) from Jun/01 to Aug/30
Create separate files for surface (0m) and 400m for temperature and salinity:
NOTE: When exporting data from ODV make sure the box "Use compact output format" is NOT checked.
- Topic 9
Working with Spreadsheet Data
Tables containing X and Y coordinates (Longitude and Latitude) and ocean parameters can be imported into QGIS and converted to a shapefile. The ocean parameters that have been extracted from World Ocean Database and processed in Ocean Data View will be used in this exercise.
- Topic 10
Edit Data in QGIS
QGIS includes some basic editing functions that allows you to create and edit several kinds of feature geometry data including points, lines, polygons, text , and tables. When you edit in QGIS, the entire workspace, that is, all the layers in the workspace are available for editing.
This tutorial introduces some basic skills needed to proceed with editing in QGIS.