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State of the resources: Improving the land resource data base - The Regional Municipality of Waterloo soil information upgrade

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Title: State of the resources: Improving the land resource data base - The Regional Municipality of Waterloo soil information upgrade
Author: Cressman, D.
Abstract: The goal of this project was to produce a grouped soil polygon map and digital data set for the Regional Municipality of Waterloo. More specifically, the objective was to convert a very detailed 1:20,000 scale soil map (from The Soils of Waterloo County, Report Number 44 of the Ontario Soil Survey (Presant and Wicklund, 1971) on an uncontrolled photo mosaic base to a scale and level of detail that is more commonly used in land use and resource management planning (1:50,000 scale) and, in a Geographic Information System (GIS), to register the new soil map to the Ontario Base Mapping (OBM). In a prior pilot project in Wilmot Township, soil polygons were grouped manually on the unregistered, published base maps and transferred to the OBM. In this project the intent was to utilize the GIS system as much as possible to group the polygons. Available from a previous project, undertaken by the Regional Municipality of Waterloo, was a complete digital data base for the 1:20,000 scale soil survey, and grouped soil polygon maps on a registered base. In order to assess the accuracy of the Region's grouped polygons, a plot of the polygons was compared with the manually-devised map of grouped soil polygons in Wilmot Township. Test results suggested the need for only minor changes to the digital soil grouping methodology. In grouping soil polygons the available digital soil polygon data in the GIS were used to automate and accelerate the mapping process. Using the digital soils information from the Regional Municipality of Waterloo, soil polygons were first grouped according to the soil association parameters established in the Wilmot Township pilot project. Initially, adjacent soils of similar association were combined and polygon boundaries between these soils dissolved in the GIS. This reduced the number of soil polygons by approximately one half. Next, hard copy maps were printed for each of the townships to show the distribution and sizes of grouped soil polygons. The maps were colour coded to show the relative sizes of soil polygons. Polygons smaller than the minimum size for map units were merged with the closest large polygon with similar soil materials. Soils were not grouped within the developed areas in subdivisions and other developed lands in the cities of Waterloo, Kitchener and Cambridge and in towns and hamlets across the Region. Slope classes for each grouped soil polygon were determined using a combination of slope information in the original soil survey and OBM digital elevation data. The soil survey slope classes were modified to conform with current CanSIS standards. The OBM data were used to perform digital terrain mapping (DTM) and to derive slope classes in areas with slope gradients larger than 10 percent. The soil polygon slope fields were then combined to produce a generalized soil/slope polygon map for the Regional Municipality of Waterloo. The final step in the process was to assign soil capability ratings to the grouped soil polygons using modified Canada Land Inventory (CLI) ratings from The Soils of Waterloo County, Report Number 44 of the Ontario Soil Survey (Presant and Wicklund, 1971).
URI: http://hdl.handle.net/10214/15017
Date: 1996
Rights: In Copyright - Non-Commercial Use Permitted
Rights Holder: Agriculture Canada


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