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3.3 Integrating Multiple Source Datasets For Cn Valuation
To generate CN values for each catchment area, three datasets are combined, but only
two can be intersected at a time. The order makes no difference for the final output, but
by first combining the watershed catchment areas with the soils delineations it is possible
to create an intermediate dataset that can be combined with a more dynamic land use
dataset. This affords more flexibility in modifying the land use dataset, and combining it
with the established Catchment-Soils dataset.
The individual datasets are representations of a particular theme. Each dataset theme
delineates boundaries around common elements forming polygons. As datasets are
combined and intersected, the number of polygons increases as their geometry is
integrated. Figure 3.1 illustrates how combining multiple data sets creates small polygons.
Each polygon within a dataset also has various attributes associated with it. As the
polygons are combined, their attributes are aggregated as well.
Figure 3.1 Intersecting Multiple Datasets
Baird & Associates
3-3
User Manual – Nemadji River
Sediment Transport Modeling