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Oak Ridges Moraine Groundwater Program - Database Manual

ORMGP Database Manual

G.33 Update of D_AREA_GEOM

Estimated Recurrence Time: As required.

The D_AREA_GEOM contains the boundaries (as polygons) for the various partner agencies, the ORMGP study area as well as the extent of geologic and hydrogeologic models. Many of these include a buffered region as well. This information is stored in two columns: GEOM and GEOM_WKB. The former holds the default ‘geometry’ type for Microsoft SQL Server while the latter has been stored in the ‘Well Known Binary’ format.

The GEOM field is populated through any external GIS software that supports the native geometry format. The GEOM_WKB is then populated using V_SYS_AREA_GEOM_WKB (using GEOM as a source).

Projections can be checked through

select
area_id
,geom.STSrid
From
d_area_geom

which returns the EPSG projection numeric for each record/object. This should conform to the code ‘26917’ (UTM Zone 17, NAD83). If these have been incorrectly assigned (from the external source), the specific records can be updated using

update d_area_geom
set
geom.STSrid= 26917
where
area_id= 76

The example here is updating the ORMGP Boundary 5km buffer layer.