smnorris / fwapg

PostgreSQL tools for working with British Columbia's Freshwater Atlas
https://smnorris.github.io/fwapg
MIT License
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Do not use watershed groups for upstream analysis #52

Open smnorris opened 3 years ago

smnorris commented 3 years ago

Watershed codes / watershed groups / assessment watersheds are not quite consistent enough to use for pre-aggregated upstream summaries.

For example, looking for area upstream of this fundamental watershed: watershed_feature_id = 8924583 wscode=100.190442.244975 localcode=100.190442.244975.541514

If we look upstream using the fundamental watersheds, almost of the Nicola River / NICL watershed group is included. If we look upstream using assessment watersheds or watershed groups, the NICL watershed group is excluded because the watershed group is coded with local code 100.190442.244975.539934 - there is a tiny bit of river polygon with that code present in the group.

Do not use watershed groups (or assessment watersheds, that are also based on group boundaries) for upstream/downstream queries.

FWA_WatershedAtMeasure and fwa_watersheds_upstream_area.sql will have to be fixed.

smnorris commented 3 years ago

Also - because they are not consistent enough to produce results equivalent to using fundamental watersheds, dropping the watershed codes from the watershed groups might be a good idea.

smnorris commented 3 years ago

fixed for fwa_watersheds_upstream_area with 6f03ce6

smnorris commented 2 years ago

When watershed codes are removed from fwa_watershed_groups_poly :