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Watershed-to-upstream-polygon pairs for one watershed group, from fwapg

Source: R/wet_upstream_pairs.R
wet_upstream_pairs.Rd

The slow oracle: the pairwise FWA_Upstream() join fwapg's own builds use, with fwapg's stored fwa_watersheds_upstream_area. It materialises every (watershed, upstream polygon) pair (722 k for SALR), so use it only to spot check wet_upstream_sums() / wet_upstream_mean() on small headwater groups. Upstream polygons are not restricted to the group.

Usage

wet_upstream_pairs(conn, wsg)

Arguments

conn

A DBI connection to an fwapg database.

wsg

Watershed group code, e.g. "SALR".

Value

data.frame(watershed_feature_id, id_up, area_up_m2, upstream_area_m2).