Distance source

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alter table ccm21.riversegments add column distance_source numeric;

The distance source is calculated by the following request : The distance sea corresponds to the distance of the downstream node of each riversegment The distance source for a riversegments A is the maximum of the distance + length of the upstream riversegment Note the upstream catchment function does not return the catchment upstream... so we have to use the upstream_segment function

In the ccm we find the cum_length which is the cumulated length of upstream riversegments but not the distance to the farthest source

select round(max(cum_len_sea+shape_leng) -(select cum_len_sea from ccm21.riversegments where gid =234706)) 
as dist_source from ccm21.riversegments where gid in (select ccm21.upstream_segments(234706));

The calculation in implemented as method in the BaseEdaCCMRiversegments.r class and called in main_CCM_France