Calculate distance from A to B along a stream

TrinityShuler02

Hello! 

I would like to know the best way to calculate the distance between two points along a stream. 

The reddish line in the photo is the NHD flowline dataset. 

Imagine the black polygon is a point - how would I calculate the distance along the NHD flowline from the black polygon to the nearest pink diamond? Then, save that distance to the attributes of the black polygons in a "distance to nearest pink diamond" field?

None of the pink diamonds intersect with the NHD flowline, they are mostly within 300ft of the flowline. 

I found a possible solution on stack exchange: https://gis.stackexchange.com/questions/452347/how-to-measure-the-distance-between-two-points-in-the-same-layer-accounting-for

But I was wondering if there was a different way to do this. I've been looking into maybe a trace network or a network analysis deal, however I'm worried those may be too complicated for this specific task. 

 

Ayan Palit

@TrinityShuler02 

The stack exchange provides a basic way of getting the distances. However, you have to repeat the entire process for new sets of points -  black polygon and pink diamond. The same link also mentions linear referencing. 

The workflow is better handled through Linear Referencing ; it does need learning some new concepts and tools. 

You can get started with the following references:

• Linear referencing datasets
• NHD flowlines may be modelled as Routes with the Start/End locations as Calibration Points or simply update measures on the vertices based on geometry length.
• You can then Locate Features Along Routes using NHD flowline as input route and the points as input features. You can provide search radius of 300 feet for the points that do not intersect the NHD routes.
• The tool will generate a event table with the located measure of each point along the NHD route. You can then do a simple calculation to find the distance between specified points.
• This method can be used to persist the measures on the NHD flowline routes. You can generate the event table by running Locate Features Along Routes for newer sets of points.