# Fluvial Transport

This app calculates the transport distance along a stream or other route. The main file is `Transport Shiny.R`; all other files are examples.
It is designed for tracking RFID tracers across multiple survey dates.

It works by assigning a location along the stream centerline for each tracer on each date. Then the distance between locations is calculated for each tracer between all dates. The scrpit relies on the `sf` and `sfnetworks` for spatial data handling and `data.table` for other data processing.

A total distance traveled is determined by selecting the maximum distance moved from all date pairs. Because a tracer may not be found in all survey dates, `NA` values are returned when a tracer is missing from a particular survey.

Processing times when using many files can be very slow.

Example data from surveys on Amethyst Brook, MA is provided. Simply place all survey files and centerline shapefiles in one folder and enter the folder path into the application.

Input files should be preprocessed to have a standardized tracer identification column, date column, and coordinate columns. See the example data for examples.