Longitudinal dispersion in Rivers

A pulse injection test is completed to determine various statistics over a stream. Listed below are the results with some data missing.

Site	Time (minutes)	Distance (meters)	Standard deviation, (m)
Initial	0	0	0
Site 1	(a)	195	(c)
Site 2	4.5	(b)	123.25
Site 3	5.24	1223	133.0

Assuming this streams average velocity is the same across the entire system, determine the stream velocity, the missing data a, b and c, and determine the longitudinal dispersion coefficient for the site.