I am working with HecGeoRAS in ArcMap 10.3.1 and I am creating the feature class RIVER. I have a shape file with polylines representing the reach and I added the columns FROM NODE and TO NODE using Feature to vertices tool. However, the nodes are not assigned to the reaches in the order that I want. I would like order the nodes from upstream to downstream of the river. I would like to know how to define the flow direction of the river and how to change the node number in function of this direction.