The density current upstream stagnation point occurs for boundary interaction type B) and D) in the image on the right. Here the flow intrudes upstream against the direction of the ambient current. The stagnation point is defined as the most upstream location of the flow.
The analysis of this flow region follows results presented by Lee and Jirka, (1981), and Jones et al., (1983). Lee and Jirka analyze the properties of a buoyant subsurface discharge in stagnant water including the effects of recirculation and buoyant restratification. Jones et al. presents a methodology to predict the upstream spreading of a buoyant radial discharge in crossflow.