In studying shallow water flows, much attention was devoted to the case of transcritical flow over a topographic bump. Suppose instead that the bump is replaced with a dip or depression as indicated schematically below. With reference to possible critical points $($where Fr $1),$ hydraulic jumps, etc., describe what will happen to the flow as it moves left$-$to$-$right. Assume subcritical conditions with Fr $<1$ on the left$-$hand side. $($Drawing an analogy with compressible gas flow is not required.$)$