Watershed / River Network

digraph ws {
  rankdir=LR;
  graph [bgcolor=transparent];
  node [shape=ellipse, style=filled, fillcolor="#dbeafe", fontname=Inter, fontsize=10];

  H1 [label="Headwater 1"]; H2 [label="Headwater 2"]; H3 [label="Headwater 3"];
  T1 [label="Tributary A"]; T2 [label="Tributary B"];
  Lake [label="Lake / reservoir", fillcolor="#bae6fd"];
  Main [label="Main stem", fillcolor="#7dd3fc"];
  Delta [label="Delta", fillcolor="#fef3c7"];
  Ocean [label="Ocean", fillcolor="#0ea5e9", fontcolor="white"];

  H1 -> T1; H2 -> T1;
  H3 -> T2;
  T1 -> Main; T2 -> Main;
  Main -> Lake -> Main;
  Main -> Delta -> Ocean;
}