diff --git a/src/app/components/pb-schema/pb-schema.component.ts b/src/app/components/pb-schema/pb-schema.component.ts
index 25cee4728088ac53d3809ab908b8387082d06be8..cd7ad1415ad9c8e27183d91a5423123ed31fb630 100644
--- a/src/app/components/pb-schema/pb-schema.component.ts
+++ b/src/app/components/pb-schema/pb-schema.component.ts
@@ -266,6 +266,12 @@ export class PbSchemaComponent implements AfterViewInit, AfterContentInit, OnIni
                 // store, to draw later
                 sortedWalls.push(c);
             }
+            this.existingWalls[basinsPair]++;
+            // draw wall Node
+            def.push(`${c.uid}["${this.itemDesription(c)}"]`); // square edges
+            def.push(`class ${c.uid} wall;`);
+            // draw "arrow" with 2 lines
+            def.push(`${upstreamBasinId}---${c.uid}-->${downstreamBasinId}`);
         }
         // sort then draw walls
         sortedWalls.sort(this.triCloisonsGaucheDroite);