diff --git a/src/app/components/pb-schema/pb-schema.component.ts b/src/app/components/pb-schema/pb-schema.component.ts
index cd7ad1415ad9c8e27183d91a5423123ed31fb630..0dddab78b08f8ccded24d1421f06ae76c44c6185 100644
--- a/src/app/components/pb-schema/pb-schema.component.ts
+++ b/src/app/components/pb-schema/pb-schema.component.ts
@@ -266,12 +266,6 @@ 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);
@@ -382,17 +376,17 @@ export class PbSchemaComponent implements AfterViewInit, AfterContentInit, OnIni
         if (item instanceof PbCloison) {
             const upstreamBasinName = item.bassinAmont === undefined
                 ? this.i18nService.localizeText("INFO_LIB_AMONT")
-                : "B" + (this.findBasinPosition(item.bassinAmont) + 1);
+                : "B" + (this.model.findBasinPosition(item.bassinAmont.uid) + 1);
             const downstreamBasinName = item.bassinAval === undefined
                 ? this.i18nService.localizeText("INFO_LIB_AVAL")
-                : "B" + (this.findBasinPosition(item.bassinAval) + 1);
+                : "B" + (this.model.findBasinPosition(item.bassinAval.uid) + 1);
             desc = upstreamBasinName + "-" + downstreamBasinName;
             // if a similar wall already exists, suffix !
             if (item.uid in this.wallsSuffixes) {
                 desc += " (" + this.wallsSuffixes[item.uid] + ")";
             }
         } else if (item instanceof PbBassin) {
-            desc = this.i18nService.localizeText("INFO_PB_BASSIN_N") + (this.findBasinPosition(item) + 1);
+            desc = this.i18nService.localizeText("INFO_PB_BASSIN_N") + (this.model.findBasinPosition(item.uid) + 1);
         } // else undefined
         return desc;
     }
@@ -408,17 +402,6 @@ export class PbSchemaComponent implements AfterViewInit, AfterContentInit, OnIni
         });
     }
 
-    private findBasinPosition(basin: PbBassin): number {
-        let i = 0;
-        for (const b of this.model.bassins) {
-            if (b === basin) {
-                break;
-            }
-            i++;
-        }
-        return i;
-    }
-
     // at this time @Input data is supposed to be already populated
     public ngOnInit() {
         this.model = this.pbSchema.pb;
@@ -508,14 +491,14 @@ export class PbSchemaComponent implements AfterViewInit, AfterContentInit, OnIni
     public get enableUpButton() {
         return (
             this._selectedItem instanceof PbBassin
-            && this.findBasinPosition(this._selectedItem) !== 0
+            && this.model.findBasinPosition(this._selectedItem.uid) !== 0
             && this.isStandaloneBasin(this._selectedItem)
         );
     }
 
     public onMoveBasinUpClick() {
         if (this._selectedItem instanceof PbBassin) {
-            this.model.moveBasin(this._selectedItem.uid, this.findBasinPosition(this._selectedItem) - 1);
+            this.model.moveBasin(this._selectedItem.uid, this.model.findBasinPosition(this._selectedItem.uid) - 1);
         }
         const basin = this._selectedItem;
         this.unselect();
@@ -530,14 +513,14 @@ export class PbSchemaComponent implements AfterViewInit, AfterContentInit, OnIni
     public get enableDownButton() {
         return (
             this._selectedItem instanceof PbBassin
-            && this.findBasinPosition(this._selectedItem) !== this.model.bassins.length - 1
+            && this.model.findBasinPosition(this._selectedItem.uid) !== this.model.bassins.length - 1
             && this.isStandaloneBasin(this._selectedItem)
         );
     }
 
     public onMoveBasinDownClick() {
         if (this._selectedItem instanceof PbBassin) {
-            this.model.moveBasin(this._selectedItem.uid, this.findBasinPosition(this._selectedItem) + 1);
+            this.model.moveBasin(this._selectedItem.uid, this.model.findBasinPosition(this._selectedItem.uid) + 1);
         }
         const basin = this._selectedItem;
         this.unselect();