Index: DamEngine/trunk/src/Deltares.DamEngine.Data.Tests/Geometry/GeometryDataTests.cs
===================================================================
diff -u -r5080 -r5264
--- DamEngine/trunk/src/Deltares.DamEngine.Data.Tests/Geometry/GeometryDataTests.cs	(.../GeometryDataTests.cs)	(revision 5080)
+++ DamEngine/trunk/src/Deltares.DamEngine.Data.Tests/Geometry/GeometryDataTests.cs	(.../GeometryDataTests.cs)	(revision 5264)
@@ -518,4 +518,53 @@
             geometryData.Surfaces.Add(new GeometrySurface());
         }
     }
+
+    [Test]
+    public void GivenGeometryData_WhenGetNextTopCurve_ThenReturnsExpectedCurve()
+    {
+        var geometryData = new GeometryData
+        {
+            Left = 0.0,
+            Right = 100.0
+        };
+        var leftCurve = new GeometryCurve(new Point2D(0.0, 10.0), new Point2D( 5.0, 200.0));
+        var curve = new GeometryCurve(new Point2D(5.0, 10.0), new Point2D( 6.0, 10.0));
+        var connectedCurveLow = new GeometryCurve(new Point2D(6.0, 10.0), new Point2D( 8.0, 11.0));
+        var connectedCurveHigh = new GeometryCurve(new Point2D(6.0, 10.0), new Point2D( 8.0, 12.0));
+        var connectedCurveExcluded = new GeometryCurve(new Point2D(6.0, 10.0), new Point2D( 8.0, 13.0));
+        var boundaryCurves = new List<GeometryCurve>
+        {
+            leftCurve, // it is connected, but only curves on the right side are considered
+            curve, // the curve for which the next top curve is to be found
+            connectedCurveLow, // even though this is connected on the right side, it is not the highest
+            connectedCurveHigh, // this is the curve we are looking for
+            connectedCurveExcluded // even though this is the highest connected curve, it is excluded
+        };
+        var excludedCurves = new List<GeometryCurve>
+        {
+            connectedCurveExcluded
+        };
+        GeometryCurve topCurve = geometryData.GetNextTopCurve(curve, boundaryCurves, excludedCurves);
+        Assert.That(topCurve, Is.EqualTo(connectedCurveHigh));
+    }
+    
+    [Test]
+    public void GivenRightCurve_WhenGetNextTopCurve_ThenReturnsNull()
+    {
+        var geometryData = new GeometryData
+        {
+            Left = 0.0,
+            Right = 100.0
+        };
+        var curve = new GeometryCurve(new Point2D(5.0, 10.0), new Point2D( 100.0, 10.0));
+        var connectedCurve = new GeometryCurve(new Point2D(100.0, 10.0), new Point2D( 50.0, 20.0));
+        var boundaryCurves = new List<GeometryCurve>
+        {
+            curve,
+            connectedCurve
+        };
+        var excludedCurves = new List<GeometryCurve>();
+        GeometryCurve topCurve = geometryData.GetNextTopCurve(curve, boundaryCurves, excludedCurves);
+        Assert.That(topCurve, Is.Null);
+    }
 }
\ No newline at end of file
Index: DamEngine/trunk/src/Deltares.DamEngine.Data/Geometry/GeometryData.cs
===================================================================
diff -u -r5258 -r5264
--- DamEngine/trunk/src/Deltares.DamEngine.Data/Geometry/GeometryData.cs	(.../GeometryData.cs)	(revision 5258)
+++ DamEngine/trunk/src/Deltares.DamEngine.Data/Geometry/GeometryData.cs	(.../GeometryData.cs)	(revision 5264)
@@ -341,7 +341,7 @@
     /// <param name="boundaryCurves"></param>
     /// <param name="excludedCurves"></param>
     /// <returns>Curve</returns>
-    private GeometryCurve GetNextTopCurve(GeometryCurve curve, List<GeometryCurve> boundaryCurves,
+    protected internal GeometryCurve GetNextTopCurve(GeometryCurve curve, List<GeometryCurve> boundaryCurves,
                                           List<GeometryCurve> excludedCurves)
     {
         // if current curve ends on right limit then that must have been the last one so stop the search