private void RunRiver(TWorld world, CellAddress springLocation)
        {
            var rnd = new Random(world.Seed + "rivers".GetHashCode());

            var current = springLocation;

            var river = new River();

            var previousSegment = (RiverSegment)null;

            while (!IsOcean(current.X, current.Y, world))
            {
                var currentCell = world.GetCell(current.X, current.Y);

                if (currentCell.RiverSegmentHere != null)
                {
                    // Now a tributary
                    if (river.Segments.Count >= RIVER_MIN_LENGTH)
                    {
                        currentCell.RiverSegmentHere.PreviousSegments.Add(previousSegment);
                        previousSegment.NextSegment = currentCell.RiverSegmentHere;

                        river.TributaryOf = currentCell.RiverSegmentHere.ParentRiver;
                        //world.AddRiver(river);

                        AddFlow(currentCell.RiverSegmentHere, 1);

                        return;
                    }

                    //Too short, abort
                    return;
                }

                previousSegment = river.AddSegment(current, previousSegment);

                current = PickNextLocation(world, current, river, rnd);

                if (current == null)
                {
                    //Dead end, abort
                    return;
                }
            }

            //Add the current location to the end of the river.
            river.AddSegment(current, previousSegment);

            if (river.Segments.Count < RIVER_MIN_LENGTH)
            {
                //Too short, abort
                return;
            }

            //Add river to world
            //world.AddRiver(river);
        }