protected void Page_Load(object sender, EventArgs e)
        {
          
            using(var db = new Model1()){
                GridView3.DataSource = db.GeographicalKoordinates.Where(X =>
                X.Id_GeographicalKoordinates > 0).Select(Y=>Y.Koordinate).ToList();
            }
            GridView3.Visible = true;
        }

GridView.DataSource =db.Some.Where().Select().toList();

 GridView3.DataSource = FloodService.GetFloodEf().Select(y => y.Post.GeographicalKoordinate.KoordinateText).ToList();