UNST-9664: dambreak may not have effect on 1d links (#797)

* UNST-9664: dambreak  may not have effect on 1d links

* UNST-9664: blank space commit

* UNST-9664: Review comments

* UNST0-9664: review comment part 2

* move test_dflowfm_dambreak for new unit test setup

* UNST-9664: Kegen can contain negative values

---------

Co-authored-by: FlorisBuwaldaDeltares <floris.buwalda@Deltares.nl>

Author: jjnoort

src/engines_gpl/dflowfm/packages/dflowfm_kernel/src/dflowfm_kernel/compute/m_dambreak_breach.f90

@@ -50,7 +50,8 @@ module m_dambreak_breach
              have_dambreaks_links, should_write_dambreaks, set_flow_areas_for_dambreaks, &
              indicate_links_that_contain_dambreaks, get_active_dambreak_index, &
              get_dambreak_names, retrieve_set_of_flowlinks_dambreak, &
-             update_counters_for_dambreaks, add_dambreak_signal
+             update_counters_for_dambreaks, add_dambreak_signal, &
+             remove_1d_links_from_dambreak_polygon_list
 
    interface
       module subroutine adjust_bobs_for_dambreaks()
@@ -148,6 +149,11 @@ pure module function get_dambreak_names() result(names)
          character(len=128), dimension(:), allocatable :: names !< the dambreak names
       end function get_dambreak_names
 
+      pure module subroutine remove_1d_links_from_dambreak_polygon_list(numgen, kegen)
+         integer, intent(inout) :: numgen !< number of flow links in kegen
+         integer, dimension(:), intent(inout) :: kegen !< array with the link indices
+      end subroutine remove_1d_links_from_dambreak_polygon_list
+
    end interface
 
    ! This type was moved to the module level to work around a linker issue with intel oneapi 2025.3.2 and the gfortran linker on linux.

src/engines_gpl/dflowfm/packages/dflowfm_kernel/src/dflowfm_kernel/compute/m_dambreak_breach_submodule.f90

@@ -1269,4 +1269,36 @@ subroutine calculate_start_link_and_widths(dambreak, start_location_x, start_loc
       end do
 
    end subroutine calculate_start_link_and_widths
+
+   !> Remove 1D links and 1D2D longitudinal links from the dambreak polygon list.
+   !! This function filters out flow links that are not suitable for dambreak calculations
+   !! by examining the flow link type (kcu). Only 2D flow links and 1D2D lateral links
+   !! are retained in the list.
+   !!
+   !! Flow link types filtered out:
+   !! - kcu = 1: 1D flow links
+   !! - kcu = 4: 1D2D longitudinal flow links
+   !!
+   !! The function compacts the kegen array by removing unwanted links and updates
+   !! numgen to reflect the new count of valid links.
+   pure module subroutine remove_1d_links_from_dambreak_polygon_list(numgen, kegen)
+      use m_flowgeom, only: kcu
+      use network_data, only: LINK_1D, LINK_1D2D_LONGITUDINAL, LINK_1D2D_STREETINLET, LINK_1D2D_ROOF
+      integer, intent(inout) :: numgen !< number of flow links in kegen
+      integer, dimension(:), intent(inout) :: kegen !< array with the link indices
+      integer :: i, cell, numcells
+      numcells = 0
+      do i = 1, numgen
+         cell = abs(kegen(i))
+         ! remove 1d links and 1d2d longitudinal links from the dambreak polygon list.
+         select case (abs(kcu(cell)))
+         case(LINK_1D, LINK_1D2D_LONGITUDINAL, LINK_1D2D_STREETINLET, LINK_1D2D_ROOF)
+         case default
+            numcells = numcells + 1
+            kegen(numcells) = kegen(i)
+         end select
+      end do
+      numgen = numcells
+   end subroutine remove_1d_links_from_dambreak_polygon_list
+
 end submodule m_dambreak_breach_submodule

src/engines_gpl/dflowfm/packages/dflowfm_kernel/src/dflowfm_kernel/prepost/flow_init_structurecontrol_implementation.f90

@@ -26,6 +26,7 @@
 !  Deltares, and remain the property of Stichting Deltares. All rights reserved.
 !
 !-------------------------------------------------------------------------------
+
 !> submodule that contains the implementation of flow_init_structurecontrol.
 submodule(m_flow_init_structurecontrol) flow_init_structurecontrol_implementation
    use precision_basics, only: dp
@@ -53,7 +54,7 @@ module function flow_init_structurecontrol() result(status)
       use m_longculverts_data, only: nlongculverts
       use m_partitioninfo, only: jampi
       use messagehandling, only: IDLEN
-      use m_dambreak_breach, only: update_counters_for_dambreaks, update_dambreak_administration
+      use m_dambreak_breach, only: update_counters_for_dambreaks, update_dambreak_administration, remove_1d_links_from_dambreak_polygon_list
       use m_update_counters_for_structures, only: update_counters_for_dambreak_or_pump
       use m_1d_structures, only: update_bedlevels_for_bridges
 
@@ -122,6 +123,7 @@ module function flow_init_structurecontrol() result(status)
             ! NOTE: kegen below does not apply to general structures. Just a placeholder for the link snapping of all structure types.
             select case (pstru%type)
             case (ST_DAMBREAK)
+               call remove_1d_links_from_dambreak_polygon_list(numgen, kegen)
                num_dambreak_links = num_dambreak_links + numgen
                call update_counters_for_dambreaks(pstru%id, numgen, dambridx, i, kedb, kegen)
             case (ST_PUMP)

src/engines_gpl/dflowfm/packages/dflowfm_kernel/test/CMakeLists.txt

@@ -26,6 +26,7 @@ f90twtest(${test_target}
         src/test_ec_module_block.f90
         src/test_unstruc_model.f90
         src/test_mdu_file_read_write.f90
+        src/test_dflowfm_dambreak.f90
     F2HFILES
         ${CMAKE_CURRENT_SOURCE_DIR}/src/test_dflowfm_kernel_example.f90
         ${CMAKE_CURRENT_SOURCE_DIR}/src/test_3d_layer_administration.f90
@@ -37,6 +38,7 @@ f90twtest(${test_target}
         ${CMAKE_CURRENT_SOURCE_DIR}/src/test_ec_module_block.f90
         ${CMAKE_CURRENT_SOURCE_DIR}/src/test_unstruc_model.f90
         ${CMAKE_CURRENT_SOURCE_DIR}/src/test_mdu_file_read_write.f90
+        ${CMAKE_CURRENT_SOURCE_DIR}/src/test_dflowfm_dambreak.f90
     OUTDIR "${CMAKE_CURRENT_BINARY_DIR}"
     LIBRARIES dflowfm_kernel test_helpers
     VISUAL_STUDIO_PATH engines_gpl/dflowfm/test

src/engines_gpl/dflowfm/packages/dflowfm_kernel/test/src/test_dflowfm_dambreak.f90

@@ -0,0 +1,27 @@
+module test_dflowfm_dambreak
+   use assertions_gtest
+   implicit none
+
+contains
+
+   !$f90tw TESTCODE(TEST, test_skip_1d_flowlinks, test_skip_1d_flowlinks, test_skip_1d_flowlinks,
+   !> Test whether remove_1d_links_from_dambreak_polygon_list removes 1D flow links from the list of polygon vertices in a dambreak test case. This is necessary to prevent the 1D flow links
+   subroutine test_skip_1d_flowlinks() bind(C)
+      use precision, only: dp
+      use m_flowgeom, only: kcu
+      use m_dambreak_breach, only: remove_1d_links_from_dambreak_polygon_list
+      integer, parameter :: PATH_LENGTH = 2
+      integer :: num_cells
+      integer, dimension(:), allocatable :: cell_numbers
+      real(kind=dp), parameter :: tolerance = 1e-8_dp
+      real(kind=dp), dimension(PATH_LENGTH) :: x, y, running_distance, expected_running_distance
+
+      cell_numbers = [1, 2, 3, 4, 5, 6, 7, 8]
+      kcu = [2, 4, 2, 3, 1, 2, -1, -2 ]
+      num_cells = size(cell_numbers)
+      call remove_1d_links_from_dambreak_polygon_list(num_cells, cell_numbers)
+      call f90_expect_eq(num_cells, 5, "number of cells must be equal to 5")
+      call f90_expect_true(all(cell_numbers(1:num_cells) == [1, 3, 4, 6, 8]), "cells numbers must be equal to [1, 3, 4, 6, 8]")
+   end subroutine test_skip_1d_flowlinks
+   !$f90tw)
+end module test_dflowfm_dambreak