diff --git a/mesh_generation/generate_mesh.py b/mesh_generation/generate_mesh.py
index 511d3b7..c9f92dc 100755
--- a/mesh_generation/generate_mesh.py
+++ b/mesh_generation/generate_mesh.py
@@ -48,32 +48,31 @@
 EARTH_R = 6.37122e6
 
 
-def mom6_mask_detection(ds, minimum_depth=None, masking_depth=None):
+def mom6_mask_detection(ds, minimum_depth=0, masking_depth=None):
     """
     Detect and generate an ocean mask (1 = wet, 0 = land) from a topog.nc.
     https://github.com/ACCESS-NRI/MOM6/blob/569ba3126835bfcdea5e39c46eeae01938f5413c/src/initialization/MOM_grid_initialize.F90#L1180
     """
 
+    # check arguments
     if "depth" not in ds:
         raise ValueError("Cannot detect topog: dataset lacks 'depth' variable!")
+    if minimum_depth < 0:
+        raise ValueError("minimum depth cannot be negative")
 
     depth = ds["depth"]
 
     # topog contains nans
     is_wet = ~np.isnan(depth)
 
-    if masking_depth is None and minimum_depth is None:
-        mask = is_wet
-    elif masking_depth is None:
-        mask = (depth > minimum_depth) & is_wet
-    elif minimum_depth is None:
-        mask = (depth > masking_depth) & is_wet
-    else:
+    if masking_depth is not None:
         if masking_depth > minimum_depth:
             raise ValueError(
                 "MASKING_DEPTH must be less than or equal to MINIMUM_DEPTH!"
             )
         mask = (depth > masking_depth) & is_wet
+    else:
+        mask = (depth > minimum_depth) & is_wet
 
     return mask.astype(np.int8).values
 
@@ -231,7 +230,7 @@ def __init__(
         lon_name=None,
         lat_name=None,
         area_name=None,
-        minimum_depth=None,
+        minimum_depth=0,
         masking_depth=None,
     ):
         """
@@ -324,7 +323,7 @@ def __init__(
         lon_name=None,
         lat_name=None,
         area_name=None,
-        minimum_depth=None,
+        minimum_depth=0,
         masking_depth=None,
     ):
         """
@@ -516,7 +515,7 @@ def main():
     parser.add_argument(
         "--minimum-depth",
         type=float,
-        default=None,
+        default=0,
         help=(
             "MINIMUM_DEPTH in metres. When a topography file is "
             "provided, any grid cell with depth <= MINIMUM_DEPTH is treated as land "
diff --git a/rof_pattern_generation/generate_rofi_pattern.py b/rof_pattern_generation/generate_rofi_pattern.py
index 41a0097..87656e5 100755
--- a/rof_pattern_generation/generate_rofi_pattern.py
+++ b/rof_pattern_generation/generate_rofi_pattern.py
@@ -128,6 +128,27 @@ def main():
         required=True,
         help="Path to the model topography file, which is used to generate the model mask.",
     )
+    regrid_aq.parser.add_argument(
+        "--minimum-depth",
+        type=float,
+        default=0,
+        help=(
+            "MINIMUM_DEPTH in metres. When a topography file is "
+            "provided, any grid cell with depth <= MINIMUM_DEPTH is treated as land "
+            "unless --masking-depth is also supplied."
+        ),
+    )
+    regrid_aq.parser.add_argument(
+        "--masking-depth",
+        type=float,
+        default=None,
+        help=(
+            "MASKING_DEPTH in metres. If set, cells with depth <= MASKING_DEPTH "
+            "become land, while cells with MASKING_DEPTH < depth < MINIMUM_DEPTH remain wet "
+            "but their depth will be raised to MINIMUM_DEPTH at runtime.  "
+            "If omitted, MINIMUM_DEPTH alone controls the land-sea mask."
+        ),
+    )
 
     regrid_aq.parse_cli()
 
@@ -162,7 +183,11 @@ def main():
 
     # find the ocean mask using the bathymetry
     topo = xr.open_dataset(regrid.args.topog_file)
-    mask = mom6_mask_detection(topo)
+    mask = mom6_mask_detection(
+        topo,
+        minimum_depth=regrid.args.minimum_depth,
+        masking_depth=regrid.args.masking_depth,
+    )
 
     # After doing the regridding, map any runoff on land cells into the ocean
     weights_da = move_runoff_on_land(