diff --git a/src/2d/bottom_friction.F90 b/src/2d/bottom_friction.F90
index 7f9ebafbfcf5d111218aa5c68ac7ea065a53288c..ad9ed9fc6a8060677999d2f929055d5a7597fb52 100644
--- a/src/2d/bottom_friction.F90
+++ b/src/2d/bottom_friction.F90
@@ -85,6 +85,10 @@
 !$OMP          FIRSTPRIVATE(j)                                         &
 !$OMP          PRIVATE(i,vel,cd,it,z0d)
 
+
+!  KK-TODO: the present implementation sets normal velocity outside open
+!           bdy cell to zero (we need proper mirror)
+
 !  zonal velocity
 !$OMP DO SCHEDULE(RUNTIME)
 #ifndef SLICE_MODEL
diff --git a/src/3d/variables_3d.F90 b/src/3d/variables_3d.F90
index 270dabce52906b75b7e4a957840425467d4aaaa5..f0744c3b52d0c15579fd2736856b5dd454cd0950 100644
--- a/src/3d/variables_3d.F90
+++ b/src/3d/variables_3d.F90
@@ -195,6 +195,7 @@
    ssen = _ZERO_ ; ssun = _ZERO_ ; ssvn = _ZERO_
    Dn = _ZERO_ ; Dun = _ZERO_ ; Dvn = _ZERO_
 
+   zub = -9999.0 ; zvb = -9999.0 ! must be initialised for gotm
    if (bottfric_method .eq. 1) then
       rru = rdrag
       rrv = rdrag
diff --git a/src/domain/domain.F90 b/src/domain/domain.F90
index 937f44e530068d990a5f2482c1a1001e4acb85aa..6d79ac17933d1501106c99d0c61c2ee57721772f 100644
--- a/src/domain/domain.F90
+++ b/src/domain/domain.F90
@@ -395,6 +395,7 @@
             call getm_error("init_domain()", &
                             "non-positive bottom roughness");
          end if
+         z0 = z0_const
          zub0 = z0_const
          zvb0 = z0_const
       case(3)
@@ -422,7 +423,7 @@
          end do
       case default
          call getm_error("init_domain()", &
-                         "A non valid z0 method has been chosen");
+                         "A non valid bottfric method has been chosen");
    end select
    if (bottfric_method.eq.2 .or. bottfric_method.eq.3) then
       if (cd_min .gt. _ZERO_) then
@@ -433,6 +434,11 @@
       if (z0d_iters .gt. 0) then
          LEVEL3 'iterations for dynamic bottom roughness: ',z0d_iters
       end if
+   else
+#ifndef CONSTANT_VISCOSITY
+      call getm_error("init_domain()", &
+                      "consistency with GOTM requires quadratic bottom friction");
+#endif
    end if
 
 #ifdef DEBUG