deltaH=abs(GM_Visbeck_depth)-abs(rF(k))
deltaH=min(deltaH,drF(k))
deltaH=max(deltaH,zero_rs)
deltaH=deltaH/GM_Visbeck_depth
VisbeckK(i,j,bi,bj)=VisbeckK(i,j,bi,bj)+deltaH
_RL deltaH,zero_rs