Index: doc/wflow_sbm.rst
===================================================================
diff -u -r934e81e3af5db3b226cf5e66a9c4ace3fe47990b -r6274a2fdab2114bbbeeefb937d8d309faaa8f629
--- doc/wflow_sbm.rst	(.../wflow_sbm.rst)	(revision 934e81e3af5db3b226cf5e66a9c4ace3fe47990b)
+++ doc/wflow_sbm.rst	(.../wflow_sbm.rst)	(revision 6274a2fdab2114bbbeeefb937d8d309faaa8f629)
@@ -372,7 +372,16 @@
    the kinematic wave reservoir
 
 
+Lower zone and leakage
+~~~~~~~~~~~~~~~~~~~~~~
 
+If the parameter MaxPercolation is set > 0 this is used to transfer water from the bottom of the
+FirstZone to a HBV-type groundwater reservoir (LowerZone). The K4 parameter is used to set the
+recession rate of the lower zone.
+
+Alternativeli a MAxLeage paramter may be se > 0. IN that case the water is lost from the FirstZoen and
+not transferred to the LowerZone.
+
 Soil temperature
 ~~~~~~~~~~~~~~~~