diff --git a/raster/r.sim/r.sim.water/main.c b/raster/r.sim/r.sim.water/main.c
index 4272922f354..98c96c2f411 100644
--- a/raster/r.sim/r.sim.water/main.c
+++ b/raster/r.sim/r.sim.water/main.c
@@ -181,7 +181,7 @@ int main(int argc, char *argv[])
     parm.traps->key = "flow_control";
     parm.traps->required = NO;
     parm.traps->description =
-        _("Name of flow controls raster map (permeability ratio 0-1)");
+        _("Name of flow controls raster map (trapping probability 0-1)");
     parm.traps->guisection = _("Input");
 
     parm.observation = G_define_standard_option(G_OPT_V_INPUT);
diff --git a/raster/r.sim/r.sim.water/r.sim.water.html b/raster/r.sim/r.sim.water/r.sim.water.html
index bfb25e1e740..6e967bfe70d 100644
--- a/raster/r.sim/r.sim.water/r.sim.water.html
+++ b/raster/r.sim/r.sim.water/r.sim.water.html
@@ -66,10 +66,11 @@ <h2>DESCRIPTION</h2>
 <b>infil</b> or a single value <b>infil_value</b> in [mm/hr] that control the rate of
 infiltration for the already flowing water, effectively reducing the flow depth and
 discharge.
-Overland flow can be further controlled by permeable check dams or similar type of structures,
-the user can provide a map of these structures and their permeability ratio
-in the map <b>flow_control</b> that defines the probability of particles to pass
-through the structure (the values will be 0-1).
+Overland flow can be further controlled by permeable check dams or similar types of structures.
+The user can provide a map of these structures as <b>flow_control</b> with values 0-1
+that give the probability of a particle being trapped by the structure at each time step.
+A trapped particle is moved slightly back instead of forward, so a higher value means lower
+permeability, holding back more water and increasing the flow depth at the structure.
 
 <p>
 Output includes a water depth raster map <b>depth</b> in [m], and a water discharge
diff --git a/raster/r.sim/r.sim.water/r.sim.water.md b/raster/r.sim/r.sim.water/r.sim.water.md
index 8980e643ba7..37775d38121 100644
--- a/raster/r.sim/r.sim.water/r.sim.water.md
+++ b/raster/r.sim/r.sim.water/r.sim.water.md
@@ -58,10 +58,12 @@ overland flow infiltration rate map **infil** or a single value
 **infil_value** in \[mm/hr\] that control the rate of infiltration for
 the already flowing water, effectively reducing the flow depth and
 discharge. Overland flow can be further controlled by permeable check
-dams or similar type of structures, the user can provide a map of these
-structures and their permeability ratio in the map **flow_control** that
-defines the probability of particles to pass through the structure (the
-values will be 0-1).
+dams or similar types of structures. The user can provide a map of
+these structures as **flow_control** with values 0-1 that give the
+probability of a particle being trapped by the structure at each time
+step. A trapped particle is moved slightly back instead of forward, so
+a higher value means lower permeability, holding back more water and
+increasing the flow depth at the structure.
 
 Output includes a water depth raster map **depth** in \[m\], and a water
 discharge raster map **discharge** in \[m3/s\]. The **error** raster map