diff --git a/DESCRIPTION b/DESCRIPTION
index 4587a6a55e7998daa06c060272935115824a12a4..5beae2942775f271ff22d54b42ac6cb83e048eae 100644
--- a/DESCRIPTION
+++ b/DESCRIPTION
@@ -1,8 +1,8 @@
 Package: airGR
 Type: Package
 Title: Suite of GR Hydrological Models for Precipitation-Runoff Modelling
-Version: 1.2.16.20
-Date: 2019-06-06
+Version: 1.2.16.21
+Date: 2019-06-07
 Authors@R: c(
   person("Laurent", "Coron", role = c("aut", "trl"), comment = c(ORCID = "0000-0002-1503-6204")),
   person("Olivier", "Delaigue", role = c("aut", "cre"), comment = c(ORCID = "0000-0002-7668-8468"), email = "airGR@irstea.fr"),
diff --git a/NEWS.rmd b/NEWS.rmd
index 36d879a1c604e230a657c312d09f9e1cd2cab61f..7f29321397e966716a75e6431b71215f400e019e 100644
--- a/NEWS.rmd
+++ b/NEWS.rmd
@@ -14,7 +14,7 @@ output:
 
 
 
-### 1.2.16.20 Release Notes (2019-06-06)
+### 1.2.16.21 Release Notes (2019-06-07)
 
 
 #### New features
diff --git a/R/plot.OutputsModel.R b/R/plot.OutputsModel.R
index 42d5fbabfb5b7faf002d7b1636fe06a2500fd162..6c0355f609dfbe06c1eb0cd15f01b5d272035878 100644
--- a/R/plot.OutputsModel.R
+++ b/R/plot.OutputsModel.R
@@ -582,6 +582,11 @@ plot.OutputsModel <- function(x, Qobs = NULL, IndPeriod_Plot = NULL, BasinArea =
          panel.first = abline(h = 0, col = "royalblue"), ...)
     axis(side = 2, at = pretty(ylim1), labels = pretty(ylim1), cex.axis = cex.axis, ...)
     mtext(side = 2, paste("flow error", plotunit), cex = cex.lab, line = line)
+    if (!is.null(BasinArea)) {
+      Factor <- Factor_UNIT_M3S
+      axis(side = 4, at = pretty(ylim1*Factor)/Factor, labels = pretty(ylim1*Factor), cex.axis = cex.axis, ...)
+      mtext(side = 4, paste("flow error", "[m3/s]"), line = line, cex = cex.lab)
+    }
     if (BOOL_Dates) {
       axis(side = 1, at = Seq1, labels = FALSE, cex.axis = cex.axis, ...)
       axis(side = 1, at = Seq2, labels = Labels2, lwd.ticks = 1.5, cex.axis = cex.axis, ...)