Fix UK drainage for very early applications

Create a function `drainage_date_UK` that does not only respect the
beginning of the drainage period on 1 October, but also the end of the
drainage period on 30 April, and use it for determining the degradation
time. Applications early in the year before 1 May will now correctly be
calculated without degradation time.

1 files changed, 1 insertions, 0 deletions

diff --git a/NAMESPACE b/NAMESPACE
index 2daa348..499e471 100644
--- a/NAMESPACE
+++ b/NAMESPACE
@@ -28,6 +28,7 @@ export(SSLRC_mobility_classification)
 export(TOXSWA_cwa)
 export(TSCF)
 export(chent_focus_sw)
+export(drainage_date_UK)
 export(drift_percentages_rautmann)
 export(endpoint)
 export(geomean)