The cumulative load curves (CLCs) was used to examine the
first-flush (the increasing rate of nutrient loads is above that of
runoff) during the rainfall events (Deletic, 1998; Lee and Bang,
2000; Sansalone and Cristina, 2004). This method plots cumulative
runoff ratio on the horizontal axis and cumulative load ratio on the
vertical axis.
where Q is the runoff and P is the nutrient load. [Pi/PPi]/[Qi/
PQi]>1 means that the cumulative load ratio is above the 45 straight line
(positive deviation), i.e., first-flush. The strength of the first-flush
was calculated using the ‘‘pollutogram” approach developed by
Rossi et al. (2005):