Impact of rainfall characteristics on the NO3 - N concentration in a tailwater recovery ditch

•We examined how rainfall characteristics impacted NO3 – N concentrations in a tailwater recovery ditch.•Rainfall events were grouped into four classes by using the k-means clustering method.•NO3 – N concentrations were strongly dependent on duration of rainfall events.•NO3 – N concentrations were also strongly dependent on the characteristics of next-to-last rainfall events.•Rainfall characteristics have significant implications on the operation and management of TWR ditches.