Volume-duration growth curves for flood estimation in permeable catchments

Abstract

The volume and duration of groundwater discharge following extreme winter recharge events in permeable catchments can often be more disruptive than the peak discharge. An estimation procedure for annual maxima flood series in permeable catchments is extended to annual flood volumes for different durations. Growth factors for durations of 1 to 30 days and return periods of up to 250 years are derived for a sample of 12 permeable catchments in the UK. In most cases, adjusting the growth curves for ‘non-flood’ years has only a small effect and L-moment parameters show little change with duration. L-CV and L-skewness are highly correlated for the sample of Chalk catchments. Keywords: Chalk, groundwater flood estimation