Stochastic point process modelling of rainfall .2. Regionalisation and disaggregation

The Neyman-Scott Rectangular Pulses rainfall model is fitted to daily and hourly data taken from 112 sites scattered throughout the UK. The model is regionalised by regressing estimates of the model parameters on harmonic and site variables, This allows the model to be applied to catchments where data do not exist or are limited. Percentage errors between the second-order properties at the 112 sites and those predicted by the regionalised model were found to be less than the sampling error (expressed as a percentage of the mean) typically found in a 20 year record of historical rainfall data, which suggests that the regionalised model can be used with reasonable confidence. A method of disaggregating the hourly rainfall time series to 5 min rainfall time series is further developed and tested. Thus, the regionalised model can be used to generate data with a resolution of 5 min if required. Some validation tests carried out with storm sewer system models indicate that the performance of the model is satisfactory for its intended application.