Relationships of flow and basin variables on the island of Newfoundland, Canada with a regional application

Abstract

A hydrological study of the island of Newfoundland (Canada) was carried out to identify the key basin characteristics associated with a range of flow measures and to assess the potential for improving flow estimates at ungauged sites using various regionalization methods. The data set was the natural flow records of 40 stations on the island with record lengths of more than ten years. The research included a detailed assessment of the flow records, selection and computation or abstraction of appropriate flow and basin variables, analysis of the relationships of the flow measures to basin characteristics, grouping of the basins (for flood analysis only) into regions of geographic and basin characteristic dataspace, development of predictive equations for all groups, and assessment of the effectiveness of the regionalization methods. A procedure was developed in this work for estimating the effective precipitation in ungauged basins from geographic and topographic variables. -- The most important explanatory variables were found to be drainage area, area controlled by lakes and swamps, fraction of barren area in the basin, and distance of the basins north and/or southwest of defined lines. A detailed assessment of five methods of regional subdivision carried out using the mean annual maximum daily flow as the measure of interest found that dividing the island into regions generally improves the estimates at ungauged sites. Clustering based on basin characteristics is a promising method of regionalization.