Scaling behaviour of twenty catchments in New South Wales in relation to regional flood frequency analysis

Flooding remains a major concern for New South Wales (NSW), Australia, impacting infrastructure, communities, and ecosystems. This paper investigates the scaling behaviour of 20 catchments in state of NSW, examining the relationship between catchments area (A) and peak discharge (Q) and the scaling exponent that governs the relationship between catchment size and peak flow. The results show that the scaling exponent varies widely for the study catchments. The value of the scaling component varies in the range of -0.73 to 2.12 (mean = 0.50 and standard deviation = 1.16). The results show that the generally recommended exponent of 0.7 is not applicable to the study data set. The relative error of estimation of the highest flow in two of the ten paired catchments is in the range of -79% to 175% (mean = -6.72% and standard deviation of 73.31%). Further study is needed to validate the scaling exponent using a greater number of catchments across Australia. The first author has adopted a project-based learning method in understanding statistical hydrology concepts presented in this paper.