TY - JOUR AU - NA Rivers-Moore, AU - RE Schulze, AU - NS Davis, PY - 2020/07/28 Y2 - 2024/03/29 TI - A regional flow type classification for South African perennial rivers JF - Water SA JA - WSA VL - 46 IS - 3 July SE - Research paper DO - 10.17159/wsa/2020.v46.i3.8648 UR - https://watersa.net/article/view/8648 SP - AB - <p>Flow classification provides a statistically robust method of defining an expected range of variability for flow metrics describing frequency, magnitude, duration and timing of events.&nbsp; Here, we characterised reference mean daily flows for 1950–1999 for all 5 838 quinary catchments of South Africa based on 150 metrics.&nbsp; Using a two-tiered approach, where sub-catchments were classified into similar flow types using principal components and cluster analyses, we defined 6 to 12 flow types for each of 8 hydrological regions reflecting rainfall seasonality.&nbsp; Redundancy between variables was 87% on average, so that site variability could be accounted for using 8–28 metrics.&nbsp; In general, flow volume metrics accounted for Axis 1 variability, while coefficients of dispersion had 1.8 times less leverage in Axis 2.&nbsp; With the incorporation into a spatial product and an associated database, this study provides a basis for defining statistically robust reference flow conditions for multiple flow metrics, against which current observed flows at specific sites may be compared.</p> ER -