Identification and estimation of ecologically relevant flow indices for non-perennial rivers, South Africa
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Date
2019
Authors
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Journal ISSN
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Publisher
University of the Western Cape
Abstract
The importance of environmental flows and establishing the balance between hydrological
response and ecological functioning of rivers has been globally recognised. Methods for
determining environmental flows range from simplistic hydrological methods, to complex
holistic approaches. Extensive research has been conducted to understand the dynamics of
perennial rivers. However, non-perennial rivers remain among the least studied freshwater
systems. Although these rivers only flow during certain periods of the year, these river
systems are still of ecological significance. This study therefore aims to characterise the flow
regime of non-perennial rivers in an ecologically meaningful way and to assess the spatial
variation of these flow attributes. This study identified a subset of ecologically relevant flow
indices that provided the opportunity to characterise the flow regime in an ecologically
meaningful way, which was based on recommendations of previous studies. Redundancy
analysis was used in the study to assess factors that account for the spatial variation of
ecologically relevant flow indices of non-perennial rivers. The results identified that mean
annual rainfall and the slope equalled or exceeded 90 % of the time were the only catchment
characteristics found to be significant at explaining the variance of flow characteristics. The
final objective of the study explored methods that can be used to predict flow characteristics
in ungauged catchments. Most catchments around the globe are ungauged or poorly gauged,
which is a core issue in hydrology.
Description
>Magister Scientiae - MSc
Keywords
Environmental flow, Aquatic ecosystems, Hydrological regionalisation, Ungauged catchments, Cluster analysis