River channel typology : an numerical approach using case studies of the River Wye and the Highland Water

Zhang, Yu (1991) River channel typology : an numerical approach using case studies of the River Wye and the Highland Water. University of Southampton, Doctoral Thesis.

Record type: Thesis (Doctoral)

Abstract

River channel typology developed by classification of river channels and with allowance for channel change involves consideration of morphological features, the details of channel processes and states, and the nature of adjustment in a fluvial system. River channel typology has become an important and necessary theme for meeting the demands of current research in geomorphology, hydrology, environmental studies and river engineering in order to develop the understanding of fluvial system for river catchment planning and river management. Previous progress in identification of channel typology indicates that channel classification has been mainly based on the relationship between forms and processes. A literature review introduces the possibility of developing a channel typology based upon energy dissipation and stream power. Specifically, there is a prospect of using channel composite roughness to present channel typology in terms of energy state and channel potential stability according to the concepts of minimum energy dissipation and geomorphological thresholds. Six rivers were selected for a pilot study in order to investigate the significance of channel roughness in reaction to channel typology. The Cowan-Chow method is used for the estimation of a composite roughness value. Channel roughness changes in response to variations in channel characteristics as indicated by analysis of histograms of component roughness change. The River Wye in mid-Wales is used as a major study area for developing a channel classification system and for establishing the relationship between channel types and flow energy dissipation patterns quantified by channel roughness values. A technique exploring the use of documentary and field sources of information is developed to give a database of channel typology which includes sixteen data fields related to drainage basin characteristics, channel morphological and process features, ecological influences and human activity. Factor analysis and cluster analysis of this data are employed to achieve a numerical approach to channel classification of the River Wye.

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