ABSTRACT
Almost a century of experience has powerfully illuminated understanding of the nature of fluvial geomorphological hazards in the mountains, hills and alluvial plains of Los Angeles County. The main processes (summarised in Fig. 1.1) are primarily activated by mid-winter storms which attack a landscape that is different from that attacked by their precedessors. The effects of storms in any one season reflect the nature of the storms, the antecedent environmental changes, the contemporary spatial variations of landscape characteristics, and the diverse ways in which communities and management agencies respond to the hazards. Some of these complex circumstances are
