Channel changes on the lower Cañada del Oro 1936-1980, and policies of flood plain management

Abstract

Maps of the lower Canada del Oro from aerial photographs taken between 1936 and 1980 show two periods of narrowing separated by one period of widening. Extensive channelization projects since 1959 have altered the naturally braided channel. Flood plain management regulations rely on maps of areas predicted to be flooded in the 100-year event. Changes in width, depth, and pattern of the stream alter the areas prone to overbank flooding. Although restricting development on the flood plain in this rapidly growing area could cut property losses in future floods, expensive structural projects to prevent bank erosion and lateral migration of the channel have proved to be more feasible politically.