RIVER PATTERNS AND SPATIAL AND TEMPORAL TRANSFORMATION MODES

Five main modes of spatial transformation of the river patterns and various factors influencing the river systems are discussed in the paper. Representative rivers in China and other countries demonstrate the river pattern transformation in response to some controlling factors. Furthermore, the fluvial processes are studied with historic fluvial deposits in ancient rivers. It is found that there are certain relationships between the modern spatial transformation and the ancient temporal evolution in some river systems. The anastomosing river pattern and its deposits are analyzed with the drilled core samples. Various spatial transformation modes of river patterns have been reported and different temporal evolution modes have been recorded in sediments of the ancient rivers. The braided-meandering transformation, either spatial or temporal, is found to occur more often than other modes. The main factors controlling the spatial transformation and temporal evolution of the river patterns are geotectonic characteristics, sea level fluctuation, climate change, vegetation, composition of sediment in banks and floodplains, flow discharge and sediment load. The order of these factors differs for transformation modes under different conditions.