Channel changes due to river regulation: the case of the Piave River, Italy

Abstract

This paper deals with the channel changes of the Piave River in the Eastern Alps, Italy, which have occurred during this century in response to human interventions in the fluvial system. The flow regime and the sediment supply of the river have been considerably altered by hydroelectric dams, flow diversions and gravel mining. In addition, river dynamics have been affected by the construction of streambank protection structures. To document these changes, a historical analysis was performed using maps and aerial photographs. Morphological features that were examined included planform configuration, channel width, braiding index and bed elevation. The results indicate that as a consequence of decreases in the flows and sediment supply, remarkable channel changes have occurred in the river during this century, especially during recent decades. The channel has undergone a general narrowing with a decrease in average width to 35 per cent of its initial value, while the braiding index has decreased from about 3 to 1·5. In several reaches the planform pattern has changed from braided to wandering. The observed trends of channel change suggest that the river has not yet reached a new equilibrium condition and it may, therefore, be predicted that reductions in width and braiding intensity are likely to continue in the immediate future. Copyright © 1999 John Wiley & Sons, Ltd.