Flood Hydrology and Geomorphology of Monsoon-dominated Rivers: The Indian Peninsula

ABSTRACT

The rivers of the southern part of the Indian Peninsula are monsoonal in nature and the hydrological characteristics of these rivers djffer markedly from those of Himalayan rivers. The rivers are subjected to severe floods during the monsoon season. In the last few decades, several large-magnitude floods (peak floods between 10,000 and 80,000 m³/s) have been recorded. In general, floods caused by precipitation from Bay of Bengal depressions include the peak flood of record. Analyses of the systematic, historical, and paleoflood records indicate that, in recent decades, the frequency of high-magnitude floods has increased significantly. Hydraulic estimates reveal that high flows are capable of bedrock erosion and transportation of coarse material.

Such large floods are important, not only from the standpoint of geomorphic work, but also in terms of social impact. Floods in the peninsular region are responsible for colossal loss of human life, crops, and property. In recent years, various measures offlood control and management have been adopted. However, flooding in such large rivers profoundly challenges flood-hazard management, because of the inadequacy of conventional data and high spatio-temporal variability of floods. To understand flood hazards and environmental change it is imperative that engineers and hydrologists utilize historical and paleoflood records to improve risk analyses as well as to estimate probable maximum flood on rivers such as these in a highly flood-prone region.