Demarcating paleoflood repositories using documentary evidence and flood geomorphic landforms

Abstract

A reconstruction of paleoflood stages reflects the magnitude and frequency of historic floods. Sediment-filled landforms store centuries-old paleoflood data, allowing examination of past events, though river changes and human activities can obscure these valuable records. Hence, identifying the plausible locale for collecting the sediment core is cumbersome. The present research proposes a methodological approach for precisely identifying the repositories. The Cauvery Delta, the largest sediment deposit on Tamil Nadu's eastern coast, is chosen for the study. The study's methodology is structured into: (1) reconstructing a catalogue of significant flood events using documentary records; (2) mapping fluvial geomorphic landforms using satellite images; (3) spatially correlating the records obtained from documentary sources with landforms, and (4) identifying flood geomorphic landforms (FGL) and demarcating promising prospective locales for future chronological studies. It has been observed that the Cauvery River has experienced recurrent instances of flooding throughout the past 8000 years. The FGL mapped using digitally processed satellite images displayed 17 types of landforms. Subsequently, the FGL are precisely identified by spatially integrating documentary data with landforms. Braided bar, channel bar, lateral bar, channel islands, natural levees, paleochannels, older flood plains, point bars, oxbow lakes, and water bodies are the most promising FGL for paleoflood research.