Paleoflood hydrology is a technique that combines elements of geology and surface water hydrology to reconstruct magnitude- frequency characteristics of floods that occurred prior to direct measurement or systematic observation. Slackwater deposit- paleostage indicator (SWD-PSI) paleoflood studies use specific evidence of flooding to define paleoflood levels in stable (bedrock-controlled) channel environments and use hydraulic modeling and geochronological methods to reconstruct the magnitude and frequency of individual flood events. Regional SWD-PSI studies provide data that are indispensable in relating spatial and temporal variations in flood frequency to global-scale variations in climatic conditions over long time period (1000s of years). We are proposing to establish a systematic method for incorporating paleoflood data into a hydroclimatological context to aid in understanding fundamental linkages between global climate and regional flood frequency. This method will rely on detailed analysis of observed hydroclimatic data sets to develop a scale- sensitive, circulation-based conceptual framework for use in assessing hydroclimatic variability over time scales represented by paleoflood records. In the course of development, we plan to use this method to address the flood-climate linkage in areas particularly sensitive to climatic variations. The methods will also be used in a continuation of research on the relationship between the regional paleoflood characteristics of Arizona and global climatic variations over the past 5000 years. Our work in southern Arizona will focus on small drainage basins(<25km2) to augment previous studies in the region that have focused on considerably larger basins subject to flooding from different hydroclimatologic mechanisms. The results of our proposed research will offer important new insights into the response of extreme events to climatic variation and may have important implications for future changes in global climate.
