An investigation of compound riverine flooding and the influence of anthropogenic drivers within large-scale catchments.

Water has always been an essential part of human life. It is necessary for every human activity and process. However, this life-sustaining resource can also cause mass destruction and loss of life. As populations grow and floods occur more frequently and at a larger scale, it becomes increasingly crucial to comprehend the variables and processes that surround flood events. Understanding these factors can help us mitigate the risks associated with floods and minimize their impact on communities. This dissertation consists of six chapters which cover two aspects of flooding. The first aspect deals with the sources of flooding events in a multi-regional basin. The second aspect concerns the impact of anthropogenic activity on flooding processes. In the first two chapters, the research motivation is presented, accompanied by a general review of the concepts that govern the research performed. Chapter three provides a statistical analysis of flood incidents based on their location and the prevailing weather conditions. The results of this chapter indicate that there has been a 6% annual increase in flooding each year across the basin of interest, with a staggering 770% increase in the last four years of the study. The main source of this increase is the lower level flood events, which are often the result of human development. Another notable observation in this chapter is that the majority of weather events that led to flooding were non-tropical in nature. Chapter four examines the relationship between land use and flooding by utilizing various statistical and machine learning techniques to identify the types of land use that contribute the most to flooding within the basin. Findings from this chapter include the loss of croplands across the entire basin, with an almost 1:1 replacement with open water surface and urban area, two land uses that produce the most runoff in precipitation events. In chapter five, we present a numerical model of the lower James River Basin in Virginia, which serves as a tool to assess the impact of land use modifications on flooding in the area. From 2004 to 2021, the basin lost over 13-million cubic meters of storage. Finally, chapter six provides an overview of future work and guidance in this area.