The societal and economic losses due to compound extremes, i.e., extreme events often result from one extreme state or amplification due to other contributing mild or extreme states, are manifold higher in magnitude compared to the impacts of those from individual extremes alone. Information on the probability of occurrence and space-time prediction of compound events is necessary to assess the future risk. To understand the future impact of compound flood events at different spatio-temporal aggregation levels and climate zones, i.e., mountains, flood plains, and coasts, it is inevitable to examine the mechanisms of compound floods. To this end, this thesis highlights the importance of an integrated process-based physical modelling approach for the proper investigation of future flood risk. The research presented in this thesis cover several relevant topics related to a complete flood risk chain (from mountains to coasts) and their impact on water resources in regions around the world (i.e., Europe and Asia). This research bolsters the fact that the hazard of co-occurrence of high river discharge and coastal water levels cannot be neglected in a robust flood risk assessment. A new valuable insight on the mechanisms of compound floods and its potential impact on water resources (both for historical and future climate) has been gained with novel modelling approaches. The outcomes generated from this thesis contribute to support climate change adaptation policy planning and outreach programs in these climate change hotspots.