Investigating the interaction of waves and river discharge during compound flooding at Breede Estuary, South Africa

Abstract. Recent studies have drawn special attention to the significant dependencies between flood drivers and occurrence of compound events in coastal areas. This study investigates flooding from tides, river discharge (Q), specifically waves using a hydrodynamic model at Breede Estuary, South Africa. We quantify vertical horizontal differences characteristics caused by driver interaction assess contribution waves. Therefore, we compare resulting scenarios those which single are omitted. find that more sensitive Q than waves, particularly when latter only coincides with high spring tides. When interacting Q, however, is high, causing 10 %–12 % larger extents 45–85 cm higher water depths, as backwater effects raised levels inside lower reaches estuary. With wave intensity, first began up 12 h earlier. Our findings provide insights on terms magnitude timing African estuary demonstrate need account for events, including future impact assessments open estuaries.