Variations in the Characteristics of Water and Sediment in Response to Extreme Weather Conditions in the Qinjiang River of the Beibu Gulf

Small and medium-sized mountain rivers have characteristics of short processes, rapid flow rates, and quick responses to extreme weather, thereby playing an important role in the global marine geochemical cycle. Understanding the changes in water and sediment characteristics of small and medium-sized rivers in response to extreme weather can provide scientific support for disaster prevention and mitigation and channel management of river basins. This study analyzed data from the past 60 years to understand the variations in the characteristics of water and sediment in the Qinjiang River of the Beibu Gulf under extreme weather conditions by estimating their variation coefficients and contribution rates. The results of the analyses show the following: (1) The Qinjiang River has an average discharge of 32 and 290 m3/s in normal and tropical cyclone weather conditions, respectively. During a tropical cyclone year, the average flow rate is 9.06 times that during normal weather. The average sediment transport rates