A Study on the Variations and Relationships between Water and Sediment in the Longchuan River, China

Abstract

Runoff and sediment transport rates are important indicators for guiding regional economic development and ecological protection. It is important to clarify the dynamic evolution processes and inner connection of runoff and sediment transport rate for the rational development of soil and water resources in Longchuan River. In this study, the Mann-Kendall test, wavelet analysis and synchronization analysis have been used to analysis the change trend, mutation situation and variation cycles of runoff and sediment transport rate. The results showed that: runoff volume was generally stable, and sediment transport rate experienced a significant increasing trend at a rate of 4.29 kg/s/a in 1970-2008 in Longchuan River. The change cycles of runoff volume and sediment transport rate were different. The first principal cycles of seasonal and annual runoff volume were all 25a, while the second and third principal cycles were different. In contrast, the first and second principal cycles of sediment transport rate were respectively 29a and 6a. There was a significant linear relationship between sediment transport rate and runoff although the relationship between water and sediment was only synchronous in 1991-2008.