Mutation analysis of annual sediment discharge at Wu Long station in Wu Jiang River Basin from 1960 to 2016.

Peng Chen,Guangming Tan,Rouxin Tang,Quanxi Xu,Jinyun Deng,Jan Nyssen

doi:10.1371/journal.pone.0225935

Abstract

This article introduces a new method for mutation detection, the approximate entropy method, which is based on the complexity of time series. The mutation of average annual sediment discharge in Wu Jiang River Basin from 1960 to 2016 is detected by the introduced approximate entropy method, and compared with the results of double cumulative curve method and B-G segmentation algorithm. The mutation physical mechanism of the sediment discharge is discussed from the aspects of sediment source, annual distribution and interannual variation, climate change, impact of water conservancy and water conservation projects on sediment transport. The results show that mutation points occurred at 1984 and 2008 at Wu Long station, and the sediment discharge has a significant change after 2008. The mutation of average annual sediment discharge in Wu Jiang River Basin is caused by both climate change and human activity. Sediment reduction effect of the hydraulic engineerings built since 1990s climate is main and direct, and the climate change have secondary effect on sediment discharge change.

Highlights

Knowledge of the transfer of sediment through river systems is essential for understanding the physical, chemical and biological processes on the Earth’s surface [1]
Based on the approximate entropy method (ApEn) method, the mutation year of sediment discharge time series during 57 years at Wu Long station is detected, and the significance level of ApEn annual sediment discharge is tested by sliding t test (Confidence level was |T0.05/2| = 2) (Table 1)
The detection results show that the annual sediment discharge has undergone two mutations in recent 57 years at Wu Long station of Wu Jiang River, occurred in 1984 and 2008, and the ApEn significant levels of sediment discharge in 1984 and 2008 are -2.113 and -4.308, respectively, which have passed the test

Summary

Introduction

Knowledge of the transfer of sediment through river systems is essential for understanding the physical, chemical and biological processes on the Earth’s surface [1]. The factors affecting sediment yield and sediment transport can be divided into natural and anthropogenic [2,3,4]. Among these factors, human activities have significantly altered global river sediment transport regimes across the planet [5,6]. The river can be divided into two parts: the upper stream above the city of Yichang, and the midlower stream from Yichang to the ocean.

Methods

Results

Discussion

Conclusion