Changes in Major Global River Discharges Directed into the Ocean

Xiaoqing Shi; Tianling Qin; Hanjiang Nie; Baisha Weng; Shan He

doi:10.3390/ijerph16081469

Changes in Major Global River Discharges Directed into the Ocean

Int J Environ Res Public Health. 2019 Apr 25;16(8):1469. doi: 10.3390/ijerph16081469.

Authors

Xiaoqing Shi^{1

2}, Tianling Qin³, Hanjiang Nie^{4

5}, Baisha Weng⁶, Shan He⁷

Affiliations

¹ State Key Laboratory of Simulation and Regulation of Water Cycle in River Basin, China Institute of Water Resources and Hydropower Research, Beijing 100038, China. sxq18@mails.tsinghua.edu.cn.
² Department of Hydraulic Engineering, Tsinghua University, Beijing 100084, China. sxq18@mails.tsinghua.edu.cn.
³ State Key Laboratory of Simulation and Regulation of Water Cycle in River Basin, China Institute of Water Resources and Hydropower Research, Beijing 100038, China. qintl@iwhr.com.
⁴ State Key Laboratory of Simulation and Regulation of Water Cycle in River Basin, China Institute of Water Resources and Hydropower Research, Beijing 100038, China. nhj16@mails.tsinghua.edu.cn.
⁵ Department of Hydraulic Engineering, Tsinghua University, Beijing 100084, China. nhj16@mails.tsinghua.edu.cn.
⁶ State Key Laboratory of Simulation and Regulation of Water Cycle in River Basin, China Institute of Water Resources and Hydropower Research, Beijing 100038, China. wengbs@iwhr.com.
⁷ State Key Laboratory of Simulation and Regulation of Water Cycle in River Basin, China Institute of Water Resources and Hydropower Research, Beijing 100038, China. hsiwhr61@163.com.

Abstract

Under the influence of global climate change, the discharges of major global rivers directed into the ocean have undergone significant changes. To study the trends and causes in discharge variation, we selected 40 large rivers and analyzed their annual discharges near their estuaries from 1960 to 2010. The method of runoff variation attribution analysis based on the Budyko hypothesis for large-scale basins was developed, in which influencing factors of human activities and glacial melting factors were added to the formula. The contribution rate of climate factors and human activities to changes in discharge were quantitatively identified. Climatic factors include precipitation, evapotranspiration and glacial melting. Human activity factors include underlying surface and artificial water transfer. The contribution rate is determined by the elastic coefficient, which is obtained by the ratio of change rate of each factor and the change rate of runoff. The results indicated that the discharges predominantly showed downward trends with a few upward trends. Rivers in North America and Africa showed downward trends, and those in Europe principally showed upward trends. Climate was the main influencing factor of discharges changes, and only approximately 25% of river discharges were greatly affected by human activities. River discharges in 75% of the basins which mainly contains subtropical monsoon humid climate and savanna climate zones showed upward trends. In the four basins which are mainly contains tropical rainforest climate and tropical monsoon climate, they all showed downward trends. The trend of discharges in the temperate monsoon climate, temperate continental climate, and temperate maritime climate cannot be accurately judged because of irregular variation. The discharges in the mid-high latitudinal zones predominantly showed upward trends, while those in the mid-low latitudinal zones with the influence of human activities showed downward trends.

Keywords: climate change; human activities; river discharges; spatial distribution; trend.

Publication types

Research Support, Non-U.S. Gov't

MeSH terms

Climate Change*
Environmental Monitoring / methods*
Environmental Monitoring / statistics & numerical data*
Humans
Oceans and Seas*
Rivers / chemistry*
Seawater / chemistry*