Homogenization and polarization of the seasonal water discharge of global rivers in response to climatic and anthropogenic effects

Yuanfang Chai; Yao Yue; Lin Zhang; Chiyuan Miao; Alistair G L Borthwick; Boyuan Zhu; Yitian Li; A J Dolman

doi:10.1016/j.scitotenv.2019.136062

Homogenization and polarization of the seasonal water discharge of global rivers in response to climatic and anthropogenic effects

Sci Total Environ. 2020 Mar 20:709:136062. doi: 10.1016/j.scitotenv.2019.136062. Epub 2019 Dec 18.

Authors

Yuanfang Chai¹, Yao Yue², Lin Zhang³, Chiyuan Miao⁴, Alistair G L Borthwick⁵, Boyuan Zhu⁶, Yitian Li⁷, A J Dolman⁸

Affiliations

¹ State Key Laboratory of Water Resources and Hydropower Engineering Science, School of Water Resources and Hydropower Engineering, Wuhan University, Wuhan 430072, China; Vrije Universiteit Amsterdam, Department of Earth Sciences, Boelelaan 1085, 1081 HV Amsterdam, the Netherlands.
² State Key Laboratory of Water Resources and Hydropower Engineering Science, School of Water Resources and Hydropower Engineering, Wuhan University, Wuhan 430072, China. Electronic address: yueyao@whu.edu.cn.
³ Independent Researcher, Churchtown Upper, Dublin, 999015, Ireland.
⁴ State Key Laboratory of Earth Surface Processes and Resource Ecology, Faculty of Geographical Science, Beijing Normal University, Beijing 100875, China.
⁵ School of Engineering, The University of Edinburgh, The King's Buildings, Edinburgh EH9 3JL, UK.
⁶ School of Hydraulic Engineering, Changsha University of Science & Technology, Changsha 410004, China.
⁷ State Key Laboratory of Water Resources and Hydropower Engineering Science, School of Water Resources and Hydropower Engineering, Wuhan University, Wuhan 430072, China.
⁸ Vrije Universiteit Amsterdam, Department of Earth Sciences, Boelelaan 1085, 1081 HV Amsterdam, the Netherlands; Nanjing University of Information Science and Technology, School of Geographical Sciences, Nanjing, China.

PMID: 31887524
DOI: 10.1016/j.scitotenv.2019.136062

Abstract

We investigate global trends in seasonal water discharge using data from 5668 hydrological stations in catchments whose total drainage area accounts for 2/3 of the Earth's total land area. Homogenization of water discharge, which occurs when the gap in water discharge between dry and flood seasons shrinks significantly, affects catchments occupying 2/5 of the total land area, and is mainly concentrated in Eurasia and North America. By contrast, polarization of water discharge, associated with widening of the gap in water discharge between dry and flood seasons, occurs in catchments covering 1/6 of the land area, most notably in the Amazon Basin and river basins in West Africa. Considering the major climatic and anthropogenic controlling factors, i.e. precipitation (P), evaporation (E), glacial runoff (G), and dam operations (D), the world's river basins are classified as P, DEP, GEP, and EP types. Contributions from each controlling factor to either the homogenization or polarization of the seasonal water discharge for each type of river have been analyzed. We found that homogenization of discharge is dominated by dam operations in GDEP and DEP river basins (contributing 48% and 64%) and by homogenized precipitation in GEP and EP river basins. Evaporation and precipitation are primary factors behind the polarization of discharge, contributing 56% and 41%. This study provides a basis for a possible decision tool for controlling drought/flood disasters and for assessing and preventing ecological damage in endangered regions.

Keywords: Dam operations; Evaporation; Glacial runoff; Global trends; Precipitation; Seasonal runoff.