Quantifying Contributions of Climate Change and Local Human Activities to Runoff Decline in the Second Songhua River Basin

Bao Shanshan,Wang Xiaojun,Li Hongyan,Yang Wei

doi:10.3390/w12102659

Abstract

In the past several decades, climate change and human activities have influenced hydrological processes, and potentially caused more frequent and extensive flood and drought risks. Therefore, identification and quantification of the driving factors of runoff variation have become a hot research area. This paper used the trend analysis method to show that runoff had a significant downward trend during the past 60 years in the Second Songhua River Basin (SSRB) of Northeast China. The upper, middle, and lower streams of five hydrological stations were selected to analyze the breakpoint of the annual runoff in the past 60 years, and the breakpoints were used to divide the entire study period into two sub-periods (1956–1974 and 1975–2015). Using the water–energy coupling balance method based on Choudhury–Yang equation, the climatic and catchment landscape elasticity coefficient of the annual runoff change was estimated, and attribution analysis of the runoff change was carried out for the Fengman Reservoir and Fuyu stations in SSRB. The change in potential evapotranspiration has a weak effect on the runoff, and change in precipitation and catchment landscape were the leading factors affecting runoff. Impacts of climate change and land cover change were accountable for the runoff decrease by 80% and 11% (Fengman), 17% and 206% (Fuyu) on average, respectively; runoff was more sensitive to climate change in Fengman, and was more sensitive to catchment landscape change in Fuyu. In Fengman, the population was small, owing to the comparatively inhospitable natural conditions, and so human activities were low. However, in Fuyu, human activities were more intensive, and so had more impact on runoff for the Lower Second Songhua River compared to the Upper Second Songhua River.

Highlights

This study firstly estimated the elasticity of runoff through the Choudhury–Yang equation based on the climate and landscape conditions of the study area; secondly, through using statistical methods to analyze the trend of runoff, detecting the mutation points of annual runoff, and dividing the time series into two periods; and thirdly, with attribution analysis of runoff changes in Second Songhua River Basin (SSRB)
The line represents the theoretical value of elastic coefficient under different catchment landscape conditions, the “point” in the Figure 7 represents the runoff elastic coefficient, including precipitation, potential evaporation, and catchment landscape parameter (n), and its value is based on the meteorological data for 1956–2015
This paper proposed an attribution method based on the Choudhury–Yang equation to quantify the contribution of climate change and land use to runoff changes in the SSRB, using statistical methods to analyze the trend in runoff, detect the change points in annual runoff, and divide the time series into two periods

Summary

Introduction

Human development and progress are facing serious challenges in addressing three major problems: Population expansion, resource shortages, and environmental degradation [1]. All three issues are closely related to water resources, and the issue of water resources in China has been growing since the 1980s [2,3]. Research shows that the measured runoff at the main control stations has significantly decreased in Chinese rivers [4]. Water 2020, 12, 2659 and human activities (land cover, reservoir operations, and withdraw water) are the major drivers altering hydrological processes, which potentially cause more frequent and extensive flood and drought risks [5]. The risks have been impacting the economy, society, and the environment for decades [6]

Methods

Results

Discussion

Conclusion