Abstract
Attributing runoff change to different drivers is vital in order to better understand how and why runoff varies, and to further support decision makers on water resources planning and management. Most previous works attributed runoff change in the arid or semi-arid areas to climate variability and human activity on an annual scale. However, attribution results may differ greatly according to different climatic zones, decades, temporal scales, and different contributors. This study aims to quantitatively attribute runoff change in a humid subtropical basin (the Qingliu River basin, East China) to climate variability, land-use change, and human activity on multiple scales over different periods by using the Soil and Water Assessment Tool (SWAT) model. The results show that runoff increased during 1960–2012 with an abrupt change occurring in 1984. Annual runoff in the post-change period (1985–2012) increased by 16.05% (38.05 mm) relative to the pre-change period (1960–1984), most of which occurred in the winter and early spring (March). On the annual scale, climate variability, human activity, and land-use change (mainly for forest cover decrease) contributed 95.36%, 4.64%, and 12.23% to runoff increase during 1985–2012, respectively. On the seasonal scale, human activity dominated runoff change (accounting for 72.11%) in the dry season during 1985–2012, while climate variability contributed the most to runoff change in the wet season. On the monthly scale, human activity was the dominant contributor to runoff variation in all of the months except for January, May, July, and August during 1985–2012. Impacts of climate variability and human activity on runoff during 2001–2012 both became stronger than those during 1985–2000, but counteracted each other. The findings should help understandings of runoff behavior in the Qingliu River and provide scientific support for local water resources management.
Highlights
IntroductionRunoff is a key quantitative indicator for water resources availability and river regimes
Runoff is a key quantitative indicator for water resources availability and river regimes.Its variation may affect water-use patterns and water resources management
River basin have been analyzed by using the simple runoff depth over the period of 1960–2012 for the Qingliu River basin have been analyzed by using linear regression method and the Mann–Kendall test method
Summary
Runoff is a key quantitative indicator for water resources availability and river regimes. Its variation may affect water-use patterns (in different sectors such as agriculture, domestic, and industry) and water resources management. Climate variability and human activity are suggested to be two primary driving factors for runoff variation [1]. Climate variability may alter runoff by changing the spatiotemporal distributions of temperature, evaporation, and precipitation [2]. Human activity includes land-use change, water withdraw, and hydraulic engineering operation, which exert impacts on runoff by changing the underlying properties and the runoff generation mechanisms of the basin [3]. Attributing the runoff change to different driving factors could help better understand how and why runoff varies, and could further support decision makers with water resources planning and management
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