Attribution Analysis for Runoff Change on Multiple Scales in a Humid Subtropical Basin Dominated by Forest, East China

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.

Hydrological Response to Natural and Anthropogenic Factors in Southern Taiwan

“…Liu et al [19] used the Variable Infiltration Capacity (VIC) model to assess the respective and combined impacts of climate and land-use changes on hydrology. Yang et al [20] used the Soil and Water Assessment Tool (SWAT) model to identify the dominant driving factors behind changes in runoff in the Qingliu River basin on multiple (monthly, seasonal, and annual) scales. Although several hydrological models can be used to analyze changes in streamflow, the parameters chosen to represent complex hydrological processes can lead to a high level of uncertainty [21].…”

Does Land Use Change Affect Green Space Water Use? An Analysis of the Haihe River Basin

“…The non-agricultural transformation of farmland is an obvious feature of LUCC. Areas that transitioned from farmland were generally larger than other types of transitions, for example, changes from farmland to woodland and grassland accounted for approximately 300 km 2 . Meanwhile, much of the bare land was converted to other land use types.…”

“…The shortage of water resources threatens economic development and the overall wellbeing of humankind in many parts of the world [1][2][3]. According to the World Water Assessment Plan (WWAP) report released by the United Nations in 2019, severe water shortages affect approximately four billion people, accounting for nearly two-thirds of the world's population [4].…”

Quantifying the Relative Contribution of the Climate Change and Human Activity on Runoff in the Choshui River Alluvial Fan, Taiwan

“…Since the hydrological process is affected by climatological and human factors, the changes in runoff are due to climate factors and human activities. Therefore, understanding the causes of changes in runoff can help decision-makers formulate policies on managing water resources more efficiently [3][4][5]. Climate change can alter the availability of water and threaten water security [6].…”