• 标题：Separating the relative contributions of climate change and ecological restoration to runoff change in a mesoscale karst basin
• 关键词：Human activity,Hydrological response,Non-flood season,Karst ecosystems,Reforestation
• 作者：Jinjiao Lian, Hongsong Chen, Fa Wang, Yunpeng Nie, Kelin Wang

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Ecological restoration changes land cover types and management practices. However, understanding of their hydrological response is limited, especially in karst ecosystems, which are vulnerable to environmental changes. This study aimed to identify the spatial variability of the hydrological response in a mesoscale karst basin to climate change and ecological restoration. We examined changes in hydrological variables and normalized difffference vegetation index (NDVI) from 1985 to 2015 in Longjiang River Basin (LRB) and its three main subbasins, namely Huanjiang (HJB), Zhongzhouxiaojiang (ZZB), and Dongxiaojiang (DXB) sub-basins. The proportions of karst landscapes (POK) were 81, 66, 61, and 26%, respectively. Three independent quantitative methods were employed to distinguish the relative contributions of climate change and human activity. Annual runoffff showed a good linear correlation with precipitation in all the basins, with insignifificantly lower average values during 2003–2015 than during 1985–2002. The relative contribution of precipitation to annual runoffff change varied from 17.5 to 52.9%. At a seasonal scale, flflood season precipitation and runoffff decreased with similar patterns of annual variation, whereas non-flflood season values increased from 1985–2007 to 2008–2015. The quantitative results showed that the relative contribution rates of human activity to non-flflood season runoffff change were strongly linked to POK values and related vegetation changes. Annual NDVI improved after the implementation of ecological restoration projects, with change rates negatively related to POK values. Human activity was the dominant cause of increased non-flflood season runoffff in the LRB and HJB (accounting for 57 and 78%, respectively), whereas increases in non-flflood season runoffff in the ZZB and DXB were mainly caused by precipitation changes (accounting for 84 and 172%, respectively). These fifindings highlighted the facts that ecological restoration had changed hydrological processes and seasonal-scale analyses might therefore facilitate a better understanding of runoffff changes in karst basins.