Abstract
The serious soil erosion problems and decreased runoff of the Loess Plateau may aggravate the shortage of its local water resources. Understanding the spatiotemporal influences on runoff changes is important for water resource management. Here, we study this in the largest tributary of the Yellow River, the Weihe River Basin. Data from four hydrological stations (Lin Jia Cun (LJC), Xian Yang (XY), Lin Tong (LT), and Hua Xian (HX)) and 10 meteorological stations from 1961–2014 were used to analyze changes in annual runoff. The Mann–Kendall test and Pettitt abrupt change point test diagnosed variations in runoff in the Weihe River basin; the time periods before and after abrupt change points are the base period (period I) and change period (period II), respectively. Within the Budyko framework, the catchment properties (ω in Fu’s equation) represent land surface changes; climate variability comprises precipitation (P) and potential evapotranspiration (ET0). All the stations showed a reduction in annual runoff during the recording period, of which 22.66% to 50.42% was accounted for by land surface change and 1.97% to 53.32% by climate variability. In the Weihe River basin, land surface changes drive runoff variation in LT and climate variability drives it in LJC, XY, and HX. The contribution of land surface changes to runoff reduction in period I was less than that in period II, indicating that changes in human activity further decreased runoff. Therefore, this study offers a scientific basis for understanding runoff trends and driving forces, providing an important reference for social development, ecological construction, and water resource management.
Highlights
In a long-term hydrological system, changes in runoff can be influenced by many factors, such as climate change and land surface changes, which has triggered a series of questions about the water
Wei River Basin (WRB; latitude 33.5◦ N–37.5◦ N; longitude 103.5◦ E–110.5◦ E), which is the largest tributary of the Yellow River (China), originates north of the Niaoshu Mountains at an altitude of 3485 m in Gansu Province; it flows for 818 km, with a drainage area of 13.5 × 104 km2, which accounts for 17.9% of the total area of the Yellow River Basin (Figure 1)
The results show that the abrupt changes in annual runoff at Lin Jia Cun (LJC), XY, and Huan Xian (HX) occurred in 1993 and at Lin Tong (LT) in 1990
Summary
In a long-term hydrological system, changes in runoff can be influenced by many factors, such as climate change (including natural and anthropogenic climate change) and land surface changes (including changes in vegetation and agricultural irrigation and changes in water quantity and quality caused by various types of water use), which has triggered a series of questions about the waterWater 2018, 10, 1792; doi:10.3390/w10121792 www.mdpi.com/journal/waterWater 2018, 10, 1792 cycle [1,2]. Many river runoff values have shown decreasing trends, but it remains unclear whether these changes were caused by climate warming or human activities, and their relative contributions are poorly understood. In response to this problem, domestic and foreign researchers have begun to attempt to quantitatively distinguish the impacts of human activities and climate change on hydrological processes. A considerable global variability of catchment hydrological processes has been observed in most basins throughout the world, and quantifying the effects of climate variability and human activities is crucial for the management and sustainable development of water resources [10]
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