Run‐off affected by climate and anthropogenic changes in a large semi‐arid river basin

Abstract

A rapid reduction in run-off has been observed in the middle reaches of the Yellow River basin in recent decades. Understanding the contributions of climate change and human activities, such as vegetation restoration and water consumption, to surface water resource reduction has become urgent and very important for future regional planning. Here, we use attribution approaches to explore the effects of climate change and human activities on run-off over the past six decades. The results showed that the observed annual run-off at Tongguan station, which is located within the mainstream of the Yellow River, exhibited a significant decreasing trend of −0.69 mm year −1 (p < .01) and varied from −0.28 to −1.46 mm year −1 (p < .01) in the eight selected tributaries from 1960 to 2015. Two relatively abrupt changes in the double mass curves occurred around 1979 and 1999; compared with Period 1 (P1; 1960-1979), the average catchment run-off decreased 32% during Period 2 (P2 ; 1980-1999) and up to 49% during Period 3 (P3;. We calculated that approximately 29% of the reduction in the run-off during P2 and 18% during P3 were attributed to climate change. Increased surface water consumption resulted in effective run-off reduction, with relative contributions of approximately 27% and 28% during P2 and P3, respectively. With the implementation of the "Grain-for-Green" project, the vegetation coverage rapidly increased from 36% in P1 to 52% in P3 and reduced run-off by 35% during P3. These findings explain the run-off reduction and benefit water resource management in the middle reaches of the Yellow River basin.

Variations in runoff, sediment load, and their relationship for a major sediment source area of the Jialing River basin, southern China

“…Understanding the effects of runoff in the upstream and midstream regions was essential for downstream and basin water resources management (Yang et al, 2020). Jiang et al (2019) reported that the water conservancy projects in the Xihanshui catchment were mainly built in the upper and middle reaches and the significant change points of the runoff in the upstream, midstream, and downstream areas all occurred in 1993, which was consistent with our results.…”

“…The simple linear regression and double mass curve are two practical empirical methods based on the relationship between runoff (sediment load) and precipitation. Recently, the two methods have been widely used to quantify the relative contributions of climate change (i.e., precipitation) and human activity to runoff and sediment load (Wu et al, 2017; Yang et al, 2020; Zhao et al, 2018). The third method for detecting the quantitative responses of runoff and sediment load to the affecting factors is the elasticity coefficient method based on the Budyko framework and sediment identify factor analysis, respectively.…”

Rainfall, runoff, and suspended sediment dynamics at the flood event scale in a Loess Plateau watershed, China

“…Since the 1970s, numerous soil conservation practices have been implemented throughout the basin, including terraces, check dams, reforestation, and fish‐scale pits. In 1999, the “Grain for Green” project, which converted steep arable land to forest or grassland, was proposed by the Chinese government, when implemented, greatly reduced soil loss to the Yellow River (Wu et al, 2017; Yang et al, 2020).…”

Causal effects of dams and land cover changes on flood changes in mainland China

“…Yang et al (2019) interpreted these trends as the results of soil conservation practices (Bai et al, 2016) and decreasing extreme rainfall (Yang et al, 2013;Wu et al, 2016). Besides, other reasons include decreasing soil moisture (Cheng et al, 2015;Yang et al, 2020a) and the impacts of cascade small soil-retaining dams (Yang et al, 2020b).…”