Spatio-temporal patterns of the effects of precipitation variability and land use/cover changes on long-term changes in sediment yield in the Loess Plateau, China

Abstract

Abstract. Within China's Loess Plateau there have been concerted revegetation efforts and engineering measures since the 1950s aimed at reducing soil erosion and land degradation. As a result, annual streamflow, sediment yield, and sediment concentration have all decreased considerably. Humaninduced land use/cover change (LUCC) was the dominant factor, contributing over 70 % of the sediment load reduction, whereas the contribution of precipitation was less than 30 %. In this study, we use 50-year time series data , showing decreasing trends in the annual sediment loads of 15 catchments, to generate spatio-temporal patterns in the effects of LUCC and precipitation variability on sediment yield. The space-time variability of sediment yield was expressed notionally as a product of two factors representing (i) the effect of precipitation and (ii) the fraction of treated land surface area. Under minimal LUCC, the square root of annual sediment yield varied linearly with precipitation, with the precipitation-sediment load relationship showing coherent spatial patterns amongst the catchments. As the LUCC increased and took effect, the changes in sediment yield pattern depended more on engineering measures and vegetation restoration campaign, and the within-year rainfall patterns (especially storm events) also played an important role. The effect of LUCC is expressed in terms of a sediment coefficient, i.e., the ratio of annual sediment yield to annual precipitation. Sediment coefficients showed a steady decrease over the study period, following a linear decreasing function of the fraction of treated land surface area. In this way, the study has brought out the separate roles of precipitation variability and LUCC in controlling spatio-temporal patterns of sediment yield at catchment scale.

Changes in streamflow and sediment for a planned large reservoir in the middle Yellow River

“…Overall, climate variability and human activities caused the reduction of streamflow with the contributions of −4.0 mm (32%) and −8.5 mm (68%), respectively. This finding is consistent with the results of some Loess Plateau's catchments in previous studies (Dai, 2002a;Dai, 2002b;Gao et al, 2016Gao et al, , 2017Li et al, 2018;Xu, 2011).…”

“…Although many case-studies have proved that anthropogenic activities accounted for more of streamflow decrease than climatic factors, there were also some exception, such as the Yan River and Beiluo River (Wu, Miao, Yang, Duan, & Zhang, 2018;Zhao et al, 2014). For the sediment change in the middle reaches of Yellow River, a study of Gao et al (2017) showed that over 70% of sediment load reduction can be attributed to human-induced land use/cover change, whereas less than 30% was associated with climate variability. Wang et al (2016) found that landscape engineering, terracing, and the construction of warping dams and reservoirs were the dominating factors to sediment load decrease of Yellow River and suggested that the Yellow River's sediment load would increase in the future after the storage of existing dams and reservoirs approaching their capacities.…”

Streamflow and Sediment Declines in a Loess Hill and Gully Landform Basin Due to Climate Variability and Anthropogenic Activities

“…On the whole, our analysis stated that human activities are the main reason for the reduction of runoff and sediment load in the Yunyan River Basin in the past few decades. This finding is consistent with that in some other Loess Plateau's catchments in previous studies [9,10,17,34,35,42]. For instance, Zhao et al [43] showed that land use changes and warping dams in 2006 reduced the sediment yield nearly by 80% in the Xiaoshilata and Yangjiagou Watersheds.…”

“…Environmental changes caused by climate variability and anthropogenic activities affect the hydrological processes, with two important indicators of changes in streamflow and sediment runoff [1][2][3][4][5]. In most of the watersheds in North China, water resource availability is low because the water demand in arid areas is far greater than the amount of water available [6][7][8][9][10]. In the past decades, soil erosion has been a great threat to the ecological environment and flood control safety.…”

Formulating an Elasticity Approach to Quantify the Effects of Climate Variability and Ecological Restoration on Sediment Discharge Change in the Loess Plateau, China

“…In 1999, this strategy was replaced by the "Grain for Green" strategy, which consists mainly of vegetation-based control measures implemented by regulating slopes on a massive scale. Recent studies have attempted to assess the success of these sediment control strategies (Gao et al, 2017;Miao et al, 2010Miao et al, , 2011Zuo et al, 2016). However, as mentioned earlier, the unrealistic input…”