Changes in sediment load in a typical watershed in the tableland and gully region of the Loess Plateau, China

Abstract. To control severe soil erosion on the Loess Plateau, China, a great number of soil conservation measures have been implemented since 1950s and subsequently, the "Grain for Green" project was implemented in 1999. The measures and the project resulted in a large scale land use/cover change (LUCC). Understanding the impacts of the measures and the project on streamflow, sediment load and their dynamic relation is essential because the three elements are closely related to the sustainable catchment management strategy on the Loess Plateau. The data for seven selected catchments in the middle reaches of the Yellow River were used and standardized with the precipitation and the controlling area for analysis. The nonparametric Mann-Kendall test and the Pettitt test were employed to detect trends and change points of the annual streamflow and annual sediment load. Simple linear regressions for the monthly streamflow and sediment load from May to October were made to express their relationship. Based on the change point identification and the time when the project began to be implemented on the Loess Plateau, the complete time for the data records was divided into three periods to compare the change degrees of streamflow, sediment load and their relation for the catchments. Results show that there are three types of responses in streamflow, sediment load, and their dynamic relations for the seven catchments. The effects of the LUCC on streamflow, sediment load, and their relationships are greatest in the three transition zone catchments followed by the two rocky mountain catchments. The effects are much weaker in the two loess hilly-gully catchments. In general, the change degrees for sediment load are much greater than those for streamflow, which results from the decreased streamflow and weakening trend of their dynamic relation period by period in catchments.

Download Full-text

Changes in Runoff and Sediment Load and Potential Causes in the Malian River Basin on the Loess Plateau

Sustainability ◽

10.3390/su13020443 ◽

2021 ◽

Vol 13 (2) ◽

pp. 443

Author(s):

Min Du ◽

Xingmin Mu ◽

Guangju Zhao ◽

Peng Gao ◽

Wenyi Sun

Keyword(s):

River Basin ◽

Loess Plateau ◽

Water Conservation ◽

Sediment Load ◽

Arable Land ◽

Annual Runoff ◽

The Loess Plateau ◽

Sediment Loads ◽

Average Annual Runoff ◽

Soil And Water

The loessial tableland is a unique landform type on the Loess Plateau in China. Long-term soil erosion has led to the retreat of gullies and the rapid reduction of fertile arable land, which has further decreased agricultural production. In this study, we chose the Malian River basin to analyze the temporal and spatial variation of its runoff and sediment load, as well as the potential causes. The annual runoff and sediment load at six hydrological stations in the study area were collected for the period between 1960 and 2016. The Mann−Kendall and Pettitt tests were respectively applied to detect temporal variations and abrupt changes in the runoff and sediment loads. The results showed that an abrupt change in the runoff and sediment loads occurred in 2003. The average annual runoff in the Malian River was 4.42 × 108 m3 yr−1 from 1960 to 2002, and decreased to 3.32 × 108 m3 yr−1 in 2003–2016. The average annual sediment load was 1.27 × 108 t yr−1 in 1960–2002, and decreased to 0.65 × 108 t yr−1 in 2003–2016. The spatial patterns in the sediment load suggested that the Hongde sub-basin contributed a higher sediment count to the Malian River, which may require additional attention for soil and water conservation in the future. Anthropogenic activities significantly affected runoff and sediment load reduction according to the double-mass curve method, accounting for 90.7% and 78.7%, respectively, whereas rainfall changes were 9.3% and 21.3%, respectively. As such, the present study analyzed the loessial tableland runoff and sediment load characteristics of the Malian River basin for soil and water erosion management.

Download Full-text

Change in water discharge and sediment load on the Loess Plateau, China

10.5194/egusphere-egu2020-3080 ◽

2020 ◽

Author(s):

Haiyan Zheng ◽

Chiyuan Miao

Keyword(s):

Loess Plateau ◽

Water Conservation ◽

Sediment Load ◽

Water Discharge ◽

Sediment Concentration ◽

Soil And Water Conservation ◽

Biological Engineering ◽

The Loess Plateau ◽

Conservation Measures ◽

Soil And Water

<p>Over the past 50 years, a series of soil and water conservation measures have been implemented on the Loess Plateau, including biological, engineering, and agricultural measures. As a result, water discharge and sediment load on the plateau have undergone significant changes. In this study, we compared the water discharge and sediment load at more than 100 hydrological stations across the Loess Plateau during the period 2008&#8211;2016 (P2) with the water discharge and sediment load during the period 1971&#8211;1987 (P1), and detected the main sources of sediment in each of the two periods. We then performed an attribution analysis to quantify the influence of different factors on the changes in sediment load. We found the following results: (1) Water discharge was reduced by 22% in P2 compared with P1, whereas the sediment load was reduced by 74%. (2) Sediment resources are mainly concentrated between Toudaoguai and Tongguan stations: this region contributed more than 88% of the total sediment load at the terminal station (Huayuankou station) in both P1 and P2. (3) When considering only the changes in sediment concentration on the Loess Plateau, we conclude that the contribution of human activities was greater than 72%. This study provides a detailed description of the temporal and spatial variations in water and sediment across the Loess Plateau, providing a reliable reference for the future development of ecological soil and water conservation measures on the Loess Plateau.</p>

Download Full-text