Dissolved organic matter in surface runoff in the Loess Plateau of China: The role of rainfall events and land‐use

2020 ◽  
Vol 34 (6) ◽  
pp. 1446-1459 ◽  
Author(s):  
Zhongwu Li ◽  
Hao Peng ◽  
Binggeng Xie ◽  
Chun Liu ◽  
Xiaodong Nie ◽  
...  
Water ◽  
2019 ◽  
Vol 12 (1) ◽  
pp. 82 ◽  
Author(s):  
Youcai Kang ◽  
Jianen Gao ◽  
Hui Shao ◽  
Yuanyuan Zhang

Climate and land-use change are the two main driving forces that affect watershed hydrological processes. Separately assessing their impacts on hydrology is important for land-use planning and water resource management. In this research, the SWAT (Soil and Water Assessment Tool) and statistical methods were applied to evaluate the effects of climate and land-use change on surface hydrology in the hilly-gully region of the Loess Plateau. The results showed that surface runoff and soil water presented a downward tendency, while evapotranspiration (ET) presented an upward tendency in the Yanhe watershed from 1982 to 2012. Climate is one the dominant factors that influence surface runoff, especially in flooding periods. The average contribution rate of surface runoff on stream flow accounted for 55%, of which the flooding period accounted for 40%. The runoff coefficient declined by 0.21 after 2002 with the land-use change of cropland transformed to grassland and forestland. The soil water exhibited great fluctuation along the Yanhe watershed. In the upstream region, the land-use was the driving force to decline soil water, which reduced the soil water by 51%. Along the spatial distribution, it converted from land-use change to climate variability from northwest to southeast. The ET was more sensitive to land-use change than climate variability in all sub-basins, and increased by 209% with vegetation restoration. To prevent the ecosystem degradation and maintain the inherent ecological functions of rivers, quantitative assessment the influence of climate variability and land-use change on hydrology is of great importance. Such evaluations can provide insight into the extent of land use/cover change on regional water balance and develop appropriate watershed management strategies on the Loess Plateau.


2017 ◽  
Author(s):  
Linjing Qiu ◽  
Yiping Wu ◽  
Lijing Wang ◽  
Xiaohui Lei ◽  
Weihong Liao ◽  
...  

Abstract. The hydrological effects of the ‘Grain for Green’ project (GFGP) on the Loess Plateau have been largely debated due to the complexity of the water system and its multiple driving factors. The aim of this study was to investigate the response of the hydrological cycle to the GFGP measures based on a case study of the Yanhe basin, a typical hilly-gully area on the Loess Plateau of China. First, we analyzed the land use and land cover (LULC) changes from 1990 to 2010. Then, we evaluated the effects of LULC changes and sloping land conversion on the main hydrological components in the basin considering the land surface characteristics and climate impacts. The Soil and Water Assessment Tool (SWAT) was used for this analysis. The results indicated that farmland exhibited a decreasing trend declining from 40.2 % of the basin area in 1990 to 17.6 % in 2010, and the woodland and grassland areas correspondingly increased due to the implementation of the GFGP in the basin. Due to land use changes from 1990 to 2010, surface runoff and the water yield exhibited decreasing trends, whereas evapotranspiration (ET) increased, resulting in a persistent decrease in soil water. Additionally, converting cropland areas with slopes ≥ 15° or > 25° to grassland and woodland had negative effects on surface runoff, the water yield and soil water and a positive effect on ET. The magnitudes of the hydrological effects generated by sloping cropland to woodland conversion were greater than those for sloping cropland to grassland conversion. These results suggest that the expansive revegetation of sloping land could reduce runoff generation, particularly in woodland areas, but these effects could reduce the soil water volume in the region. Overall, this study can be used to improve sustainable land use planning and water resource management on the Loess Plateau in China.


2021 ◽  
Author(s):  
Yixin Zhang ◽  
Peng Li ◽  
Guoce Xu

<p>Changes in land use patterns have important implications for soil structure and soil nutrient transport processes. This paper is based on the project of returning farmland to forests in the Loess Plateau-Ziwuling area of China. Explore the phase changes of the aggregate structure and nutrients content and its effect on soil infiltration and erodibility during the changing land use process. Identify the effective time domain for soil management in the area, which provide a scientific basis for coordinating regional land use and efficient soil erosion control. The results showed that with the increase of soil recovery/opening time, the content of soil water stable aggregates (SWAG), soil organic matter (SOM), total nitrogen (TN) and total phosphorus (TP) showed an increasing /decreasing trend. In the process of soil reclamation, the content of organic matter in large-size aggregates (>5mm) decreases first at a higher rate, while in land restoration process, the content of organic matter in small-sized (2-5mm) aggregates increases rapidly. With the increase of soil reclamation time, the initial time of runoff production is advanced. In the 30-year of the land restoration process, the erodibility K decreased by 87%, and the SOC content has reached 96% to the common forest level, indicate that the soil quality is greatly improved when the land returns to this moment, the ability to resist erosion reaches a certain level and tends to be stable, and it is considered that the input and output of the governance before the time node is relatively high.</p>


2019 ◽  
Vol 250 ◽  
pp. 109531 ◽  
Author(s):  
Rongqin Zhang ◽  
Qianqian Huang ◽  
Taoyu Yan ◽  
Jianfeng Yang ◽  
Yue Zheng ◽  
...  

2017 ◽  
Vol 21 (12) ◽  
pp. 6485-6499 ◽  
Author(s):  
Linjing Qiu ◽  
Yiping Wu ◽  
Lijing Wang ◽  
Xiaohui Lei ◽  
Weihong Liao ◽  
...  

Abstract. The hydrological effects of the Grain for Green project (GFGP) on the Loess Plateau have been extensively debated due to the complexity of the water system and its multiple driving factors. The aim of this study was to investigate the response of the hydrological cycle to the GFGP measures based in a case study of the Yanhe Basin, a typical hilly–gully area on the Loess Plateau of China. First, we analyzed the land use and land cover (LULC) changes from 1990 to 2010. Then, we evaluated the effects of LULC changes and sloping land conversion on the main hydrological components in the basin using the Soil and Water Assessment Tool (SWAT). The results indicated that cropland exhibited a decreasing trend, declining from 40.2 % of the basin area in 1990 to 17.6 % in 2010, and that the woodland and grassland areas correspondingly increased. With the land use changes from 1990 to 2010, the water yield showed a decreasing trend which was mainly due to decrease in surface runoff. In contrast, evapotranspiration (ET) showed an increasing trend over the same period, resulting in a persistent decrease in soil water. The conversion of sloping cropland to grassland or woodland exerted negative effects on water yield and soil water. Compared with the land use condition in 2010, the negative effects were most evident where cropland with a slope  ≥  15° was converted to woodland, with decreases in surface runoff and soil water of 17.1 and 6.4 %, respectively. These results suggest that the expansive reforestation on sloping land in the loess hilly–gully region decreased water yield and increased ET, resulting in reduced soil water. The results of this study can be used to support sustainable land use planning and water resource management on the Loess Plateau in China.


2010 ◽  
Vol 55 (3) ◽  
pp. 1159-1171 ◽  
Author(s):  
Clayton J. Williams ◽  
Youhei Yamashita ◽  
Henry F. Wilson ◽  
Rudolf Jaffé ◽  
Marguerite A. Xenopoulos

Sign in / Sign up

Export Citation Format

Share Document