Effects of climatic variability and human activity on runoff in the Loess Plateau of China

The Loess Plateau in north-central China has a long history of human activities. As a result of climate change, deforestation and sparse vegetative cover, the region suffers from water shortages and severe soil erosion, significantly influencing efforts for sustainable social development. In order to understand the impacts of climatic variability and human activities on runoff and other hydrological factors in this region, the Luoyugou catchment and its paired catchments (Qiaozidong and Qiaozixi) were selected. Statistical analysis indicated precipitation did not vary significantly whereas the annual runoff decreased from 1986 to 2008, with an abrupt change in 1994. Actual evapotranspiration (AET) increased slightly but not significantly. A comparison of runoff in the paired catchments showed land use changes reduced runoff by more than 38% under the same rainfall conditions. Human activities were the strongest contributor to changes in runoff and AET, at 67% and 90% respectively, while the remaining contributor was climate variation. The influence of various human activities on runoff is quite different, and soil-water conservation initiatives have a greater impact on runoff (about 41%). Thus, human activities were the primary reason for the reduction in runoff in the study catchment compared to climate. Greater emphasis should be given to afforestation and soil-water conservation measures.

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Quantifying the Impacts of Coal Mining and Soil-Water Conservation on Runoff in a Typical Watershed on the Loess Plateau, China

Water ◽

10.3390/w13223229 ◽

2021 ◽

Vol 13 (22) ◽

pp. 3229

Author(s):

Binbin Lin ◽

Yicheng Wang ◽

Hejia Wang ◽

Weihua Xiao

Keyword(s):

Soil Water ◽

Coal Mining ◽

Loess Plateau ◽

Water Conservation ◽

Human Activities ◽

Water Resource Management ◽

Assessment Tool ◽

The Loess Plateau ◽

Runoff Decrease ◽

The Impact

Coal mining and soil-water conservation are the two major human interventions on the Loess Plateau in China. Analyzing their impacts on hydrological processes is of great significance for sustainable water resource management. Using hydrological simulation (Soil and Water Assessment Tool, SWAT) and a data-driven method (double mass curve, DMC), the contributions of these two human activities and climate change to the runoff decrease were analyzed in the upper Fenhe River. The runoff in the three affected periods (1967–1987, 1988–1994, and 1995–2017) decreased by 7.5%, 28.2%, and 24.1%, respectively, compared with the base period (1957–1966). In the first affected period (1967–1987), the amount of coal mining activities was small, human activities had little impact on runoff. In the second (1988–1994) and third (1995–2017) periods, as the coal mining and soil-water conservation intensified, their contributions to the runoff decrease rapidly increased. Due to the uncertainties in the model structure and parameters, in addition to the impact of the data accuracy, the results obtained from the two methods were different, but the proportions and the trends of the contribution rates in the different periods were consistent.

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Effects of Vegetation Restoration on Soil Erosion on the Loess Plateau: A Case Study in the Ansai Watershed

International Journal of Environmental Research and Public Health ◽

10.3390/ijerph18126266 ◽

2021 ◽

Vol 18 (12) ◽

pp. 6266

Author(s):

Hui Wei ◽

Wenwu Zhao ◽

Han Wang

Keyword(s):

Land Use ◽

Soil Erosion ◽

Loess Plateau ◽

Water Conservation ◽

Large Scale ◽

Land Use Changes ◽

Vegetation Restoration ◽

The Loess Plateau ◽

Local Soil ◽

Erosion Environment

Large-scale vegetation restoration greatly changed the soil erosion environment in the Loess Plateau since the implementation of the “Grain for Green Project” (GGP) in 1999. Evaluating the effects of vegetation restoration on soil erosion is significant to local soil and water conservation and vegetation construction. Taking the Ansai Watershed as the case area, this study calculated the soil erosion modulus from 2000 to 2015 under the initial and current scenarios of vegetation restoration, using the Chinese Soil Loess Equation (CSLE), based on rainfall and soil data, remote sensing images and socio-economic data. The effect of vegetation restoration on soil erosion was evaluated by comparing the average annual soil erosion modulus under two scenarios among 16 years. The results showed: (1) vegetation restoration significantly changed the local land use, characterized by the conversion of farmland to grassland, arboreal land, and shrub land. From 2000 to 2015, the area of arboreal land, shrub land, and grassland increased from 19.46 km2, 19.43 km2, and 719.49 km2 to 99.26 km2, 75.97 km2, and 1084.24 km2; while the farmland area decreased from 547.90 km2 to 34.35 km2; (2) the average annual soil erosion modulus from 2000 to 2015 under the initial and current scenarios of vegetation restoration was 114.44 t/(hm²·a) and 78.42 t/(hm²·a), respectively, with an average annual reduction of 4.81 × 106 t of soil erosion amount thanks to the vegetation restoration; (3) the dominant soil erosion intensity changed from “severe and light erosion” to “moderate and light erosion”, vegetation restoration greatly improved the soil erosion environment in the study area; (4) areas with increased erosion and decreased erosion were alternately distributed, accounting for 48% and 52% of the total land area, and mainly distributed in the northwest and southeast of the watershed, respectively. Irrational land use changes in local areas (such as the conversion of farmland and grassland into construction land, etc.) and the ineffective implementation of vegetation restoration are the main reasons leading to the existence of areas with increased erosion.

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Detecting the Quantitative Hydrological Response to Changes in Climate and Human Activities at Temporal and Spatial Scales in a Typical Gully Region of the Loess Plateau, China

Water ◽

10.3390/w14020257 ◽

2022 ◽

Vol 14 (2) ◽

pp. 257

Author(s):

Peng Guo ◽

Jiqiang Lyu ◽

Weining Yuan ◽

Xiawan Zhou ◽

Shuhong Mo ◽

...

Keyword(s):

Loess Plateau ◽

Water Conservation ◽

Human Activities ◽

Water Resource Management ◽

Vegetation Index ◽

Spatial Scales ◽

Shaanxi Province ◽

Hydrological Response ◽

The Loess Plateau ◽

Temporal And Spatial

This study examined the Chabagou River watershed in the gully region of the Loess Plateau in China’s Shaanxi Province, and was based on measured precipitation and runoff data in the basin over a 52-year period (1959–2010), land-use types, normalized difference vegetation index (NDVI), and other data. Statistical models and distributed hydrological models were used to explore the influences of climate change and human activity on the hydrological response and on the temporal and spatial evolution of the basin. It was found that precipitation and runoff in the gully region presented a downward trend during the 52-year period. Since the 1970s, the hydrological response to human activities has become the main source of regional hydrological evolution. Evapotranspiration from the large silt dam in the study area has increased. The depth of soil water decreased at first, then it increased by amount that exceeded the evaporation increase observed in the second and third change periods. The water and soil conservation measures had a beneficial effect on the ecology of the watershed. These results provide a reference for water resource management and soil and water conservation in the study area.

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Spatiotemporal distribution of polycyclic aromatic hydrocarbons in sediments of a typical river located in the Loess Plateau, China: Influence of human activities and land-use changes

Journal of Hazardous Materials ◽

10.1016/j.jhazmat.2021.127744 ◽

2021 ◽

pp. 127744

Author(s):

Yixuan Zhang ◽

Dandong Cheng ◽

Yali Lei ◽

Jinxi Song ◽

Jun Xia

Keyword(s):

Land Use ◽

Polycyclic Aromatic Hydrocarbons ◽

Loess Plateau ◽

Aromatic Hydrocarbons ◽

Human Activities ◽

Land Use Changes ◽

Spatiotemporal Distribution ◽

The Loess Plateau ◽

Polycyclic Aromatic

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Integrating a mini catchment with mulching for soil water management in a sloping jujube orchard on the semiarid Loess Plateau of China

Solid Earth ◽

10.5194/se-7-167-2016 ◽

2016 ◽

Vol 7 (1) ◽

pp. 167-175 ◽

Cited By ~ 18

Author(s):

H. C. Li ◽

X. D. Gao ◽

X. N. Zhao ◽

P. T. Wu ◽

L. S. Li ◽

...

Keyword(s):

Soil Water ◽

Loess Plateau ◽

Water Conservation ◽

Rainy Season ◽

Water Storage ◽

Soil Water Storage ◽

Fish Scale ◽

The Loess Plateau ◽

Bare Land ◽

Water Compensation

Abstract. Conserving more soil water is of great importance to the sustainability of arid and semiarid orchards. Here we integrated fish-scale pits, semicircular mini-catchments for hill slope runoff collection, with mulches to test their effects on soil water storage in a 12-year-old dryland jujube orchard on the Loess Plateau of China, by using soil water measurements from April 2013 to November 2014. This experiment included four treatments: fish-scale pits with branch mulching (FB), fish-scale pits with straw mulching (FS), fish-scale pits without mulching (F), and bare land treatment (CK). Soil water was measured using the TRIME®-IPH time-domain reflectometer (TDR) tool in 20 cm intervals down to a depth of 180 cm, and was measured once every 2 weeks in the 2013 and 2014 growing seasons. The results showed that fish-scale pits with mulching were better in soil water conservation. Average soil water storage (SWS, for short) of FB at soil layer depths of 0–180 cm increased by 14.23 % (2013) and 21.81 % (2014), respectively, compared to CK, but only increased by 4.82 % (2013) and 5.34 % (2014), respectively, for the F treatment. The degree of soil water compensation, WS, was employed here to represent to what extent soil water was recharged from precipitation at the end of the rainy season relative to that at the beginning of the rainy season. A positive (negative) WS larger (lower) soil water content at the end of rainy season than at the beginning. For the treatment of FB, the values of WS over the entire soil profile were greater than 0; for the treatment of F, negative values of WS were observed in depths of 60–100 cm in both years. However, the bare land treatment showed negative values in depths of 40–180 cm. This indicated that integrating fish-scale pits with mulching could significantly increase soil water storage by increasing infiltration and decreasing evaporation, and it showed greater soil water storage and degree of soil water compensation compared to fish-scale pits alone. Since the branches used for mulching here were trimmed jujube branches, the cost of mulching materials was largely reduced. Therefore, integration of fish-scale pits with branch mulching is recommended in orchards for soil water conservation on the Loess Plateau and potentially for other regions.

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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.

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Integrating a mini catchment with mulching for soil water management in a sloping jujube orchard on the semiarid Loess Plateau of China

Solid Earth Discussions ◽

10.5194/sed-7-3199-2015 ◽

2015 ◽

Vol 7 (4) ◽

pp. 3199-3222

Author(s):

H. C. Li ◽

X. D. Gao ◽

X. N. Zhao ◽

P. T. Wu ◽

L. S. Li ◽

...

Keyword(s):

Soil Water ◽

Water Deficit ◽

Loess Plateau ◽

Water Conservation ◽

Flat Surface ◽

Soil Evaporation ◽

Fish Scale ◽

Soil Water Deficit ◽

The Loess Plateau ◽

The Cost

Abstract. Conserving more soil water is of great importance to the success of arid and semiarid orchards. On the hilly areas of the Loess Plateau of China, mini catchments, named fish-scale pits, are widely used in orchards for collecting surface runoff to infiltrate more soil water. However, the flat surface inside fish-scale pits would increase soil evaporation during non-rainfall periods. Therefore, we integrated fish-scale pits with mulching, a popular meaning to reduce soil evaporation, to test whether this integration could improve soil water conservation. The results showed that soil water deficit was observed for all treatments. However, soil water deficit was further intensified in the dry month. An index was used to represent the soil water supply from rainfall infiltration denoted WS. For the fish-scale pit with branch mulching treatment in the entire soil profile, the compensation degree of SWS were greater than 0. However, the CK treatment showed negative values in the 40–180 cm. In conclusion, integrating fish-scale pits with mulching could conserve significantly more soil water by increasing infiltration and decreasing evaporation compared to fish-scale pits alone. Since the mulching branches were trimmed jujube branches, the integration of fish-scale pit with branch mulching is recommended in jujube orchards in order to both preserve more soil water and reduce the cost of mulching materials.

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Evaluation of Three Different Machine Learning Methods for Object-Based Artificial Terrace Mapping—A Case Study of the Loess Plateau, China

Remote Sensing ◽

10.3390/rs13051021 ◽

2021 ◽

Vol 13 (5) ◽

pp. 1021

Author(s):

Hu Ding ◽

Jiaming Na ◽

Shangjing Jiang ◽

Jie Zhu ◽

Kai Liu ◽

...

Keyword(s):

Machine Learning ◽

Random Forest ◽

Loess Plateau ◽

Water Conservation ◽

Nearest Neighbor ◽

Gradient Boosting ◽

K Nearest Neighbor ◽

The Loess Plateau ◽

Object Based ◽

Extreme Gradient Boosting

Artificial terraces are of great importance for agricultural production and soil and water conservation. Automatic high-accuracy mapping of artificial terraces is the basis of monitoring and related studies. Previous research achieved artificial terrace mapping based on high-resolution digital elevation models (DEMs) or imagery. As a result of the importance of the contextual information for terrace mapping, object-based image analysis (OBIA) combined with machine learning (ML) technologies are widely used. However, the selection of an appropriate classifier is of great importance for the terrace mapping task. In this study, the performance of an integrated framework using OBIA and ML for terrace mapping was tested. A catchment, Zhifanggou, in the Loess Plateau, China, was used as the study area. First, optimized image segmentation was conducted. Then, features from the DEMs and imagery were extracted, and the correlations between the features were analyzed and ranked for classification. Finally, three different commonly-used ML classifiers, namely, extreme gradient boosting (XGBoost), random forest (RF), and k-nearest neighbor (KNN), were used for terrace mapping. The comparison with the ground truth, as delineated by field survey, indicated that random forest performed best, with a 95.60% overall accuracy (followed by 94.16% and 92.33% for XGBoost and KNN, respectively). The influence of class imbalance and feature selection is discussed. This work provides a credible framework for mapping artificial terraces.

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