scholarly journals Effects of rainfall intensity on the sediment concentration in the Loess Plateau, China

2020 ◽  
Vol 30 (3) ◽  
pp. 455-467
Author(s):  
Xiaoyan Liu ◽  
Suzhen Dang ◽  
Changming Liu ◽  
Guotao Dong
Keyword(s):  
Loess Plateau ◽  
Rainfall Intensity ◽  
Sediment Concentration ◽  
The Loess Plateau

scholarly journals Effects of wheat stubble on runoff, infiltration, and erosion of farmland on the Loess Plateau, China, subjected to simulated rainfall

Solid Earth ◽  
2017 ◽  
Vol 8 (2) ◽  
pp. 281-290 ◽  
Author(s):  
Linhua Wang ◽  
Bo Ma ◽  
Faqi Wu
Keyword(s):  
Loess Plateau ◽  
Sediment Concentration ◽  
Simulated Rainfall ◽  
The Loess Plateau ◽  
Water Losses ◽  
Runoff Volume ◽  
Runoff Reduction ◽  
Wheat Stubble ◽  
Summer Fallow ◽  
Soil And Water

Abstract. Soil and water losses in agriculture are major environmental problems worldwide, especially on the Loess Plateau, China. Summer fallow management may help to control soil erosion and conserve water. This study investigated the effects of wheat stubble on runoff, infiltration, and soil loss in laboratory plots under simulated rainfall. The treatments comprised wheat stubble cover (WS) and traditional plowing (TP) in runoff plots (4.0 m  ×  1.0 m) with three slope gradients (5, 10, and 15°) under simulated rainfall at 80 mm h−1 for 1 h. The runoff volume from WS plots was significantly less than that from TP. The runoff reduction with WS ranged from 91.92 to 92.83 % compared with TP. The runoff rates varied with the runoff volume in the same manner. The infiltration amount was higher with WS (94.8–96.2 % of rainwater infiltrated) than TP (35.4–57.1 %). The sediment concentration was significantly lower with WS than TP. Compared with TP (304.31–731.23 g m−2), the sediment losses were reduced dramatically in WS (2.41–3.78 g m−2) and the sediment loss slightly increased with slope; however, it was greatly increased as slope increased in TP. These results revealed that the stubble cover was the main factor reducing runoff and sediment losses and improving infiltration and that stubble showed a great potential to control erosion and conserve soil and water resources during the summer fallow period in the Loess Plateau region.

scholarly journals Individual Rainfall Change Based on Observed Hourly Precipitation Records on the Chinese Loess Plateau from 1983 to 2012

Water ◽  
2020 ◽  
Vol 12 (8) ◽  
pp. 2268
Author(s):  
Wenbin Ding ◽  
Fei Wang ◽  
Kai Jin ◽  
Jianqiao Han ◽  
Qiang Yu ◽  
...  
Keyword(s):  
Loess Plateau ◽  
Heavy Rainfall ◽  
Rainfall Intensity ◽  
Rainfall Amount ◽  
The Loess Plateau ◽  
Total Rainfall ◽  
Rainfall Events ◽  
Rainfall Duration ◽  
Rainfall Frequency ◽  
Annual Total

The magnitude and spatiotemporal distribution of precipitation are the main drivers of hydrologic and agricultural processes in soil moisture, runoff generation, soil erosion, vegetation growth and agriculture activities on the Loess Plateau (LP). This study detects the spatiotemporal variations of individual rainfall events during a rainy season (RS) from May to September based on the hourly precipitation data measured at 87 stations on the LP from 1983 to 2012. The incidence and contribution rates were calculated for all classes of rainfall duration and intensity to identify the dominant contribution to the rainfall amount and frequency variations. The trend rates of regional mean annual total rainfall amount (ATR) and annual mean rainfall intensity (ARI) were 0.43 mm/year and 0.002 mm/h/year in the RS for 1983–2012, respectively. However, the regional mean annual total rainfall frequency (ARF) and rainfall events (ATE) were −0.27 h/year and −0.11 times/year, respectively. In terms of spatial patterns, an increase in ATR appeared in most areas except for the southwest, while the ARI increased throughout the study region, with particularly higher values in the northwest and southeast. Areas of decreasing ARF occurred mainly in the northwest and central south of the LP, while ATE was found in most areas except for the northeast. Short-duration (≤6 h) and light rainfall events occurred mostly on the LP, accounting for 69.89% and 72.48% of total rainfall events, respectively. Long-duration (≥7 h) and moderate rainfall events contributed to the total rainfall amount by 70.64% and 66.73% of the total rainfall amount, respectively. Rainfall frequency contributed the most to the variations of rainfall amount for light and moderate rainfall events, while rainfall intensity played an important role in heavy rainfall and rainstorms. The variation in rainfall frequency for moderate rainfall, heavy rainfall, and rainstorms is mainly affected by rainfall duration, while rainfall event was identified as a critical factor for light rainfall. The characteristics in rainfall variations on the Loess Plateau revealed in this study can provide useful information for sustainable water resources management and plans.

The Geo-Hazards Triggered of Serial Reclamation Land of Extreme Precipitation in Typical Regions of the Loess Plateau

2020 ◽  
Author(s):  
Zhe Gao
Keyword(s):  
Loess Plateau ◽  
Water Conservation ◽  
Rainfall Intensity ◽  
Soil And Water Conservation ◽  
Land Consolidation ◽  
Geological Hazards ◽  
The Loess Plateau ◽  
The World ◽  
Soil And Water ◽  
Land Consolidation Project

<p>The Geo-Hazards Triggered of Serial Reclamation Land of Extreme Precipitation in Typical Regions of the Loess Plateau<br>Gao Zhe<sup>1</sup>,Zhang Genguang <sup>1*</sup>,Gao Jian'en<sup>1,2,3</sup>,Li Xingyao<sup>1</sup>,Han Jianqiao<sup>2,3</sup>,Kang Youcai<sup>3</sup>,Guo Zihao<sup>3</sup>,Long Shaobo<sup>2</sup>,Dou Shaohui<sup>2</sup>,Zhang Yuanyuan<sup>3</sup><br>1. College of Water Resources and Architectural Engineering, Northwest A&F University, 712100, Yangling, Shaanxi, China;<br>2. Institute of Soil and Water Conservation, Northwest A&F University, 712100, Yangling, Shaanxi, China;<br>3. Institute of Soil and Water Conservation, Chinese Academy of Sciences and Ministry of Water Resources, 712100, Yangling, Shaanxi, China;</p><p>The “Gully Land Consolidation Project”(GLCP) was widely carried out all over the world, such as Spain, the United States and China. It was a new attempt to solve the shortage of regional land resources. Aiming at the problem that the influence of extreme rainstorms on the “Gully Land Consolidation Project”(GLCP) on the Loess Plateau.By using the method of actual measurement and analysis of categorical data, the erosion disaster in July 26 2017 was investigated in Niu Xue Gully of Wuding River Watershed in Zizhou County of the Central part of the Loess Plateau. The results showed : </p><p>(1) The Niu Xue Gully Small Watershed in Zizhou County (109°55'25"E, 37°39'46"N), which was located in the central part of the Loess Plateau and belonged to the northern Shaanxi Loess Hilly-Gully region. The Niu Xuegou catchment covered an area of 0.48 km<sup>2</sup> and the average altitude of the region in about 1000-1200 meters, land consolidation in the basin about 38 mu（25333.3m<sup>2</sup>）since 2014.</p><p>(2) This storm was characterized by "long duration and large precipitation", the accumulated rainfall was 147.9 mm, the average rainfall intensity was 13.45 mm/h, the maximum rainfall intensity was close to 5 mm/min, the maximum flood peak discharge was 44.64 m<sup>3</sup>/s, the flood duration was about 11 hours, and the flood recurrence period was more than once in a hundred years.</p><p>(3) The storm caused nearly a thousand geological hazards at the channel of the basin. The main types of disasters were as follows, gravity erosion types, such as landslides, landslides, and mudflows, account for 14.85% of the conventional geological hazards; secondary disasters of water erosion types, such as trench erosion and dam erosion, occurring at different locations on the slope, accounted for 51.05% and composite new-derived land destruction and dam break disasters account for nearly 10% .</p><p>(4) The damage of cascade land preparation was closely related to the average flood discharge, embankment height and ecological vegetation cover in the watershed.<br>The investigation provided technical support for the consolidation of the Chinese implementation of the "Cropland to Forest (Grass)" results on the Loess Plateau, and also provided theoretical support for the safe implementation of the “Gully Land Consolidation Project”(GLCP) around the world.<br><br></p><p>Keywords: The loess plateau; Extreme rainstorm;The “Gully Land Consolidation Project”(GLCP)</p><p>Funding:(National Key R&D Program of China: 2017YFC0504703)；(National Natural Science Foundation of China,41877078,41371276,51879227);(Research and Development and Integrated demonstration of key Technologies in soil and Water Conservation Engineering,A315021615)</p><p><strong>        </strong></p>

Estimating Raindrop Kinetic Energy: Evaluation of a Low-Cost Method

2017 ◽  
Vol 33 (4) ◽  
pp. 551-558 ◽  
Author(s):  
Jian Wang ◽  
Dexter B. Watts ◽  
Qinqian Meng ◽  
Thomas R. Way ◽  
Qingfeng Zhang
Keyword(s):  
Soil Erosion ◽  
Kinetic Energy ◽  
Loess Plateau ◽  
Filter Paper ◽  
Rainfall Intensity ◽  
Low Cost ◽  
Rotating Disks ◽  
The Loess Plateau ◽  
Rainfall Events ◽  
Raindrop Impact

Abstract. The Loess Plateau of China is regarded as the most intensively eroded region in the world and soil erosion caused by raindrop impact is a common occurrence on agricultural land within this region. Therefore, understanding the influence of rainfall energy on the soil surface is needed to improve prescriptions for best management practices aimed at mitigating erosion. Disdrometers for measuring rainfall energy are presently available; however, these are relatively expensive and their use may not be justified for determining raindrop energy for predictive soil erosion models in regions where there are limited economic resources. To overcome this constraint, a device was tested for evaluating size and velocity of water drops during rainfall events. This device utilized two rotating disks combined with filter paper to obtain raindrop diameter and velocity which can then be used for determining the kinetic energy of falling raindrops. With this device, raindrop diameter was determined from the resultant raindrop stain left on the filter paper during rainfall events and velocity was calculated from the time it took a falling raindrop to travel between the pair of rotating disks. Measurements were taken for approximately 10 minutes during each of six rainfall events of different intensities over a three month period (from June to August of 2013). The smallest raindrop measured was 0.39 mm diameter and the largest was 5.92 mm diameter. The event average raindrop diameter increased with increasing event rainfall intensity. The minimum raindrop impact velocity was 1.47 m s-1, the maximum was 9.45 m s-1, and the event average terminal velocity increased as event rainfall intensity increased. Estimated raindrop kinetic energy ranged from 0.04 × 10-6 J to 4728.21 × 10-6 J, with event mean raindrop kinetic energy ranging from 40.33 x 10-6 J to 276.94 × 10-6 J. The relationship between estimated event rainfall kinetic energy and event rainfall intensity was represented by an exponential function. The disk device was also compared to an optical disdrometer. The data collected for rainfall intensity, raindrop diameter, and velocity were statistically similar between the two devices. Results from this study show that this low-cost method can be used to estimate rainfall kinetic energy in the Loess Plateau region of Northwest China. Keywords: Loess Plateau, Raindrop diameter, Raindrop velocity, Rainfall intensity.

Formulating an elasticity approach to quantify the effects of ecological restoration and climate variability on streamflow and sediment discharge changes in the Loess Plateau of China

2020 ◽  
Author(s):  
Guangyao Gao
Keyword(s):  
Climate Variability ◽  
Suspended Sediment ◽  
Ecological Restoration ◽  
Loess Plateau ◽  
Yellow River ◽  
Water Discharge ◽  
Sediment Concentration ◽  
Sediment Discharge ◽  
The Loess Plateau ◽  
Check Dams

<p>Ecological restoration (ER) has strong consequences on hydrological responses. The China’s Loess Plateau (LP) contributed nearly 90% of sediment load in the Yellow River, which was once the world’s largest carrier of fluvial sediment. ER efforts including the soil and water conservation measures (SWCMs, especially terracing and construction of check dams) since 1950s and large-scale ecological restoration campaigns such as Grain-for-Green project (i.e., returning sloping cropland to afforestation and pasture reestablishment) in 1999, has resulted in extensive land use/cover change, leading to considerable decreases of streamflow (Q), suspended sediment yield (SSY) and sediment concentration (C) in the LP over the past 60 years. However, it remains challenging to quantify the impacts of ER and climate variability on declines of Q and especially SSY. In this study, we formulate the notion of elasticity of sediment discharge, by associating SSY change to climate variability and ER over the period 1950s to 2014. Our results strongly support the hypothesis that changes to both streamflow volumes and to the suspended sediment concentration versus water discharge (C-Q) relationships result in reduced SSY, so that streamflow is reduced but runs clearer. We find that two of the ER strategies resulted in weaker relative impacts of climate variability, largely by reducing streamflow (by 55% to 75%). Meanwhile, ER predominantly decreased SSY (by 63% to 81%). Regarding ER practices, (i) the predominant measure acting to reduce SSY changed, over time, from engineering to reforestation; (ii) check-dams preferentially act to regulate the C-Q relationships whereas reforestation preferentially acts to moderate streamflow. Overall, our results suggest that a combination of engineering and vegetation measures is critical to achieving high-efficiency ER. While change to the ER strategy increased the efficiency of streamflow for SSY control, the lost water discharge per unit SSY reduction increased from 5.2 to 6.4 m<sup>3</sup>·t<sup>-1</sup>. Conflicting demands for water necessitate that further ER should target precision management by revegetation of targeted areas in the Loess Plateau.</p>

The drought trend and its relationship with rainfall intensity in the Loess Plateau of China

2015 ◽  
Vol 77 (1) ◽  
pp. 479-495 ◽  
Author(s):  
L. N. Wang ◽  
Q. K. Zhu ◽  
W. J. Zhao ◽  
X. K. Zhao
Keyword(s):  
Loess Plateau ◽  
Rainfall Intensity ◽  
The Loess Plateau

scholarly journals Plant litter estimation and its correlation with sediment concentration in the Loess Plateau

2019 ◽  
Author(s):  
Qian Li ◽  
Ligang Ma ◽  
Suhong Liu ◽  
Adilai Wufu ◽  
Yinbo Li ◽  
...  
Keyword(s):  
Remote Sensing ◽  
Time Series ◽  
Loess Plateau ◽  
Predictive Models ◽  
Social Economic ◽  
Sediment Concentration ◽  
Plant Litter ◽  
Economic Factors ◽  
The Loess Plateau ◽  
Litter Cover

Background. Sediment concentration in the water of the loess Plateau region has dramatically decreased during the past two decades. Plant litter is considered to be one of the most important factors for this change. Existing remote sensing studies that focus on plant litter mainly use extraction methods based on vegetation indices or changes in the plant litter. Few studies have conducted time series analyses of plant litter or considered the correlation between plant litter and soil erosion. In addition, social factors are not given enough consideration in the remote sensing and soil community. Methods. This study performs time series estimation of plant litter by integrating three-scale remotely sensed data and a random forest (RF) modeling algorithm. Predictive models are used to estimate the spatially explicit plant litter cover for the entire Loess Plateau over the last two decades (2000–2018). Then, the sediment concentration in the water was classified into 9 grades based on environmental and social-economic factors. Results. Our results demonstrate the effectiveness of the proposed predictive models at the regional scale. The areas with increased plant litter cover accounted for 67% of the total area, while the areas with decreased plant litter cover accounted for 33% of the total area. In addition, plant litter is demonstrated to be one of the top three factors contributing to the decrease in the river sediment concentration. Social-economic factors were also important for the decrease of the sediment concentration in the water, for example, the population of the rural area.

scholarly journals Influences of conservation measures on runoff and sediment yield in different intra-event-based flood regimes in the Chabagou watershed

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Shan-Shan Wang ◽  
Zhan-Bin Li ◽  
Le-Tao Zhang ◽  
Bo Ma
Keyword(s):  
Soil Erosion ◽  
Loess Plateau ◽  
Sediment Yield ◽  
Suspended Sediment Concentration ◽  
Sediment Concentration ◽  
The Loess Plateau ◽  
Flood Duration ◽  
Conservation Measures ◽  
Event Based ◽  
Measurement Period

AbstractThe Loess Plateau in China has suffered severe soil erosion. To control soil erosion, extensive conservation measures aimed at redistributing rainfall, hindering flow velocity and intercepting sediment were implemented on the Loess Plateau. To accurately evaluate the combined effect of conservation measures in the Chabagou watershed, this study classified intra-event-based floods into four regimes via cluster and discriminant analyses. Regime A was characterized by short flood duration and low erosive energy, regime B was characterized by short flood duration and high erosive energy, regime C was characterized by long flood duration and low erosive energy, and regime D was characterized by long flood duration and high erosive energy. The results indicated that peak discharge (qp), runoff depth (H), mean discharge (qm), and runoff erosion power (E) decreased by 75.2%, 56.0%, 68.0% and 89.2%, respectively, in response to conservation measures. Moreover, area-specific sediment yield (SSY), average suspended sediment concentration (SCE), and maximum suspended sediment concentration (MSCE) decreased by 69.2%, 33.3% and 11.9%, respectively, due to conservation measures. The nonlinear regression analysis revealed a power function relationship between SSY and E in both the baseline (1961–1969) and measurement period (1971–1990) in all regimes. Conservation measures reduced sediment yield by not only reducing the runoff amount and soil erosion energy but also transforming the flood regime, for example, transforming a high-sediment-yield regime into a low-sediment-yield regime. Moreover, conservation measures altered the SSY-E relationship in regime A, whereas no obvious difference in regime B or C/D was observed between the measurement period and the baseline period. This study provides a better understanding of the mechanism of runoff regulation and the sediment yield reduction under comprehensive conservation measures in a small watershed on the Chinese Loess Plateau.

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