Gully System Research Articles

Correlation Between Water Erosion and Hydraulics of Slope–Gully Systems According to Check Dam Siltation Depth

Correlation Between Water Erosion and Hydraulics of Slope–Gully Systems According to Check Dam Siltation Depth

Soil erosion resistance of gully system under different plant communities on the Loess Plateau of China

AbstractGully erosion, considered as a type of intensive erosion, is the dominant source of sediment at small watershed scales in certain environments. Variation of vegetation may result in the changes in near soil surface characteristics, which likely further affect the resistance of gully systems to erosion. However, the potential effects of near soil surface characteristics of plant communities on resistance to erosion are still unclear in gully systems. This study was performed to investigate the variations in resistance of gully systems to erosion under different plant communities and to identify the dominant influencing factors leading to these variations on the Loess Plateau. Five typical plant communities (two grasses, two shrubs and one forest) that distributed on different gully systems were selected. Six hundred undisturbed soil samples collected from different sites of gully systems were subjected to detach by overland flow under six different shear stresses (6.66 to 15.02 Pa). The results showed that the mean soil detachment capacity of gully systems covered by grass and shrub communities was 0.15 and 0.37 times to that of gully system covered by forest. Compared to forest gully systems, rill erodibility reduced by 29.8% to 85.6% for the other four plant communities. The relative rill erodibility of different vegetation communities generally increased from grass to shrub and forest communities. The critical shear stress of forest gully system was 58.7% and 63.8% of gully systems covered by grass (6.22 Pa) and shrub (5.73 Pa) communities. Bulk density, soil cohesion, water stable aggregate, root mass density, and the thickness of biological soil crust were the dominant factors affecting the resistance of gully systems to soil erosion. Rill erodibility decreased logarithmically with increasing soil cohesion, water stable aggregate and root mass density. Critical shear stress increased with the increase of soil cohesion and root mass density as a power function, and linearly with the increase of water stable aggregate. These results show how vegetation can mitigate against the erosion induced by concentrated flow in relatively stable gully systems.

The importance of terrain factors in the spatial variability of plant cover diversity in a steppe gully

Information about the slope angle and its exposure is often given when describing plant communities. However, the slope angle should be noted to affect a complex of different phenomena and processes. The slope angle affects the albedo and thermal regime of the soil. The slope angle affects the redistribution of moisture and determines the moisture availability of a particular area. The slope angle also determines the risks of erosion processes. In turn, erosion processes determine the depth of the soil layer and the content of organic matter in it, which greatly affects the conditions for plant life and their dynamics. Therefore, the slope angle of the relief is a complex environmental indicator, which is its most important weakness. The information on the slope angle of the relief surface does not indicate which environmental factor is limiting and determines the characteristics of the vegetation cover. Similarly, the quantitative orientation of a slope using rhumb lines is a rather crude way to indicate the role of terrain in the redistribution of solar energy. With a certain degree of accuracy, rhumbs characterize incoming solar radiation, but are not sensitive to estimating the amount of diffuse radiation. Modern geoinformation technologies make it possible to determine the amount of solar radiation reaching the terrain surface using a digital elevation model. The aim of the article was to identify the role of relief factors in terms of topographic wetness index, erosion index, and solar radiation in the spatial variability of the vegetation diversity of a steppe gully. There was no linear correlation between the other predictors. Some correlations can be interpreted as the result of certain nonlinear patterns. In this sense, the geomorphological predictors are mostly linearly independent and thus each of them carries independent information for characterizing environmental conditions. The vegetation cover of the gully system was represented by 263 plant species. The analysis of the synoptic phytosociological table allowed us to find out that the vegetation cover of the studied gully system is represented by six classes of vegetation. The geomorphological predictors allowed for a classification of vegetation types with an accuracy of 23.8% to 100%. The topographic wetness index was the most important for classification. Altitude and insolation were also important for classification (94 and 95 respectively). The topographic wetness index provided an accurate identification of wetland vegetation of the Phragmito-Magnocaricetea class. Naturally, this type of vegetation preferred biotopes with the highest level of soil moisture. High insolation accurately labeled the locations where Festuco-Brometea steppe vegetation was most likely to be found. Some of the artificial tree plantations that occurred in the thalweg of the gully can be clearly identified by the high level of the topographic wetness index. Another group of artificial tree plantations is located on relatively high relief areas and should be differentiated from Galio-Urticetea communities, which prefer locations with higher light levels, and from Molinio-Arrhenatheretea, which prefer locations with a higher risk of erosion. The most arid locations are preferred by Agropyretalia intermedio-repentis vegetation. Steppe and meadow vegetation located at altitudes less than 116 meters also differ in their preferred height. Steppe vegetation is usually located at a level higher than 95 meters. Natural steppe and meadow vegetation at elevations below 116 meters differs from semi-natural Galio-Urticetea vegetation in that the latter usually prefers more well lit locations. Steppe communities are misclassified as meadow in 15.3% of cases, and meadow is misclassified as steppe in 18.5% of cases. Artificial tree plantations are misclassified as steppe in 42.9% of cases and 14.3% are misclassified as Agropyretalia intermedio-repentis. In its turn, Agropyretalia intermedio-repentis is misclassified as Festuco-Brometea in 6.7% of cases, as Molinio-Arrhenatheretea or Onopordetalia acanthii in 3.3% of cases, and as Galio-Urticetea in 10.0% of cases. The Onopordetalia acanthii community was misclassified as Festuco-Brometea, Molinio-Arrhenatheretea and Galio-Urticetea in 6.7% of cases, respectively.

Morphologic and morphometric differences between gullies formed in different substrates on Mars: new insights into the gully formation processes

Abstract. Martian gullies are kilometer-scale, geologically young features with a source alcove, transportation channel, and depositional fan. On the walls of impact craters, these gullies typically incise into bedrock or surfaces modified by the latitude-dependent mantle (LDM; inferred as consisting of ice and admixed dust) and glaciation. To better understand the differences in the alcoves and fans of gullies formed in different substrates and infer the flow types that led to their formation, we have analyzed the morphology and morphometry of 167 gully systems in 29 craters distributed between 30 and 75∘ S. Specifically we measured length, width, gradient, area, relief, and relief ratio of the gully alcoves and fans; Melton ratio, relative concavity index, and perimeter; and form factor, elongation ratio, and circularity ratio of the gully alcoves. Our study reveals that gully alcoves formed in LDM/glacial deposits are more elongated than the gully alcoves formed in bedrock, and they possess a distinctive V-shaped cross section. We have found that the mean gradient of fans formed by gullies sourced in bedrock is steeper than the mean gradient of fans of gullies sourced in LDM/glacial deposits. These differences between gullies were found to be statistically significant and discriminant analysis has confirmed that alcove perimeter, alcove relief, and fan gradient are the most important variables for differentiating gullies according to their source substrates. The comparison between the Melton ratio, alcove length, and fan gradient of Martian and terrestrial gullies reveals that Martian gully systems were likely formed by terrestrial debris-flow-like processes. Present-day sublimation of CO2 ice on Mars may have provided the adequate flow fluidization for the formation of deposits akin to terrestrial debris-flow-like deposits.

Estimating peppermint essential oil levels: water-stream and classical hydroponic systems

Background: The leaves of peppermint and the essential oil received from them are used in medicine. The chemical content of essential oil is quite complex. It contains about 30 terpene compounds. The content of essential oil in flowers is 4-6%; in leaves – 2.4-2.8%, and in stems 0.3%. The main components that define the quality of essential oils are menthol, menthone, limonene, menthofuran, and isomenthone. Peppermint is used in the form of tea, tincture, extract, and salves. It has a regulating influence on the heart and circulatory system. It calms the heartbeat and supports the decrease of blood pressure, and the oil stream is used for dyspnea in the form of inhalation. Plant cream is used against insect bites, eczema, hemorrhoids, muscle pains, and some chronic diseases.Context and purpose of this study: The work aimed to study the content of the main components from the quality indicators of the essential oil of peppermint grown in different water-stream and classical hydroponic systems for the first time in Armenia.Results: From the analyses, it was revealed that the strengthening of the essential oil of peppermint grown in different systems of the water-stream hydroponics (cylindrical, gully, continuous) and classical hydroponics was observed in August. At the same time, high-yield plants of cylindrical and classical hydroponic systems exceeded other variants by 1.3-1.5 times with the essential oil output. In hydroponic systems, the specificities of the physical-chemical indices of peppermint essential oil were also studied. In August, the refractive indicator of essential oil increased to some extent in all variants, except for continuous hydroponics. The lack of increase in continuous hydroponics can likely be explained by the change in the ratio of essential oil to different compounds. At the end of vegetation, in September, some increase of essential oils' specific gravity was observed in the gully (2.1-3.5%) and continuous (4.5-4.7%) modules, while in cylindrical and classical hydroponics the change was minor. During vegetation, the essential oil of plant leaves was subject to not only quantitative but also qualitative changes. The cylindrical system exceeded other water-stream hydroponics variants with the main essential oil menthol component by 1.1-1.4 times and classical hydroponics by 1.1 times. The Gully system exceeded other water-stream systems with the content of D-Limonene and Menthyl acetate 3.6-9.7 and 1.3-3.0 times, respectively. And classical hydroponics 1.4 and 1.7 times, respectively. In the continuous system, the content of Isomentone, Pulegone, and Mint furanone was 1.3-2.0, 3.3-3.5, and 5.7-6.2 times higher, respectively, compared with the other water-stream hydroponic systems, and 1.6, 2.6, and 1.7 times, compared with classical hydroponics. Classical hydroponics exceeded all variants of water-stream hydroponics in the content of Piperidone by 3.3-4.1 times.Conclusion:Although the strengthening of essential oil biosynthesis was observed in all hydroponic variants in August, the cylindrical hydroponic system excelled in the content of essential oils, the most important qualitative indicator of menthol. High output of essential oil in plant raw material was observed in classical hydroponics and cylindrical system of water-stream hydroponics, which provides optimal regimen for the normal growth and development of plants.Keywords: cylindrical, medicinal plant, bioactive compounds, menthol

Analysis of the Dynamics of Water Flow and Suspension Flow Discharge in Volcano Watershed with Settlement Land Use

Suspension flow into the upstream of volcano watershed is sensitive to land use. In Indonesia, a settlement is a form of land use in several volcanic landscapes. There is currently no detailed study on the suspension flow sediment from the settlement land use. The purpose of this study is to investigate the characteristics of the relationship between water and suspension flow discharge. The study was conducted through the measurements at a gully outlet that produced 747 suspension load data. For each rainfall event, suspension load measurements were made in the field, followed by laboratory analysis. Additionally, field surveys were used to determine the characteristics of settlement land use and the water flow into the gully system. According to the findings, the peak flow discharge corresponds to the peak suspension discharge, the peak flow discharge comes before the peak suspension discharge, and the peak flow discharge happens after the peak suspension discharge. The average time lag between initial rainfall events and suspension flow was 10.36 minutes, and the suspension peak content varied by an average of 2.22 gl-1. The grain size was also dominated by the clay fraction, averaging 67.86% on the ascending branch and 67.82% on the descending branch.
 Keywords: Erosion; Discharge; Settlements; Suspension; Watershed
 
 Copyright (c) 2023 Geosfera Indonesia and Department of Geography Education, University of Jember
 This work is licensed under a Creative Commons Attribution-Share A like 4.0 International License

Quantitative Long-Term Monitoring (1890–2020) of Morphodynamic and Land-Cover Changes of a LIA Lateral Moraine Section

Aerial photographs of the European Alps usually only reach back to the middle of the 20th century, which limits the time span of corresponding studies that quantitatively analyse long-term surface changes of proglacial areas using georeferenced orthophotos. To the end of the Little Ice Age, this leads to a gap of about 100 years. Using digital monoplotting and several historical terrestrial photographs, we show the quantification of surface changes of a Little Ice Age lateral moraine section until the late second half of the 19th century, reaching a total study period of 130 years (1890–2020). The (initial) gully system expands (almost) continuously over the entire study period from 1890 to 2020. Until 1953, the vegetation-covered areas also expanded (mainly scree communities, alpine grasslands and dwarf shrub communities), before decreasing again, especially between 1990 and 2003, due to large-scale erosion within the gully system. Furthermore, our results show that the land-cover development was impacted by temperature and precipitation changes. With the 130-year study period, we contribute to a substantial improvement in the understanding of the processes in the proglacial by analysing the early phase and thus the immediate response of the lateral moraine to the ice exposure.

Object‐based image analysis (OBIA)‐based gully erosion dynamics, sediment loading rate and sediment yield study in Lake Hawassa Sub‐basin, Ethiopia

AbstractGully erosion is a serious environmental issue in Lake Hawassa Sub‐basin. It has affected a large portion of the catchment, and a large amount of sediment has been transported into the lake. This condition needs to be addressed. However, before conservation techniques are implemented, the gully systems should be mapped, their extent and changes over time need to be measured, and their capacity to produce sediment from their catchments should be determined. The objective of this study were, therefore, to map and analyse the change in gully erosion and quantify the sediment loading rate and sediment yield from the active and connected gullies in Lake Hawassa Sub‐basin using object‐based image analysis (OBIA) with high‐resolution SPOT 5 satellite image of the years 2011 and 2020. This method was integrated with field observation for mapping gully features of the study area, in comparison with automatic digitization carried out with the help of eCogenition Developer Version 9.1 and ArcGIS tools. Overall accuracy and Kappa coefficient were determined and were found to be 85.2% and 0.81, respectively, for the image of year 2020 and 81.1% and 0.76, respectively, for the image of year 2011. Based on the OBIA method, the extent of gullies (in area) were found to be 63.5 km2 in 2011 and 79.9 km2 showing a rapid increase between 2011 and 2020 (an increase of 16.4 km2 (24.4%) in the 10 years considered). The later result shows that 5.53% of the area of the Lake Hawassa Sub‐basin is affected by gully erosion. The maximum gully density in the study area was found to be 589 km/km2 in 2011 and this increased to 884 km/km2 in 2020. The sediment loading rate from the Lake's catchment was found to be in the range of 12.62 to 38.59 ton per hectare per year. The sediment yield from the Lake's catchment was 8.83 to 27.02 t/ha/year. The total annual volume‐based sediment yield at the Lake generated from the gully was 2.39 million cubic meter considering sediment delivery ratio of 70% for fully connected gullies. This result shows that 0.21% of the storage capacity of the Lake was being lost due to sedimentation from the gully system every year. From the result by dividing the total volume of the sediment by the surface area of the lake, one can see that a silt thickness of 2.51 cm was being deposited in the Lake every year.

Characteristics of sediment particle size distribution in the Pisha sandstone area of the middle Yellow River under the effects of vegetation and complex erosion

AbstractPisha sandstone is a soft bedrock composed of sandstone, sand shale and mudstone, with very low diagenesis and erosion resistance. The sources of coarse sediment and the processes of sediment production and transportation in Pisha sandstone areas are currently little understood. Understanding these processes will help us to comprehend the characteristics of sediment particle size distribution on slopes and gullies under the effects of vegetation and complex erosion. This will provide a scientific basis for the control of coarse sediments of the Yellow River and ecological restoration of the Pisha sandstone area. In this study, the process of sediment selectivity and transportation in the slope–gully system was analyzed through soil sampling in different seasons in the Erlaohugou small watershed, China. There is a clear selectivity phenomenon in the process of transporting sediment particles from the slope to the gully, and the coarse sediment particles are transported preferentially from the slope to the gully. There is a good response relationship between the distribution characteristics of sediment particles and the multi‐dynamic interaction. The complex erosion type in different seasons has a significant impact on sediment production and transportation, and most particles were transported under hydraulic power.

Classification and Provenance on Geochemical Lithogenes: A Case Study on Rock–Soil–Sediment System in Wanquan Area of Zhangjiakou, North China

Geochemical lithogenes have been successfully applied as an innovative concept in the field of composition classification and source traceability of geological materials recently. This paper introduces the background of the development of geochemical genes and the construction and application of LG01 and LG03 lithogenes. Based on LG01 and LG03, the LG_CR classification and provenance are applied and verified on a weathering profile, ten gully sedimentary profiles and regional stream sediments in the Wanquan area of Zhangjiakou city, Hebei province, China. The geochemical lithology of the weathering profile shows a gradual variation from basic-like in the bottom rock to acidic-like at the upper soils compositionally with heterogeneity. The classification results on 10 sedimentary gully profiles (each with five samples) indicate that soils at the bottom of the gully system are dominated with 11 types of LG_CR materials, while the top materials are made up of 21 types, reflecting the mixing of the upstream soils. The results of stream sediments from a regional geochemical survey with a scale of 1:200,000 in this area illustrate that the classification results of LG_CR on stream sediments are basically consistent with the petrological results derived from regional geological mapping. Therefore, LG_CR can be used not only as an effective tool for classification and traceability of geological materials but also has great potential in lithological mapping in petrological-overburdened areas.

Linear polygonal faults initiated Gully system around the margin slope of middle Miocene carbonate platform in the Northwest South China sea

An ancient gully system was revealed in the Northwest South China Sea using high-resolution three-dimensional (3D) seismic data. They are straight, regular, and intensely spaced sediment transporting routines, and are much smaller in size than channels. The gully system was distributed on the margin slope of the peri-carbonate platform in the middle Miocene. Two different types of gullies were identified based on the variation in the seismic response. Among them, most of the gullies are filled by low seismic amplitude reflectors, except a unique one, developed on the east slope of the study area, and is characterised by high seismic amplitude reflectors. The head of this gully reaches the carbonate platform, which provides carbonate clasts to the gully. The other gullies, expressing low seismic amplitude reflectors, develop limitedly on the slope of the carbonate platform and seldom receive source sediments from the carbonate platform. The gullies sit on the polygonal faults of middle Miocene, exhibit same strike with larger-scale linear ones of polygonal faults. These linear polygonal faults elongate from northwest to southeast, perpendicular to the slope contours, and in the same direction as the gullies. The coincidence between gullies and polygonal faults exhibits that the formation of gullies has been triggered mainly by the polygonal fault system (PFS) in the middle Miocene. These findings suggest that the middle Miocene carbonate platform provides favourable fine-grained lithology conditions for the formation of the PFS, while the linear polygonal faults initiate the gully system peri-carbonate platforms. Subsequently, the following gravity flows shape the initial configuration into the final features, while different provenances and different types of gravity flows create various characteristics of gullies.

The Shrink–Swell Process of the Granite Residual Soil with Different Weathering Degree in a Gully System in Southern China

The soil shrink–swell phenomenon produces crack networks and slope instability. However, few studies have involved the continuous shrink–swell process of granite residual soils. The objective of the study is to explore the shrink–swell process of weathered granite soils and its effects on gully development in southern China. The bulk density, soil water content (SWC), shrink–swell ratio (SSR), clay mineral content, and mechanical composition, etc., of soil samples from five soil layers (at depths of 0.3 m, 3.0 m, 7.0 m, 12.0 m, and 16.0 m) along a profile in Yudu County was analyzed. After quantifying the soil properties at different soil depths, we analyzed these data statistically in an effort to identify strong parametric relationships. The results indicated that some properties such as bulk density and shear stress increased with soil depth, while other soil properties, such as plasticity index and liquid limit, were inversely related to depth. Soil cohesion, the angle of internal friction, and shear stress were closely related to the SWC. Every 1% decrease in the SWC resulted in a shear stress reduction of 6.62 kPa. The SSR values exhibited significant variation between the three dry–wet cycles and were closely related to the bulk density values of our kaolin and montmorillonite samples. As an environmental factor, the SWC can trigger changes in internal soil properties such as shear stress and the SSR. Using these data and observations made during our field survey, it can be proposed that continuous shrink–swell variation in deep granite-weathering crust can result in crack formation and gully erosion. It can be inferred that crack development velocity and gully retreat rate may be affected by the soil’s shrink–swell process. Consequently, this information provides insight to understanding the mechanism of gully development in southern China.

Estimation of gully erosion rate and its determinants in a granite area of southeast China

Gully erosion is the most serious threat to sustainable development of global ecosystem and economy, with declining soil productivity and fertility threatening agricultural production. However, due to limitations in quantifying gully erosion rate, origin of erosion could be hardly distinguished. This study aimed to figure out this problem by developing a soil erosion estimation method based on unmanned aerial vehicles (UAV) monitoring techniques. Specifically, 18 gullies with different terrain characteristics were selected across typical erosion regions in southeast China, and UAV low-altitude photography, weather station monitoring, and field sampling investigation were conducted from 2020 to 2021to monitor their total erosion volume (VE), collapse volume (VC), proportion of collapse volume to total erosion volume (VC%), morphological parameters (e.g., total length of scour channels, L; erosion area, A; residual volume, V; and hypsometric integral) and soil-environmental factors (rainfall, temperature, and soil properties). It showed that 92.65 % of VE was resulted from colluvial deposits, attributing to the variation of L. Additionally, VC quantifying the amount of gravity erosion was determined by soil clay content in the upper catchment (Clay1). And percentage of VC to VE, characterized by VC%, possessed a significant linear correlation with HI (R2 = 0.571, p < 0.001). Moreover, regional differences of VE and VC was mainly attributed to soil clay content in colluvial deposits (Clay3) and HI. Collectively, clay content in the gully system inhibited gully erosion, while all the morphologic factors facilitated the development of gully erosion. Meanwhile, rainfall and temperature had significant impacts on VE and the regional difference of VC, probably due to the limited monitoring period.

Influence of Topographic Factors on the Characteristics of Gully Systems in Mountainous Areas of Ningnan Dry-Hot Valley, SW China.

A gully system is an important indicator that reflects the development of regional topography and landforms, and topography is one of the most important factors affecting the development of gullies. However, at present, research on the impact of topography on the development of gully systems in the mountainous area of Ningnan dry-hot valley still needs to be strengthened. In order to study the characteristics of gullies and the influence of topography on the development of gully systems, based on both the visual interpretation of remote sensing images and field investigations, five topographic factors (elevation, slope gradient, aspect, relief, and dissection) were employed and three gully erosion indexes (gully length, density, and frequency) were calculated. The geographical information system was used in this study to carry out the spatial analysis, Ward’s hierarchical clustering and correlation analysis. Results showed that the development of gully systems is greatly affected by the degree of relief and dissection, and there is a significant positive correlation (p < 0.01; p < 0.05), while elevation, slope gradient and aspect have little influence on it. Analysis of the gully systems showed that the gully erosion is the most intense in the area with an elevation of 2800–3200 m and slope gradients ≥ 38°. Furthermore, the degree of erosion on shady slopes was greater than that on sunny slopes. These results will help us to understand the spatial distribution and formation of gully systems in mountainous areas.

Remote Sensing and Nuclear Techniques for Soil Erosion Research in Forest Areas: Case Study of the Crveni Potok Catchment

Hilly terrains characterized by the looseness of the surface soil layer and the slope of the topographic surface are subjected to diverse erosion processes, which could greatly impact forest management. An erosive process was identified along the unstable slopes in most of the Crveni potok catchment in the southeastern part of Serbia. The results of this study indicate two erosion types of variable intensity, dominated by weak and moderate erosion, while severe erosion is identified at several locations. Water pressure in the pores of loose soil in the Crveni potok catchment generates gully erosion in parts of the catchment that are geologically predisposed by the composition of the parent substrate. The paper discusses the factors influencing gully erosion, such as soil density, the slope of the topographic surface, rainfall (precipitation amount, annual distribution), and vegetation characteristics. The set of used methodologies, including remote sensing, nuclear, and geospatial ones, provided an integrated assessment of factors affecting erosion in unstable forest areas. The soil erosion rates in the study area are estimated from inventories of fallout radionuclide 137Cs using conversion models. Airborne photogrammetry, terrestrial Structure-from-Motion 360-degree camera photogrammetry, and Terrestrial LiDAR Scanning (TLS) are used to model complex geomorphological features of forest terrain. These techniques are found to be convenient for the quantification of the existing state of erosion (length, width, volume, and density of the gully systems) in the forest gullies. The remote sensing techniques provided an insight into the physiographic characteristics of the studied area important for determining its parts affected by erosion. The models obtained using different techniques are compared, techniques are evaluated, and their advantages and disadvantages are pointed out. This approach enables the identification of priority targets for soil conservation and site-specific remediation measures to foster sustainable forest management.

Spatial distribution characteristics of discontinuous hillslope gullies on the Loess Plateau of China: A special focus on spoon gullies

Gullies characterized by frequent material exchanges and dramatic morphological changes sculpt fragmented surface landscapes and generate severe soil erosion, yet research on discontinuous gullies is currently lacking on the Loess Plateau of China. A special kind of discontinuous gully isolated on a hillslope, termed a spoon gully, was observed during a field investigation on the Loess Plateau. Spoon gullies are permanent gullies that are basically spoon-shaped with fat heads and thin tails. The confluences between spoon gullies and other gullies mainly occur in the subsurface. According to image interpretations and field verifications, 4077 spoon gullies were recognized on the Loess Plateau. These gullies were mainly distributed in the western part and northern fringes of the Loess Plateau with an obvious spatial clustering tendency, forming four concentrated areas with high gully densities. The topography distinctly affects the spatial distribution of spoon gullies. A total of 81.92% of the spoon gullies were located on slopes of 10–30°, and 73.29% of these gullies were located on semi-sunny or semi-shady slopes. Furthermore, the spatial distribution of spoon gullies was associated with loess landforms and soil erosion intensities. A total of 66.37% of the spoon gullies occurred in loess ridge, loess tableland, or loess hill regions, and more than 50% of them arose in areas of strong or moderate water erosion. Overall, spoon gullies were mainly distributed in areas where continuous gullies developed insufficiently, and this finding can be regarded as the integrated result of precipitation, loess thickness and texture, vegetation coverage, and agricultural activities, suggesting that spoon gullies may represent an early stage in the development of continuous loess gully systems. These results not only provide new insights for understanding the formation and evolution of gully landforms but also have significant implications for soil erosion management on the Loess Plateau.

Comparison study of channel coding on non-orthogonal multiple access techniques

Some of the benefits of fifth-generation (5G) mobile communications include low latency, fast data rates, and increased amount of perceived service quality of users and base station capacity. The purpose of this paper is to solve some of the problems in the traditional mobile system by increasing the channel capacity, non-orthogonal multiple access (NOMA), has a chance of winning the race, power-domain NOMA (PD-NOMA) is widely used in but it requires a large power imbalance between the signals allocated to various users to work. This paper also proposes an improved mobile system model and compares it with a traditional mobile system, then evaluates the effect of channel coding types on the spectrum efficiency performance. A proposed mobile system relied on increasing the number of users as well as increasing the frequency spectrum and is also proposed to improve the error rate, which is incorporated into NOMA and orthogonal frequency division multiplexing (OFDM) schemes at the same time to provide great flexibility and compatibility with other services, such as the 5G and sixth-generation (6G) systems. The mobile gully system (MGS) system is compared to a traditional system, the result is demonstrated that the proposed outperforms the orthogonal multiple access (OMA) system in terms of sum-rate capacity, and bit error rate (BER) performance.

An Exploration of Loess Landform Development Based on Population Ecology Method

The study of gully characteristics is one of the most effective ways to explore the loess landform development in the Loess Plateau of China. However, current studies mostly focus on gullies’ overall characteristics and ignore the different composition of the whole gully system. Therefore, a new perspective is provided in this paper for exploring loess landform development from the population characteristics of the gully system. Firstly, different types of gullies were extracted based on DEM and high-resolution images in three sample watersheds, including hillslope ephemeral gully, bank gully and different-level valley gully. Secondly, population characteristics from the amount, length, age structure and convergent relationship were calculated and analyzed by referring to the biological population in ecology. Finally, the development stages of loess landform in three watersheds were explored based on their population characteristics. The results showed that: (1) The population characteristics, including number density, length density, age structure and convergence, were obviously different in three sample watersheds. (2) The development differences of three watersheds were obtained by synthesizing all population characteristics: Linjiajian was the most developed and oldest watershed, followed by Yangjiaju and then Wangjiagou. (3) The comparison based on the existing soil erosion intensity map and predisposing factors proved that the findings of this paper were more reasonable than that of the traditional hypsometric integral. This research provides a new quantitative-based approach to explore the development degree of loess landform from the gully population, and is a beneficial attempt to combine geomorphology and ecology, further supplementing and improving the study of loess landform development.

Synergistic Effects of Grass Coverage and Dam Land Sedimentation on Runoff and Sediment Yields in a Slope–Gully System in the Loess Plateau, China

Synergistic Effects of Grass Coverage and Dam Land Sedimentation on Runoff and Sediment Yields in a Slope–Gully System in the Loess Plateau, China

The Dynamics of Flow Discharge and Suspension Flow Discharge in Volcano Watershed with Agroforestry Land Cover

The suspension flow from the upper part of a volcano watershed, which has a very thick soil condition, is sensitive to landuse form. Agroforestry is the dominant landuse form in the volcanic landscape of Indonesia. There is a lack of detailed studies about suspension flow in the upper watershed where agroforestry is the land cover. This research, performed in agroforestry area, covered the correspondence between flow discharge and suspension flow discharge, the time lag of initial rain events and the formation of suspension flow; and the characteristics of the grain size of the suspensions during the flow. The suspension flow was measured at the outlet of a gully in key watershed areas, which yielded a total of 436 suspension data. The measurement analysis was conducted at every rain event in the field and in the laboratory. The crop characteristics in the rain catchment area were recorded in details during the field survey. The characteristics of the channels converging toward the gully system were observed during the field survey. There were three relationship patterns between the peak flow discharge and the peak suspension discharge, namely (1) the peak flow discharge corresponded to the peak suspension discharge, (2) the peak flow discharge preceded the peak suspension discharge, (3) the peak flow discharge occurred after the peak suspension discharge. The average time interval between the rain events and the occurrence of suspension flow was 17.7 minutes. The peak suspension content varied from 0.0016 g/L up to 4.71 g/L with an average of 1.03 g/L. The grain size of the suspension was dominated by 71-76% of clay fraction with an average of 73% at the rising phase and 68-71% of clay fraction with an average of 69% at the falling stage