Erosion control of Chinese loess using polymer SH and ryegrass

The China Loess Plateau is subjected to severe soil erosion triggered by intense rainfall,resulting in significant harm and losses to both human society and the natural surroundings.In this study,a novel technique for managing loess erosion is introduced,which involves the utilization of a combined polymer SH and ryegrass.A comprehensive series of tests were undertaken,including rainfall erosion tests,disintegration experiments,and scanning electron microscopy examinations,to assess the accumulative sediment yield(ASY),disintegration ratio,and microstructural features of both untreated and treated loess samples.The results showed a significant reduction in ASY with increased dry density of untreated loess.Furthermore,the combined technique effectively controlled erosion,limiting ASY to 266.2 g/cm^(2)in 60 minutes.This was approximately one-sixth,one-ninth,and one-fifteenth of the ASY in SH-treated loess(L-SH),ryegrass-treated loess(L-R),and untreated loess,respectively.It resisted disintegration better than ryegrass alone but slightly less than SH.This improvement was due to the combined effect of SH and ryegrass,which reduced raindrop impact,improved loess microstructure,and boosted ryegrass growth.The innovative technique holds the potential to be applied as a field-scale technique in the Loess Plateau region of China.

Effect of coir geotextile and geocell on ephemeral gully erosion in the Mollisol region of Northeast China

The unique geomorphological features and farming methods in the Mollisol region of Northeast China increase water catchment flow and aggravate the erosion of ephemeral gully(EG).Vegetation suffers from rain erosion and damage during the growth stage,which brings serious problems to the restoration of grass in the early stage.Therefore,effects of coir geotextile and geocell on EG erosion under four confluence intensities were researched in this study.Results of the simulated water discharge erosion test showed that when the confluence strength was less than 30 L/min,geocell and coir geotextile had a good effect on controlling EG erosion,and sediment yield of geocell and coir geotextile was reduced by 25.95%–37.82%and 73.73%–88.96%,respectively.However,when confluence intensity increased to 40 L/min,protective effect of coir geotextile decreased,and sediment yield rate increased sharply by 189.03%.When confluence intensity increased to 50 L/min,the protective effect of coir geotextile was lost.On the other hand,geocell showed that the greater the flow rate,the better the protective effect.In addition,with the increase in confluence intensity,erosion pattern of coir geotextile developed from sheet erosion to intermittent fall and then to completion of main rill,and the protective effect was gradually weakened.In contrast,the protective effect of EG under geocell was gradually enhanced from the continuous rill to the intermittent rill and finally to the intermittent fall.This study shows that coir geotextile and geocell can prevent EG erosion,and the effect of geocell is better than that of coir geotextile on the surface of EG.

Comparison of erosion and erosion control works in Macedonia,Serbia and Bulgaria

While soils are as essential to human society as air and water,soil degradation has not received nearly as much attention as the threats to these other elements.On the map of water erosion of Europe,Southern Europe is red"colored".Erosion in the Balkan countries,through both on and offsite effects is a major cause of soil and water degradation.This paper compares erosion control works in several countries from the Balkan region(Macedonia,Serbia,and Bulgaria).The basis for comparative analyses was various country reports as well as available published papers.Quantitative method-text analyze method was used for these study.Natural conditions in the Balkan countries contribute to the appearance of various erosion forms and the intensity of the erosion processes.Over the history of these countries,people who settled this region used the available natural resources to fill their needs(tree cutting,incorrect plugging,overgrazing),which contributed to soil erosion.Organized erosion control works in the Balkans started in the beginning of the 20th century(1905 in Bulgaria).The highest intensity of erosion control works were carried out during the period 1945-1990.Various erosion control works were launched.Bulgaria had a large anti-erosion afforestation,almost 1 million ha.Bulgaria's ecological river restoration approach has been in use for almost 50 years.Serbia contributed significant erosion and torrent control works on hilly agricultural areas.Specific screen barrages and afforestation on extremely dry areas are characteristic in Macedonia.A common characteristic for all countries is a high decrease in erosion control works in the last 20 years.

Evaluation of soil erosion from chestnut forests: A case study in the Yanshan Mountains, China

Soil erosion from chestnut forests has many types and intensities. However, less attention has been paid to the increasing soil erosion in the chestnut forests of Yanshan Mountains region, North China. The objective of this study was to discuss forest ages(<5, 5~<10, 10~<20, and 20~ yr), slopes(5°~<15°, 15°~<25°, 25°~<35°, and 35°~), slope positions(upslope, midslope, downslope, and whole slope), and slope aspects(sunny, half-sunny, shade, and half-shade) effects on soil erosion types and intensities in chestnut forests. A field survey was applied to investigate in detail the contiguous chestnut forests near Changfu village of Hebei Province, China on October 9-30, 2016. Results showed that chestnut forests are dominated by moderate erosion in this region, and the soil erosionfrom chestnut forests tended to deteriorate gradually. The average land degradation index was 0.31. The erosion intensity from chestnut forests will gradually increase with the year of planting. Most of the slopes are greater than 15°, accounting for 86.7% of the total chestnut forests. Most of the chestnut forests occupy the whole slope, accounting for 47.5% of the total area. Moderate erosion occurs most commonly for different slope aspects. In conclusion, improving the preparation efficiency of chestnut forests and enhancing the construction standards of soil and water conservation measures would be useful measures to avoid soil erosion from chestnut forests reaching a more severe level.

Experimental study on mitigating wind erosion of calcareous desert sand using spray method for microbially induced calcium carbonate precipitation

Wind erosion is one of the significant natural calamities worldwide, which degrades around one-third of global land. The eroded and suspended soil particles in the environment may cause health hazards, i.e.allergies and respiratory diseases, due to the presence of harmful contaminants, bacteria, and pollens.The present study evaluates the feasibility of microbially induced calcium carbonate precipitation(MICP)technique to mitigate wind-induced erosion of calcareous desert sand(Thar desert of Rajasthan province in India). The temperature during biotreatment was kept at 36℃ to stimulate the average temperature of the Thar desert. The spray method was used for bioaugmentation of Sporosarcina(S.) pasteurii and further treatment using chemical solutions. The chemical solution of 0.25 pore volume was sprayed continuously up to 5 d, 10 d, 15 d, and 20 d, using two different concentration ratios of urea and calcium chloride dihydrate viz 2:1 and 1:1. The biotreated samples were subjected to erosion testing(in the wind tunnel) at different wind speeds of 10 m/s, 20 m/s, and 30 m/s. The unconfined compressive strength of the biocemented crust was measured using a pocket penetrometer. The variation in calcite precipitation and microstructure(including the presence of crystalline minerals) of untreated as well as biotreated sand samples were determined through calcimeter, scanning electron microscope(SEM), and energydispersive X-ray spectroscope(EDX). The results demonstrated that the erosion of untreated sand increases with an increase in wind speeds. When compared to untreated sand, a lower erosion was observed in all biocemented sand samples, irrespective of treatment condition and wind speed. It was observed that the sample treated with 1:1 cementation solution for up to 5 d, was found to effectively resist erosion at a wind speed of 10 m/s. Moreover, a significant erosion resistance was ascertained in15 d and 20 d treated samples at higher wind speeds. The calcite content percentage, thickness of crust,bulk density, and surface strength of biocemented sand were enhanced with the increase in treatment duration. The 1:1 concentration ratio of cementation solution was found effective in improving crust thickness and surface strength as compared to 2:1 concentration ratio of cementation solution. The calcite crystals formation was observed in SEM analysis and calcium peaks were observed in EDX analysis for biotreated sand.

海水进退、滩坪出没、云化岩溶等与碳酸盐岩储层关系研究——以上扬子地台龙王庙组为例

大量的油气勘探开发实践证实碳酸盐岩储层类型主要有礁滩储层、白云岩储层、岩溶储层及裂缝性(灰岩)储层。因此,在进一步的油气勘探生产中,能否成功预测这些储层的分布及评价就成为了关键任务。应用碳酸盐岩台地滩坪组合快速分析法对四川盆地及其周缘6条野外基干剖面进行实测、2口钻井基干剖面进行描述以及81个露头和钻井等资料点的重新解释以及岩石薄片、阴极发光等室内分析。在此基础上,编制了大量的单因素图、综合沉积模式图、储层分布预测图等,并经过综合研究,总结出了"滩、云滩、云溶滩"(加裂缝),储层物性渐次变好的规律。并认为:1)扬子台地龙王庙组,在特殊气候异常蒸发风暴发育时期,海水进退、滩坪出没、云化岩溶等因素共同控制了滩体储层的发育、云化、岩溶等储层优化作用。2)因初始孔隙系统的重要性及其对后期演化提供有利条件,所以同生、准同生及准同生后早期的白云化作用及岩溶作用对储层形成意义重大;表生岩溶作用(及裂缝),既可大大改善储层物性,也可形成新的储集空间。3)扬子台地龙王庙期滩相发育的特殊时期和环境条件——台平、坡陡、盆深的古地理沉积格局,适用"碳酸盐岩台地滩坪组合快速沉积相分析法"。即"以滩为原点"取相对古水深10 m(最佳区间在5～15 m之间),通过岩性、沉积构造(如滩条组合或滩坪组合)等沉积特征快速识别浅水环境和相对深水环境,快速识别沉积相;并对其定量赋值取20 m和0 m,恢复古水深。通过该方法可以快速绘制相对海平面升降变化曲线,识别层序、划分体系域,最终在研究区识别出了"台地之上滩连滩"以及"滩坪组合"的新型沉积模式,为储层的成因和分布研究奠定了可靠的地质学基础。

中国南方崩岗侵蚀驱动因素的空间尺度效应

Gully erosion,an integrated result of various social and environmental factors,is a severe problem for sustainable development and ecology security in southern China.Cur-rently,the dominant driving forces on gully distribution are shown to vary at different spatial scales.However,few systematic studies have been performed on spatial scaling effects in identifying driving forces for gully erosion.In this study,we quantitatively identified the de-terminants of gully distribution and their relative importance at four different spatial scales(southern China,Jiangxi province,Ganxian county,and Tiancun township,respectively)based on the Boruta algorithm.The optimal performance of gully susceptibility mapping was investigated by comparing the performance of the multinomial logistic regression(MLR),lo-gistic model tree(LMT),and random forest(RF).Across the four spatial scales,the total contributions of gully determinants were classified as lithology and soil(32.65%)≥topogra-phy(22.40%)>human activities(22.31%)>climate(11.32%)>vegetation(11.31%).Among these factors,precipitation(7.82%),land use and land cover(6.16%),rainfall erosivity(10.15%),and elevation(11.59%)were shown to be the predominant factors for gully erosion at the individual scale of southern China,province,county,and township,respectively.In addition,contrary to climatic factors,the relative importance of soil properties and vegetation increased with the decrease of spatial scale.Moreover,the RF model outperformed MLR and LMT at all the investigated spatial scales.This study provided a reference for factor selection in gully susceptibility modeling and facilitated the development of gully erosion management strategies suitable for different spatial scales.

Biochar granulation reduces substrate erosion on green roofs

Green roofs are exposed to high winds and harsh environmental conditions that can degrade vegetation and erode substrate material,with negative consequences to ecosystem services.Biochar has been promoted as an effective substrate additive to enhance plant performance,but unprocessed biochars are susceptible to wind and water erosion.Applications of granulated biochars or chemical dust suppressants are suggested as a means to mitigate biochar and substrate erosion;however,research on biochar type and chemical dust suppressant use on biochar and substrate erosion is lacking.Vegetation is a crucial factor that influences substrate erosion,yet plant responses may vary with biochar type and chemical dust suppressant;thus,the effects of possible mitigation measures on biochar and substrate erosion are unclear.We investigated the effects of surface-applied granulated and unprocessed biochars and an organic dust suppressant(Entac™)on biochar and substrate erosion on green roofs with Sedum album L.and a native plant mix.Our results show that 94%of unprocessed biochars were lost from green roofs after 2 years regardless of the Entac™amendment,likely due to the lightweight nature and fragmentation of biochar particles.In contrast,granulation of biochars reduced the biochar erosion and total substrate erosion by 74%and 39%,respec-tively,possibly due to enhanced biochar bulk density and particle size and improved moisture retention of biochar-amended substrates.Additionally,Sedum album better reduced biochar and substrate erosion than the native plant mix,likely due to rapid development of high vegetation cover that reduced wind exposure and enhanced substrate moisture retention.We conclude that applications of granulated biochars can substantially reduce biochar and sub-strate erosion on green roofs,improving green roof sustainability.