China＇s dryland region has serious wind erosion problem and is sensitive to climate change due to its fragile ecological condition. Wind erosion climatic erosivity is a measure of climatic factors influencing wind er...China＇s dryland region has serious wind erosion problem and is sensitive to climate change due to its fragile ecological condition. Wind erosion climatic erosivity is a measure of climatic factors influencing wind erosion, therefore, evaluation of its intensity and response to recent climate changes can contribute to the understanding of climate change effect on wind erosion risk. Using the FAO equation, GIS and statistical analysis tools, this study quantified the climatic erosivity, analyzed its spatiotemporal variations, and detected the trend and sen- sitivity to climate factors during 1961-2012. The results indicate that mean annual climatic erosivity was 2-166 at 292 stations and 237-471 at 6 stations, with the spatial distribution highly in accordance with wind speed （R^2 = 0.94）. The climatic erosivity varied greatly over time with the annual variation （CV） of 14.7%-108.9% and monthly variation （concentration degree） of 0.10-0.71 in the region. Meanwhile, annual erosivity showed a significant down- ward trend at an annual decreasing rate mostly above 1.0%. This significantly decreasing trend was mainly attributed to the obvious decline of wind speed during the period. The results suggest that the recent climate changes were highly possible to induce a decrease of wind erosion risk in China＇s dryland region.展开更多
Soils in the hydro-fluctuation belts of the reservoirs are most highly influenced by the special hydro-conditions and reservoir operation,leading to unique soil erosion process and largely accelerate soil erosion inte...Soils in the hydro-fluctuation belts of the reservoirs are most highly influenced by the special hydro-conditions and reservoir operation,leading to unique soil erosion process and largely accelerate soil erosion intensity.The present study aimed to estimate soil erosion rate in the hydro-fluctuation belt of the Pubugou Reservoir,Southwest China,based on the framework of Universal Soil Loss Equation(USLE).An attempt has been made to modify the original USLE by including the reservoir water erosivity(W),a new factor into the model.Soil erosion rate from different land use types were quantitatively estimated,using the USLE and the modified USLE respectively.Field observation showed that soil erosion rate in dry farmland,bare land and grassland was 4700,44600 and 5050 t/km2,respectively.The erosion rate assessed by the modified USLE was closely related to that recorded from the field monitoring data.The findings of this study clearly highlight the importance of inclusion of the W factor to the original USLE model while assessing soil erosion in the reservoir hydro-fluctuation belt.展开更多
Reservoir sedimentation dynamics were interpreted using Cs-137 activity, particle size and rainfall erosivity analysis in conjunetion with sediment profile coring. Two sediment cores were retrieved from the Changshou ...Reservoir sedimentation dynamics were interpreted using Cs-137 activity, particle size and rainfall erosivity analysis in conjunetion with sediment profile coring. Two sediment cores were retrieved from the Changshou reservoir of Chongqing, which was dammed in 1956 at the outlet of Longxi catchment in the Three Gorges Area using a gravity corer equipped with an aerylie tube with an inner diameter of 6 em. The extracted cores were sectioned at 2 cm intervals. All sediment core samples were dried, sieved （〈2 mm） and weighed. 137Cs activity was measured by y-ray spectrometry. The particle size of the core samples was measured using laser particle size granulometry. Rainfall erosivity was calculated using daily rainfall data from meteorological records and information on soil conservation history was collated to help interpret temporal sedimentation trends. The peak fallout of 137Cs in 1963 appeared at a depth of 84 cm in core A and 56 cm in core B. The peaks of sand contents were related to the peaks of rainfall erosivity which were recorded in 1982, 1989, 1998 and 2005, respectively. Sedimentation rates were calculated according to the sediment profile chronological controls of 1956, 1963, 1982, 1989, 1998 and 2oo5. The highest sedimentation rate was around 2.0 cm·a^-1 between 1982 and 1988 when the Chinese national reform and the Household Responsibility System were implemented, leading to accelerated soil erosion in the Longxi catchment. Since 1990s, and particularly since 2005, sedimentation rates clearly decreased, since a number of soil conservation programs have been carried out in the catchment. The combined use of ^137Cs chronology, particle size and rainfall erosivity provided a simple basis for reconstructing reservoir sedimentation dynamics in the context of both physical processes and soil restoration. Its advantages include avoiding the need for full blown sediment yield reconstruction and the concomitant consideration of core correlation and corrections for autochthonous inputs and reservoir trap efficiency.展开更多
Rainfall erosivity in Tibet from 2000 to 2OlO was estimated based on simplified erosion prediction model using daily rainfall data derived from the Tropical Rainfall Measurement Misssion （TRMM） 3B42 rainfall measure...Rainfall erosivity in Tibet from 2000 to 2OlO was estimated based on simplified erosion prediction model using daily rainfall data derived from the Tropical Rainfall Measurement Misssion （TRMM） 3B42 rainfall measurement algorithm. Semi- monthly erosive rainfall and rainfall erosivity were validated using weather station data. The spatial distribution of annual rainfall erosivity as well as its seasonal and annual variation in Tibet was also examined. Results showed that TRMM 3B42 data could serve as an alternative data source to estimate rainfall erosivity in the area where only data from sparsely distributed weather stations are available. The spatial distribution of rainfall erosivity in Tibet generally resembles the distribution of multi-year average of annual rainfall. Annual rainfall erosivity in Tibet decreased from the southeast to the northwest. The concentration degree of rainfall erosivity shows an increasing trend from the southeast to the northwest. High rainfall erosivity accompanies low rainfall erosivity concentration degree and vice versa. Rainfall erosivity increased in the middle and western Tibet and decreased in the southeastern Tibet during the 11 years of this study.展开更多
Rainfall erosivity is an important climatic factor for predicting soil loss. Through the application of high-resolution pluviograph data at 5 stations in Huangshan City, Anhui Prov- ince, China, we analyzed the perfor...Rainfall erosivity is an important climatic factor for predicting soil loss. Through the application of high-resolution pluviograph data at 5 stations in Huangshan City, Anhui Prov- ince, China, we analyzed the performance of a modified Richardson model that incorporated the seasonal variations in parameters α andβ. The results showed that （1） moderate to high seasonality was presented in the distribution of erosive rainfall, and the seasonality of rainfall erosivity was even stronger; （2） seasonal variations were demonstrated in both parameters α and β of the Richardson model; and （3） incorporating and coordinating the seasonality of parameters αandβgreatly improved the predictions at the monthly scale. This newly modi- fied model is therefore highly recommended when monthly rainfall erosivity is required, such as, in planning soil and water conservation practices and calculating the cover-management factor in the Universal Soil Loss Equation （USLE） and Revised Universal Soil Loss Equation （RUSLE）.展开更多
Sand-fflled splash cups were used to study the erosive power of rainfall and throughfall in the humid subtropics of Southeast China. The splash cup measurements yielded precise and reproducible results under both open...Sand-fflled splash cups were used to study the erosive power of rainfall and throughfall in the humid subtropics of Southeast China. The splash cup measurements yielded precise and reproducible results under both open field conditions and forest vegetation. The splash cups were exposed to specific forest stands of different ages and to selected species （Schima superba, Castanopsis eyrei, Daphniphyllum oldhamii, Lithocarpus glaber） in the Gutianshan （古田山） National Nature Reserve （GNNR）. The results of the measurements under forest vegetation show that the erosive power of throughfall drops to be 2.59 times higher compared to the open field. This accentuates the importance of shrub, herb and litter layers in forest ecosystems to protect the soil against erosion. Coalescing drops from leaves and branches （drips） are responsible for this notable gain in erosive power. Moreover, differences in sandloss between the investigated tree species （deciduous, evergreen） revealed that the erosion potential and the spatial heterogeneity of throughfall are species-specific. This highlights the importance of selecting specific species for afforestation projects considering the prevention of soil erosion.展开更多
Climate change can affect wind erosion power and hence induce changes in wind erosion rates.In this study,the wind erosion climate factor(C-factor),proposed by the Food and Agriculture Organization of the United Natio...Climate change can affect wind erosion power and hence induce changes in wind erosion rates.In this study,the wind erosion climate factor(C-factor),proposed by the Food and Agriculture Organization of the United Nations,was used to assess the impact of changes in climate on wind erosion climatic erosivity.The Mann-Kendall test was employed to detect trends in the C-factor during the period of 1961–2017 in the farming-pastoral zone of northern China.Sensitivity analysis was used to determine the sensitivity of the C-factor to changes in key climate factors.Furthermore,a comparison of the contributions of different climate factors was carried out to understand their impact on changes in the C-factor.The results indicated that most of the surveyed region exhibited decreasing trends in wind speed at a confidence level of 90%,while maximum and minimum temperatures showed increasing trends throughout the study area.As a consequence of decreasing wind speed,the annual C-factor exhibited significant decreasing trends,with a mean slope of–0.58/yr.Seasonal analysis revealed that in most regions,the changes in the C-factor had significant decreasing trends in spring,winter,and autumn,while in more than two-thirds of the study area,no significant change trends in the C-factor were detected in summer at a confidence level of 90%.Sensitivity analysis showed that the C-factor was most sensitive to wind speed,and that the sensitivity coefficients from July to September were much higher than those in other months.Contribution analysis revealed that,for most stations,wind speed(with greater values of sensitivity coefficients)was the dominant factor in the change of C-factor,while for some stations,the minimum temperature made the most contribution to the C-factor’s change due to its dramatic changes during the study period.Although the minimum temperature sensitivity coefficient was the lowest of all the sensitivity coefficients,it is urgent to evaluate the expected impact of minimum temperature due to its possible changes in the future.展开更多
Rainfall erosivity is an indicator of rainfall potential to cause soil erosion.The Melamchi extreme flood occurred on June-15 and recurred on July-31,2021 in Nepal.During these flooding events,a large volume of sedime...Rainfall erosivity is an indicator of rainfall potential to cause soil erosion.The Melamchi extreme flood occurred on June-15 and recurred on July-31,2021 in Nepal.During these flooding events,a large volume of sediments were eroded,transported and deposited due to the high rainfall erosivity of the basin.In this study,the temporal and the spatial distribution of rainfall erosivity within the Melamchi River Basin was estimated and further linked to sediment discharge and concentration at various sites along the river segments.The daily rainfall data for the event year 2021 of the entire basin were used.Validation was performed by post-flooding grain size sampling.The result showed that rainfall and rainfall erosivity exhibit pronounced intensity within the Melamchi River basin,particularly at Sermathang and Tarkeghang,both located in the middle section of the basin.The average annual rainfall in the Melamchi region was 3140.39 mm with an average annual erosivity of 18302.06(MJ mm)/(ha h yr).The average daily erosivity of the basin was 358.67(MJ mm)/(ha h)during the first event and 1241(MJ mm)/(ha h)for the second event.In the upper section of sampling,the sediment size ranged from 0.1 mm to>8 mm and was poorly graded.However,the lower region had smaller sediment ranging from 0.075 mm to>4.75 mm and also well graded.The smaller size(<1 mm)sediment passing was much higher in the Chanaute(78%)and Melamchi(66.5%)river segments but the larger size(>100 mm)sediments were passed relatively higher from the Kiwil(8.20%)and Ambathan(8.39%)river segments.During premonsoon and monsoon seasons,the highest sediment concentration was found to be 563.8 g/L and 344.3 g/L in Bhimtar and the lowest was 238.5 g/L and 132.1 g/L at the Ambathan,respectively.The sediment concentration during the pre-monsoon was found to be higher than the sediment concentration during the monsoon season in the Melamchi River.The more erosive regions in the basin were associated with the presence of highly fractured rock,weathered rocks and a thrust(weak)zone.The higher rainfall erosivity at upstream and the higher sediment concentration at downstream during flooding events have coincided well in the basin.Thus,the estimation of rainfall erosivity at the catchment scale and its influences on sediment concentration in the river are crucial for erosion control measures during flooding times in the Himalaya.展开更多
The objective of this research is to estimate the annual and seasonal rainfall erosivity over Jordan based on three different regression models. Readily available annual and seasonal precipitation data with long recor...The objective of this research is to estimate the annual and seasonal rainfall erosivity over Jordan based on three different regression models. Readily available annual and seasonal precipitation data with long records (40 - 53 years) pertaining to 40 weather stations were utilized to estimate rainfall erosivity. The spatial distribution of rainfall erosivity over Jordan is controlled largely by morphological (relief) and climatic factors. The lowest R-values (28 MJ mm.ha-1.h-1.yr-1) are found in the arid zone, where the average annual rainfall is below 100 mm, whereas the highest R-values are found in the northern highlands (505 MJ mm.ha-1.h-1.yr-1) where the average annual rainfall approaches 650 mm. The correlation between annual and seasonal precipitation (mm) and annual erosivity exhibits a very strong relationship (R varies from 0.964 to 1.0, and all correlations are significant at 0.01 level [2-tailed test]). Moderate positive correlations were achieved between latitude (N) and the mean annual/seasonal precipitation (R ranges from 0.407 to 0.642, and all correlations are significant at 0.01 level [2-tailed test]). Spatial differences observed in erosivity, afforded a substantial source of information and maps for predicting erosion in Jordan. According to the present analysis, two parameters proved to be useful to predict rainfall erosivity on a national level. These parameters are the average annual precipitation, and latitude.展开更多
Despite being in arid and semi-arid areas,erosion is largely a result of infrequent but heavy rainfall events; therefore,rainfall erosivity data can be used as an indicator of potential erosion risks.The purpose of th...Despite being in arid and semi-arid areas,erosion is largely a result of infrequent but heavy rainfall events; therefore,rainfall erosivity data can be used as an indicator of potential erosion risks.The purpose of this study was to investigate the spatial distribution of annual rainfall erosivity in North Jordan.A simplified procedure was used to correlate erosivity factor R values in both the universal soil loss equation (USLE) and the revised universal soil loss equation (RUSLE) with annual rainfall amount or modified Fournier index (F mod ).Pluviometric data recorded at 18 weather stations covering North Jordan were used to predict R values.The annual values of erosivity ranged between 86-779 MJ mm ha ?1 h ?1 year ?1 .The northwest regions of Jordan showed the highest annual erosivity values,while the northeastern regions showed the lowest annual erosivity values.展开更多
Soil erosion by water is the most important land degradation problem worldwide. In this paper a new procedure was developed to estimate the rainfall-runoff erosivity factor （R） based on Tropical Rainfall Measuring M...Soil erosion by water is the most important land degradation problem worldwide. In this paper a new procedure was developed to estimate the rainfall-runoff erosivity factor （R） based on Tropical Rainfall Measuring Mission （TRMM） satellite-estimated precipitation data, which consists of 3-h rainfall intensity data. In this method, R was calculated as the product of the maximum 180-min rainfall intensity and the rainfall energy. This procedure was applied to the Daling River basin in Liaoning Province, China, R in terms of yearly, monthly and event-based rainfall in 2005 was computed separately using TRMM 3B42 data. The TRMM data showed a significant correlation with the interpolated rain-gauge data. Furthermore, because the TRMM data are based on rainfall intensity, they can represent the impact on erosion more accurately. It reflects both the spatial distribution and the intensity of rainfall. The procedure is a new approach to estimate the rainfall erosivity for soil water erosion modeling, especially in areas lacking rain-gange stations.展开更多
Rainfall erosivity,one of the factors in the Universal Soil Loss Equation.quantifies the effect of rainfall and runoffon soil erosion.High-resolution data are required to compute rainfall erosivity,but are not widely ...Rainfall erosivity,one of the factors in the Universal Soil Loss Equation.quantifies the effect of rainfall and runoffon soil erosion.High-resolution data are required to compute rainfall erosivity,but are not widely available in many parts of the world.As the temporal resolution of rainfall measurement decreases,computed rainfall erosivity decreases.The objective of the paper is to derive a series of conversion factors as a function of the time interval to compute rainfall erosivity so that the R factor computed using data at different time intervals could be converted to that computed using 1-min data.Rainfall data at 1-min intervals from 62 stations over China were collected to first compute the~ue'R factor values.Underestimation of the R factor was systematically evaluated using data aggregated at 5,6.10,15,20,30,and 60-min to develop conversion factors for the R factor and the 1-in-10-year storm EI30 values.Compared with true values,the relative error in R factor using data at fixed intervals of≤10min was<10%for at least 44 out of 62 stations.Errors increased rapidly when the time interval of the rainfall data exceeded 15 min.Relative errors were>10%using 15-min data for 66.1%of stations and>20%using 30-min data for 61.3%of stations.The conversion factors for the R factor,ranging from 1.051 to 1.871 for 5 to 60-min data,are higher than those for the 1-in-10-years storm EI30,ranging from 1.034 to 1.489 for the 62stations.展开更多
Northeast China(NEC)is one of the vital commercial grain bases in China and it has suffered from soil erosion due to prolonged cultivation and lack of protection.To determine long-term trends of precipi-tation and rai...Northeast China(NEC)is one of the vital commercial grain bases in China and it has suffered from soil erosion due to prolonged cultivation and lack of protection.To determine long-term trends of precipi-tation and rainfall erosivity over NEC during the latest decades,daily precipitation for the entire year during 1961-2020 and hourly precipitation for the warm season(May to September)during 1971-2020 were collected for 192 and 126 stations,respectively.Three seasons,including the cold season(October to April),early warm season(May to June),and late warm season(July to September)were divided according to the combination of precipitation and vegetation.Results demonstrate:(1)Daily precipita-tion reveals total precipitation and rainfall erosivity in the cold season and early warm season increase significantly at relative rates of 3.1%-6.1%compared with the average during 1961-2020,and those in the late warm season decrease insignificantly.(2)Hourly precipitation reveals storms occurring in the early and late warm seasons have undergone significant increasing changes,which shift towards longer storm duration,larger amount,peak intensity,kinetic energy,and rainfall erosivity during 1971-2020.Moreover,the frequency of extreme storms increased.(3)Rainfall erosivities estimated from daily pre-cipitation during 1971-2020 increase insignificantly for the early and late warm season,whereas those from hourly precipitation increase significantly(6.1%and 5.5%,respectively),which indicates daily precipitation may not be able to capture the trend fully under the warming background,and precipi-tation at higher resolutions than the daily scale is necessary to detect trends of rainfall erosivity more accurately.展开更多
The Tibetan Plateau(TP)in China has been experiencing severe water erosion because of climate warming.The rapid development of weather station network provides an opportunity to improve our understanding of rainfall e...The Tibetan Plateau(TP)in China has been experiencing severe water erosion because of climate warming.The rapid development of weather station network provides an opportunity to improve our understanding of rainfall erosivity in the TP.In this study,1-min precipitation data obtained from 1226 weather stations during 2018–2019 were used to estimate rainfall erosivity,and subsequently the spatial-temporal patterns of rainfall erosivity in the TP were identified.The mean annual erosive rainfall was 295 mm,which accounted for 53%of the annual rainfall.An average of 14 erosive events occurred yearly per weather station,with the erosive events in the wet season being more likely to extend beyond midnight.In these cases,the precipitation amounts of the erosive events were found to be higher than those of the daily precipitations,which may result in implicit bias as the daily precipitation data were used for estimating the rainfall erosivity.The mean annual rainfall erosivity in the TP was 528 MJ mm·ha^(-1)·h^(-1),with a broader range of 0–3402 MJ mm·ha^(-1)·h^(-1),indicating a significant spatial variability.Regions with the highest mean annual rainfall erosivity were located in the forest zones,followed by steppe and desert zones.Finally,the precipitation phase records obtained from 140 weather stations showed that snowfall events slightly impacted the accuracy of rainfall erosivity calculation,but attention should be paid to the erosion process of snowmelt in the inner part of the TP.These results can be used as the reference data for soil erosion prediction in normal precipitation years.展开更多
Rainfall erosivity is defined as the potential of rain to cause erosion.It has great potential for application in studies related to natural disasters,in addition to water erosion.The objectives of this study were:ⅰ)...Rainfall erosivity is defined as the potential of rain to cause erosion.It has great potential for application in studies related to natural disasters,in addition to water erosion.The objectives of this study were:ⅰ)to model the Rday using a seasonal model for the Mountainous Region of the State of Rio de Janeiro(MRRJ);ⅱ)to adjust thresholds of the Rday index based on catastrophic events which occurred in the last two decades;andⅲ)to map the maximum daily rainfall erosivity(Rmaxday)to assess the region's suscepti-bility to rainfall hazards according to the established Rday limits.The fitted Rday model presented a satisfactory result,thereby enabling its application as a Rday estimate in MRRJ.Events that resulted in Rday>1500 MJ ha-1.mm.h-1.day-1 were those with the highest number of fatalities.The spatial distribution of Rmaxday showed that the entire MRRJ has presented values that can cause major rainfall.The Rday index proved to be a promising indicator of rainfall disasters,which is more effective than those normally used that are only based on quantity(mm)and/or intensity(mm.h-1)of the rain.展开更多
Temporal change in rainfall erosivity varies due to the rainfall characteristic(amount,intensity,frequency,duration),which affects the conservation of soil and water.This study illustrates the variation of rainfall er...Temporal change in rainfall erosivity varies due to the rainfall characteristic(amount,intensity,frequency,duration),which affects the conservation of soil and water.This study illustrates the variation of rainfall erosivity due to changing rainfall in the past and the future.The projected rainfall is generated by SDSM(Statistical DownScaling Model)after calibration and validation using two GCMs(general circulation model)data of HadCM3(A2 and B2 scenario)and CGCM3(A1B and A2 scenario).The selected study area is mainly a cultivable area with an agricultural based economy.This economy depends on rainfall and is located in a part of the Narmada river basin in central India.Nine rainfall locations are selected that are distributed throughout the study area and surrounding.The results indicate gradually increasing projected rainfall while the past rainfall has shown a declined pattern by Mann–Kendall test with statistical 95%confidence level.Rainfall erosivity has increased due to the projected increase in the future rainfall(2080 s)in comparison to the past.Rainfall erosivity varies from32.91%to 24.12%in the 2020s,18.82 to 75.48%in 2050 s and 20.95–202.40%in 2080s.The outputs of this paper can be helpful for the decision makers to manage the soil water conservation in this study area.展开更多
Mass wasting is globally recognized as a key geomorphic agent in permanent gully expansion and greatly contributes to watershed sediment losses.Though its formation process has been assessed by some physical models,th...Mass wasting is globally recognized as a key geomorphic agent in permanent gully expansion and greatly contributes to watershed sediment losses.Though its formation process has been assessed by some physical models,the occurrence and rainfall threshold have been rarely documented.In this study,rainfall-induced mass wasting events in two permanent gullies located in the Mollisols region of Northeast China,with Mollisols(gully 1)and sandy soil(gully 2)underneath were observed,and their differences were explored based on their soil strengths,hydraulic properties,excess topographies,and theoretical rainfall amounts.The sandy soil had a higher strength,faster pore water pressure dissipation rate,and lower suction stress at a specific soil moisture content compared to the black soil.The erosion thickness of the gully bed and sidewalls in gully 1 was shallower compared to gully 2.This was confirmed by the relationship between the erosion thickness and excess topography.The differences in the mass wasting erosion of the gully bed and sidewalls were due to the higher shear strength and well-drained hydraulic properties of the sandy soil compared to the black-soil.An infinite model was chosen to examine the temporal order of the mass wasting in the two gullies.It was found that the mass wasting in gully 2 occurred earlier than that in gully 1.This was likely due to the occurrence of an intense storm with less rainfall at the location of gully 2,while a light storm with heavier rainfall occurred in the location of gully 1.As Mollisols and sandy soil are the typical soil horizons in the Mollisols region worldwide,the results of this work could provide insightful knowledge for understanding the physical process of permanent gully expansion,which may be helpful for developing prediction models for sediment losses in some watersheds with vast Mollisols and highly developed gully system.展开更多
Glacier landslide cascading hazards pose threats to communities and infrastructure,affected by complex processes including the amplification of mass flow volume through erosion and entrainment,transformation of hazard...Glacier landslide cascading hazards pose threats to communities and infrastructure,affected by complex processes including the amplification of mass flow volume through erosion and entrainment,transformation of hazard types,ice-water phase change,and enhanced mobility of the mass flow.Scientifically simulating these physical phenomena proves challenging.This study introduces GMFA(glacier mass flow analysis),an integrated numerical model that advances the field by:(1)proposing depth-averaged fluctuation energy and internal energy equations,(2)incorporating the ice-water phase change and the entrainment-deposition process,and(3)capturing their effects on mass flow runout characteristics.The model employs the finite volume method to solve the multi-physics coupled governing equations,enabling efficient large-scale simulations.The model is verified through three numerical tests covering flow dynamics,temperature evolution,and thermo-hydro-mechanical runout processes.The model is applied to analyze a hazard chain that occurred on 10 September 2020 on the Tibetan Plateau.The multi-scenario simulation results indicate an entrained mass volume of(4.95±0.11)×10^(5)m^(3),and a ratio of entrained mass volume to source material volume of 0.44.The solid concentration decreases from 0.6-0.7 to 0.1-0.15 with increasing runout distance,indicating a transition from avalanche to debris flood.The internal energy rises by(3-4)×10^(3)kJ/m^(3),driving rapid ice melting from 0.1 to 0.2 to near-zero concentration.The model effectively quantifies volume amplification,ice-water phase changes,and multi-hazard transformations.This model pushes the geoscience frontier,extending computational capability from single-to multi-hazard simulations and providing a powerful tool for analyzing glacier cascading hazards.展开更多
During electrochemical machining(ECM),the passivation film formed on the surface of titanium alloy can lead to uneven dissolution and pitting.Solid particle erosion can effectively remove this passivation film.In this...During electrochemical machining(ECM),the passivation film formed on the surface of titanium alloy can lead to uneven dissolution and pitting.Solid particle erosion can effectively remove this passivation film.In this paper,the electrochemical dissolution behavior of Ti-6.5Al-2Zr-1Mo-1V(TA15)titanium alloy at without particle impact,low(15°)and high(90°)angle particle impact was investigated,and the influence of Al_(2)O_(3)particles on ECM was systematically expounded.It was found that under the condition of no particle erosion,the surface of electrochemically processed titanium alloy had serious pitting corrosion due to the influence of the passivation film,and the surface roughness(Sa)of the local area reached 10.088μm.Under the condition of a high-impact angle(90°),due to the existence of strain hardening and particle embedding,only the edge of the surface is dissolved,while the central area is almost insoluble,with the surface roughness(S_(a))reaching 16.086μm.On the contrary,under the condition of a low-impact angle(15°),the machining efficiency and surface quality of the material were significantly improved due to the ploughing effect and galvanic corrosion,and the surface roughness(S_(a))reached 2.823μm.Based on these findings,the electrochemical dissolution model of TA15 titanium alloy under different particle erosion conditions was established.展开更多
Freeze-thaw cycles(FTCs)have an important effect on soil aggregate stability by altering soil structures,thereby influencing soil wind and water erosion on the eastern Qinghai-Tibet Plateau.However,the effects of FTCs...Freeze-thaw cycles(FTCs)have an important effect on soil aggregate stability by altering soil structures,thereby influencing soil wind and water erosion on the eastern Qinghai-Tibet Plateau.However,the effects of FTCs on the stability of these soils remain unclear.Here,we conducted freeze-thaw simulations in laboratory to investigate the effects of FTCs(0 to 15 cycles)on the wet-and dry-sieving aggregate stability of undisturbed sandy loam from Maqu county,which was treated with different initial soil moisture contents(1%to 25%in increments of 4%)and initial aggregate diameters(<2,2-5,5-10,and 10-15 mm).Results show that soil aggregates with initial diameters larger than 2 mm exhibit higher soil organic carbon contents(1.45%-1.57%)and silt contents(34.63%-35.52%)than those smaller than 2 mm(0.93%and 31.38%,respectively).The stability of both wet-and dry-sieving aggregates increases with larger initial diameters.Increasing initial soil moisture content from 1%to 25%reduces aggregate stability,with reductions of 2.4%-88.0%for wet-sieving aggregates and 2.1%-25.5%for dry-sieving aggregates(>2 mm).With increasing FTCs,wet-sieving aggregate(>2 mm)stability exhibits a fluctuating upward trend,with increases of 79.2%-87.4%after 15 FTCs,while dry-sieving aggregate(>2 mm)stability decreases significantly(5.7%-21.7%)upon the first FTC and remains unchanged thereafter.The stability of both the wet-and dry-sieving aggregates smaller than 2 mm remains unchanged with increasing FTCs(p>0.05).SOC content decreases by 22.3%on average with increasing FTCs from 1 to 15 and shows no significant correlations with wet-and dry-sieving aggregate stability.Higher silt content(r=0.39,p<0.05)and lower sand content(r=-0.38,p<0.05)enhances the wet-sieving aggregate stability of sandy loam.Frequent FTCs tend to improve wet-sieving aggregate stability but reduce dry-sieving aggregate stability in the sandy loam.The findings provide certain guidance for preventing freeze-thaw-induced wind erosion.展开更多
文摘China＇s dryland region has serious wind erosion problem and is sensitive to climate change due to its fragile ecological condition. Wind erosion climatic erosivity is a measure of climatic factors influencing wind erosion, therefore, evaluation of its intensity and response to recent climate changes can contribute to the understanding of climate change effect on wind erosion risk. Using the FAO equation, GIS and statistical analysis tools, this study quantified the climatic erosivity, analyzed its spatiotemporal variations, and detected the trend and sen- sitivity to climate factors during 1961-2012. The results indicate that mean annual climatic erosivity was 2-166 at 292 stations and 237-471 at 6 stations, with the spatial distribution highly in accordance with wind speed （R^2 = 0.94）. The climatic erosivity varied greatly over time with the annual variation （CV） of 14.7%-108.9% and monthly variation （concentration degree） of 0.10-0.71 in the region. Meanwhile, annual erosivity showed a significant down- ward trend at an annual decreasing rate mostly above 1.0%. This significantly decreasing trend was mainly attributed to the obvious decline of wind speed during the period. The results suggest that the recent climate changes were highly possible to induce a decrease of wind erosion risk in China＇s dryland region.
基金financially supported by the National Key Research and Development Program of China(Grant No.SQ2018YFD080041)the Sichuan Science and Technology Program(Grant No.2017SZ0188)。
文摘Soils in the hydro-fluctuation belts of the reservoirs are most highly influenced by the special hydro-conditions and reservoir operation,leading to unique soil erosion process and largely accelerate soil erosion intensity.The present study aimed to estimate soil erosion rate in the hydro-fluctuation belt of the Pubugou Reservoir,Southwest China,based on the framework of Universal Soil Loss Equation(USLE).An attempt has been made to modify the original USLE by including the reservoir water erosivity(W),a new factor into the model.Soil erosion rate from different land use types were quantitatively estimated,using the USLE and the modified USLE respectively.Field observation showed that soil erosion rate in dry farmland,bare land and grassland was 4700,44600 and 5050 t/km2,respectively.The erosion rate assessed by the modified USLE was closely related to that recorded from the field monitoring data.The findings of this study clearly highlight the importance of inclusion of the W factor to the original USLE model while assessing soil erosion in the reservoir hydro-fluctuation belt.
基金funded by the Chinese Academy of Sciences(Grant No.KZCX2-XB3-09)the Ministry of Science and Technology of China(Grant No.2011BAD31B03)the National Natural Science Foundation of China(Grant Nos.41101259,41102224 and 41201275)
文摘Reservoir sedimentation dynamics were interpreted using Cs-137 activity, particle size and rainfall erosivity analysis in conjunetion with sediment profile coring. Two sediment cores were retrieved from the Changshou reservoir of Chongqing, which was dammed in 1956 at the outlet of Longxi catchment in the Three Gorges Area using a gravity corer equipped with an aerylie tube with an inner diameter of 6 em. The extracted cores were sectioned at 2 cm intervals. All sediment core samples were dried, sieved （〈2 mm） and weighed. 137Cs activity was measured by y-ray spectrometry. The particle size of the core samples was measured using laser particle size granulometry. Rainfall erosivity was calculated using daily rainfall data from meteorological records and information on soil conservation history was collated to help interpret temporal sedimentation trends. The peak fallout of 137Cs in 1963 appeared at a depth of 84 cm in core A and 56 cm in core B. The peaks of sand contents were related to the peaks of rainfall erosivity which were recorded in 1982, 1989, 1998 and 2005, respectively. Sedimentation rates were calculated according to the sediment profile chronological controls of 1956, 1963, 1982, 1989, 1998 and 2oo5. The highest sedimentation rate was around 2.0 cm·a^-1 between 1982 and 1988 when the Chinese national reform and the Household Responsibility System were implemented, leading to accelerated soil erosion in the Longxi catchment. Since 1990s, and particularly since 2005, sedimentation rates clearly decreased, since a number of soil conservation programs have been carried out in the catchment. The combined use of ^137Cs chronology, particle size and rainfall erosivity provided a simple basis for reconstructing reservoir sedimentation dynamics in the context of both physical processes and soil restoration. Its advantages include avoiding the need for full blown sediment yield reconstruction and the concomitant consideration of core correlation and corrections for autochthonous inputs and reservoir trap efficiency.
基金supported by the Natural Science Foundation of China (Grant No. 40925002)the National Science and Technology Supporting Program in the Eleventh Five-Year Plan of China (Grant No. 2007BAC06B06)
文摘Rainfall erosivity in Tibet from 2000 to 2OlO was estimated based on simplified erosion prediction model using daily rainfall data derived from the Tropical Rainfall Measurement Misssion （TRMM） 3B42 rainfall measurement algorithm. Semi- monthly erosive rainfall and rainfall erosivity were validated using weather station data. The spatial distribution of annual rainfall erosivity as well as its seasonal and annual variation in Tibet was also examined. Results showed that TRMM 3B42 data could serve as an alternative data source to estimate rainfall erosivity in the area where only data from sparsely distributed weather stations are available. The spatial distribution of rainfall erosivity in Tibet generally resembles the distribution of multi-year average of annual rainfall. Annual rainfall erosivity in Tibet decreased from the southeast to the northwest. The concentration degree of rainfall erosivity shows an increasing trend from the southeast to the northwest. High rainfall erosivity accompanies low rainfall erosivity concentration degree and vice versa. Rainfall erosivity increased in the middle and western Tibet and decreased in the southeastern Tibet during the 11 years of this study.
基金Fund for Creative Research Groups of National Natural Science Foundation of China, No.41321001 the National Natural Science Foundation of China, No.51379008 the Open Research Fund of the State Key Lab of Simulation and Regulation of Water Cycle in River Basin, No.2014QN04.
文摘Rainfall erosivity is an important climatic factor for predicting soil loss. Through the application of high-resolution pluviograph data at 5 stations in Huangshan City, Anhui Prov- ince, China, we analyzed the performance of a modified Richardson model that incorporated the seasonal variations in parameters α andβ. The results showed that （1） moderate to high seasonality was presented in the distribution of erosive rainfall, and the seasonality of rainfall erosivity was even stronger; （2） seasonal variations were demonstrated in both parameters α and β of the Richardson model; and （3） incorporating and coordinating the seasonality of parameters αandβgreatly improved the predictions at the monthly scale. This newly modi- fied model is therefore highly recommended when monthly rainfall erosivity is required, such as, in planning soil and water conservation practices and calculating the cover-management factor in the Universal Soil Loss Equation （USLE） and Revised Universal Soil Loss Equation （RUSLE）.
基金supported by the Deutsche Forschungsgemein-schaft (German Science Foundation) (No. DFG FOR 891/1)the National Natural Science Foundation of China (Nos. 30710103907, 30930005)
文摘Sand-fflled splash cups were used to study the erosive power of rainfall and throughfall in the humid subtropics of Southeast China. The splash cup measurements yielded precise and reproducible results under both open field conditions and forest vegetation. The splash cups were exposed to specific forest stands of different ages and to selected species （Schima superba, Castanopsis eyrei, Daphniphyllum oldhamii, Lithocarpus glaber） in the Gutianshan （古田山） National Nature Reserve （GNNR）. The results of the measurements under forest vegetation show that the erosive power of throughfall drops to be 2.59 times higher compared to the open field. This accentuates the importance of shrub, herb and litter layers in forest ecosystems to protect the soil against erosion. Coalescing drops from leaves and branches （drips） are responsible for this notable gain in erosive power. Moreover, differences in sandloss between the investigated tree species （deciduous, evergreen） revealed that the erosion potential and the spatial heterogeneity of throughfall are species-specific. This highlights the importance of selecting specific species for afforestation projects considering the prevention of soil erosion.
基金Under the auspices of National Natural Science Foundation of China(No.41901355)National Key R&D Program of China(No.2021YFD1500702)。
文摘Climate change can affect wind erosion power and hence induce changes in wind erosion rates.In this study,the wind erosion climate factor(C-factor),proposed by the Food and Agriculture Organization of the United Nations,was used to assess the impact of changes in climate on wind erosion climatic erosivity.The Mann-Kendall test was employed to detect trends in the C-factor during the period of 1961–2017 in the farming-pastoral zone of northern China.Sensitivity analysis was used to determine the sensitivity of the C-factor to changes in key climate factors.Furthermore,a comparison of the contributions of different climate factors was carried out to understand their impact on changes in the C-factor.The results indicated that most of the surveyed region exhibited decreasing trends in wind speed at a confidence level of 90%,while maximum and minimum temperatures showed increasing trends throughout the study area.As a consequence of decreasing wind speed,the annual C-factor exhibited significant decreasing trends,with a mean slope of–0.58/yr.Seasonal analysis revealed that in most regions,the changes in the C-factor had significant decreasing trends in spring,winter,and autumn,while in more than two-thirds of the study area,no significant change trends in the C-factor were detected in summer at a confidence level of 90%.Sensitivity analysis showed that the C-factor was most sensitive to wind speed,and that the sensitivity coefficients from July to September were much higher than those in other months.Contribution analysis revealed that,for most stations,wind speed(with greater values of sensitivity coefficients)was the dominant factor in the change of C-factor,while for some stations,the minimum temperature made the most contribution to the C-factor’s change due to its dramatic changes during the study period.Although the minimum temperature sensitivity coefficient was the lowest of all the sensitivity coefficients,it is urgent to evaluate the expected impact of minimum temperature due to its possible changes in the future.
基金supported by the Collaborative Research Program of the Alliance of International Science Organization(ANSO)(ANSOCR-KP-2021-09)CAS Interdisciplinary Innovation Team(xbzg-zdsys-202104)President’s International Fellowship Initiative(PIFI)visiting scientist grant for the Chinese Academy of Science(CAS)international talent(2023VCC0001,2024VEA0001)。
文摘Rainfall erosivity is an indicator of rainfall potential to cause soil erosion.The Melamchi extreme flood occurred on June-15 and recurred on July-31,2021 in Nepal.During these flooding events,a large volume of sediments were eroded,transported and deposited due to the high rainfall erosivity of the basin.In this study,the temporal and the spatial distribution of rainfall erosivity within the Melamchi River Basin was estimated and further linked to sediment discharge and concentration at various sites along the river segments.The daily rainfall data for the event year 2021 of the entire basin were used.Validation was performed by post-flooding grain size sampling.The result showed that rainfall and rainfall erosivity exhibit pronounced intensity within the Melamchi River basin,particularly at Sermathang and Tarkeghang,both located in the middle section of the basin.The average annual rainfall in the Melamchi region was 3140.39 mm with an average annual erosivity of 18302.06(MJ mm)/(ha h yr).The average daily erosivity of the basin was 358.67(MJ mm)/(ha h)during the first event and 1241(MJ mm)/(ha h)for the second event.In the upper section of sampling,the sediment size ranged from 0.1 mm to>8 mm and was poorly graded.However,the lower region had smaller sediment ranging from 0.075 mm to>4.75 mm and also well graded.The smaller size(<1 mm)sediment passing was much higher in the Chanaute(78%)and Melamchi(66.5%)river segments but the larger size(>100 mm)sediments were passed relatively higher from the Kiwil(8.20%)and Ambathan(8.39%)river segments.During premonsoon and monsoon seasons,the highest sediment concentration was found to be 563.8 g/L and 344.3 g/L in Bhimtar and the lowest was 238.5 g/L and 132.1 g/L at the Ambathan,respectively.The sediment concentration during the pre-monsoon was found to be higher than the sediment concentration during the monsoon season in the Melamchi River.The more erosive regions in the basin were associated with the presence of highly fractured rock,weathered rocks and a thrust(weak)zone.The higher rainfall erosivity at upstream and the higher sediment concentration at downstream during flooding events have coincided well in the basin.Thus,the estimation of rainfall erosivity at the catchment scale and its influences on sediment concentration in the river are crucial for erosion control measures during flooding times in the Himalaya.
文摘The objective of this research is to estimate the annual and seasonal rainfall erosivity over Jordan based on three different regression models. Readily available annual and seasonal precipitation data with long records (40 - 53 years) pertaining to 40 weather stations were utilized to estimate rainfall erosivity. The spatial distribution of rainfall erosivity over Jordan is controlled largely by morphological (relief) and climatic factors. The lowest R-values (28 MJ mm.ha-1.h-1.yr-1) are found in the arid zone, where the average annual rainfall is below 100 mm, whereas the highest R-values are found in the northern highlands (505 MJ mm.ha-1.h-1.yr-1) where the average annual rainfall approaches 650 mm. The correlation between annual and seasonal precipitation (mm) and annual erosivity exhibits a very strong relationship (R varies from 0.964 to 1.0, and all correlations are significant at 0.01 level [2-tailed test]). Moderate positive correlations were achieved between latitude (N) and the mean annual/seasonal precipitation (R ranges from 0.407 to 0.642, and all correlations are significant at 0.01 level [2-tailed test]). Spatial differences observed in erosivity, afforded a substantial source of information and maps for predicting erosion in Jordan. According to the present analysis, two parameters proved to be useful to predict rainfall erosivity on a national level. These parameters are the average annual precipitation, and latitude.
基金Supported by the Deanship of Research, Jordan University of Science and Technology (No. 91/2004)
文摘Despite being in arid and semi-arid areas,erosion is largely a result of infrequent but heavy rainfall events; therefore,rainfall erosivity data can be used as an indicator of potential erosion risks.The purpose of this study was to investigate the spatial distribution of annual rainfall erosivity in North Jordan.A simplified procedure was used to correlate erosivity factor R values in both the universal soil loss equation (USLE) and the revised universal soil loss equation (RUSLE) with annual rainfall amount or modified Fournier index (F mod ).Pluviometric data recorded at 18 weather stations covering North Jordan were used to predict R values.The annual values of erosivity ranged between 86-779 MJ mm ha ?1 h ?1 year ?1 .The northwest regions of Jordan showed the highest annual erosivity values,while the northeastern regions showed the lowest annual erosivity values.
基金supported by the National High Technology Research and Development Program of China("863"Program)(Grant No. 2008AA12Z112)
文摘Soil erosion by water is the most important land degradation problem worldwide. In this paper a new procedure was developed to estimate the rainfall-runoff erosivity factor （R） based on Tropical Rainfall Measuring Mission （TRMM） satellite-estimated precipitation data, which consists of 3-h rainfall intensity data. In this method, R was calculated as the product of the maximum 180-min rainfall intensity and the rainfall energy. This procedure was applied to the Daling River basin in Liaoning Province, China, R in terms of yearly, monthly and event-based rainfall in 2005 was computed separately using TRMM 3B42 data. The TRMM data showed a significant correlation with the interpolated rain-gauge data. Furthermore, because the TRMM data are based on rainfall intensity, they can represent the impact on erosion more accurately. It reflects both the spatial distribution and the intensity of rainfall. The procedure is a new approach to estimate the rainfall erosivity for soil water erosion modeling, especially in areas lacking rain-gange stations.
基金the Second Tibetan Plateau Scien tifc Expedition and Research Program(STEP)(No.2019QZKK0306)the National Key R&D Program(No.2018YFC0507006)Na tional Natural Science Foundation of China(No.41877068).
文摘Rainfall erosivity,one of the factors in the Universal Soil Loss Equation.quantifies the effect of rainfall and runoffon soil erosion.High-resolution data are required to compute rainfall erosivity,but are not widely available in many parts of the world.As the temporal resolution of rainfall measurement decreases,computed rainfall erosivity decreases.The objective of the paper is to derive a series of conversion factors as a function of the time interval to compute rainfall erosivity so that the R factor computed using data at different time intervals could be converted to that computed using 1-min data.Rainfall data at 1-min intervals from 62 stations over China were collected to first compute the~ue'R factor values.Underestimation of the R factor was systematically evaluated using data aggregated at 5,6.10,15,20,30,and 60-min to develop conversion factors for the R factor and the 1-in-10-year storm EI30 values.Compared with true values,the relative error in R factor using data at fixed intervals of≤10min was<10%for at least 44 out of 62 stations.Errors increased rapidly when the time interval of the rainfall data exceeded 15 min.Relative errors were>10%using 15-min data for 66.1%of stations and>20%using 30-min data for 61.3%of stations.The conversion factors for the R factor,ranging from 1.051 to 1.871 for 5 to 60-min data,are higher than those for the 1-in-10-years storm EI30,ranging from 1.034 to 1.489 for the 62stations.
基金This work was supported by the National Key Research and Development Program of China(Grant No.2021YFE0113800)the National Key Research and Development Program of China(Grant No.2021YFD1500705)the Project for Recruited Talents to Start Up Their Work and Research in Beijing Normal University at Zhuhai(310432116).
文摘Northeast China(NEC)is one of the vital commercial grain bases in China and it has suffered from soil erosion due to prolonged cultivation and lack of protection.To determine long-term trends of precipi-tation and rainfall erosivity over NEC during the latest decades,daily precipitation for the entire year during 1961-2020 and hourly precipitation for the warm season(May to September)during 1971-2020 were collected for 192 and 126 stations,respectively.Three seasons,including the cold season(October to April),early warm season(May to June),and late warm season(July to September)were divided according to the combination of precipitation and vegetation.Results demonstrate:(1)Daily precipita-tion reveals total precipitation and rainfall erosivity in the cold season and early warm season increase significantly at relative rates of 3.1%-6.1%compared with the average during 1961-2020,and those in the late warm season decrease insignificantly.(2)Hourly precipitation reveals storms occurring in the early and late warm seasons have undergone significant increasing changes,which shift towards longer storm duration,larger amount,peak intensity,kinetic energy,and rainfall erosivity during 1971-2020.Moreover,the frequency of extreme storms increased.(3)Rainfall erosivities estimated from daily pre-cipitation during 1971-2020 increase insignificantly for the early and late warm season,whereas those from hourly precipitation increase significantly(6.1%and 5.5%,respectively),which indicates daily precipitation may not be able to capture the trend fully under the warming background,and precipi-tation at higher resolutions than the daily scale is necessary to detect trends of rainfall erosivity more accurately.
基金This research was jointly supported by the Second Tibetan Plateau Scientific Expedition and Research Program(Grant No.2019QZKK0307)the Strategic Priority Research Programof Chinese Academy of Sciences(Grant No.XDA20100300)+1 种基金the National Science Foundation for Young Scientists of China(Grant No.41905048)the Basic Research Special Project of the Chinese Academy of Meteorological Sciences(Grant No.2019Z008).
文摘The Tibetan Plateau(TP)in China has been experiencing severe water erosion because of climate warming.The rapid development of weather station network provides an opportunity to improve our understanding of rainfall erosivity in the TP.In this study,1-min precipitation data obtained from 1226 weather stations during 2018–2019 were used to estimate rainfall erosivity,and subsequently the spatial-temporal patterns of rainfall erosivity in the TP were identified.The mean annual erosive rainfall was 295 mm,which accounted for 53%of the annual rainfall.An average of 14 erosive events occurred yearly per weather station,with the erosive events in the wet season being more likely to extend beyond midnight.In these cases,the precipitation amounts of the erosive events were found to be higher than those of the daily precipitations,which may result in implicit bias as the daily precipitation data were used for estimating the rainfall erosivity.The mean annual rainfall erosivity in the TP was 528 MJ mm·ha^(-1)·h^(-1),with a broader range of 0–3402 MJ mm·ha^(-1)·h^(-1),indicating a significant spatial variability.Regions with the highest mean annual rainfall erosivity were located in the forest zones,followed by steppe and desert zones.Finally,the precipitation phase records obtained from 140 weather stations showed that snowfall events slightly impacted the accuracy of rainfall erosivity calculation,but attention should be paid to the erosion process of snowmelt in the inner part of the TP.These results can be used as the reference data for soil erosion prediction in normal precipitation years.
基金We acknowledge the Coordination of Superior Level Staff Improvement-CAPES[grant number 88882.306661/2018-01]the National Council for Scientific and Technological Development-CNPQ[grant number 301556/2017-2]for supporting and funding this work.
文摘Rainfall erosivity is defined as the potential of rain to cause erosion.It has great potential for application in studies related to natural disasters,in addition to water erosion.The objectives of this study were:ⅰ)to model the Rday using a seasonal model for the Mountainous Region of the State of Rio de Janeiro(MRRJ);ⅱ)to adjust thresholds of the Rday index based on catastrophic events which occurred in the last two decades;andⅲ)to map the maximum daily rainfall erosivity(Rmaxday)to assess the region's suscepti-bility to rainfall hazards according to the established Rday limits.The fitted Rday model presented a satisfactory result,thereby enabling its application as a Rday estimate in MRRJ.Events that resulted in Rday>1500 MJ ha-1.mm.h-1.day-1 were those with the highest number of fatalities.The spatial distribution of Rmaxday showed that the entire MRRJ has presented values that can cause major rainfall.The Rday index proved to be a promising indicator of rainfall disasters,which is more effective than those normally used that are only based on quantity(mm)and/or intensity(mm.h-1)of the rain.
基金The authors express their thanks to the Indian Meteorological Department(IMD)for the rainfall data and the Pacific Climate Impacts Consortium(PCIC)for the GCM and NCEP Data.The authors are also thankful to the Council of Scientific&Industrial Research(CSIR)(Roll no.200773,Ref.No.20-12/2009(ii)EU-IV)for financial assistance.
文摘Temporal change in rainfall erosivity varies due to the rainfall characteristic(amount,intensity,frequency,duration),which affects the conservation of soil and water.This study illustrates the variation of rainfall erosivity due to changing rainfall in the past and the future.The projected rainfall is generated by SDSM(Statistical DownScaling Model)after calibration and validation using two GCMs(general circulation model)data of HadCM3(A2 and B2 scenario)and CGCM3(A1B and A2 scenario).The selected study area is mainly a cultivable area with an agricultural based economy.This economy depends on rainfall and is located in a part of the Narmada river basin in central India.Nine rainfall locations are selected that are distributed throughout the study area and surrounding.The results indicate gradually increasing projected rainfall while the past rainfall has shown a declined pattern by Mann–Kendall test with statistical 95%confidence level.Rainfall erosivity has increased due to the projected increase in the future rainfall(2080 s)in comparison to the past.Rainfall erosivity varies from32.91%to 24.12%in the 2020s,18.82 to 75.48%in 2050 s and 20.95–202.40%in 2080s.The outputs of this paper can be helpful for the decision makers to manage the soil water conservation in this study area.
基金primarily supported by the National Key Research and Development Program of China(Grant No.2024YFD1501201-3)partially supported by the National Key Research and Development Program of China(Grant No.2021YFD1500700)。
文摘Mass wasting is globally recognized as a key geomorphic agent in permanent gully expansion and greatly contributes to watershed sediment losses.Though its formation process has been assessed by some physical models,the occurrence and rainfall threshold have been rarely documented.In this study,rainfall-induced mass wasting events in two permanent gullies located in the Mollisols region of Northeast China,with Mollisols(gully 1)and sandy soil(gully 2)underneath were observed,and their differences were explored based on their soil strengths,hydraulic properties,excess topographies,and theoretical rainfall amounts.The sandy soil had a higher strength,faster pore water pressure dissipation rate,and lower suction stress at a specific soil moisture content compared to the black soil.The erosion thickness of the gully bed and sidewalls in gully 1 was shallower compared to gully 2.This was confirmed by the relationship between the erosion thickness and excess topography.The differences in the mass wasting erosion of the gully bed and sidewalls were due to the higher shear strength and well-drained hydraulic properties of the sandy soil compared to the black-soil.An infinite model was chosen to examine the temporal order of the mass wasting in the two gullies.It was found that the mass wasting in gully 2 occurred earlier than that in gully 1.This was likely due to the occurrence of an intense storm with less rainfall at the location of gully 2,while a light storm with heavier rainfall occurred in the location of gully 1.As Mollisols and sandy soil are the typical soil horizons in the Mollisols region worldwide,the results of this work could provide insightful knowledge for understanding the physical process of permanent gully expansion,which may be helpful for developing prediction models for sediment losses in some watersheds with vast Mollisols and highly developed gully system.
基金supports from the National Natural Science Foundation of China(Grant No.U20A20112)the Research Grants Council of the Hong Kong SAR Government,China(Grant Nos.T22-606/23-R and 16206923).
文摘Glacier landslide cascading hazards pose threats to communities and infrastructure,affected by complex processes including the amplification of mass flow volume through erosion and entrainment,transformation of hazard types,ice-water phase change,and enhanced mobility of the mass flow.Scientifically simulating these physical phenomena proves challenging.This study introduces GMFA(glacier mass flow analysis),an integrated numerical model that advances the field by:(1)proposing depth-averaged fluctuation energy and internal energy equations,(2)incorporating the ice-water phase change and the entrainment-deposition process,and(3)capturing their effects on mass flow runout characteristics.The model employs the finite volume method to solve the multi-physics coupled governing equations,enabling efficient large-scale simulations.The model is verified through three numerical tests covering flow dynamics,temperature evolution,and thermo-hydro-mechanical runout processes.The model is applied to analyze a hazard chain that occurred on 10 September 2020 on the Tibetan Plateau.The multi-scenario simulation results indicate an entrained mass volume of(4.95±0.11)×10^(5)m^(3),and a ratio of entrained mass volume to source material volume of 0.44.The solid concentration decreases from 0.6-0.7 to 0.1-0.15 with increasing runout distance,indicating a transition from avalanche to debris flood.The internal energy rises by(3-4)×10^(3)kJ/m^(3),driving rapid ice melting from 0.1 to 0.2 to near-zero concentration.The model effectively quantifies volume amplification,ice-water phase changes,and multi-hazard transformations.This model pushes the geoscience frontier,extending computational capability from single-to multi-hazard simulations and providing a powerful tool for analyzing glacier cascading hazards.
基金supported by the National Natural Science Foundation of China(No.52175414)the Natural Science Foundation of Jiangsu Province of China(No.BK20220134)+1 种基金the Fundamental Research Funds for the Central Universities,China(No.NE2023002)the Postgraduate Research&Practice Innovation Program of Jiangsu Province,China(No.KYCX24_0559)。
文摘During electrochemical machining(ECM),the passivation film formed on the surface of titanium alloy can lead to uneven dissolution and pitting.Solid particle erosion can effectively remove this passivation film.In this paper,the electrochemical dissolution behavior of Ti-6.5Al-2Zr-1Mo-1V(TA15)titanium alloy at without particle impact,low(15°)and high(90°)angle particle impact was investigated,and the influence of Al_(2)O_(3)particles on ECM was systematically expounded.It was found that under the condition of no particle erosion,the surface of electrochemically processed titanium alloy had serious pitting corrosion due to the influence of the passivation film,and the surface roughness(Sa)of the local area reached 10.088μm.Under the condition of a high-impact angle(90°),due to the existence of strain hardening and particle embedding,only the edge of the surface is dissolved,while the central area is almost insoluble,with the surface roughness(S_(a))reaching 16.086μm.On the contrary,under the condition of a low-impact angle(15°),the machining efficiency and surface quality of the material were significantly improved due to the ploughing effect and galvanic corrosion,and the surface roughness(S_(a))reached 2.823μm.Based on these findings,the electrochemical dissolution model of TA15 titanium alloy under different particle erosion conditions was established.
基金supported by National Natural Science Foundation of China(Grant No.42201080)Young Scientific and Technological Talents Program of Shaanxi Province(Grant No.2025ZC-KJXX-57)Special Scientific Research Program of the Shaanxi Provincial Department of Education(Grant No.21JK0967)。
文摘Freeze-thaw cycles(FTCs)have an important effect on soil aggregate stability by altering soil structures,thereby influencing soil wind and water erosion on the eastern Qinghai-Tibet Plateau.However,the effects of FTCs on the stability of these soils remain unclear.Here,we conducted freeze-thaw simulations in laboratory to investigate the effects of FTCs(0 to 15 cycles)on the wet-and dry-sieving aggregate stability of undisturbed sandy loam from Maqu county,which was treated with different initial soil moisture contents(1%to 25%in increments of 4%)and initial aggregate diameters(<2,2-5,5-10,and 10-15 mm).Results show that soil aggregates with initial diameters larger than 2 mm exhibit higher soil organic carbon contents(1.45%-1.57%)and silt contents(34.63%-35.52%)than those smaller than 2 mm(0.93%and 31.38%,respectively).The stability of both wet-and dry-sieving aggregates increases with larger initial diameters.Increasing initial soil moisture content from 1%to 25%reduces aggregate stability,with reductions of 2.4%-88.0%for wet-sieving aggregates and 2.1%-25.5%for dry-sieving aggregates(>2 mm).With increasing FTCs,wet-sieving aggregate(>2 mm)stability exhibits a fluctuating upward trend,with increases of 79.2%-87.4%after 15 FTCs,while dry-sieving aggregate(>2 mm)stability decreases significantly(5.7%-21.7%)upon the first FTC and remains unchanged thereafter.The stability of both the wet-and dry-sieving aggregates smaller than 2 mm remains unchanged with increasing FTCs(p>0.05).SOC content decreases by 22.3%on average with increasing FTCs from 1 to 15 and shows no significant correlations with wet-and dry-sieving aggregate stability.Higher silt content(r=0.39,p<0.05)and lower sand content(r=-0.38,p<0.05)enhances the wet-sieving aggregate stability of sandy loam.Frequent FTCs tend to improve wet-sieving aggregate stability but reduce dry-sieving aggregate stability in the sandy loam.The findings provide certain guidance for preventing freeze-thaw-induced wind erosion.
