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Determination of a Mathematical Model of Erosion Taking into Account the intensity of rainfall and Soil Slopes from the Global MNT Model

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Engineering（科研） 2022年第7期14卷 274-284页

作者： Eric Flavien Mbiakouo-Djomo Timothée Thierry Odi-Enyegue André Abanda Gilbert Tchemou Ulrich Florin Djiofack-Tiagho Denis Tcheukam-Toko Ngouffo Koukougnang Réné Didier Fokwa Ebénézer Njeugna Department of Rural Engineering FASA University of Dschang Dschang Cameroon Department of Civil Engineering ENSPD University of Douala Douala Cameroon Department of Mechanical Engineering College of Technology University of Buea Buea Cameroon Department of Civil Engineering ENSET Douala Cameroon Laboratory of Mechanics and Modeling of Physical Systems University of Dschang Dschang Cameroon

Our study is being carried out in the Wouri Estuary more precisely in the Nylon area, Douala. This area is influenced by abundant rainfall which promotes the phenomenon of rain erosion. This erosion contributes to the degradation of structures and soils. To better understand and predict this phenomenon of rainfall erosion, we set out to establish a mathematical model that takes into account precipitation and topography. To this end, the data collected in the field and in the laboratory made it possible. First, we graphically modeled the variation of the potential as a function of the intensity of rainfall and the slope of the ground. Next, we identified a mathematical model from cubic spline surface interpolation. Finally, we obtained the mathematical model which makes it possible to evaluate and predict the erosion potential. The results obtained allowed to have an erosion potential of 153.67 t/ha/year with field data and 153.94 t/ha/year with laboratory data. We compared the results obtained with those existing in the literature on the same study site. This comparison made it possible to validate the established mathematical model. This mathematical model is a decision support tool and can predict problems related to water, erosion and the environment.

关键词： Erosion Erosion Potential Mathematical Model rainfall intensity Soil Slope

Impact of the rainfall intensity and Seepage on Slope Stability in Loess Plateau

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Earthquake Research in China 2020年第4期34卷 560-579页

作者： ZHANG Yu YANG Lixia HAN Bingbing WU Yajie School of Traffic and Transportation Lanzhou Jiaotong UniversityLanzhou 730070China Gansu Institute of Engineering Geology Lanzhou 730000China Shanghai Municipal Engineering Design Institute Group Tenth Municipal Design Institute Co. Ltd.Lanzhou 730070China

In recent years,with the increase of traffic construction in mountainous areas in China,road slope traffic accidents have become more and more common.In addition,natural disasters such as landslides,collapses and subgrade settlements caused by rainfall,driving load,seasonal variation and groundwater distribution are frequent.In particular,rainfall is one of the most common factors leading to slope instability(landslide).Therefore,this paper proposes the seep module based on the application software Geo-studio,and analyzes the slope soil parameters and slope stability under five types of rainfall conditions:light rain(10 mm/d),moderate rain(25 mm/d),heavy rain(50 mm/d),rainstorm(100 mm/d),and torrential rain(250 mm/d).The critical safety factor under rainfall intensity is fitted with nonlinear curve by sine function.The results show that the fitting curve of rainfall intensity and safety factor on the upper slope is excellent.The residual points are evenly distributed in the belt area of±0.1,and the data basically conform to the nonlinear sine model,indicating that the curve plays an essential role in slope health diagnosis.

关键词： rainfall intensity Seepage Data monitoring Stability analysis

Effects of rainfall on the weekday traffic flow in major cities of the Beijing-Tianjin-Hebei region, China, in 2021

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Advances in Climate Change Research 2022年第6期13卷 858-867页

作者： Ming-Ming XIONG Zhen-Yu HAN Bo LU Jun GUO Shu XU Yan-Juan YANG He HUANG Tianjin Climate Center Tianjin Meteorological ServiceTianjin 300074China National Climate Center China Meteorological AdministrationBeijing 100081China Tianjin Meteorological Observatory Tianjin Meteorological ServiceTianjin 300074China

rainfall can bring uncertainties to the traffic flow and influence the normal function of urban transportation systems.The impact of precipitation on the urban traffic flow,especially the different impacts among cities and areas within a city,is worth investigating.Here,we analysed the impact of precipitation on the traffic flow in the urban areas of the Beijing-Tianjin-Hebei region by comparing the traffic flow in non-precipitation and rainy weather with different hourly precipitation intensities in 2021.The increase in the travel time index(TTI)is chosen to represent the influence of precipitation on the transportation system.The results show that the maximum of the average TTI increases on the city scale under various rainfall intensities by 3.3%,6.6%and 10.8%in Beijing,Tianjin and Shijiazhuang,respectively.In general,the increase in the TTI contributed by precipitation is the greatest at morning and afternoon peak hours,and the traffic congestion degree increases with the rainfall intensity.However,in the morning peak,afternoon peak and midday hours in Beijing and Tianjin,the influences of the weak rainfall intensity on the traffic flow are generally great,whereas the traffic congestion degree caused by heavy precipitation is relatively low.Particularly,in morning peak hours,the congestion reduction reaches approximately 2%,which may be related to the spatial difference in the impacts of precipitation on the traffic flow and the changes in people's travel intention under different rainfall intensities.The findings can help better understand the relationship between rainfall and urban traffic flow characteristics and also potentially contribute to the development of impact-oriented climate predictions.

关键词： rainfall intensity Urban traffic flow Beijing-Tianjin-Hebei region Auto Navi map road condition data

Impacts of rainfall intensity on Soil Solute Loss in a Small Basin

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Meteorological and Environmental Research 2012年第5期3卷 22-24页

作者： HE Jia-ji YANG Chuan-guo XIANG Long YAN Wen-ming College of Hydrology and Water Resource Hohai UniversityNanjing 210098China State Key Laboratory of Hydrology-Water Resourcesand Hydraulic Engineering Nanjing 210098China

[Objective] The study aimed to analyze the impacts of rainfall intensity on soil solute loss. [ Method] Hydrus-1D model was used to sim- ulate surface runoff process and soil solute loss process under different rainfall intensities in Meilin basin, Yixing City, and its reliability was verified. Afterwards, the model was used to simulate the movement of total nitrogen （TN） in the soil under various rainfall intensities. [Result] Hydrus-1D model had a good effect in the simulation of soil moisture and TN content in surface soil. During the rainfall, TN loss from surface soil （0 -20 cm） accounted for above 95% of total loss from the whole soil （0 -100 cm）. In addition, TN loss increased with the enhancement of rainfall intensities. However, TN loss tended to be stable when rainfall intensity exceeded 0.030 0 cm/min. [Conclusion] The research could provide theoretical refer- ences for the control of agricultural nonpoint source pollution in future.

关键词： Soil solute rainfall intensity Hydrus-lD model Surface runoff China

Effects of rainfall intensities and slope gradients on nitrogen loss at the seedling stage of maize(Zea mays L.)in the purple soil regions of China

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International Journal of Agricultural and Biological Engineering 2022年第2期15卷 142-148页

作者： Shuqin He Yuanbo Gong Ziheng Zheng Ziteng Luo Bo Tan Yunqi Zhang College of Forestry Sichuan Agricultural UniversityChengdu 611130China College of Resources Science Sichuan Agricultural UniversityChengdu 611130China

Loss of soil nitrogen has been reported to reduce soil productivity and result in eutrophication.The objective of this work was to understand the mechanisms of nitrogen loss at the maize seedling stage from purple soil in the sloping farmlands of southwest China.The characteristics of nitrogen loss were explored in experiments simulating rainfall conditions during the maize seedling stage at different rainfall intensities(60 mm/h,90 mm/h,and 120 mm/h)and slope gradients(10°,15°,and 20°).The results showed that the runoff and sediment yield increased with time.The surface runoff and sediment yield increased with the rainfall intensity and slope gradient.Nitrogen losses increased in the surface runoff and sediment but decreased in the interflow as the rainfall intensity and slope gradient increased.Dissolved total nitrogen(DTN)was the main form of nitrogen in the surface runoff and interflow,and nitrate nitrogen(NO3-N)was the main form of DTN.The surface runoff and sediment accounted for less than half of the TN losses.Thus,interflow was the main pathwayfor nitrogen loss.The regression lines between the surface runoff and forms of nitrogen losses in the runoff and interflow were linear.The results indicated that an increasing rainfall intensity and slope gradient generally increased the surface runoff,sediment,andnitrogen losses.However,the opposite trend was observed for the interflow and its nitrogen losses.

关键词： forms of nitrogen surface runoff interflow sediment yield slope gradient rainfall intensity

An improved method that incorporates the estimated runoff for peak discharge prediction on the Chinese Loess Plateau

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International Soil and Water Conservation Research 2023年第2期11卷 290-300页

作者： Wenhai Shi Miaomiao Wang Donghao Li Xianwei Li Mengying Sun Key Laboratory of Subsurface Hydrology and Ecological Effects in Arid Region Chang'an UniversityMinistry of EducationChina School of Water and Environment Chang'an UniversityChina

An accurate prediction of peak discharge in watersheds is critical not only for water resource manage-ment,but also for understanding the complex relationships of hydrological processes.In this study,a modified peak discharge formula based on the Chemicals,Runoff,and Erosion from Agricultural Man-agement Systems(CREAMS)model was developed by introducing rainfall intensity and soil moisture factors.The reliability of the proposed method was tested with data from 1464 storm events in 41 watersheds and was applied to 256 storm events in five remaining typical watersheds using the opti-mized parameters.The results indicate that the proposed method is highly accurate in terms of model efficiency,as determined by Nash-Sutcliffe efficiencies(NSEs)of 88.60%,74.04%,and 90.12%during the calibration,validation,and application cases,respectively.Furthermore,it performed better than the original and modified CREAMS methods.Subsequently,using the parameters derived from the initial 41 watersheds and the runoff estimated using the modified Soil Conservation Service curve number(SCS-CN)method,the proposed method was used to predict the peak discharge from the last five typical watersheds.Large NSE(63.88-80.83%)and low root mean square error(RMSE)values(0.31-35.93 m^(3)s^(-1))were obtained for the five watersheds.Overall,the proposed peak discharge model,combined with the modified SCS-CN method,may accurately predict event-based peak discharge and runoff for general applications under various hydrological and geomorphic conditions in the Loess Plateau region.

关键词： Chemicals,Runoff,and Erosion from agricultural management systems (CREAMS) NRCS-CN Peak discharge Surface runoff rainfall intensity

Predicting the severity of traffic accidents on mountain freeways with dynamic traffic and weather data

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Transportation Safety and Environment 2023年第4期5卷 135-144页

作者： Juan Li Fengxiang Guo Yanning Zhou Wenchen Yang Dingan Ni Faculty of Transportation Engineering Kunming University of Science and TechnologyKunming 650500China Shenzhen Urban Transport Planning Center Co. LtdShenzhen 518000China National Engineering Laboratory For Surface Transportation Weather Impacts Prevention Broad Vision Engineering Consultants Co.LtdKunming 650200China Yunnan Key Laboratory of Digital Communications Yunnan Communications Investment&Construction Group Co.LtdK unming 650103China Intelligent Transportation Systems Research Center Wuhan University of TechnologyWuhan 430000China

Traffic accident severity prediction is essential for dynamic traffic safety management.To explore the factors influencing the severity of traffic accidents on mountain freeways and to predict the severity of traffic accidents,four models based on machine learning algorithms are constructed using support vector machine(SVM),decision tree classifier(DTC),Ada_SVM and Ada_DTC.In addition,random forest(RF)is used to calculate the importance degree of variables and the accident severity influences with high importance levels form the RF dataset.The results show that rainfall intensity,collision type,number of vehicles involved in the accident and toad section type are important variables influencing accident severity.The RF feature selection method improves the classification performance of four machine leaming algorithms,resulting in a 9.3%,5.5%,7.2% and 3.6% improvement in prediction accuracy for SVM,DTC,Ada_SVM and Ada_DTC,respectively.The combination of the Ada_SVM integrated algorithm and RF feature selection method has the best prediction performance,and it achieves 78.9% and 88.4% prediction precision and accuracy,respectively.

关键词： mountain freeways accident severity prediction machine learning rainfall intensity

Effects of rainfall and Underlying Surface on Flood Recession——The Upper Huaihe River Basin Case

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International Journal of Disaster Risk Science 2021年第1期12卷 111-120页

作者： Yashan Cheng Yanfang Sang Zhonggen Wang Yuhan Guo Yin Tang Key Laboratory of Water Cycle and Related Land Surface Processes Institute of Geographic Sciences and Natural Resources ResearchChinese Academy of SciencesBeijing 100101China University of Chinese Academy of Sciences Beijing 100049China

The effects of rainfall and underlying surface conditions on flood recession processes are a critical issue for flood risk reduction and water use in a region.In this article,we examined and clarified the issue in the upper Huaihe River Basin where flood disasters frequently occur.Data on 58 rainstorms and flooding events at eight watersheds during 2006–2015 were collected.An exponential equation(with a key flood recession coefficient)was used to fit the flood recession processes,and their correlations with six potential causal factors—decrease rate of rainfall intensity,distance from the storm center to the outlet of the basin,basin area,basin shape coefficient,basin average slope,and basin relief amplitude—were analyzed by the Spearman correlation test and the Kendall tau test.Our results show that 95%of the total flood recession events could be well fitted with the coefficient of determination(R2)values higher than 0.75.When the decrease rate of rainfall intensity(Vi)is smaller than 0.2 mm/h2,rainfall conditions more significantly control the flood recession process;when Vi is greater than 0.2 mm/h2,underlying surface conditions dominate.The result of backward elimination shows that when Vi takes the values of0.2–0.5 mm/h2 and is greater than 0.5 mm/h2,the flood recession process is primarily influenced by the basin’s average slope and basin area,respectively.The other three factors,however,indicate weak effects in the study area.

关键词： Backward elimination China Correlation test Flood recession Huaihe River Basin rainfall intensity

Influences of sand cover on erosion processes of loess slopes based on rainfall simulation experiments

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Journal of Arid Land 2018年第1期10卷 39-52页

作者： ZHANG Xiang LI Zhanbin LI Peng TANG Shanshan WANG Tian ZHANG Hui Post-doctoral Research Station of Xi'an Chan-Ba National Ecological District Xi'an 710024China State Key Laboratory of Soil Erosion and Dryland Farming on the Loess Plateau Institute of Soil and Water ConservationChinese Academy of Science and Ministry of Water ResourcesYangling 712100China State Key Laboratory Base of Eco-Hydraulic Engineering in Arid Area Xi'an University of TechnologyXi'an 710048China

Aeolian-fluvial interplay erosion regions are subject to intense soil erosion and are of particular concern in loess areas of northwestern China. Understanding the composition, distribution, and transport processes of eroded sediments in these regions is of considerable scientific significance for controlling soil erosion. In this study, based on laboratory rainfall simulation experiments, we analyzed rainfall-induced erosion processes on sand-covered loess slopes （SS） with different sand cover patterns （including length and thickness） and uncovered loess slopes （LS） to investigate the influences of sand cover on erosion processes of loess slopes in case regions of aeolian-fluvial erosion. The grain-size curves of eroded sediments were fitted using the Weibull function. Compositions of eroded sediments under different sand cover patterns and rainfall intensities were analyzed to explore sediment transport modes of SS. The influences of sand cover amount and pattern on erosion processes of loess slopes were also discussed. The results show that sand cover on loess slopes influences the proportion of loess erosion and that the compositions of eroded sediments vary between SS and LS. Sand cover on loess slopes transforms silt erosion into sand erosion by reducing splash erosion and changing the rainfall-induced erosion processes. The percentage of eroded sand from SS in the early stage of runoff and sediment generation is always higher than that in the late stage. Sand cover on loess slopes aggravates loess erosion, not only by adding sand as additional eroded sediments but also by increasing the amount of eroded loess, compared with the loess slopes without sand cover. The influence of sand cover pattern on runoff yield and the amount of eroded sediments is larger than that of sand cover amount. Furthermore, given the same sand cover pattern, a thicker sand cover could increase sand erosion while a thinner sand cover could aggravate loess erosion. This difference explains the existence of intense erosion on slopes

关键词： aeolian-fluvial erosion sand-covered loess slopes sand cover amount sand cover pattern rainfall intensity grain-size distribution Inner Mongolia Reach of the Yellow River