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Comparison of the influences of vegetation stem parameters on hydraulic variables and sediment transport capacity

International Soil and Water Conservation Research 2023年第1期11卷 135-144页

作者： Hongli Mu suhua fu Department of Geography and Spatial Information Techniques Center for Land and Marine Spatial Utilization and Govemance ResearchNingbo UniversityNingbo315211PR China Bejing Key Laboratoryof Evironmental Remote Sensingand Dgital Cities Facultyof Gegraphical Scence Beijing Nomal UniversityBejing1000875 China

The hydraulic variables(Hv)and sediment transport capacity(Tc)of overland flow have changed immensely due to large-scale revegetation.However,research comparing the influences of stem pa-rameters(diameter,cover,and arrangement)on Hv and Tc is limited.The objectives of this study were to explore and compare the influences of stem parameters on Hv and Tc.Data on three treatment groups with varying stem diameters,covers,arrangements,flow discharges and slopes were collected in this study.With increasing stem diameter,Hv and Tc increased;Hv included the Reynolds and Froude numbers,flow velocity(v),shear stress(τ),stream power(Ω),and unit stream power(ω).However,the trend of the Darcy-Weisbach friction coefficient(f)was opposite.Hv and Tc were significantly influenced by stem diameter and cover.The effect of stem diameter on Hv and Tc was greater than the effects of cover and arrangement.Stem cover as a variable could not be used to adequately estimate the Tc when there were various stem diameters.A new exponential equation involving stem cover and stem diameter was demonstrated to be an appropriate predictor of Tc.Stem diameter and arrangement had no obvious influence on the relationship between Tc and v,and v as an indicator could explain the effect of stem parameters on Hv and Tc.This result could illustrate why the variables,including v,were able to predict Tc under vegetation stem and litter cover.

关键词： Hydraulic variables Stem arrangement Stem cover Stem diameter Transport capacity

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Comparison and quantitative assessment of two regional soil erosion survey approaches

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International Soil and Water Conservation Research 2023年第4期11卷 660-668页

作者： Lixia Dong suhua fu Baoyuan Liu Bing Yin Faculty of Geographical Science Beijing Normal UniversityBeijing100875PR ChinaFaculty of Geographical ScienceBeijing Normal UniversityBeijing100875PR China Advanced Institute of Natural Sciences Beijing Normal University at Zhuhai519087PR China State Key Lab Soil Erosion and Dryland Farming on the Loess Plateau Institute of Soil and Water ConservationNorthwest A&F UniversityPR China

Regional soil erosion surveys are the first step of soil conservation planning.Grid and sampling ap-proaches are commonly used for soil erosion surveys at the regional scale.With the grid approach,the region is divided into grids(e.g.,1 km × 1 km),and the soil erosion rate of each grid was calculated.With the sampling approach,a small portion of the area(typically 4%or less)was taken and then the soil erosion rate was calculated.Based on the above calculation,both approaches evaluated the soil erosion area(which is the area where the soil erosion rate is greater than the soil loss tolerance(t))and its distribution in the whole region.The purpose of this paper is to compare the assessment results of the two approaches and analyse their practicality using Yunyang County,Chongqing,China(area is 3636 km^(2)).The soil erosion rate,percentage of soil erosion area(PSEA,which is the ratio of the area where the soil erosion rate is greater than the soil loss tolerance(t)to the area of the total study region)and its spatial distribution were compared between the two approaches.The results showed that the grid approach overestimated the average soil erosion rate and PSEA overall for all 33 sample units and the whole region in comparison to the sampling approach.The sampling approach can yield a reasonable spatial distribution of the soil erosion rate in the whole region.In addition,the soil erosion regions were more clustered than those using the grid approach,which can be more suitable for soil conservation planning.Therefore,the sampling approach is an efficient and practical approach in regional soil erosion surveys.The results can provide insights into regional soil erosion surveys.

关键词： Regional soil erosion Soil erosion survey Grid approach Sampling approach CSLE

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Effects of sediment characteristics on the sediment transport capacity of overland flow

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International Soil and Water Conservation Research 2023年第1期11卷 75-85页

作者： Chenguang Liu suhua fu Zhanbin Li Zeyu Zhang Jianhui Zeng Institute of Soil and Water Conservation Northwest A&F UniversityYanglingShaanxi712100PR China State Key Laboratory of SoilErosion and Dryland Farming on the Loess Plateau Institute of Soil and Water ConservationChinese Academy of Sciences and Ministry of Water ResourceYanglingShaanxi712100PR China Beijing Key Laboratory of Environmental Remote Sensing and Digital City Faculty of Geographical ScienceBejing Normal UniversityBejing100875PR China

The transport of sediments is a crucial part of soil erosion.Accurately calculating the sediment transport capacity is key to the construction of soil erosion process models.Research on Tc has focused mainly on the dynamics of a single particle of sediment and hydraulic variables.There have been few studies of the impact of soil aggregates on the Tc.To clarify how sediment characteristics,including those for single particles and aggregates,affect the Tc of overland flow with no raindrop import,flume experiments were implemented at slope gradients varying from 5.24%to 26.80%and flow discharges ranging from 0.68 to 5.41×10^(-3)m^(2)s^(-1).The experimental materials were five typical soils in China.The results indicated that the correlation between the measured Tc and sediment mechanical composition indexes of the five soils was indistinctive in this study.The sediment settling velocity with aggregates has a significant corre-lation with the measured Tc.New equations,including for the sediment settling velocity with aggregatesωud75,were established to calculate the Tc.The empirical equation that includedωud75,slope gradient and unit discharge performed greatly in predicting Tc(R^(2)=0.93,NSE=0.90).ωud75 can effectively improve the calculation accuracy of Tc.The new equation including flow and sediment properties obtained through dimensional analysis performed well in predicting Tc(R^(2)=0.99,NSE=0.91),and the calculation accuracy was better than that of the empirical model derived in this study.These findings indicate that the sediment settling velocity is an important variable in the equation for predicting sediment transport capacity of overland flow.

关键词： Sediment transport capacity Soil mechanical composition Soil aggregates Sediment settling velocity Dimensional analysis

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Quantifying spatial distribution of interrill and rill erosion in a loess at different slopes using structure from motion(SfM)photogrammetry

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International Soil and Water Conservation Research 2022年第3期10卷 393-406页

作者： Tao He Yang Yang Yangzi Shi Xiaozhen Liang suhua fu Gege Xie Baoyuan Liu Yingna Liu State Key Laboratory of Earth Surface Processes and Resource Ecology Faculty of Geographical ScienceBeijing Normal UniversityBeijing100875China School of Geography Faculty of Geographical ScienceBeijing Normal UniversityBeijing100875China Beijing Key Laboratory of Environmental Remote Sensing and Digital Cities Faculty of Geographical ScienceBeijing Normal UniversityBeijing100875China State Key Laboratory of Soil Erosion and Dryland Farming on the Loess Plateau Chinese Academy of Sciences and Ministry of Water ResourcesYangling712100China

The spatial distribution of interrill and rill erosion is essential for unravelling soil erosion principles and the application of soil and water conservation practices.To quantify interrill and rill erosion and their spatial development,four 30-min rainfalls at 90 mm h^(-1)intensity were consecutively simulated on runoff plots packed with a loess at six slopes of 10°,15°,20°,25°,30°and 35°.The soil surface was measured using the structure from motion(SfM)photogrammetry upon each simulation run,and the runoff and sediment samples were collected and measured at every 10 min.Rills did not develop until the third simulation run.During the initial two runs,the lower third section was more severely eroded than the upper and middle thirds along the slope direction,yet the interrill erosion was statistically uniform from left to right.Rills tended to emerge by both sidewalls and in the lower portion in the third run.The corresponding rill erosion increased with slope from 10°to 20°and then decreased for the slopes steeper,which was consistent with the slope trend of the sediment yield directly measured.The rills expanded substantially primarily via head retreat and to a lesser extent via sideward erosion after receiving another 30-min rainfall.Rill erosion contributed 69.3%of the total erosion loss,and shifted the critical slope corresponding to the maximum loss from 20°to 25°.These findings demonstrate the significance of rill erosion not only in total soil loss but also in its relation to slope,as well as the effectiveness of SfM photogrammetry in quantifying interrill and rill erosion.

关键词： Interrill and rill erosion Spatial distribution Structure from motion(SfM) photogrammetry Slope Rainfall simulation

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基于高分7号卫星DEM的坡度坡长计算精度评价

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水土保持学报 2024年第2期38卷 136-146页

作者：赵云龙符素华北京师范大学地理科学学部北京100875

[目的]坡度和坡长作为重要的地形因子,其计算的准确性直接影响坡面土壤侵蚀模型的评价精度。高分7号卫星的高精度高程测量能力在地形因子的准确提取上具有较大潜力,期望能将其利用到坡度和坡长提取之中,实现对地形的准确表达。这需要对... 详细信息

[目的]坡度和坡长作为重要的地形因子,其计算的准确性直接影响坡面土壤侵蚀模型的评价精度。高分7号卫星的高精度高程测量能力在地形因子的准确提取上具有较大潜力,期望能将其利用到坡度和坡长提取之中,实现对地形的准确表达。这需要对利用高分7号卫星DEM提取坡度坡长的结果进行精度评价。[方法]利用地形因子(LS)计算工具,对陕西省吴堡县4个小流域高分7号卫星、1∶10000地形图、激光雷达影像生成的DEM进行坡度、坡长的提取。采用相关系数(r)、相对偏差和绝对偏差作为评价指标,评价高分7号提取地形因子的精度。[结果]与激光雷达和1∶10000地形图的坡度和坡长相比,高分7号提取的流域平均坡度偏低7.50%~9.02%,坡长偏大1.83%~19.35%,但坡长和坡度分级的面积比例并不存在显著差异;高分7号提取的坡度结果偏差(16.46%~44.26%)明显小于坡长的偏差(75.25%~140.87%);高分7号所提取的坡度坡长在沟间地上的相对偏差(坡度15.48%~56.63%,坡长50.02%~130.79%)明显低于沟谷地(坡度21.28%~63.61%,坡长93.01%~192.51%)。[结论]利用高分7号DEM提取坡度坡长时,对于获取坡长坡度面积分级和对指定点的坡度提取时是可行的,而对于指定点的坡长提取时则结果不够可靠,在研究流域中坡长坡度的空间分布上具有较大优势,而提取具体某一位置处的坡长坡度时的优势则不明显。

关键词：高分7号地形因子 DEM 土壤侵蚀模型

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Efficient Priority-Flood depression filling in raster digital elevation models

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International Journal of Digital Earth 2019年第4期12卷 415-427页

作者： Hongqiang Wei Guiyun Zhou suhua fu Center for Information Geoscience University of Electronic Science and Technology of ChinaChengduPeople’s Republic of China School of Resources and Environment University of Electronic Science and Technology of ChinaChengduPeople’s Republic of China State Key Laboratory of Soil Erosion and Dryland Farming on the Loess Plateau Institute of Soil and Water ConservationChinese Academy of SciencesYanglingPeople’s Republic of China Faculty of Geographical Science Beijing Normal UniversityBeijingPeople’s Republic of China

Depressions in raster digital elevation models(DEM)present a challenge for extracting hydrological networks.They are commonly filled before subsequent algorithms are further applied.Among existing algorithms for filling depressions,the Priority-Flood algorithm runs the fastest.In this study,we propose an improved variant over the fastest existing sequential variant of the Priority-Flood algorithm for filling depressions in floating-point DEMs.The proposed variant introduces a series of improvements and greatly reduces the number of cells that need to be processed by the priority queue(PQ),the key data structure used in the algorithm.The proposed variant is evaluated based on statistics from 30 experiments.On average,our proposed variant reduces the number of cells processed by the PQ by around 70%.The speed-up ratios of our proposed variant over the existing fastest variant of the Priority-Flood algorithm range from 31%to 52%,with an average of 45%.The proposed variant can be used to fill depressions in large DEMs in much less time and in the parallel implementation of the Priority-Flood algorithm to further reduce the running time for processing huge DEMs that cannot be dealt with easily on single computers.

关键词： Depression filling DEM drainage network

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A fast and simple algorithm for calculating flow accumulation matrices from raster digital elevation

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Frontiers of Earth Science 2019年第2期13卷 317-326页

作者： Guiyun ZHOU Hongqiang WEI suhua fu Center for Information Geoscience University of Electronic Science and Technology of ChinaChengdu 611731China School of Resources and Environment University of Electronic Science and Technology of ChinaChengdu 611731China State Key Laboratory of Soil Erosion and Dryland Farming on the Loess Plateau Institute of Soil and Water ConservationChinese Academy of SciencesYangling 712100China Faculty of Geographical Science Beijing Normal UniversityBeijing 100875China

Calculating the flow accumulation matrix is an essential step for many hydrological and topographical analyses.This study gives an overview of the existing algorithms for flow accumulation calculations for singleflow direction matrices.A fast and simple algorithm for calculating flow accumulation matrices is proposed in this study.The algorithm identifies three types of cells in a flow direction matrix: source cells,intersection cells,and interior cells.It traverses all source cells and traces the downstream interior cells of each source cell until an intersection cell is encountered.An intersection cell is treated as an interior cell when its last drainage path is traced and the tracing continues with its downstream cells.Experiments are conducted on thirty datasets with a resolution of 3 m.Compared with the existing algorithms for flow accumulation calculation,the proposed algorithm is easy to implement,runs much faster than existing algorithms,and generally requires less memory space.

关键词： flow accumulation flow direction DEM GIS

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西南小流域洪峰流量估算

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水土保持研究 2024年第2期31卷 142-148,157页

作者：李宁张志兰符素华于秀娟黄嵩北京师范大学地理科学学部北京100875 重庆市水土保持监测总站重庆401147

[目的]准确预测小流域的洪峰流量,为小流域水文应用和水保措施设计提供支撑。[方法]利用重庆万州刘家沟小流域2013—2021年共215次降雨事件数据,采用皮尔逊相关分析的方法,分析了重庆小流域次暴雨洪峰流量与降雨参数和径流参数的相关关... 详细信息

[目的]准确预测小流域的洪峰流量,为小流域水文应用和水保措施设计提供支撑。[方法]利用重庆万州刘家沟小流域2013—2021年共215次降雨事件数据,采用皮尔逊相关分析的方法,分析了重庆小流域次暴雨洪峰流量与降雨参数和径流参数的相关关系,进而采用线性回归和非线性回归方法,根据降雨径流资料估算了洪峰流量。[结果]研究建立了适用于西南小流域的洪峰流量公式,使用172场降雨事件数据进行参数率定,其模型有效系数为0.85;使用43场降雨事件对模型进行验证,相应的模型有效系数为0.82,结果表明新公式在研究区是可以接受的。[结论]研究建立的洪峰流量公式,能够较好地预测研究流域的洪峰流量,新建公式将为重庆乃至中国西南小流域进行水土保持措施的决策、水土保持工程设施设计和土壤侵蚀评价等提供一定技术基础。

关键词：洪峰流量小流域水土保持径流

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The assessment of soil loss by water erosion in China

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International Soil and Water Conservation Research 2020年第4期8卷 430-439页

作者： Baoyuan Liu Yun Xie Zhiguang Li Yin Liang Wenbo Zhang suhua fu Shuiqing Yin Xin Wei Keli Zhang Zhiqiang Wang Yingna Liu Ying Zhao Qiankun Guo Faculty of Geographical Science Beijing Normal UniversityBeijing100875China Soil Conservation Monitoring Centre Ministry of Water Resources of People's Republic of ChinaBeijing100053China Institute of Soil Science Chinese Academy of SciencesNanjing210008China China Institute of Water Resources and Hydropower Research Ministry of Water Resources of People's Republic of ChinaBeijing100038China

Soil erosion is a major environmental problem in China.Planning for soil erosion control requires accurate soil erosion rate and spatial distribution information.The aim of this article is to present the methods and results of the national soil erosion survey of China completed in 2011.A multi-stage,unequal probability,systematic area sampling method was employed.A total of 32,948 sample units,which were either 0.2-3 km2 small catchments or 1 km2 grids,were investigated on site.Soil erosion rates were calculated with the Chinese Soil Loss Equation in 10 m by 10 m grids for each sample unit,along with the area of soil loss exceeding the soil loss tolerance and the proportion of area in excess of soil loss tolerance relative to the total land area of the sample units.Maps were created by using a spatial interpolation method at national,river basin,and provincial scales.Results showed that the calculated average soil erosion rate was 5 t ha-1 yr-1 in China,and was 18.2 t ha-1 yr-1 for sloped,cultivated cropland.Intensive soil erosion occurred on cropland,overgrazing grassland,and sparsely forested land.The proportions of soil loss tolerance exceedance areas of sample units were interpolated through the country in 250 m grids.The national average ratio was 13.5%,which represents the area of land in China that requires the implementation of soil conservation practices.These survey results and the maps provide the basic information for national conservation planning and policymaking.

关键词： National soil erosion survey CSLE Sample units Chinese soil loss map Soil erosion rate Ratio of soil erosion area

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Non-invasive estimation of pulmonary hypertension and clinical deterioration risk in pediatric congenital heart disease: Development and validation of predictive tools

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中华医学杂志(英文版) 2024年第11期137卷 2024 Apr 8页

作者： Wang Ting Zhou Dansha Chen Yuqin Kuang suhua Xing Yue Yi Qijian Pan Zhengxia Xu Weibin Rao Jiao Liu Yunqi Lu Guoliang Lin Ziying Li Xiang Xie Yi Wu Yulong An Peng Deng Xiaoxiao He Jiayue Xie Jiayi Li Chenxi Geng Gang Tian Daiyin Liu Enmei Huang Jingsi fu Zhou Wang Jian Department of Respiratory Chongqing Higher Institution Engineering Research Center of Children’s Medical Big Data Intelligent Application National Clinical Research Center for Child Health and Disorders Ministry of Education Key Laboratory of Child Development and Disorders Children’s Hospital of Chongqing Medical University Chongqing China State Key Laboratory of Respiratory Diseases National Center for Respiratory Medicine Guangdong Key Laboratory of Vascular Diseases National Clinical Research Center for Respiratory Diseases Guangzhou Institute of Respiratory Health the First Affiliated Hospital of Guangzhou Medical University Guangzhou Medical University Guangzhou Guangdong China Department of Cardiac Surgery The First Affiliated Hospital of Guangzhou Medical University Guangzhou Medical University Guangzhou Guangdong China Department of Cardiovascular Medicine Children’s Hospital of Chongqing Medical University National Clinical Research Center for Child Health and Disorders Ministry of Education Key Laboratory of Child Development and Disorders Children’s Hospital of Chongqing Medical University Chongqing China Department of Thoracic and Cardiac Surgery Children’s Hospital of Chongqing Medical University National Clinical Research Center for Child Health and Disorders Ministry of Education Key Laboratory of Child Development and Disorders Children’s Hospital of Chongqing Medical University Chongqing China Department of Cardiac Center of Guangdong Women and Children Hospital Guangzhou Guangzhou Guangdong China Department of Guangzhou Laboratory Guangzhou International Bio Island Guangzhou Guangdong China

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