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1.
In order to understand the process of surface erosion and acquire basic data of conditions on hillslope without vege tation, a sprinkling experiment is conducted on a bare slope in Mt. Tanakami in the central part of Japan. Based on the mea surements of runoff, mean soil erosion depth, and sediment yield, etc. , the results suggest the following characteristics in the process of surface erosion in the experimental area. (1) The occurrence of sediment discharge is interrupted; (2) Surface runoff is a saturated overland flow; (3) The mean soil erosion depth is thick compared with other areas in Mt. Tanakami;(4) Sediment discharge process is detachment- limited. 相似文献
2.
Effects of uncertainties in the position and orientation of both the transmitter and receivers on marine controlled-source electromagnetic data 总被引：2，自引：0，他引：2
Simulation and interpretation of marine controlled-source electromagnetic (CSEM) data often approximate the transmitter source as an ideal horizontal electric dipole (HED) and assume that the receivers are located on a flat seabed. Actually, however, the transmitter dipole source will be rotated, tilted and deviated from the survey profile due to ocean currents. And free-fall receivers may be also rotated to some arbitrary horizontal orientation and located on sloping seafloor. In this paper, we investigate the effects of uncertainties in the transmitter tilt, transmitter rotation and transmitter deviation from the survey profile as well as in the receiver’s location and orientation on marine CSEM data. The model study shows that the uncertainties of all position and orientation parameters of both the transmitter and receivers can propagate into observed data uncertainties, but to a different extent. In interpreting marine data, field data uncertainties caused by the position and orientation uncertainties of both the transmitter and receivers need to be taken into account. 相似文献
3.
Uncertainty of slope length derived from digital elevation models of the Loess Plateau,China 总被引：2，自引：1，他引：1
Although many studies have investigated slope gradient uncertainty derived from Digital Elevation Models（DEMs）, the research concerning slope length uncertainty is far from mature. This discrepancy affects the availability and accuracy of soil erosion as well as hydrological modeling. This study investigates the formation and distribution of existing errors and uncertainties in slope length derivation based on 5-m resolution DEMs of the Loess Plateau in the middle of China. The slope length accuracy in three different landform areas is examined to analyse algorithm effects. The experiments indicate that the accuracy of the flat test area is lower than that of the rougher areas. The value from the specific contributing area（SCA） method is greater than the cumulative slope length（CSL）, and the differences between these two methods arise from the shape of the upslope area. The variation of mean slope length derived from various DEM resolutions and landforms. The slope length accuracy decreases with increasing grid size and terrain complexity at the six test sites. A regression model is built to express the relationship of mean slope length with DEM resolution less than 85 m and terrain complexity represented by gully density. The results support the understanding of the slope length accuracy, thereby aiding in the effective evaluation of the modeling effect of surface process. 相似文献
4.
Mine waste debris flows continue to occur in China, and the disaster prevention and mitigation of these flows faces severe challenges since the mechanisms determining erosion and transport of mine waste along gullies are not yet fully understood. The erosion and delivery process of mine waste heaps was reproduced through flume experiments with the method based on field survey data of the Daxicha mine waste debris flow gully in the Xiaoqinling gold mining area. The results showed that the erosion and movement of mine wastes could be divided into three modes: minimal sediment movement, sediment sorting and delivery, and a large amount of sediment transfer. Moreover, there was an obvious amplification effect on peak discharge along with the formation and failure of temporary landslide dams during the erosion process. The correlation between the coefficient of peak discharge amplification and three dimensionless influencing factors, flume gradient, dimensionless volume, and dimensionless particle size, were comprehensively analyzed. An empirical formula for the coefficient of peak discharge amplification was proposed and verified based on 16 sets of experimental data. These preliminary results can provide a scientific reference for future research on disaster prevention and mitigation of mine waste debris flows. 相似文献
5.
In watersheds that have not sufficient meteorological and hydrometric data for simulating rainfall-runoff events, using geomorphologic and geomorphoclimatic characteristics of watershed is a conventional method for the simulation. A number of rainfall-runoff models utilize these characteristics such as Nash-IUH, Clark-IUH, Geomorphologic Instantaneous Unit Hydrograph(GIUH), Geomorphoclimatic Instantaneous Unit Hydrograph(GcIUH), GIUH-based Nash(GIUH-Nash) and GcIUH-based Clark(GcIUH-Clark). But all these models are not appropriate for mountainous watersheds. Therefore, the objective of this study is to select the best of them for the simulation. The procedure of this study is: a) selecting appropriate rainfall-runoff events for calibration and validation of six hybrid models, b) distinguishing the best model based on different performance criteria(Percentage Error in Volume(PEV); Percentage Error in Peak(PEP); Percentage Error in Time to Peak(PETP); Root Mean Square Error(RMSE) and Nash-Sutcliffe model efficiency coefficient(ENS)), c) Sensitivity analysis for determination of the most effective parameter at each model, d) Uncertainty determination of different parameters in each model and confirmation of the obtained results by application of the performance criteria. For application of this procedure, the Navrood watershed in the north of Iran as a mountainous watershed has been considered. The results showed that the ClarkIUH and GcIUH-Clark are suitable models for simulation of flood hydrographs, while other models cannot simulate flood hydrographs appropriately. The sensitivity analysis shows that the most sensitive parameters are the infiltration constant rate and time of concentration in the Clark-IUH model. Also, the most sensitive parameters include the infiltration constant rate and storage coefficient in the GcIUHClark model. The Clark-IUH and GcIUH-Clark models are more sensitive to their parameters. The Latin Hypercube Sampling(LHS) on Monte Carlo(MC) simulation method was used for evaluation of uncertainty of data in rainfall-runoff models. In this method 500 sets of data values are produced and then the peak discharge of flood hydrographs for each produced data set is simulated with rainfall-runoff models. The uncertainty of data changes the value of simulated peak discharge of flood hydrograph. The uncertainty analysis shows that the observed peak discharges of different rainfall-runoff events are within the range of values of simulated by the six hybrid rainfall-runoff models and IUH that inputs of these models were the produced data sets. The range of the produced peak discharge of flood hydrographs by the Clark-IUH and GcIUH-Clark models is wider than those of other models. 相似文献
6.
《山地科学学报》2015,(1)
Under global warming, storm events tend to intensify, particularly in monsoon-affected regions.As an important agricultural area in China, the purple soil region in the Sichuan Basin, where it has a prevailing monsoon climate, is threatened by serious soil erosion. Tillage operations alter runoff and soil erosion processes on croplands by changing the physical properties of the soil surface. To clarify the relationship between tillage and soil erosion in the purple soil region, three different tillage practices in this region were investigated at the plot scale over 4 years: bare land with minimum tillage(BL),conventional tillage(CT) and seasonal no-tillage ridges(SNTR) which was initially designed to prevent soil erosion by contoured ridges and no-tillage techniques. The results showed that although there were no significant differences in the surface runoff and soil erosion among the three practices, BL causedrelatively high surface runoff and soil erosion,followed by CT and SNTR. Classification and comparison of the rainfall events based on cluster analysis(CA) verified that the surface runoff was not significantly different between most intensive event and long intensive events but was significantly different between most intensive and short and medium-duration events. Only the rainfall events with the highest rainfall intensity could trigger serious soil erosion, up to 1000 kg ha-1 in the region. Further detailed investigations on the effects of tillage operations on the soil erosion in a subtropical region with a monsoon climate are needed to provide a basis for modeling catchments and designing better management practices. 相似文献
7.
针对川中丘陵区紫色土坡耕地严重水土流失,选取典型代表李子溪流域为研究区,构建了其SWAT的模型数据库,包括地形、土壤、气象和土地利用数据库。并利用赵家祠水文站1970-1979年的实测径流和泥沙资料,对该流域的SWAT模型参数进行率定再采用1980-1986年的实测资料,对模型的适用性进行验证,同时用相对误差Re和Nash确定性系数Ens评价模拟效果。结果显示,径流和泥沙模拟相对误差均在±15%范围以内,Nash确定性系数均大于等于0.70,说明SWAT模型对李子溪流域年、月径流和年泥沙量的模拟精度较高。同时模拟值与实测值和降雨量的变化趋于一致。可见,用SWAT模型模拟和预测雨量较为丰沛、土壤侵蚀较严重的紫色丘陵地区的产流产沙是实用、可行的。 相似文献
8.
Ruzhong Li 《中国地理科学(英文版)》2008,18(4):348-355
Many kinds of uncertainties are involved, such as random, fuzzy, grey, unascertained property and so on, in soil erosion process. To exactly predict the non-point source pollution loads, some uncertainties should be taken into consideration. Aiming at the deficiency of present blind number theory being helpless for fuzziness, a novel blind number, i.e. extended-blind number, was introduced by substituting a set of triangular fuzzy numbers （TFNs）, expressed as a-cuts, for interval values in present blind number, and the expected value of extended-blind number was also brought forward by referring to the current blind number theory. On the basis of denoting the parameters of Uni- versal Soil Loss Equation （USLE） as extended-blind parameters, a novel USLE model was established for quantitatively evaluating soil erosion loss and non-point source pollution loads. As a case, the uncertain USLE was employed for predicting the soil erosion loss and non-point source pollution loads of absorbed nitrogen and phosphorus in a dis- trict in the Hangbu-Fengle River basin, in the upstream of Chaohu Lake watershed. The results show that it is feasible in theory to extend blind number into fuzzy environment and reliable on conclusion to apply extended-blind number theory for predicting non-point source pollution loads. 相似文献
9.
Accurate prediction of the hydrographs of outburst floods induced by landslide dam overtopping failure is necessary for hazard prevention and mitigation. In this study, flume model tests on the breaching of landslide dams were conducted. Unconsolidated soil materials with wide grain size distributions were used to construct the dam. The effects of different upstream inflow discharges and downstream bed soil erosion on the outburst peak discharge were investigated. Experimental results reveal that the whole hydrodynamic process of landslide dam breaching can be divided into three stages as defined by clear inflection points and peak discharges. The larger the inflow discharge, the shorter the time it takes to reach the peak discharge, and the larger the outburst flood peak discharge. The scale of the outburst floods was found to be amplified by the presence of an erodible bed located downstream of the landslide dam. This amplification decreases with the increase of upstream inflow. In addition, the results show that the existence of an erodible bed increases the density of the outburst flow, increasing its probability of transforming from a sediment flow to a debris flow. 相似文献
10.
Adriana García-Rama Stefano Giorgio Pagano Francesco Gentile Mario Aristide Lenzi 《山地科学学报》2016,13(6):957-970
Suspended sediment transport in streams is an effective indicator of soil erosion at the watershed scale. This process was studied using the data obtained from two continuous monitoring stations installed in Italian watersheds, the Rio Cordon and Torrente Carapelle. The catchments have substantially different climatic, morphological and land use characteristics. The Rio Cordon, a small Alpine watershed, has been monitored since 1986, while in the Torrente Carapelle, a medium-size Mediterranean watershed, the monitoring station has provided data since 2007. Several flood events with suspended sediment transport were isolated in the two catchments, excluding those determined by snowmelt in the Rio Cordon as this process does not affect the Carapelle watershed. Analysis of the events showed different behavior in terms of hysteresis loop trends between water discharge (m3 s-1) and suspended sediment concentration (g l-1) values, as the Rio Cordon confirms clockwise relationships most frequently, while counter-clockwise trends represent the majority of cases for the Carapelle Torrent. The different behavior of the two watersheds was further analyzed by evaluating relationships between the main hydrological parameters related to suspended sediment transport. Runoff controls the total sediment budget in both catchments. In contrast, it was noted that the runoff process does not interfere in the magnitude of the suspended sediment transport in the Rio Cordon catchment, while variations due to the larger size of the catchment area characterize the events in the Carapelle watershed. Lastly, a flow peak threshold that determines the advance or delay of the hydrograph peak with respect to the sedigraph peak was established for the Carapelle Torrent, while it was not reported in the Rio Cordon. 相似文献
11.
Leila GHOLAMI Abdulavahed KHALEDI DARVISHAN Veliber SPALEVIC Artemi CERDà Ataollah KAVIAN 《山地科学学报》2021,(3):706-715
Raindrop size,rainfall intensity and runoff discharge affect the detachment and transportation of soil particles.Among these three factors,the rainfall intensity seems to be more important because it can change other two factors.Storm patterns can be determined by changing the rainfall intensity during the storm.Therefore,the objective of this research is to test the influence of storm pattern on runoff,soil erosion and sediment concentration on a rangeland soil slope under field rainfall simulation.Four storm rainfall intensity patterns were selected for examining the effects of variations in storm event characteristics on soil erosion processes.The selected storm patterns were:I(45,55 and 70 mm h-1);II(45,70 and 55 mm h-1);III:(70,55 and 45 mm h-1);and IV(55,45 and 70 mm h1).The last pattern is a new one instead of the uniform pattern which has been sufficiently studied in previous researches.The experiments were conducted in field plots(in Kojour watershed,Mazandaran Province,Iran)with an area of one square meter and an constant slope gradient of 18%,surrounded by galvanised sheets.Following the nonuniform prioritization of the storm patterns for the studied variables,time to runoff(I>II>IV>III),runoff volume(III>IV>II>I),sediment concentration(IV>III>I>II)and soil erosion(III>IV>II>I)),it can be generally inferred that each pattern has specific effect on soil erosion processes during a storm.The results of the general linear model(GLM)test indicated that the effects of storm pattern on time to runoff,total runoff volume,runoff coefficient and soil erosion were significant at a level of 99%.The Duncan test showed that the storm patterns can be divided into three groups of III,IV;II;I(for time to runoff),I,II;IV,III(for runoff coefficient),and I;II;IV,III(for runoff volume and soil erosion). 相似文献
12.
Based on the data from gauging stations,the changes in water discharge and sediment load of the Huanghe (Yellow)River were analyzed by using the empirical mode decomposition(EMD)method.The results show that the periodic oscillation of water discharge and sediment load of the Huanghe River occurs at the interannual,decadal,and multi-decadal scales,caused by the periodic oscillations of precipitation,and El Nio/Southern Oscillation(ENSO)affects water discharge by influencing precipitation distribution and contributes to periodic varations in precipitation and water discharge at interannual timescale.The water discharge and sediment load of the Huanghe River have decreased since the 1960s under the influence of precipitation and huamn activities,and human activities attribute more than precipitation to the reduction in the water discharge and sediment load,furthermore,water abstraction and water-soil conservation practices are the main causes of the decrease in water discharge and sediment load,respectively.The reduction in sediment load has directly impacted on the lower reaches of the Huanghe River and the river delta, causing considerable erosion of the river channel in the lower reaches since the 1970s along with River Delta changing siltation into erosion around 2000. 相似文献
13.
基于DEM提取坡谱信息的不确定性 总被引：3，自引：1，他引：2
坡谱是黄土高原地学分析新方法、新思路的探索。本文基于坡谱不确定性的概念及其过程分布模型的论述,以陕北黄土高原国家1∶10000和1∶50000DEM数据为基本信息源,分析了坡谱不确定性的产生原因、主要影响因素与影响规律,阐述了坡谱提取与应用中应注意的主要问题,为正确应用坡谱进行地学分析提供重要依据。 相似文献
14.
参数优化方法是准确估计生态模型参数、降低其不确定性的有效手段。本文提出一种基于贝叶斯机器学习的No-U-Turn Sampler（NUTS）生态模型参数优化方法。NUTS是一种高效的参数优化方法,每次取样中利用递归算法生成候选参数集（二叉树）推断参数的后验信息,如果满足约束条件“非U型回转”,不断构建子树更新参数;否则,记录本次抽样的“最优”参数集,并开始下一次取样,直到获取足够样本。该算法在每次取样中充分优化参数,避免因随机游走行为产生冗余抽样,提高了参数优化效率。本文以千烟洲亚热带人工针叶林碳通量模拟为例,基于Pymc3框架利用NUTS参数优化方法实现了碳通量（Net Ecosystem Exchange,NEE）模型参数反演,并与Metropolis-Hastings（MH）方法进行对比。结果表明,本文算法的参数值达到稳定波动时的抽样次数减少了85%左右,参数优化效率提升3倍左右。参数优化后,2种NEE模型中7个参数不确定性降低10%~53%。此外,NEE模拟效果明显提升,模拟值与实测值的R2分别提高23%和17%,RMSE分别降低3%和4%。综上所述,本文提出的参数优化方法对生态领域的参数估计或数据同化工作具有一定的借鉴意义。 相似文献
15.
1INTRODUCTIONIntheHuanghe(Yellow) Riverbasin, soilerosionisaseriousproblem,whilerunoffandsedimentyieldsim-ulation hasnotbeenextensivelystudiedonthebasisofGIS(GeographicInformationSystem) and dis-tributedhydrologicalmodel.Inthisstudy,theLushiwatershed,whichislocatedattheupstreamoftheLushiHydrologicalStationintheLuoheRiver—thebiggesttributary oftheHuanghe Riveranddown-streamofXiaolangdiDam,isselectedasthestudyarea.ThelevelofsoilerosioninLushiwatershedismoderatein theHuangheRiverbas… 相似文献
16.
Soil conservation practices can greatly affect the soil erosion process, but limited information is available about its influence on the particle size distribution(PSD) of eroded sediment, especially under natural rainfall. In this study, the runoff, sediment yields, and effective/ultimate PSD were measured under two conventional tillage practices, downhill ridge tillage(DT) and plat tillage(PT) and three soil conservation practices, contour ridge tillage(CT), mulching with downhill ridge tillage(MDT), and mulching with contour ridge tillage(MCT) during 21 natural rainfall events in the lower Jinsha River. The results showed that(1) soil conservation practices had a significant effect on soil erosion. The conventional tillage of DT caused highest runoff depth(0.58 to 29.13 mm) and sediment yield(0.01 to 3.19 t hm-2). Compared with DT, the annual runoff depths and sediment yields of CT, MDT and MCT decreased by 12.24%-49.75% and 40.79%-88.30%, respectively.(2) Soil conservation practices can reduce the decomposition of aggregates in sediments. The ratios of effective and ultimate particle size(E/U) of siltand sand-sized particles of DT and PT plots were close to 1, indicating that they were transported as primary particles, however, values lower/greater than 1 subject to CT, MDT and MCT plots indicated they were transported as aggregates. The ratios of E/U of claysized particles were all less than 1 independently of tillage practices.(3) The sediments of soil conservation practices were more selective than those of conventional tillage practices. For CT, MDT and MCT plots, the average enrichment ratios(ERs) of clay, silt and sand were 1.99, 1.93 and 0.42, respectively, with enrichment of clay and silt and depletion of sand in sediments. However, the compositions of the eroded sediments of DT and PT plots were similar to that of the original soil. These findings support the use of both effective and ultimate particle size distributions for studying the size selectivity of eroded sediment, and provide a scientific basis for revealing the erosion mechanism in the purple soil area of China. 相似文献
17.
The well-known Three Gorges Dam(TGD) within the Yangtze catchment launched its operation in 2003. The effect of the TGD operation on the sediment size on the East China Sea shelf is rarely known. High resolution(0.5 cm sampling) grain size analysis and 137 Cs and 210 Pb dating of the DH8-1 core were conducted with core collected from the distal part of a main sink for the modern Yangtze sediment entering the sea, the Min-Zhe Coastal Mud Deposits(MZCMD) on the inner East China Sea shelf. The 137 Cs dating results show that the core DH8-1 formed during 1946–2012 with a mean deposition rate of 0.65 cm yr~(-1), indicating that the 0.5 cm sampling for grain size analysis in this local area could reflect environmental changes generally on a one-year time scale. The mean grain size of DH8-1 core sediment that deposited after 2003 is significantly larger than that deposited during 1988–2002. After ruling out other possible factors, we infer that the sediment coarsening of DH8-1 core after 2003 is attributed to the TGD operation which causes the erosion of the Yangtze subaqueous delta. Specifically, the TGD operation significantly intensifies the declining trend of the Yangtze sediment loads to the sea despite no decreased water discharge, which results in extensive erosion of the Yangtze subaqueous delta. The relatively coarse sediment of the subaqueous delta is eroded and resuspended by ocean dynamics and then transported by coastal current, finally depositing on the MZCMD area. In addition, the general sediment fining of core DH8-1 that deposited during 1988–2002, comparing with 1946–1987, is mainly caused by dam construction and soil and water conservation within the Yangtze catchment. Our findings are helpful for better understanding the effects of such a huge dam as the TGD on a sediment sink like the MZCMD of such a large river as the Yangtze River. 相似文献
18.
大地测量数据往往包含许多不确定性,可能导致所建立的函数模型产生病态,影响参数估计的准确性和可靠性。通过研究边坡变形非线性时变系统的力学原理,利用多项式拟合方法改进原模型,在参数解算过程中,考虑到测量数据的不确定性给解算结果带来消极影响,通过限制不确定度,利用min-max准则,提高参数解算的准确性,并将预测变形结果与实测边坡位移数据对比。结果表明,带不确定性的平差算法（least-square with uncertainty,ULS）与最小二乘平差（least-squares,LS）和整体最小二乘平差（total least-square,TLS）相比,其预测结果更接近实际测量数据,证明了改进的边坡变形非线性时变系统预测变形的有效性。 相似文献
19.
Adaptive finite element modeling of marine controlled-source electromagnetic fields in two-dimensional general anisotropic media 总被引：4，自引：0，他引：4
In this paper, we extend the scope of numerical simulations of marine controlled-source electromagnetic (CSEM) fields in a particular case of anisotropy (dipping anisotropy) to the general case of anisotropy by using an adaptive finite element approach. In comparison to a dipping anisotropy case, the first order spatial derivatives of the strike-parallel components arise in the partial differential equations for generally anisotropic media, which cause a non-symmetric linear system of equations for finite element modeling. The adaptive finite element method is employed to obtain numerical solutions on a sequence of refined unstructured triangular meshes, which allows for arbitrary model geometries including bathymetry and dipping layers. Numerical results of a 2D anisotropic model show both anisotropy strike and dipping angles have great influence on the marine CSEM responses. 相似文献
20.
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