Effects of Roughness Elements Distribution on Overland Flow Resistance

Roughness elements are various in a mountain area; they include gravel and ground surface vegetation that often result in surface friction drag to resist overland flows. The variation and characteristics of flow resistance strongly impact the overland flow process and watershed floods. In view of the universal existence of natural vegetation, such as Chlorophytum malayense(CM) or Ophiopogon bodinieri(OB), and the sand-gravel bed of the river channel, it is important to understand the role of different types of roughness elements in flow resistance. This study was performed to investigate and compare through flume experiments the behaviors of overland flow resistance by the reaction of multi-scale configuration of different roughness elements. The result showed that the resistance coefficient gradually reduced versus the increase of flow rate in unit width and tended to be a constant when q = 3.0 l/s.m, Fr = 1.0, and Re = 4000 for slopes of 6 to 10 degrees. The gap of the vegetated rough bed and the gravel rough bed is limited to the same as the gap of the two types of vegetation, CM and OB. It was noted that the vegetation contributed to the increase in form resistance negatively and may lead to the mean resistance on decrease. To classify the flow pattern, the laminar flows were described by DarcyWeisbach's equation. In the study the f-Re equation of vegetated bed was developed with f ?5000 Re.The friction coefficient for laminar flows can be regarded as the critical value for identifying the transformation point of the flow pattern.     

Evaluation of the stability of vegetated slopes according to layout and temporal changes

Vegetation in slopes can effectively improve slope stability.However,it is difficult to estimate the effects of vegetation on slope stability because of variations in plant species and environmental conditions.Moreover,influences of plant growth on slope stability change with time,resulting in changes in the safety factor.This study was conducted to evaluate the stability of vegetated slopes with time and investigate the effects of different layouts of plant species on slope stability.Here,we used a plant growth model and slope stability analysis to build an evaluation model.To accomplish this,one species of tree,shrub and grass was chosen to set six layout patterns.A slope with no vegetation served as a control.The safety factors of the seven slopes were then calculated using the developed evaluation model and differences in the safety factors of slopes were compared and discussed.The slope vegetated with Platycladus orientalis reached the most stable state at the age of 60 years.Shrub slope(Vitex negundo)had the maximum safety factor after 20 years.Overall,the safety factor of vegetated slopes increased from 12.1%to 49.6% compared to the slope with no vegetation.When wind force was considered,the safety factor value of the slope changed from 3.5%to 43.5%.Vegetation mixtures of trees and grasses resulted in the best slope stability.Planting grasses on slopes can improve slope stability of trees to a greater degree than that of slopes with shrubs in the early stage of growth.     

Analytical models for velocity distributions in compound channels with emerged and submerged vegetated floodplains

The lateral distributions of depth-averaged velocity in open compound channels with emerged and submerged vegetated floodplains were analyzed based on the analytical solution of the depth-integrated Reynolds-Averaged Navier-Stokes equation with a term to account for the effects of vegetation. The three cases considered for open channels were two-stage rectangular channel with emerged vegetated floodplain, rectangular channel with submerged vegetated corner, and two-stage rectangular channel with submerged vegetated floodplain, respectively. To predict the depth-averaged velocity with submerged vegetated floodplains, we proposed a new method based on a two-layer approach where flow above and through the vegetation layer was described separately. Moreover, further experiments in the two-stage rectangular channel with submerged vegetated floodplain were carried out to verify the results. The analytical solutions of the cases indicated that the corresponding analytical depth-averaged velocity distributions agree well with the simulated and experimental prediction. The analytical solutions of the cases with theoretical foundation and without programming calculation were reasonable and applicable, which were more convenient than numerical simulations. The analytical solutions provided a way for future researches to solve the problems of submerged vegetation and discontinuous phenomenon of depth-averaged velocity at the stage point for compound channels. Understanding the hydraulics of flow in compound channels with vegetated floodplains is very important for supporting the management of fluvial processes.     

地形复杂山区常用植被指数的地形校正对比

植被指数能反映地表植被生长、覆盖等情况,常作为反演植物生物物理参量的有效参数。然而,在地形复杂的山区,由于地形效应的影响,导致一些植被指数适用性受限。基于以上现状,本文以贵州省江口县为研究区,采用4种地形校正模型（Teillet-回归模型、Minnaert模型、C模型、SCS+C模型）对常用植被指数（SR、MSR、NDVI、SAVI、MSAVI、EVI）进行地形校正,以评价不同坡度条件下植被指数地形校正效果。结果表明：地形校正对缓解波段比形式的植被指数（SR、MSR、NDVI）地形效应的作用有限,而对非波段比形式的植被指数（SAVI、MSAVI、EVI）效果较好。另外,随着坡度增加,地形效应显著,地形校正效果也更明显：坡度较小时,波段比形式的植被指数无需进行地形校正,而建议非波段比形式的植被指数进行地形校正;坡度较大时,建议2类植被指数都进行地形校正,但非波段比形式的植被指数可能会发生过度校正现象。此外,地形校正后非波段比形式的植被指数与森林地上生物量线性回归模型的精度明显提高。因此,建议在地形复杂山区利用非波段比形式的植被指数进行定量反演时,先进行地形校正。     

A Simulating Experiment in the Process of Soil Erosion on Bare Land in Mt. Tanakami

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.     

Soil detachment and transport under the combined action of rainfall and runoff energy on shallow overland flow

Rainfall and runoff energy results in soil erosion. This paper presents new the concepts of rainfall and runoff energy and analyzes the relationship of rainfall energy and runoff energy with sediment transport based on the conversion theory of kinetic and potential energy using artificial rainfall and mechanical calculation. The results show that the ratio of sediment detachment in sloping fallow overland flow increases with the slope gradient, rainfall energy and runoff energy, while the sediment detachment ratio under raindrop impact are significantly higher than those under no raindrop impact. The sediment concentration increases with the slope gradient and rainfall energy; when the slope gradient and rainfall energy are constant, the sediment concentration decreases as the runoff energy increases. Rainfall disturbance coefficients have a logarithmic correlation with the rate of rainfall energy and runoff energy. On the same slope gradient, when the rainfall energy is constant, the disturbance coefficient decreases as the runoff energy increases, while when the runoff energy is constant, the disturbance coefficient increases as the rainfall energy increases. Rainfall energy results in sediment detachment, and runoff energy is the transportation for erosion sediment. This showed that rainfall energy and runoff energy are important in the sediment detachment and transportation of shallow overland flow.     

Influence of vegetation cover and other sources of variability on sediment and runoff response in a burned forest in South Korea

Post-fire field measurements of sediment and run off yield were undertaken in natural rainfall event-basis during five rainy months in Korea on a total of 15 small plots: four replica burned unseeded plots, six replica burned seeded plots, and five replica unburned plots. The main aim was to evaluate the effects of vegetation recovery and spatial distribution patterns on sediment and runoff response between and within the treatment replica erosion plots. Six-years after the wildfire, total sediment and runoff yield in the burned unseeded plots with 20%-30% vegetation cover was still 120.8 and 20.6 times higher than in the unburned treatment plots with 100% ground cover, 8.3 and 6.7 times higher than in the burned seeded plots with 70%-80% vegetation cover, while only 1.6 and 2.0 times higher than in the burned seeded plots with 50%-60% vegetation cover, respectively. The differences in sediment and runoff yield between the treatment plots was proportional to total vegetation cover, distance of bare soil to vegetation cover, magnitude of rainfall characteristics and changes in soil properties, but not slope gradient. Three out of the six within-treatment pairs of two replica plots showed large differences in sediment and runoff yield of up to 6.0 and 4.2 times and mean CV of up to 99.1% and 62.2%, respectively. This was due to differences in the spatial distribution patterns of surface cover features, including aggregation of vegetation and litter covers, the distance of bare soil exposed to vegetation cover closer to the plot sediment collector and micro topographic mounds and sinks between pairs of replica plots. Small differences in sediment and runoff of only 0.9-1.4 folds and mean CV of 8.6%-25% were observed where the within-treatment pairs of replica plots had similar slope, total surface cover components and comparable spatial distribution pattern of vegetation and bare soil exposed surface covers. The results indicated that post-fire hillslopes undergoing effective vegetation recovery have the potential to reduce sediment and runoff production nearer to unburned levels within 6-years after burning while wildfire impacts could last more than 6-years on burned unseeded ridge slopes undergoing slow vegetation recovery.     

Mapping the vegetation distribution of the permafrost zone on the Qinghai-Tibet Plateau

In this paper,an updated vegetation map of the permafrost zone in the Qinghai-Tibet Plateau(QTP) was delineated.The vegetation map model was extracted from vegetation sampling with remote sensing(RS) datasets by decision tree method.The spatial resolution of the map is 1 km×1 km,and in it the alpine swamp meadow is firstly distinguished in the high-altitude areas.The results showed that the total vegetated area in the permafrost zone of the QTP is 1,201,751 km~2.In the vegetated region,50,260 km~2 is the areas of alpine swamp meadow,583,909 km~2 for alpine meadow,332,754 km~2 for alpine steppe,and 234,828 km~2 for alpine desert.This updated vegetation map in permafrost zone of QTP could provide more details about the distribution of alpine vegetation types for studying the vegetation mechanisms in the land surface processes of highaltitude areas.     

喀斯特地区植被覆盖度变化及地形与人口效应研究

喀斯特山地流域植被变化具有独特性,探究其植被变化特征有利于石漠化治理和退耕还林工程科学实施。本文选取1990-2016年贵州石阡河流域Landsat系列遥感影像,采用像元二分模型和相关分析等方法研究流域植被覆盖度时空变化特征,并探究其变化的地形效应和人口效应。研究表明：① 1990-2016年贵州石阡河流域植被覆盖度总体处于上升趋势,植被恢复取得较好效果;② 1990-2016年贵州石阡河流域植被覆盖度变化的地形效应中,随海拔和坡度上升,植被覆盖度总体处于稳定上升趋势。随坡向变化中,无坡向地区植被覆盖度最低,其他坡向差异不明显;③ 1990-2016年贵州石阡河流域植被覆盖度变化的人口效应中,随人口密度上升,植被覆盖度总体处于下降趋势。研究结果可以为喀斯特地区退耕还林还草和石漠化治理提供科学依据。     

Soil carbon stock and flux in plantation forest and grassland ecosystems in Loess Plateau,China

Carbon sequestration occurs when cultivated soils are re-vegetated. In the hilly area of the Loess Plateau, China, black locust(Robinia pseudoacacia) plantation forest and grassland were the two main vegetation types used to mitigate soil and water loss after cultivation abandonment. The purpose of this study was to compare the soil carbon stock and flux of these two types of vegetation which restored for 25 years. The experiment was conducted in Yangjuangou catchment in Yan′an City, Shaanxi Province, China. Two adjacent slopes were chosen for this study. Six sample sites were spaced every 35–45 m from summit to toe slope along the hill slope, and each sample site contained three sampling plots. Soil organic carbon and related physicochemical properties in the surface soil layer(0–10 cm and 10–20 cm) were measured based on soil sampling and laboratory analysis, and the soil carbon dioxide(CO2) emissions and environmental factors were measured in the same sample sites simultaneously. Results indicated that in general, a higher soil carbon stock was found in the black locust plantation forest than that in grassland throughout the hill slope. Meanwhile, significant differences in the soil carbon stock were observed between these two vegetation types in the upper slope at soil depth 0–10 cm and lower slope at soil depth 10–20 cm. The average daily values of the soil CO2 emissions were 1.27 μmol/(m2·s) and 1.39 μmol/(m2·s) for forest and grassland, respectively. The soil carbon flux in forest covered areas was higher in spring and less variation was detected between different seasons, while the highest carbon flux was found in grassland in summer, which was about three times higher than that in autumn and spring. From the carbon sequestration point of view, black locust plantation forest on hill slopes might be better than grassland because of a higher soil carbon stock and lower carbon flux.     

Flow variability along a vegetated natural stream under various sediment transport rates

The influence of vegetation and sediment on flow characteristics in open channels cannot be neglected. To study the flow variability under the effects of the instream natural vegetation and sediment supply, experiments were conducted with varied water and sediment supply in a movable bed of a river prototype. The instantaneous three-dimensional velocities near two types of vegetation patches (the shrub and the weed) and along the centerline of the main channel with vegetation belts were measured using a 3-D side-looking acoustic Doppler velocimetry. The experimental results show that both the instream vegetation and sediment supply strongly affect the flow and turbulence characteristics. In the case of vegetation patches, both the shrub and weed have a considerable influence on the distribution of the streamwise velocity and turbulence intensity of their surrounding water. The streamwise velocity distribution followed as J-shape and linear shape around the weed and shrub under different experimental conditions. The turbulence intensity was large at the top of the weed and shrub; the shrub had its greatest influence on the downstream water flow. In the case of vegetation belts, the streamwise velocity along the centerline of the main channel exhibited an S-shape, J-shape and linear shape at different locations under varied water, vegetation structures and riverbed configurations. The turbulence intensity along the centerline of the main channel ranged from 0.0 to 0.1. The upstream turbulence intensity was affected considerably by a sediment supply, while the downstream turbulence intensity changed with the varied vegetation characteristics and riverbed topography. The second flow coefficient M-value increased longitudinally and was almost positive along the centerline of the main channel, implying that the rotational direction of the secondary current cell was clockwise.     

Agriculture development-induced surface albedo changes and climatic implications across northeastern China

To improve the understandings on regional climatic effects of past human-induced land cover changes,the surface albedo changes caused by conversions from natural vegetation to cropland were estimated across northeastern China over the last 300 years,and its climatic effects were simulated by using the Weather Research and Forecasting (WRF) model.Essential natural vegetation records compiled from historical documents and regional optimal surface albedo dataset were used.The results show that the surface albedo decreased by 0.01-0.03 due to conversions from grassland to cropland in the Northeast China Plain and it increased by 0.005-0.015 due to conversions from forests to cropland in the surrounding mountains.As a consequence,in the Northeast China Plain,the surface net radiation increased by 4-8 W/m 2,2-5 W/m 2,and 1-3 W/m 2,and the climate was therefore warmed by 0.1℃-0.2℃、0.1℃-0.2℃、 0.1℃-0.3 ℃ in the spring,autumn and winter,respectively.In the surrounding mountain area,the net radiation decreased by less than 1.5 W/m 2,and the climate was therefore cooled too slight to be detected.In summer,effects of surface albedo changes on climate were closely associated with moisture dynamics,such as evapotranspiration and cloud,instead of being merely determined by surface radiation budget.The simulated summer climatic effects have large uncertainties.These findings demonstrate that surface albedo changes resulted in warming climate effects in the non-rainy seasons in Northeast China Plain through surface radiation processes while the climatic effects in summer could hardly be concluded so far.     

Comparative Assessment of Tundra Vegetation Changes Between North and Southwest Slopes of Changbai Mountains,China, in Response to Global Warming

Vegetation in high altitude areas normally exhibits the strongest response to global warming. We investigated the tundra vegetation on the Changbai Mountains and revealed the similarities and differences between the north and the southwest slopes of the Changbai Mountains in response to global warming. Our results were as follows: 1) The average temperatures in the growing season have increased from 1981 to 2015, the climate tendency rate was 0.38℃/10 yr, and there was no obvious change in precipitation observed. 2) The tundra vegetation of the Changbai Mountains has changed significantly over the last 30 years. Specifically, herbaceous plants have invaded into the tundra zone, and the proportion of herbaceous plants was larger than that of shrubs. Shrub tundra was transforming into shrub-grass tundra. 3) The tundra vegetation in the north and southwest slopes of the Changbai Mountains responded differently to global warming. The southwest slope showed a significantly higher degree of invasion from herbaceous plants and exhibited greater vegetation change than the north slope. 4) The species diversity of plant communities on the tundra zone of the north slope changed unimodally with altitude, while that on the tundra zone of the southwest slope decreased monotonously with altitude. Differences in the degree of invasion from herbaceous plants resulted in differences in species diversity patterns between the north and southwest slopes. Differences in local microclimate, plant community successional stage and soil fertility resulted in differential responses of tundra vegetation to global warming.     

机载LiDAR点云密度和插值方法对DEM及地表粗糙度精度影响分析

机载LiDAR点云是获取高质量数字高程模型(Digital Elevation Model, DEM)的主要数据源,而地表粗糙度作为DEM的主要派生产品,在地学研究中发挥了重要作用,但点云密度和插值方法对DEM及地表粗糙度精度影响程度并没有明确结论。为此,本文利用不同地形条件下的林区机载LiDAR点云为实验对象,将原始点云随机缩减为不同的采样密度,利用5种常用插值方法(克里金(Ordinary Kriging, OK),径向基函数(Radial Basis Function, RBF),不规则三角网(Triangulated Irregular Network, TIN),自然邻域(Natural Neighbor, NN)和反距离加权(Inverse Distance Weighting, IDW))构建各个测区不同采样密度条件下的DEM,并通过空间特征和统计特征两方面对DEM及其地表粗糙度精度分析。结果表明:(1) DEM插值算法的精度随点云密度缩减而降低,且数据量缩减至原始数据量的30%后,不同算法精度区别较为明显,其中,RBF和OK精度最优,IDW精度最低;(2) DEM误差与...     

Phosphorus speciation in wetland sediments of Zhujiang (Pearl) River Estuary, China

Phosphorus fractions and adsorption-release characteristics of sediments in the Zhujiang(Pearl) River estuary wetland were investigated.Results showed that the total phosphorus(TP) content in surface sediments ranged from 648.9 mg/kg to 1064.0 mg/kg;inorganic phosphorus(IP) was the major fraction of TP and ranged from 422.5 mg/kg to 643.9 mg/kg.Among the inorganic phosphorus,the main fractions were phosphorus bound to Al and Fe(Fe/Al-P),and calcium-bound phosphorus(Ca-P),accounting for 23%–42% and 21%–67% of IP,respectively.The vertical distribution of TP contents were significantly positive correlated with organic phosphorus(Org-P) and Fe/Al-P contents.The bio-available phosphorus contents in vertical sediments varied from 128.6 mg/kg to 442.9 mg/kg,mainly existed in Fe-Al/P fraction,and increased from the bottom to top sediments.The transport of phosphorus in sediment-water interface was controlled by the soil characteristics.The active Fe and Al content was considered as the main factor that determines adsorption capacity in vegetated marsh wetland.The P buffering capacity of the sediments in vegetated marsh wetland was greater than that in mudflat wetland.The potential risk of eutrophication in the study area is high.Reducing terrestrial phosphorus discharge and preventing the sediment Fe/Al-P release to the interstitial water are the possible solutions to reduce the risk of eutrophication in estuary wetlands,and planting vegetation in estuary wetland can also reduce the release of phosphorus in surface sediment.     

Effects of spatial information of soil physical properties on hydrological modeling based on a distributed hydrological model

The spatial distribution of soil physical properties is essential for modeling and understanding hydrological processes. In this study, the different spatial information (the conventional soil types map-based spatial information (STMB) versus refined spatial information map (RSIM)) of soil physical properties, including field capacity, soil porosity and saturated hydraulic conductivity are used respectively as input data for Water Flow Model for Lake Catchment (WATLAC) to determine their effectiveness in simulating hydrological processes and to expound the effects on model performance in terms of estimating groundwater recharge, soil evaporation, runoff generation as well as partitioning of surface and subsurface water flow. The results show that: 1) the simulated stream flow hydrographs based on the STMB and RSIM soil data reproduce the observed hydrographs well. There is no significant increase in model accuracy as more precise soil physical properties information being used, but WATLAC model using the RSIM soil data could predict more runoff volume and reduce the relative runoff depth errors; 2) the groundwater recharges have a consistent trend for both cases, while the STMB soil data tend to produce higher groundwater recharges than the RSIM soil data. In addition, the spatial distribution of annual groundwater recharge is significantly affected by the spatial distribution of soil physical properties; 3) the soil evaporation simulated using the STMB and RSIM soil data are similar to each other, and the spatial distribution patterns are also insensitive to the spatial information of soil physical properties; and 4) although the different spatial information of soil physical properties does not cause apparent difference in overall stream flow, the partitioning of surface and subsurface water flow is distinct. The implications of this study are that the refined spatial information of soil physical properties does not necessarily contribute to a more accurate prediction of stream flow, and the selection of appropriate soil physical property data needs to consider the scale of watersheds and the level of accuracy required.     

盆地多级次地下水流系统盐分运移实验模拟

地下水年龄和滞留时间包含了地下水循环和演化的重要信息,被广泛用于盆地地下水循环模式的研究。使用多级次地下水流系统演示仪,实验模拟了三级水流系统模式中地下水年龄及滞留时间分布。研究发现,盆地底部、区域流线的下游、盆地滞留区最晚响应;浅部的局部水流系统稳定后的浓度值相对较低;中间水流系统相对深部的区域水流系统也较低,滞留区盐分积累,浓度值相对较大。盆地内部所有监测点的地下水年龄分布曲线都为单峰,区域水流系统的循环时间大于中间水流系统以及局部水流系统。在排泄区监测的滞留时间分布显示不同级次补给会产生早、中、晚峰,并且峰值与地下水流系统的级次性完全对应,可以通过排泄区的峰值判断地下水是从局部、中间或区域水流系统补给而来,以此判断污染物的来源。本研究成果对于地下水的循环演化和地下水流系统理论的完善具有一定的意义。      

Effects of topography and land use on woody plant species composition and beta diversity in an arid Trans-Himalayan landscape,Nepal

Distribution patterns of plant species are believed to be impacted by small-scale habitat heterogeneity. However, there have been few comparative studies examining how woody vegetation composition and diversity varies with aspects of different orientations in the Trans-Himalayan region at a local scale. Here, we examined the effects of incoming solar radiation on variation in woody species composition and compared the diversity between the northeast- and southwest-facing slopes in a Trans-Himalayan valley of Nepal. We also examined the implicit interactions between slope orientation and land use in determining the compositional variations between the slopes. We selected two pairs of northeast- and southwest-facing slopes where the first pair has a similar land use and differs in exposure only（Pisang site） while the other pair has clear differences in land use in addition to slope exposure（Braka site）. In each site, we sampled 72 plots（36 on each slope） in which the presence and absence of woody species, environmental variables, and disturbance were recorded. Correspondence Analysis（CA） results suggested that the woody species composition significantly varied between northeast- and southwest-facing slopes at both sites, and was significantly correlated with measured environmental variables such as radiation index, altitude, and canopy openness. In the Braka site,mean alpha diversity was significantly higher on southwest-facing slopes. In contrast, beta diversity and gamma diversity were greater on northeast-facing slopes at both sites. Our results suggest that topographic variables（e.g., radiation index） affect species composition between the slopes, likely due to their influence on small scale abiotic environmental variables. However, the effects of land use, such as livestock browsing/grazing may interact with the effects of slope exposure, effectively reducing differences in species composition within slopes but enhancing the differences in beta diversity between contrasting slopes in the Br     

Assessment of the performance of WEPP in purple soil area with simulated rainfall experiments

The water erosion prediction project(WEPP) model is a popular water erosion prediction tool developed on the basis of the physical processes of water erosion.Although WEPP has been widely used around the world,its application in China is still insufficient.In this study,the performance of WEPP used to estimate the runoff and soil loss on purple soil(Calcaric Regosols in FAO taxonomy) sloping cropland was assessed with the data from runoff plots under simulated rainfall conditions.Based on measured soil properties,runoff and erosion parameters,namely effective hydraulic conductivity,inter-rill erodibility,rill erodibility,and critical shear stress were determined to be 2.68 mm h-1,5.54 × 106 kg s-1 m 4,0.027 s m 1 and 3.5 Pa,respectively,by using the recommended equations in the WEPP user manual.The simulated results were not good due to the low Nash efficiency of 0.41 for runoff and negative Nash efficiency for soil loss.After the four parameters were calibrated,WEPP performed better for soil loss prediction with a Nash efficiency of 0.76.The different results indicated that the equations recommended by WEPP to calculate parameters such as erodiblity and critical shear stress are not suitable for the purple soil areas,Sichuan Province,China.Although the predicted results can be accepted by optimizing the runoff and erosion parameters,more research related to the determination of erodibility and critical sheer stress must be conducted to improve the application of WEPP in the purple soil areas.     

A method for surface roughness parameter estimation in passive microwave remote sensing

Surface roughness parameter is an important factor and obstacle for retrieving soil moisture in passive microwave remote sensing.Two statistical parameters,root mean square (RMS) height (s) and correlation length (l),are designed for describing the roughness of a randomly rough surface.The roughness parameter measured by traditional way is independence of frequency,soil moisture and soil heterogeneity and just the ″geometric″ roughness of random surface.This ″geometric″ roughness can not fully explain the scattered thermal radiation by the earth's surface.The relationship between ″geometric″ roughness and integrated roughness (contain both ″geometric″ roughness and ″dielectric″ roughness) is linked by empirical coefficient.In view of this problem,this paper presents a method for estimating integrated surface roughness from radiometer sampling data at different frequencies,which mainly based on the flourier relationship between power spectral density distribution and spatial autocorrelation function.We can obtain integrated surface roughness at different frequencies by this method.Besides "geometric" roughness,this integrated surface roughness not only contains "dielectric" roughness but also includes frequency dependence.Combined with Q/H model the polarization coupling coefficient can also be obtained for both H and V polarization.Meanwhile,the simulated numerical results show that radiometer with a sensitivity of 0.1 K can distinguish the different surface roughness and the change of roughness with frequency for the same rough surface.This confirms the feasibility of radiometer sampling method for estimating the surface roughness theoretically.This method overcomes the problem of ″dielectric″ roughness measurement to some extent and can achieve the integrated surface roughness within a microwave pixel which can serve soil moisture inversion better than the ″geometric″ roughness.