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1.
A study on the hyperspectral signatures of sandy soils with varying texture and water content 总被引：1，自引：1，他引：0
This paper examines the hyperspectral signatures (in the visible near-infrared (VNIR)–shortwave infrared (SWIR) regions) of different samples of sandy soils possessing varying grain size and water content. Ten samples of sandy soils with differing textures and water contents were examined using a hyperspectral radiometer operating in the 350–2,500-nm range, and the spectral curves were obtained. Analyses of the curves indicate that grain size of sand has a considerable influence on the spectral response in the visible, NIR and SWIR regions, i.e. there is a decrease in the overall reflectance with increase in grain size. While the 350–575-nm region exhibits maximum overlap of spectral reflectance and, hence, least spectral separability between the soil types, the 2,000–2,100-nm region exhibits highest spectral separability between the sand samples of different textures. As regards the water content, it is seen that overall reflectance increases with decreasing water content in the sample, especially in the 1,400–1,800-nm regions. Further, the slope of the curves in the 1,890–2,100-nm region shows a well-defined relationship with the water content. Based on these well-defined relations, it is inferred that hyperspectral radiometry in the VNIR and SWIR regions can be used to estimate the texture and water content of sandy soils. 相似文献
2.
Soil erosion susceptibility assessment and validation using a geostatistical multivariate approach: a test in Southern Sicily 总被引：2，自引：0，他引：2
A certain number of studies have been carried out in recent years that aim at developing and applying a model capable of assessing
water erosion of soil. Some of these have tried to quantitatively evaluate the volumes of soil loss, while others have focused
their efforts on the recognition of the areas most prone to water erosion processes. This article presents the results of
a research whose objective was that of evaluating water erosion susceptibility in a Sicilian watershed: the Naro river basin.
A geomorphological study was carried out to recognize the water erosion landforms and define a set of parameters expressing
both the intensity of hydraulic forces and the resistance of rocks/soils. The landforms were mapped and classified according
to the dominant process in landsurfaces affected by diffuse or linear water erosion. A GIS layer was obtained by combining
six determining factors (bedrock lithology, land use, soil texture, plan curvature, stream power index and slope-length factor)
in unique conditions units. A geostatistical multivariate approach was applied by analysing the relationships between the
spatial distributions of the erosion landforms and the unique condition units. Particularly, the density of eroded area for
each combination of determining factors has been calculated: such function corresponds, in fact, to the conditional probability
of erosion landforms to develop, under the same geoenvironmental conditions. In light of the obtained results, a general geomorphologic
model for water erosion in the Naro river basin can be depicted: cultivated areas in clayey slopes, having fine-medium soil
texture, are the most prone to be eroded; linear or diffuse water erosion processes dominate where the topography is favourable
to a convergent or divergent runoff, respectively. For each of the two erosion process types, a susceptibility map was produced
and submitted to a validation procedure based on a spatial random partition strategy. Both the success of the validation procedure
of the susceptibility models and the geomorphological coherence of the relationships between factors and process that such
models suggest, confirm the reliability of the method and the goodness of the predictions. 相似文献
3.
遥感与GIS支持下的南桐矿区水土流失评价与区划 总被引：2，自引：0，他引：2
以重庆市南桐矿区为研究对象,运用遥感和GIS技术获取对水土流失影响较大的植被覆盖度、地形坡度、土地利用类型等信息并进行空间叠加分析,计算了水土流失类型及面积。研究结果表明,南桐矿区水土流失面积262.91km2,侵蚀模数2281t/(km2?a),水土流失强度以轻度和中度为主,其中轻度流失132.37km2,中度流失108.95km2。根据区域地貌类型以及水土流失特征,将研究区水土流失划分为盆边低山丘陵中强度流失区、北部坪状低山中轻度流失区和盆边中山轻度流失区三个类型区,盆边低山丘陵中强度流失区以中度流失为主;北部坪状低山中轻度流失区以轻度流失为主;盆边中山轻度流失区虽然以轻度流失为主,但微度流失也占有相当部分的比重。 相似文献
4.
Xi Wang Zhang Bing Fang Wu Xiao Song Li Shan Long Lu 《Environmental Earth Sciences》2012,65(1):221-229
The spatial pattern of soil erosion can provide valuable insights into the soil erosion processes that require a rapid assessment
in practical applications. Generally, quantitative technique is expensive and time-consuming. The objective of this paper
is to reveal the spatial pattern of erosion with a rapid assessment method. The affecting factors such as land cover, vegetation
fraction and slope gradient are integrated into this method using a qualitative means. Beijing-1 images in 2006 were used
to produce land-cover and vegetation fraction, and 1:50,000 topographic maps were used to calculate slope gradient. The study
area was classified into six grades. Results show that the upstream area of Guanting Reservoir, in general, is exposed to
a moderate risk; there are 17,740.33 km2 of land that suffered from water soil erosion in 2006, occupied 40.69% of the total area, and most of the soil erosion area
is on the light and moderate risk, which occupied 25.05 and 62.83% of the eroded area, respectively. Eight elevation zones
and six slope gradient zones were overlaid with the assessed risk. The analyzed results show that: (1) the areas above 2,000 m
have the lowest erosion risk, which is only 0.75% of the eroded area; 1,250–1,500 m elevation zone has the highest erosion
risk, which is 34.72% of the eroded area. (2) The slope gradient zone less than 5 degrees and greater than 35 degrees have
the lowest erosion risk, which is 0.02 and 0.75% of the eroded area, respectively; the slope gradient zone with 8–15 degrees
has the highest erosion risk, which is 36.40% of the eroded area. These results will be useful for water and soil conservation
management and the planning of mitigation measures. 相似文献
5.
短波红外光谱技术在浅剥蚀斑岩铜矿区勘查中的应用——以西藏念村矿区为例 总被引：14，自引：5，他引：9
作为世界上最重要的一种矿床类型,斑岩铜矿一直是工业界勘查的首选.对此类矿床的勘查,在中-深剥蚀程度的矿区相对简单,而在浅剥蚀的矿区则变得较为困难,这是因为在浅剥蚀的矿区,矿床热液/矿化中心很难快速有效定位.近年来,在矿产勘查领域逐渐得到广泛应用的短波红外光谱技术,可通过特定蚀变矿物反射光谱特征参数系统变化的规律来厘定热液/矿化中心,在块状硫化物及浅成低温矿床中显示出良好的应用效果,这为浅剥蚀斑岩铜矿热液/矿化中心的快速、有效厘定提供了一种途径.为此,文章选择了位于冈底斯斑岩铜矿带东段、剥蚀较弱的念村(即夏玛日)矿区,拟通过矿区样品短波红外光谱的系统测量,寻找出蚀变矿物反射光谱特征参数系统变化的规律,进而约束矿床热液/矿化中心.本次研究在念村矿区共识别出7种蚀变矿物,按出现频率由多至少依次为伊利石、绿泥石、蛋白石、叶蜡石、高岭石、绿帘石及多硅白云母;而且,矿区外围以伊利石-绿泥石±绿帘石蚀变矿物组合为主,向内逐渐过渡为伊利石±蛋白石、伊利石-叶蜡石±高岭石组合.通过对伊利石反射光谱特征参数的计算发现,伊利石结晶度及Al-OH吸收峰位,这些通常被认为与伊利石形成温度有关的光谱学参数,在该矿区呈现出系统的变化规律:在矿区东北部,伊利石结晶度较大(＞1.6),Al-OH吸收峰位较小(＜2 203 nm),而该区域的外围,伊利石结晶度变小,Al-OH吸收峰位变大.这表明矿区东北部伊利石的形成温度更高,暗示该区域可能为矿床热液/矿化中心.因此,建议在本次研究所圈定的热液/矿化中心范围内,在适当开展物探工作的基础上,尽快布置勘查工程进行验证,以实现矿床的尽快查找和突破. 相似文献
6.
硫酸侵蚀下水泥土的电阻率特性研究 总被引：13，自引：0，他引：13
通过室内试验模拟了水泥土试块受不同浓度硫酸（H2SO4）溶液侵蚀的过程,采用电阻率法研究了电阻率与各参数、无侧限抗压强度之间的关系。结果表明,受H2SO4侵蚀后,水泥土电阻率、孔隙水电阻率、水泥土抗压强度均随着溶液浓度的增加而减小,而水泥土的结构因子和重度均随着溶液浓度的增加而增加,水泥土抗压强度与水泥土电阻率成正比。在试验的基础上,考虑侵蚀因素对水泥土电阻率的影响,通过对Archie法则进行修正,得到了H2SO4侵蚀下水泥土电阻率模型。通过对无侧限抗压强度试验结果的分析,并结合试块表观变化,提出了利用电阻率来评价侵蚀程度的方法。 相似文献
7.
西南喀斯特区土层浅薄、成土速率低等特点决定了其允许土壤流失量小,土壤一旦流失,极难恢复,土壤侵蚀及其造成的石漠化现象已成为制约该区可持续发展最严重的生态环境问题。文章首先明晰西南喀斯特区土壤侵蚀特征,从坡面、小流域和区域三个尺度上系统概括西南喀斯特区土壤侵蚀的相关研究进展。针对当前喀斯特区土壤侵蚀研究野外径流小区、小流域及区域空间尺度数据缺少和相关研究模型限制性强等不足,建议从不同尺度深入研究喀斯特区土壤侵蚀发生发展规律及时空演化格局,并结合高新遥感、地球物理探测技术及模型,同步监测坡面—小流域—区域土壤流失,对土壤侵蚀进行定量评估,结合不同空间尺度土壤侵蚀特征构建系统性水土保持生态恢复治理模式和监测系统评价体系。 相似文献
8.
Zhaoling Zhang Shiliang Liu Shikui Dong Wei Fu Baoshan Cui 《Frontiers of Earth Science》2009,3(4):389-396
The construction of roads has direct and indirect impacts on soil erosion, with spatio-temporal variations existing among
different levels of road zones. Aiming to quantitatively analyze the soil loss, this paper explored the relationship between
the erosion of soil and its distance from the road in Fengqing county, Southwest China in 1987 and 2004, respectively. The
average soil erosion was calculated and expressed with grid map using universal soil loss equation (USLE) model based on GIS
and RS. Along the different levels of roads classified as trunk, county, town, village and unpaved road, the buffer zones
were subdivided into five stripes, each of which was 200 meters wide. The average soil erosion modulus of each buffer zone
was also counted. Results show that the soil loss decreases with increasing distance to the road except rare trunk roads in
the region. In addition, the declined intensity varies with the different levels of roads. Soil erosion was more serious along
the lower level road than the higher ones. And soil erosion was more severe for all levels of roads in 1987 than those in
2004 because much more rainfalls affected the situation of soil erosion in 1987. 相似文献
9.
It has been reported that sand production, which is a simultaneous production of soil particles along with gas and water into a production well, forced to terminate the operation during the world's first offshore methane production test from hydrate-bearing sediments in the Eastern Nankai Tough. The sand production is induced by internal erosion, which is the detachment and migration of soil particles from soil skeleton due to seepage flow. The inflow of the eroded soil particles into the production well leads to damage of the production devices. In the present study, a numerical model to predict the chemo-thermo-mechanically coupled behavior including internal erosion during hydrate dissociation has been formulated based on the multiphase mixture theory. In the proposed model, the internal erosion is expressed as mass transition of soil particles from soil skeleton to the fluidized soil particles. Since the internal erosion is considered to depend on the soil particle size, mass of soil particles are divided into several groups that have different representative particle diameters, and the constitutive equations for the onset condition and the mass transition rate of the internal erosion are formulated for each group. Also, transportation of soil particles in the liquid phase is formulated for each particle size group in the proposed model. Finally, a simulation of the methane gas production from the hydrate-bearing sediment by depressurization method is presented, and the internal erosion and the dissociation behavior are discussed. 相似文献
10.
John B. Adams Peter M. Bell James E. Conel H.K. Mao Thomas B. McCord Douglas B. Nash 《Geochimica et cosmochimica acta》1973,37(4):731-743
Visible and near-infra-red spectra of chemically analyzed grains of glass and minerals from the Luna 20 sample were compared with diffuse reflectance spectra of the bulk soil. As in the spectra of soil samples from other localities on the Moon, pyroxene contributes two broad absorption features near 1 μm and 2 μm. The soil has a high integral reflectance (or albedo) arising from plagioclase, which appears to be the dominant mineral in the lunar highlands. The Luna 20 soil curve is most similar to the reflectance curves of the non-rayed soils at Apollo 16, in agreement with the generally similar mineralogy of these samples. The average pyroxene composition in the Luna 20 soil, as determined from the absorption bands in the diffuse reflectance spectra, and analyses of single crystals, is more calcic than in the lithic fragments. Thus, the soil appears to have a few per cent of admixed material derived from mare basalts. Comparison of the soil spectrum with telescopic curves of nearby areas reveals a close similarity; however, the Luna 20 sample is slightly less mature than expected. Luna 20 may have sampled subsurface material that is fresher than the regional surface soil, or alternatively, the Luna 20 area may contain an admixture of relatively recently exposed material from a ray crater. 相似文献
11.
Arid and semi-arid regions are susceptible to high levels of erosion.A rapid and cost effective methodological erosion assessment for these regions is required to describe and monitor the processes that control erosion.This study uses remote sensing to describe the contribution of several factors that control erosion.Topography,land use,vegetation density,soil properties and climatic proxies are used to determine erosion risk and to provide basic maps of water and soil conservation practices. A hierarchi... 相似文献
12.
沁水盆地地层剥蚀量研究 总被引：3，自引：0，他引：3
[摘 要]沁水盆地自晚三叠世以来不断抬升,遭受了多次剥蚀,但其累积剥蚀量一直悬而未决,对盆地模拟和资源评价产生了不良影响。本文在沁水盆地沉积-构造演化史、热演化史研究的基础上,根据野外露头和钻井资料,以镜质体反射率反演方法为主,辅以声波时差法和构造剖面法,较为准确地确定了沁水盆地中新生代以来的累积地层剥蚀量。研究表明,沁水盆地石炭-二叠系煤层在燕山运动时期遭受最高地温,其后回返抬升并伴有地温梯度下降。参照济阳坳陷连续沉积剖面建立了镜质体反射率与深度关系,经地温梯度校正后,计算出了沁水盆地石炭-二叠系最大埋深,从而得到其此后抬升过程中的累积剥蚀量,经与声波时差法、构造剖面法计算结果对比,三者计算结果较为符合。研究结果表明,晚三叠世以来沁水盆地累积地层剥蚀量在1400～3300m之间,其中盆地中部剥蚀量较少,一般小于2500m,盆地边缘剥蚀量较大,可达3000m以上。主要剥蚀时期为晚白垩世至新近纪,地层剥蚀量可达2000m以上;其次为晚三叠世至早侏罗世,地层剥蚀量一般小于1000m。 相似文献
13.
14.
Fei Zhang Tashpolat Tiyip Jianli Ding Hsiangte Kung Verner C. Johnson Mamat Sawut Nigara Tashpolat Dongwei Gui 《Environmental Earth Sciences》2013,69(8):2743-2761
There has been growing interest in the use of reflectance spectroscopy as a rapid and inexpensive tool for soil characterization. In this study, 53 soil samples were collected from the oasis in the Weigan and Kuqa River delta along the middle reaches of Tarim River to investigate the level of soil chemical components in relation to soil spectral. An approach combining spectral technology and multi-variant statistical analysis was used to determine the reflectance spectral features of saline soil. The spectral data was first pretreated to remove noises and absorption bands from water, which eliminated influence from instrument errors and other external background factors. Several spectral absorption features were calculated for several saline soil samples to confirm that soil at the same salinity level had similar absorption spectral properties. Secondly, a correlation relationship between reflectance spectra and salinity factors was estimated by bivariate correlation method. Fourteen salinity factors including eight major ions and soil electrical conductivity (EC), soil salt content (SSC), pH, and total dissolved solid (TDS) in the saline soil were evaluated. Datasets of the salinity factors that correlated significantly with field data measurements of reflectance rate and the corresponding spectrum data were used to construct quantitative regression models. According to the multiple linear regression analysis, SSC, SO4 2?, TDS, and EC had a correlation coefficient at 0.746, 0.908, 0.798, and 0.933 with the raw spectral data, respectively, which confirmed strong correlation between salinity factors and soil reflectance spectrum. Findings from this study will have significant impact on characterization of spectral features of saline soil in oasis in arid land. 相似文献
15.
Granular filters are an essential component in earth dams to protect the dam core from seepage erosion. This paper uses the particle flow method (PFM) to study the mechanism of particle transport in a base soil–filter system. The distributions of the eroded base-soil particles in different filters are traced and analyzed. The eroded mass and intruding depth of the eroded particles into the filters are obtained under different times and hydraulic gradients. The simulation results show that the eroded mass and intruding depth of the base-soil particles into the filter are related to the representative particle size ratio of the base soil to the filter, hydraulic gradient and erosion time. The numerical predictions are also compared with the empirical filter design criterion. The results show that the particle flow model provides an effective approach for studying the filtration micro-property and the erosion mechanism in a base soil–filter system, which is useful for filter design. 相似文献
16.
Variations in soils derived from an erodible sandstone formation and factors controlling their susceptibility to erosion and landslide 总被引：4，自引：0，他引：4
Environmental degradations caused by erosion and landslide within an area in the South-eastern part of Nigeria were assessed, and also an attempt to characterize the underlying soils based on their degree of susceptibility to erosion and landslide. Factors affecting soil erodibility such as physical and chemical properties of soil, as well as vegetation density and slope gradient was determined in 20 different areas. Simple linear regression and principal component analysis were employed to relate the factors controlling erosion and landslide to the erosion and slide densities, and to determine the pattern that exists in the data and as well express the data in such a way as to highlight their similarities and differences. Four vertical horizons and two horizontal zones of soil were distinguished based on their degree of weathering as well as their chemical and mineralogical composition; hence the soils were classified into six different types based on their degree of susceptibility to erosion and landslide. Variations in their degree of susceptibility to erosion and landslide were majorly controlled by its chemical and mineralogical composition rather than its particle size distribution. 相似文献
17.
Structural crust is a thin layer formed on the soil surface after a rainstorm. The crust is the result of a physical segregation and rearrangement of soil particles in a way that affects some of the soil properties, such as infiltration, runoff and soil erosion. In practice, there is no rapid, in situ method for monitoring, assessing and mapping crust intensity and quality. In this study, a controlled spectral investigation of the structural crust across the NIR–SWIR spectral region was conducted on three selected Israeli soils, to study the potential of reflectance radiation to detect structural crust in soils. Two major factors served as the driving forces for this study: (1) there is no valid method for in situ assessment of the crust's characteristics in the agriculture field, and (2) the crust might bias thematic remote sensing of soils, because the thin layer of crust blocks photon–matter interaction, which represents the relevant soil body. Through the use of a laboratory rainfall simulator and a sensitive spectrometer, it was revealed that for three selected soils, significant spectral differences occurred between the crust and its bulk soil. The spectral information was found to be related to changes in particle size distribution and texture at the surface of the soil. This conclusion was based on indications of absorption of OH in clay lattice, OH in adsorbed water and CO3 in carbonates. It was concluded that the structural crust is a phenomenon that should not be ignored by remote-sensing users. In fact, in the field of agriculture, the spectral properties of crust can be used as tools for estimating the crust's intensity. 相似文献
18.
月表矿物含量反演是研究月球地质起源和演化的关键.太空风化作用普遍发生在月球表面,对矿物纯净光谱造成了不可忽视的影响,它弱化光谱吸收特征, 降低反射率,影响矿物含量遥感反演精度.基于Relab光谱库和Hapke辐射传输模型,将月表 4种矿物(单斜辉石、斜方辉石、斜长石、橄榄石)的二向性反射率转换成同向性的单次散射反照率,然后计算矿物的光学常数;再根据亚微观金属铁SMFe(submicroscopic metallic iron)的质量分数模拟6种不同程度太空风化效应,得到端元矿物的反射率光谱;最后基于上述方法,利用多端元线性分解方法和M3(moon mineralogy mapper,月球矿物绘图仪)高光谱数据反演不同风化程度下的矿物含量,得到月表虹湾地区辉石、斜长石、橄榄石3种矿物的含量分布.实验表明,利用多端元线性分解可以有效模拟太空风化效应对矿物光谱的影响,是研究太空风化效应影响下矿物识别及含量反演的一种行之有效的方法. 相似文献
19.
Juan Pablo de Rosas Alexander Dario Esquivel Diego Martinez Heimann Agustin E. Negri Flavia Lohaiza Diego Leonardo Valladares Alejandro I. Zavala Hugo Huck Jimena Juri Ayub 《Environmental Earth Sciences》2018,77(16):587
This work presents the results of a soil erosion study using the 7Be technique. This technique estimates the water erosion/deposition from the comparison between 7Be soil content of a reference site and an eroded or sedimented site. The soil samples were collected from an agricultural area of the semiarid region of Argentina near San Luis City, which has a marked rainfall season. The area has been used for crop cultivation, being subjected to plowing practices. The 7Be in the Reference Site was in the first centimeter of soil, showing the typical exponential decreasing of 7Be soil content with depth, with the 7Be inventories value being 340?±?50 Bq m?2 for the dry season and 571?±?48 Bq m?2 for the rainy season. The 7Be technique was applied to a potential eroded site subjected to traditional tillage practices (plowing). A net soil erosion value of 13.5 t ha?1 (1.35 kg m?2) was obtained. From the assumptions of the applied technique, we can draw the inference that this erosion was caused by rains produced in the month prior to the date of soil sampling. 相似文献
20.
Gilgit-Baltistan region is covering the northern most part of Pakistan where the rocks of the Kohistan-Ladakh island arc and Karakoram plate are exposed. The area has greater potential for precious and base metals deposits which are needed to be explored through spectroscopy and remote sensing techniques. Minerals and rocks can nowadays be identified through the measurement of their absorption and reflectance features by spectroscopic analysis. Spectral reflectance analysis is also very important in selecting the appropriate spectral bands for remote-sensing data analysis of unknown or inaccessible areas. In this study, reflectance spectra in the spectral range of 0.35–2.5 μm of different types of unaltered and altered rocks found in the Machulu and Astor areas of northern Pakistan were obtained using an ASD spectroradiometer. The fresh rock samples showed low spectral reflectance as compared to the altered rock samples. The minerals jarosite, goethite, and hematite showed depth of absorption minima in the range of 0.4–1.15 μm due to the presence of iron (Fe), while jarosite and limonite showed absorption depth at 2.2 μm due to the presence of hydroxyl ions (OH¯). The clay minerals montmorillonite and illite showed absorption depth at 1.93 and 2.1 μm, respectively. Muscovite showed depth of absorption minima at 1.4 and 1.9 μm in some samples. Calcite showed deep absorption minima at 2.32 μm, while anorthite showed absorption features at 1.4, 1.9, 2.24, and 2.33 μm. Olivine showed a slight depressed absorption feature at 1.07 μm. The copper-bearing phases malachite, chrysocolla, and azurite showed, respectively, a broad absorption feature in the range of 0.6–0.9 μm, a small absorption at 1.4 μm, and a deep absorption at 1.93 μm. The unmineralized samples exhibited high reflectance in the wavelength ranges of 0.6–0.8, 1.6–1.9, 2.0–2.3, 2.1–2.25, and 2.4–2.5 μm, respectively, while the mineralized samples showed reflectance bands in the wavelength ranges of 0.4–0.6, 1.3–1.8, and 2.1–2.2 μm. On this basis, the band ratio combinations 7/5–4/3–6/3 and 7/5–6/3–4/3 of Landsat 8 and 4/7–4/3–2/1 for ASTER data were found to be very effective in the lithological differentiation of major rock units. 相似文献