共查询到17条相似文献，搜索用时 187 毫秒
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为了精准解译面域尺度土壤盐分特征，有必要建立分层土壤盐分信息精确解译模型。该文应用通径分析方法，研究获得了土壤全盐量、土壤含水率、体积质量、黏粒质量分数、地下水电导率、地下水埋深等作用因子对土壤表观电导率值的方差贡献率及作用强弱排序。依据各作用因子的方差贡献率大小，结合设定的累积贡献率阀值，选取出磁感式土壤表观电导率的主导作用因子，确定为磁感式土壤盐分信息解译模型的参数体系。采用多因子及互作项逐步回归法，通过引入因子间的互作效应建立优化的基于磁感式探测的分层（0～20，＞20～60，＞60～100，＞100～160 cm）土壤盐分信息解译模型。验证结果表明，模型解译误差基本在10%以内，达到了较高精度水平。 相似文献
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不同水质膜下滴灌棉田盐分空间变异特征 总被引：3，自引：0，他引：3
为评价不同水质膜下滴灌棉田土壤盐分空间分布及变异性,采用EM38-MK2型电磁感应仪对微咸及淡水滴灌田块进行盐分调查。解译模型获得的土壤含盐质量比描述性统计特征表明,微咸水滴灌的积盐程度高于淡水滴灌,但其变异系数相对较小。采用GS+软件拟合最优半方差函数模型,微咸水处理为指数模型,淡水处理为高斯模型,均表现为强的空间相关性;微咸水处理变程大于淡水处理,增加了土壤盐分的空间相依性。Kriging空间插值及变异分析表明,淡水滴灌棉田土壤盐分微域及全域空间变异程度强于微咸水滴灌,二者均存在影响棉花出苗的盐斑。建议用水紧张时,可基于EM38-MK2型电磁感应仪的盐分调查结果,重点淋洗盐斑集中分布区域,以节水增产。 相似文献
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长江河口地区典型地段土壤盐分特征研究 总被引：2，自引：0，他引：2
运用电磁感应仪EM38,结合GIS技术和地统计方法对长江河口地区典型地段土壤含盐量的空间变异性进行研究。结果表明,3个研究区土壤盐分含量的变幅有较大差异,其中以寅阳镇为最大,其次为大兴镇,北新镇土壤盐分变化幅度最小;各研究区土壤盐分含量均符合正态分布且均属于中等变异强度;各研究区的土壤盐分含量均表现为强的空间相关性,寅阳镇和北新镇土壤盐分含量半方差函数均符合球状模型,大兴镇土壤盐分含量半方差函数为指数模型。Kriging插值结果表明,各研究区土壤盐分的空间分布均呈现出条带状和斑块状格局;从空间尺度上来看,研究区土壤盐分南部高于北部;3个研究区土壤盐分含量具有明显的差别,寅阳镇土壤盐分含量明显高于其他2个镇,北新镇土壤盐分含量最低。 相似文献
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基于电磁感应技术的区域三维土壤盐分空间变异研究 总被引：3，自引：0，他引：3
以孔雀河流域典型地带为研究区域,利用电磁感应式大地电导率快速测定技术探测获得表观土壤电导率数据,构建了基于电磁感应技术的区域尺度剖面分层土壤盐分精确解译模型,精准解译出研究区剖面土壤盐分含量信息,并以此为数据源采用三维普通克里格法解析并评估了研究区土壤盐分三维空间分布特征。研究表明,不同测量位数据的综合应用能够表征剖面土壤盐分信息,构建出的剖面分层土壤盐分解译模型具有较好的精度;研究区不同区位土壤盐分三维分布呈现明显差异;研究区土壤主体属中度以上盐渍化,局部地带属于重度以上盐渍化土壤,需采取有效治理措施对土壤盐渍化进行可靠防控。 相似文献
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基于EM38-MK2的滨海土壤电导率精确解译模型 总被引：1，自引：0，他引：1
以黄河三角洲为研究对象,通过土壤样品分层采集进行室内分析获得土壤电导率(1∶5)及采用EM38-MK2在采样点测量水平和垂直模式下土壤表观电导率,应用回归及多元逐步回归模拟分析的方法,研究土壤表观电导率与不同深度土层土壤电导率的相关性,并进行精度验证,以获得基于新型电磁感应仪的不同剖面深度处土壤电导率精确解译模型,实现区域尺度土壤盐分在不同剖面深度处空间分布格局快速评定.研究结果表明:多模式下测定的土壤表观电导率与不同土层土壤电导率呈现不同程度的显著性相关;联合多模式下土壤表观电导率解译土壤电导率的精度高于单一模式;表层土壤电导率协同土壤表观电导率可以提高亚表层及底层土壤电导率的预测精度.本研究可以为快速调查土壤盐渍化及盐渍土改良与利用提供思路,以节约成本和提高效率. 相似文献
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该文采用EM38电磁感应电导率仪测量辽宁省阜新市海州露天矿场复垦区一块面积为5 000 m2的覆土层的表观电导率,试探性研究表观电导率（ECa）与矿区排土场覆土厚度（TSLT）的相关性。测定结果证实ECa与相同点位剖面挖掘所得的深度数据有很好的负相关性,而两层土壤的电导率差值与上层土壤深度之间存在一定的正相关性。结合地统计克里格插值,得到了该复垦区覆土深度分布的预测趋势图。研究结论指出,基于EM38测量的表观电导率预测矿区复垦区覆土层厚度具有良好的可行性,为废弃矿区复垦质量的客观评估,提供了一种实用、简捷的工程检测 手段。 相似文献
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滩涂土壤电磁感应仪与方差四叉树法采样布局研究 总被引：3，自引：1，他引：2
将电磁感应仪EM38和方差四叉树法VQT相结合,以EM38测量的土壤表观电导率作为土壤盐分的辅助变量,以表观电导率的空间分布为先验信息,利用VQT法对苏北滩涂围垦地土壤盐分的优化采样布局进行了设计、验证与精度评价。结果表明,VQT法设计的采样方案经Kriging插值形成的空间分布图与原始图件极其相似,但两者的样点数目相差近1/2。相同的样本数目,VQT法获取的空间分布图与原始图件的相似度高于网格采样法;同样的成图精度,VQT法需要的样本数量小于网格采样法;在允许最大偏差指数为10%的条件下,VQT法采样效率比网格法提高17.3%。该方法具有可根据局部部位变异大小进行密集或稀疏采样的优势,EM38和VQT法的结合运用为滩涂区降低采样成本、提高采样效率提供了有效手段与理论依据。 相似文献
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《中国农村水利水电》2017,(1)
土壤盐渍化是制约干旱区经济发展的重要因素,准确获取土壤盐分信息成为治理干旱区土壤盐渍化的前提。利用采集自渭干河-库车河绿洲的67个表层(0~10 cm)土壤样品,通过可见光/近红外(visible-near infrared spectroscopy,VNIR)光谱技术结合实验室测定的土壤盐分数据,在相关分析提取敏感波段的基础上,运用偏最小二乘回归(PLSR)和支持向量机(SVM)方法进行土壤含盐量的建模并对比分析;此外,利用地统计方法,将最优模型预测得到的土壤含盐量数据进行空间插值,最终获取土壤含盐量的空间分异规律。结果表明:1利用原始一阶微分经支持向量机方法(SVM)建立的土壤含盐量模型,预测集决定系数R2为0.853,均方根误差RMSE为0.381,该模型具有较高的预测精度和较好的稳健性,可以作为有效手段估算干旱区绿洲土壤含盐量。2土壤表层含盐量属于中等空间变异,且空间结构比小于25%,具有强空间自相关。3利用支持向量机得到的土壤含盐量盐分分布图中,土壤含盐量预测值和实测值的决定系数R2为0.786,均方根误差(RMSE)为0.528,显示了较高的预测精度,该研究为快速获取干旱区绿洲土壤含盐量空间分异规律提供了一种新方法。 相似文献
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Quantitative evaluation of soil salinity and its spatial distribution using electromagnetic induction method 总被引：4，自引：0，他引：4
Rongjiang Yao 《Agricultural Water Management》2010,97(12):1961-1970
In the Lower Yellow River Delta, soil salinity is a problem due to the presence of a shallow, saline water table and marine sediments. Spatial information on soil salinity at the field level is increasingly needed, particularly for better soil management and crop allocation in this area. In this paper, a mobile electromagnetic induction (EMI) system including EM38 and EM31 is employed to perform field electromagnetic (EM) survey, and fast determination and quantitative evaluation of the spatial pattern of soil salinity is discussed using the field EM survey data. Optimal operation modes of EM38 and EM31 are determined to establish multiple linear regression models for estimating salinity from apparent soil electrical conductivity (ECa). Spatial trend and semivariogram are illustrated and spatial distribution of field salinity status is further visualized and quantitatified. The results suggest that ECa (EM38 and EM31) data is highly correlated with salinity, and that the interpretation precision of soil salinity at various layers can be improved using EM38h and EM31h (where h represents the horizontal mode of EM measurement). Both EM38h and EM31h exhibit significant geographic trend. Nested spherical models fit the semivariance of EM38h and EM31h better than single spherical models. Spatial autocorrelation of EM31h is stronger than that of EM38h, and short-range variation is the chief constitute of spatial heterogeneity for both EM38h and EM31h. Quantitative classification shows that soil salinity exhibits the trend of accumulation in the root zone. In 0-1.0 m solum, heavy salinized and saline soils are the predominant soil types, accounting for 54% and 41% of total survey area, respectively. The area of light and moderate salinized soils is comparatively small, which accounts for only 0.4% and 4.6%, respectively. 相似文献
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矿区农田土壤重金属分布特征与污染风险研究 总被引：4，自引：0，他引：4
对渭北旱原矿区130个农田土壤样品的Cd、Cr、Cu、Pb、Zn含量进行了测定,结果显示,Cd、Cu、Pb平均含量均高于陕西省土壤背景值,而Cr和Zn含量低于背景值。利用地统计方法得到的土壤重金属含量分布图显示,土壤各重金属含量由西向东呈下降趋势,水泥厂周边土壤重金属含量最高。相关性分析和主成分分析结果表明,5种重金属之间呈极显著正相关,说明其存在较高的同源性或复合关系。第1主成分主要由Cd构成,且主要反映了人为活动的影响,而第2主成分中的Cr所占负荷最高,体现了成土母质的作用,Cu、Pb和Zn含量受人为活动和成土母质共同影响。分别利用污染负荷指数(PLI)法和潜在生态危害指数(PER)法对研究区域土壤污染风险进行了评价,评价结果为煤矿区呈无污染或轻微到中度污染,水泥厂区土壤呈中度污染水平,单一元素污染程度由高到低依次为Cd、Pb、Cu、Cr、Zn。 相似文献
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The 2004 Indian Ocean tsunami inundated about 37,500 ha of coastal farmland in Aceh, and crops planted after the tsunami were severely affected by soil salinity. This paper describes the changes of soil salinity over time on tsunami affected farms and the implications for resuming crop production after natural disasters.Soil salinity and salt leaching processes were assessed across the tsunami affected region by measuring soil apparent electrical conductivity (ECa) using an electromagnetic induction soil conductivity instrument (EM38) combined with limited soil analysis. The ECa was measured 5 times between August 2005 and December 2007 in both the vertical (EMv) and horizontal (EMh) dipole orientations at 23 sites across Aceh. The level of salinity and direction of salt movement were assessed by comparing changes in mean profile ECa and relative changes in EMv and EMh.Eight months after the tsunami the average soil salinity in the 0-1.2 m soil depth varied from ECe 22.6 to 1.6 dS m−1 across sites in the affected region and three years after the tsunami it varied from 13.0 to 1.4 dS m−1. Soil salinity tended to be higher in rice paddy areas that trapped saline tsunami sediments and held seawater for longer periods. Leaching of salts occurred slowly by both vertical displacement and horizontal movement in surface waters. Hence, soil salinity persisted at a level which could reduce crop production for several years after the 2004 tsunami. High soil salinity persisted three years after the tsunami even though there had been more than 3000-7000 mm of accumulated rainfall to leach salts. The slow leaching is likely to have been due to the loss of functional drainage systems and general low relief of the affected areas.Monitoring of soil salinity with EM38 assisted local agricultural extension agencies to identify sites that were too saline for crops and determine when they were suitable for cropping again. The methodology used in this study could be used after similar disasters where coastal agriculture areas become inundated by seawater from storm surges or future tsunamis. 相似文献
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Allan Fulton Larry Schwankl Kris Lynn Bruce Lampinen John Edstrom Terry Prichard 《Irrigation Science》2011,29(6):497-512
Orchard and vineyard producers conduct preplant site evaluations to help prevent planting permanent tree and vine crops on
lands where the crop will not perform to its highest potential or attain its full life expectancy. Physical soil characteristics
within specific soil profiles and spatially throughout an orchard influence decisions on land preparation, irrigation system
selection, horticultural choices, and nutrient management. Producers depend on soil surveys to help them understand the soil
characteristics of the land and may be interested in technology that provides additional information. Electromagnetic induction
(EM38) and four-probe soil resistance sensors (VERIS) are being used in combination with global positioning systems to map
spatial variability of soils using apparent soil electrical conductivity (ECa). The hypothesis evaluated in this study is
whether rapid, in situ, and relatively low-cost methods of measuring ECa (EM38 and VERIS) can effectively identify and map
physical soil variability in non-saline soils. The supposition is that in non-saline soils, ECa levels will relate well to
soil texture and water-holding capacity and can be used to map physical soil variability. In turn, the information can be
used to guide decisions on preplant tillage, irrigation system design, water and nutritional management, and other horticultural
considerations. Two sites in the Sacramento Valley were mapped each with EM38 and VERIS methods. Site-specific management
zones were identified by each provider on ECa maps for each site, and then soil samples were collected by University of California
researchers to verify these zones. Results showed that on non-saline soils, ECa measured with both EM38 and VERIS correlate
with physical soil properties such as gravel, sand, silt, and clay content but the relationship between conductivity and these
physical soil properties varied from moderately strong to weak. The strength of the correlation may be affected by several
factors including how dominant soil texture is on conductivity relative to other soil properties and on methods of equipment
operation, data analysis and interpretation. Overall, the commercial providers of ECa surveys in this study delivered reasonable
levels of accuracy that were consistent with results reported in previous studies. At one site, an ECa map developed with
VERIS provided more detail on physical soil variability to supplement published soil surveys and aided in the planning and
development of a walnut orchard. At a second site, almond yield appeared to correlate well with distinctly different soil
zones identified with EM38 mapping. 相似文献
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黄河三角洲地区土壤容重空间变异性分析 总被引：13，自引：2，他引：11
以黄河三角洲地区典型区域作为研究对象,运用传统统计学和地统计学相结合的方法研究了不同土层土壤容重的空间变异特征。结果表明:研究区各层土壤表现出一定的紧实趋势,土壤容重均属于弱变异强度。受结构性与随机性因素的共同作用,土壤容重均表现为中等的空间相关性。分维数分析表明,各层土壤容重的空间依赖性小,含黏层厚度与分布的不均一性是引起其空间异质性的关键原因。Kriging插值结果表明,土壤容重的空间分布与土壤质地密切相关,不同层次土壤容重在一定范围内表现出相似的空间分布规律。进一步的相关性分析表明各层土壤容重间存在极显著的正相关关系。通过研究不同层次土壤容重的空间变异性,获取区域土壤容重空间分布图,为该地区中、低产地及障碍土壤的分区管理和治理改良提供一定的参考依据。 相似文献
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基于GIS的土壤盐分空间变异及盐分监测样点合理布设研究 总被引：3，自引：0，他引：3
在GIS技术支持下,采用经典统计学和地统计学方法对山东省房寺镇0～20 cm土壤盐分空间变异及其监测合理采样数量进行了研究.结果表明,研究区域土壤盐分属中等强度变异,受结构因素和随机因素的共同作用,土壤盐分具有中等强度的空间相关性;Kriging插值分析表明,土壤盐分的空间分布受微地形、气候和河流水入渗的影响,在地势较... 相似文献