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1.
基于神经网络模型的干旱区绿洲土壤盐渍化评价分析 总被引：1，自引：0，他引：1
土壤盐渍化严重制约了农业可持续发展和生态安全,土壤盐渍化的精确评价分析,对土壤盐渍化的改善和治理具有重要的意义。本文以新疆焉耆盆地为研究对象,Landsat8 OLI遥感影像和实测采样数据相结合,提取地下水埋深（GD）、盐分指数（SI）、地表蒸散量（SET）和改进型温度植被干旱指数（MTVDI）建立了土壤盐渍化评价模型。结果表明：①结合野外实测土壤盐分数据,对BP神经网络模型进行训练。最终以最优的4-4-1结构的3层BP神经网模型对研究区土壤盐渍化进行了预测（R2=0.864,RMSE=0.569）。相比传统多元线性回归模型（R2=0.741,RMSE=0.767）,神经网络模型对土壤盐渍化的预测精度更高;②土壤盐渍化分布与GD、SI、SET和MTVDI等存在较强的关联性,不同等级的土壤盐渍化是不同影响因素不同程度上组合而引起的结果,盐渍化土地主要分布在地下水位较低以及土地开垦之后没有利用的荒地区域;③整个研究区大部分区域受到不同程度的盐渍化影响,耕地退化为盐渍地导致该区域土壤盐渍化以及土壤次生盐渍化进一步加剧。 相似文献
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L波段对不同盐类土壤的微波介电特性分析 总被引：1，自引：0，他引：1
土壤盐碱化是世界面临的一大难题。微波遥感探测土壤具有优势,L波段对土壤含水量和含盐量较为敏感。为了分析不同盐类对土壤介电特性的影响,本文利用L波段(1.43 GHz)微波谐振腔测量了我国盐碱土中普遍存在的3种盐类(NaCl,Na2SO4,NaHCO3)土壤样品的介电常数,研究了土壤介电常数与含水量、含盐量和盐种类的关系。得出结论:实部主要由土壤的含水量决定,含盐量对实部的影响无明显规律;虚部值随含水量和含盐量的增加而增大;3种盐类土壤介电常数虚部随含盐量变化呈现不同的递增趋势,在含盐浓度一定的条件下,虚部值是ε″ NaCI>ε″ NaHCO3>ε″ Na2SO4;在某一含盐量点3种盐类土壤虚部随含水量变化的斜率不同,以此能将3种盐类区分。该研究为建立含不同盐类土壤介电常数模型和微波遥感监测土壤盐碱化提供了实验的依据。 相似文献
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Influences of soil moisture and salt content on loess shear strength in the Xining Basin,northeastern Qinghai-Tibet Plateau 总被引：1，自引：0，他引：1
FU Jiang-tao HU Xia-song LI Xi-lai YU Dong-mei LIU Ya-bin YANG You-Qing QI Zhao-xin LI Shu-xia 《山地科学学报》2019,(5)
Moisture and salt content of soil are the two predominant factors influencing its shear strength. This study aims to investigate the effects of these two factors on shear strength behavior of loess in the Xining Basin of Northeast Qinghai-Tibet Plateau, where such geological hazards as soil erosion, landslides collapse and debris flows are widespread due to the highly erodible loess. Salinized loess soil collected from the test site was desalinized through salt-leaching in the laboratory. The desalinized and oven-dried loess samples were also artificially moisturized and salinized in order to examine how soil salinity affects its shear strength at different moisture levels. Soil samples prepared in different ways(moisturizing, salt-leaching, and salinized) were measured to determine soil cohesion and internal friction angle. The results show that salt-leaching up to 18 rounds almost completely removed the salt content and considerably changed the physical components of loess, but the soil type remained unchanged. As salt content increases from 0.00% to 12.00%, both the cohesion and internal friction angle exhibit an initial decrease and then increase with salt content. As moisture content is 12.00%, the salt content threshold value for both cohesion and internal friction angle is identified as 3.00%. As the moisture content rises to 16.0% and 20.00%, the salt content threshold value for cohesion is still 6.00%, but 3.00% for internal friction angle. At these thresholds soil shear strength is the lowest, below which it is inversely related to soil salinity. Beyond the thresholds, however, the relationship is positive. Dissimilar to salinity, soil moisture content exerts an adverse effect on shear strength of loess. The findings of this study can provide a valuable guidance on stabilizing the engineering properties of salinized loess to prevent slope failures during heavy rainfall events. 相似文献
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I INTRODUCTIONNatllral environment and water transform in theworld have changed faster and faster under the effect ofhuman activities. The study on effect of human activities to hydrological processes, and its extent and tendency has been more and more important as one of theresearch projects of hydrology in the world (RAI et al.,1998, BASS et al., 1998, WANGet al.,, 1998; HILLet al., 1998; LIU, 1997). It became one of the mainresearch program of international Hydrological Decade(… 相似文献
5.
西北地区土壤资源特征及其开发利用与保护 总被引：10，自引：8，他引：2
在分析西北地区土壤分布规律的基础上,研究了不同类型区土壤的资源特征及其在开发利用中存在的问题,认为黄土地区土壤土质疏松、粉砂含量高、富含碳酸钙是水土流失的物质基础;干旱区广为分布的荒漠土壤资源的性能低劣、绿洲区水土资源的利用比例失调是造成土地荒漠化、土壤盐渍化的根本原因;而高原土壤的粗骨性、土层浅薄、有效肥力低则加速了草场的退化和沙漠化.提出了西北地区土壤资源的合理利用与生态环境保护相协调的途经,即搞好农田基本建设,采用旱作技术节水和合理用水,扩大林草植被,保护天然草场和林木.并认为西北土壤资源的开发利用要在充分发挥其生产潜力的同时,首先应遵循生态规律,开发与保护并重,防止土壤资源衰竭和破坏. 相似文献
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Masoud EDRAKI Sayyed Ahang KOWSAR 《山地科学学报》2007,4(2):136-145
Water is the most important limiting factor in the development of arid environments; therefore, optimization of water use is a necessity in desert reclamation projects. Evapotranspiration of a 6-year-old river red gum (Eucalyptus camaldulensis Dehnh.) plantation, located in a sedimentation basin of an artificial recharge of the Gareh Bygone Plain groundwater system in Iran’s southern Zagros Mountains, was studied during a 7-month period. A neutron moisture probe was used to monitor soil water changes in the root zone. Soil water depletion following rapid drainage for blocks receiving relatively high, medium and low volumes of floodwater were 809.6, 312.4, and 203.1 mm, respectively, for a 150-day period. Soil water potential during most of the study period was below -1.5 MPa. This study proves that river red gum in not a suitable species for desertification control where water conservation is of vital importance. Flood irrigation of trees on 8 Aug. 1991 provided the opportunity to throw doubt upon the claim of summer dormancy of river red gum. 相似文献
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某生产CaCl2化工厂因环境问题被停止生产,厂区周边土壤和地下水受到不同程度的污染。为掌握污染土壤中污染因子的含量和地下水受污染情况,布置了土壤采样点和地下水监测点,利用厂区周边已有机民井进行水样采集,通过室内检测、分析研究等工作,得出在厂区周边土壤60~300 cm深度范围内存在Ca^2+,Cl^-富集,鉴于土壤的天然吸附和自净能力,目前条件下,厂区及周边地下水污染状况受影响较小。通过抽水试验、渗水试验和弥散试验,圈定了污染物的影响范围,查明了污染物的影响程度,并在此基础上进行了污染物影响变化情况的预测分析,为后续区域污染地块的风险评估和修复治理工作提供了数据支持。 相似文献
10.
银川平原盐渍土时空格局及其与土地利用强度变化关联关系的空间区位特征,可从土地利用强度的角度阐释土壤盐渍化的动因,为盐渍化因地制宜的治理提供参考依据。本文重点研究了盐渍土空间分布定量遥感生成方法,通过土地利用遥感制图、半方差函数的地统计学方法和灰色关联度分析法,对2004-2010 年银川平原的土地利用强度变化、土壤盐渍化程度变化及各类盐渍土与土地利用强度的关联度,进行了空间区位分布特征的可视化表达。研究结果表明:银川平原的发展仍具集聚效应,土地利用强度变化与城镇体系格局、交通干线、沟渠分布、土壤盐分含量密切相关;2004-2010 年间,银川平原土壤盐渍化存在整体减轻、局部加重的空间分布特征,与土地利用强度变化间的响应关系,存在较明显的空间差异;银川平原土壤盐渍化程度变化与土地利用强度变化间的关联度为0.7781,与水体、耕地这2 种土地类型间的关联程度最高。银川平原土壤盐渍化的干扰活动中,水体与耕地类型的利用行为是较重要的影响因子。 相似文献
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西宁地区次生盐渍土主要分布于山麓斜坡带高阶地和河谷高漫滩,前者属中～弱硫酸、亚硫酸盐渍土,且多具中等～强烈湿陷性,盐份主要来自斜坡后缘含盐碎屑岩风化物及易溶盐;后者为中等亚氯、亚硫酸盐渍土,溶于土中的盐份系浅层咸地下水常年毛细上升蒸发所致。其次生盐渍土的松胀性、溶陷性、腐蚀性较强,工程建设要引起重视。 相似文献
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在乡村振兴战略背景下,在镇域尺度上构建适宜性评价指标体系,划定高标准农田建设分区,用以指导商店镇高标准农田项目的建设方向。以适宜性评价、障碍度模型为研究方法,研究结果显示商店镇高标准农田建设适宜性一级区主要分布在镇域的中南部地区,二级区基本环绕在一级区外侧,三级区分散于镇域各地,以镇域北部居多,有城镇发展的需求,较不适宜建设高标准农田。商店镇高标准农田建设的障碍因子主要包括耕地连片度、灌溉保证率、盐渍化、有机质含量以及乡镇建设需求。耕地连片度、盐渍化、有机质含量以及乡镇建设需求这4个建设障碍问题在镇域北部都明显存在;镇域东部主要表现为盐渍化问题与耕地连片度,在东部地区高标准农田建设时需重点解决;南部主要存在耕地连片度与灌溉保证率的问题,需加大农田基础设施建设。商店镇高标准农田建设可划分为优先建设区、重点发展区与后备保留区,基于障碍因素进一步细化为12个分区,总体来说,商店镇高标准农田建设南部以完善农田基础设施建设、改良土壤为主,北部地区整治方向为规模化整治、促进农业产业化发展。 相似文献
14.
THE IMPACT OF HUMAN ACTIVITIES ON GROUNDWATER RESOURCES IN THE SOUTH EDGE OF TARIM BASIN，XINJIANG 总被引：2，自引：0，他引：2
In the modern times ,the population growth,development of industrial and agricultural production and the petroleum exploitation,brought about the unceasing expansion of artificial oasis and abrupt increase of water demand .The artificial hydraulic irrigation engineering took the place of the natural river systerm,the reservoirs took the placeof natural lakds,which in turn enhanced the space-time redistribution of surface water based on the natural evolution,and so did groundwater.The groundwater recharge reduced 26.2% in 46 years from 1950 to 1995 in the southern piedmont fold plain of Tarim Basin due to mean yearly population increase rate of 27.7‰ and associated with the water use rate increasing from 24.6% to 58.4%.At the same time the artificial water system seepage give primary play to groundwater recharge,which is up to 57.6% whilst that of the natural system reduce to 33.7%.As a result,groundwater level drop 3-5m widespread except some irrigation area and surrounding of plain reservoir.Sping water discharge also reduce about 37.6% and discharge some continuously move away to the north with the value of 0.5-1.2km in the past 40 years. 相似文献
15.
Construction of big dams on rivers develops artificial lakes or water reservoirs which conceive alterations in soil properties of the upstream catchment area. An undulating topography and freckly soil properties cause ups and downs in tree diversity, composition and distribution. The study aimed to evaluate the effect of Gobind Sagar reservoir on soil properties relative to the distance from it and assess its effect on tree diversity, evenness and their distribution in tropical and subtropical forests. Based on data analysis it was found that the soil moisture and organic carbon decreased along with increasing distance from the reservoir. It played a significant role in varying tree diversity. The sites distributed within0-2 km showed significantly higher α and β-diversity indices. Tree species richness and diversity indices showed a strong correlation(p 0.05) with soil moisture and organic carbon content. Simpson's and Mc Intosh evenness indices showed a strong negative correlation with soil bulk density. Indirect Detrended Correspondence Analysis(DCA) identified soil moisture and soil organic carbon as two major environmental gradients that influenced tree diversity and their distribution in five tropical and four subtropical forests in an upstream catchment of the reservoir. Mixed forests inhabited moist sites andAcacia-Pinus forests showed an inclination to dry areas. Canonical Correspondence Analysis(CCA)revealed that the tree species in tropical forests were mainly affected by driving forces such as soil moisture,organic carbon and bulk density whereas, in subtropical forest tree species were influenced by elevation, soil p H, EC and clay content. 相似文献
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To simulate the soil moisture variation in cropland, a two-parameter exponential recession model was derived to depict the recession process of soil moisture in the root zone. The model is based on the assumption that the recession rate of soil water is propor- tional to the potential evapotranspiration rate and the difference of soil water content and steady soil water content. Two parameters in this model are soil texture-dependent recession constant and steady soil water content. The model was calibrated and validated with measured soil water data at two experiment sites in North China with different soil textures and cropping systems. Coefficients of de- termination between measured and model simulated soil water content were all greater than 0.7, indicating that both models gave satis- factory simulation results. Results showed that values of two parameters mentioned above are both larger for finer soil than those for coarser soil. At the same potential evapotranspiration rate and soil water content, the recession rate of finer soil is usually lower than that of coarser soil. The proposed model can be used in irrigation management to predict approximate date for irrigation, as well as be em- bedded into watershed hydrological models to estimate the antecedent precipitation index. 相似文献
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Based on data from 22 sample plots and applying the Canonical Correspondence Analysis (CCA),this paper discusses the vegetation-environment relationships between the northern slope of Karlik Mountain and Naomaohu Basin,which is situated in the easternmost end of the Tianshan Mountains,Xinjiang Uygur Autonomous Region,China.For the zonal vegetation,community diversity of mountain vegetation is higher than that of the desert vegetation due to environmental factors.The CCA ordination diagram revealed that the composition and distribution of vegetation types are mainly determined by altitude,soil pH and soil salt content.With increasing elevation,the soil pH and total salt content decrease but the contents of soil organic matter,soil water,total nitrogen and total phosphorus increase gradually.In the CCA ordination diagrams,the sample plots and main species can be divided into five types according to their adaptations to the environmental factors.Type I is composed of desert vegetation distributed on the low mountains,hills,plains and deserts below an elevation of 1900 m;type II is distributed in the mountain and desert ecotone with an elevation of 1900-2300 m,and includes steppe desert,desert steppe and wetland meadow;type III is very simply composed of only salinized meadow;type IV is distributed above an elevation of 2300 m,containing mountain steppe,meadow steppe,subalpine meadow and alpine meadow;type V only contains salinized meadow.The results show that with increasing elevation,species combination changes from the xerophytic shrubs,semi-shrubs and herbs distributed in the low altitude zone with arid climate to the cold-tolerant perennial herbs growing in the high altitudinal zone with cold climate. 相似文献
18.
Saline water intrusion and its influence in the Laizhou area 总被引：1，自引：0，他引：1
ImODUcrIONSalinewaterintrusionwasfoundinIsraelqacobsetal.,l96O),Thailand(Sun,l989),Spain(Custodi0,l985)andtheFujiarea,Japan"'InChina,thelargescaleseawaterintru-sioninthelasttwentyyearshasgtaduallyforrneserious,totheextentthattheintrusionareanachedto4OO~5OOkm2inthecoastalareaofShandongProvince(Zha0,l99l,Xueetal.,l992,Qiu,l991).Thereareaisos0mesmallaff~areasinLia0dongPenin-sulaandthesouthcoastareaofChina,lbrexamPle,SubeiPlain(Zhouetal.,l988),GuangxiOi,l988;Chenetal.,l99O)andHainan-… 相似文献
19.
Sven GRASHEY-JANSEN Martin KUBA Bernd CYFFKA müt HALIK Tayierjiang AISHAN 《中国地理科学(英文版)》2014,(6):647-657
The floodplain -egetation of the Tarim River in Northwest China is strongly influenced by irrigated agriculture. The abstrac- tion of river water disturbs; the natural dynamics of the floodplain ecosystem. The human impact on the hydrological system by bank dams and the irrigation of cotton plantings have caused adverse changes of the Tarim River and its floodplains, so the current stocks of the typical Tugai vegetation show significant signs of degradation. Field studies of soils and statistical analysis of soil moisture data have shown that the vitality of the Tugai vegetation is primarily determined by its position to the riverbank and the groundwater. There exist complex interactions between soil hydrological conditions and the vitality of the vegetation. But the availability of water is not only influenced by the groundwater level and seasonal flood events. The spatial distribution of stocks at different states of vitality seems also to be decisively influenced by physical soil properties. Our results show that the water supply of plant communities is strongly in- fluenced by the soil texture. Spatial differences of soil moisture and corresponding soil water tensions may be the decisive factors for the zonafion of vegetation. Physical soil properties control the water retention and rising of capillary water from deeper soil layers and the phreatic zone and may supply the root systems of the phreatophytic vegetation with water. Keywords： soil moisture;soil texture; soil water tensions; Tarim River; water retention 相似文献
20.
YANG Zisheng LIU Yansui BAO Guangjing LI Zhiguo HE Yimei 《山地科学学报》2006,3(3):237-246
The rocky desert in a karst area directly causes the lack of soil, water and forest, hence leading to the poverty there. In 1990, the villagers from the Muzhe Village in Benggu Township, Xichou County, Yunnan declared a war against rocky desert in an attempt to ask the fields for more yields. They invented a distinctive land rehabilitation and sustainable use pattern called ＂transforming heaven and earth＂ that had been practiced in Southwest China＇s karst areas. The key mechanism of the pattern was to develop terraced fields with well conserved soil, water and fertility by exploding rocks in the fields, building stone walls, gathering more soil, and improving soil quality and productivity for the fields in combination with building of irrigation facilities and roads, as well as with forestation and agriculture structure adjustment. The purpose of the pattern was to alleviate poverty in the karst areas by improving soil productivity and promoting agricultural development. A typical area was studied with the help of Participatory Rural Appraisal （PRA） and the pattern was carried out there for fifteen years, have produced excellent ecological benefits and good economic benefits. Its application in the area approved that it was a sustainable land use pattern for rocky desert areas. 相似文献