The Pingluo area, as an experimental study area in Yinchuan, has been subjected to major environmental degradation due to soil salinization problems. Soil salinization is one of the main problems of land degradation in arid and semiarid regions. In the present study, remote sensing was integrated with mathematical modeling to evaluate soil salinization adequately. To detect soil salinization, soil water content and electrical conductivity of soil samples were analyzed. The reflectance of soil samples was measured using a spectrometer (SR-3500) with 1024 bands. Indices of soil salinity, vegetation and drought were analyzed using Landsat images over the study area. Based on Landsat images, physicochemical analysis, reflectance of sensitive bands for soil salinization and environmental indices, canopy response salinity index (CRSI), perpendicular drought index (PDI) and enhanced normalized difference vegetation index (ENDVI), a new model was established for simulation and prediction of soil salinization in the study area. Correlation analyses and multiple regression methods were used to construct an accurate model. The results showed that green, blue and near-infrared light was significantly correlated with soil salinity and that the spectral parameters improved this correlation significantly. Therefore, the model was more effective when combining spectral parameters with sensitive bands with modeling. After mathematical transformation of soil reflectance, the correlations of bands sensitive to soil salinization were 0.739 and 0.7 for electrical conductivity and water content, respectively. After transformation of vegetation reflectance, the correlation coefficient of soil salinity became 0.577. After inversion of the model based on soil hyperspectral and water content, the significance became 0.871 and 0.726, respectively, which can be used to predict soil salinity and water content. The spectral soil salinity model had a coefficient of 0.739 for soil salinity prediction. Among the salinity indices, the CRSI was selected as the most significant, with R2 of 0.571, whereas the R2 for PDI reached only 0.484. Among the vegetation indices, the ENDVI had the highest response to soil salinity, with R2 of 0.577. After scale conversion, the correlation percentages between CRSI and measured soil salinity and between ENDVI and measured soil salinity increased to 16.2% and 8.5%, respectively. Following the correlation between PDI and soil water content, the percentage of correlation increased to 11.6%. The integration of hyperspectral remote sensing, ground methods and an inversion method for salinity is a very important and effective technique for rapid and nondestructive monitoring of soil salinization.
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1.
祁连山中部亚高山草地作物系数估算 总被引：1，自引：1，他引：0
利用Lysimeter蒸散仪于2011-2014年对祁连山中部黑河上游天涝池流域亚高山草地实际蒸散量进行观测。用FAO Penman-Monteith模型对草地参考蒸散量进行估算,根据草地植被高度结合气象数据,以估算日尺度作物系数,以估算的作物系数与模拟的参考蒸散量计算草地实际蒸散量,并用观测值进行验证。结果表明：FAO改进后的作物系数计算方法适合该区域草地作物系数的计算;以FAO Penman-Monteith模型估算的日蒸散量为0.50~7.26 mm,生长季日均蒸散量有年际变化,2011年 > 2014年 > 2012年 > 2013年。总体来看,土壤蒸发总量年际变化不大,影响蒸散量年际变化的主要部分是植被的蒸腾。 相似文献
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干旱缺水条件下麦田蒸散量的计算方法 总被引：20，自引：0，他引：20
本文从试验资料出发,分析了干旱缺水条件下的麦田蒸散规律,以水量平衡方程为基础,且综合考虑影响麦田蒸散的天气条件、土壤水分状况和小麦本身的生物学特性,选用蒸发力、相对土壤有效含水量和作物的叶面积指数三因素建立了干旱缺水条件下麦田蒸散量的计算模型以及农田土壤水分变化的预测方法。 相似文献
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近20 a中亚净初级生产力与实际蒸散发特征分析 总被引：3，自引：0，他引：3
中亚碳、水循环在气候变异和人为活动的影响下呈现新的时空特征。但由于观测数据稀缺,生态过程特殊,植被、土壤空间异质性强,中亚植被净初级生产力(NPP)、实际蒸散发(AET)的时空特征相关信息相对不足,且时效性不高。利用全球尺度的NPP、AET、土地覆被数据,气象站点与区域气候数据分析近20 a中亚地区NPP和AET的时空特征。结果表明：与1990年相比,2000年中亚地区农田NPP增幅小于自然植被,植被总固碳量增加了254.65 Tg C;近20 a中亚地区实际总蒸散量先增后降,农田对中亚水资源散失的贡献减小,自然植被的贡献增大,自然植被与农田面积变化决定中亚总蒸散量动态;北部农田区、东部山区及山前绿洲为NPP和AET的高值区,中西部荒漠为低值区。 相似文献
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基于MODIS数据的无定河流域蒸散模拟 总被引：9，自引：0，他引：9
利用黄土高原无定河流域水文气象资料、MODIS数据及GIS背景信息,应用分布式生态水文模型（VIP模型）,按250m空间分辨率模拟了该流域水量平衡各分量的时空分布。结果表明:20002003年无定河流域年蒸散量分别为300 mm、397 mm、460 mm和443 mm;流域蒸散有明显的由南向北,由东到西的梯度递减特征,降水量和地表植被覆盖度的差异是其空间变异的主要因素;蒸腾与蒸发空间分异显著,但两者的变化相互补偿,降低了蒸散的空间变异性。整个流域平均而言,不同植被类型间的年蒸散总量差异不明显。白家川等9个子流域年蒸散量的模拟结果与水量平衡法估计结果具有较好的一致性。 相似文献
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农田蒸散,土壤蒸发与水分有效利用 总被引：38，自引：0，他引：38
本文通过试验研究和模型模拟，对作物生长期间的水分条件，作物蒸散规律，土壤蒸发占蒸散的比例，覆盖的节水效应和灌溉对作物生长的影响进行了研究，对如何科学合理有效地利用水分提供依据。 相似文献
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遥感反演土壤蒸发/植被蒸腾二层模型在华北地区的应用 总被引：5，自引：2，他引：3
利用一种可操作的地表蒸散遥感反演二层模型,以我国华北平原为研究区,选择2004年的3月至6月华北地区主要农作物冬小麦的生长季节作为研究时段,利用MODIS遥感卫星数据,结合地面130多个气象台站的空气温湿度实测数据,实现了土壤蒸发和植被蒸腾的反演。采用国家生态网络禹城综合试验站利用涡度相关系统观测的地表总蒸散半小时平均的数据进行了模型验证,结果表明模型估算的地表可利用能量与地面实测数据的相关系数可以达到0.92,均方差为30.4w.m-2;模型估算的地表总蒸散值与地面实测数据的相关系数为0.85,均方差为21.3 w.m-2,由此证明了模型的可用性。 相似文献
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Soil texture greatly influences soil water movement, thus may affect the water balance and vegetation growth in the desert–Loess Plateau transition zone. This study is to determine if the water balance differs in homogeneous and layered soils with Caragana korshinkii stands in semiarid region. Soil water measurements up to 500-cm depth were taken in 2006 and 2007 on homogeneous sandy soil, homogeneous silt loam soil, and layered soil with sand overlying silt loam. HYDRUS-1D was used to simulate the soil water balance. The results indicated the annual water balance components were greatly affected by soil layering. The ratio of average actual evapotranspiration (ETa) to precipitation (P) during the two years in the layered soil was slightly lower than that in homogeneous soils. The ratios of annual actual transpiration (Tr) to evapotranspiration were 50.9%, 41.2% and 30.6% in layered soil, homogeneous sandy soil, and homogeneous silt loam soil, respectively. C. korshinkii grown in layered soil had deeper soil water recharge and higher Tr/ETa ratio, thus had more available water for transpiration than that in homogeneous soils. This study suggested the layered soil with sand overlying silt loam is more favorable to C. korshinkii growth in terms of water use than homogeneous soils in the desert–Loess Plateau transition zone. 相似文献
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科尔沁沙地农田玉米耗水规律研究 总被引：12，自引：5，他引：7
首先采用波文比-能量平衡法分析了科尔沁沙地农田玉米(Zeamays L.)不同发育阶段晴天的能量分配特征,在此基础上估算了玉米的蒸散量,并对估算结果和蒸渗仪测定结果进行比较,最后运用作物蒸散量和参考作物蒸散量计算了玉米的作物系数。结果表明:①在玉米的整个生长过程中,能量交换以水分蒸散耗热为主;②根据试验年份的降雨分布情况,该地区的自然降水不能满足玉米对水分需求,玉米各生育阶段水分亏缺比较严重;③科尔沁地区玉米4个生长阶段(苗期、营养期、生殖期、成熟期)的作物系数分别为0.52、0.90、1.13和0.64;④波文比能量平衡法可以较准确的估算玉米农田晴天时的蒸散量。 相似文献
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黄土高原半干旱区天然锦鸡儿灌丛对土壤水分的影响 总被引：13，自引：4，他引：13
本文选择黄土高原半干旱区定西地区的一种地带性植被,天然甘蒙锦鸡儿灌丛,将其0～99m深的土壤水分含量与人工柠条锦鸡儿灌丛、人工杏树林、天然草地、放牧荒坡和农地的土壤水分含量进行了比较。结果发现,天然锦鸡儿灌丛在1m以下土壤各层的水分含量均高于人工柠条灌丛和人工杏树林,而与放牧荒坡和农地的土壤湿度接近,略低于农地。天然锦鸡儿灌丛4m以上土层的土壤湿度还明显高于天然草地;天然锦鸡儿灌丛形成的难效—无效水层深度在2m土层以上,而人工柠条灌丛形成的难效无效水层则深达56m,人工杏树林42m,天然草地、放牧荒坡分别为36m和33m,农地1m。 相似文献
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It is a very complicated problem to estimate evapotranspiration (ET) over a large area of land surface. In this paper, the evapotranspiration estimation models for dense vegetation and bare soil are presented, based on the information of parameters like vegetation cover-degree and surface albedo. Combined with vegetation cover-degree data, a model for regional evapotranspiration estimation over the heterogeneous landscape is derived. Through a case study using remote sensing data over Northwest China, the accuracy of the model for regional evapotranspiration estimation is checked. The result shows that the accuracy of the model is satisfactory. The features of evapotranspiration over Northwest China are also discussed with the application of the model. 相似文献
14.
1 IntroductionThe method for estimating evapotranspiration (ET) was first given by Dalton in 1802, and a number of models for ET estimation have been presented since then. Those models, from the experiential and semi-experiential models[1,2] and physical models[3,4] to the models in terms of the mechanism for energy and water fluxes in soil-vegetation-atmosphere transfer system such as SiB, have improved the precision of ET estimation. It is, however, difficult to calculate regional ET by … 相似文献
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植被是陆地生态系统中最重要、同时也是气候变化最敏感的组分,而高原植被系统行为往往比其他地区能更早、更明显地预兆全球变化。探讨青藏高原区域干湿状况及其与植被变化的关系有助于更好地认识和理解陆地生态系统对气候变化的响应和适应机理,对高原生态安全屏障计划的实施以及全球生态建设有重要意义。基于地面气象台站观测数据和MODIS EVI数据集,2001-2010年生长季干湿状况和植被覆盖的时空变化格局,对青藏高原干湿状况与植被覆盖变化的关系进行了分析与探讨。结果表明：（1）高原整体上呈现由东南向西北渐干的趋势,干旱及半干旱区占高原总面积的67%。10 a间高原有25%的区域在逐渐变干,且南北差异明显;（2）高原生长季EVI的空间格局与干湿格局相近,且东西部界线分明。10 a间高原植被活动由东南向西北整体上呈现“退化-增强-变化不大”的规律;（3）区域干湿程度对EVI空间格局差异有显著影响,特别是在占高原面积44%的半干旱区,两者相关性最大。人为干扰对高原EVI变化的作用不明显,但EVI与干湿程度相关性相对偏小的区域人为干扰程度往往较大;（4）从高原96个气象站点生长季[EVI]对干燥度指数变化的敏感性来看,敏感程度较大的气象站点主要集中在高原东北部、高原中部及雅鲁藏布江中上游区域,60%以上的气象站点随着干旱程度的加深植被呈退化趋势。 相似文献
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Remote Sensing Inversion for Simulation of Soil Salinization Based on Hyperspectral Data and Ground Analysis in Yinchuan,China 总被引：2，自引：0，他引：2
Wu Dan Jia Keli Zhang Xiaodong Zhang Junhua Abd El-Hamid Hazem T. 《Natural Resources Research》2021,30(6):4641-4656
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在西北荒漠-绿洲生态系统中,山区水循环对下游水资源管理具有重要作用。为了准确地理解高寒山区水文过程,以降水、温度和潜在蒸散发的遥感数据为模型输入,建立叶尔羌河流域的MIKE SHE模型。根据模型输出,从径流、积雪和蒸散发三方面探讨了流域的水文过程。结果表明：经校正后的遥感产品在叶尔羌河流域的水文模拟中取得了良好的应用效果,出山口卡群站日径流的效率系数达0.71,相关系数达0.85。河道的年平均径流深为146.66 mm,其中稳定的基流补给占21.3%。流域的年平均降雪231 mm,占总降水的74%左右;73.9%的融雪发生在7-9月,积雪主要分布于5000 m以上区域。蒸散发以7-9月中低山区植被覆盖良好的针叶林和草地为主。选用合适的方法对遥感数据进行验证和率定,有助于提高对资料缺失的高寒山区流域水文过程的认识。对不同水文要素进行分析验证,可更准确地理解水资源的转化、储存方式及其时空分布,以便为下游水资源管理提供依据。 相似文献
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利用波文比能量平衡法对天山北麓绿洲荒漠过渡带芨芨草地的夏季蒸散量进行测定,采用通径分析与相关分析相结合的方法探讨了蒸散与主要环境因子之间的关系,建立了适合该地区的蒸散预测模型。结果表明：（1）各种环境因子对蒸散影响的大小排序为：净辐射Rn）>土壤热通量（G）>空气温度（T气）>空气相对湿度（RH）>5 cm土壤温度（T土-5 cm）>实际水汽压（ea）>风速（Vwind）>5 cm土壤含水率（S土-5 cm）;（2）各因子通过[Rn]对蒸散产生的间接作用都大于其自身直接作用,反映出净辐射是制约蒸散大小的主导因子,是决定干旱区蒸散量的关键;（3）土壤热通量对蒸散的直接负效应远小于通过其他因子的间接正效应,出现其直接负效应与综合效应相反的结果;（4）建立并经过检验的蒸散预测模型表明：与温暖湿润区蒸散依靠水、热并重情况不同的是,极端干旱区主要依靠热量因子强度的增加,才能有较大的蒸散量。 相似文献
19.
Abstract:Hydrological regimes influence ecological patterns and processes as well as alter rates of wetland evapotranspiration.This study aimed to investigate the impact of groundwater fluctuation on evapotranspiration of Phragmites australis.Supported by field data obtained from the Baiyangdian Lake in northern China,the variations in groundwater levels were explored,and the changes in soil water and evapotranspiration of reed were analyzed to investigate different groundwater level scenarios using HYDRUS-1D model.The results showed that soil water content,recharged by groundwater,remained stable in the lower soil layer but varied strongly in the upper layer of the soil profile;in comparison to evaporation,Phragmites australis transpiration contributed significantly more to the overall evapotranspiration rate;the high levels of evapotranspiration could be maintained when groundwater levels vary between 1.0 m and 1.8 m,while it was reduced with an increase in groundwater levels as a result of water stress conditions.The results also indicated that the evapotranspiration of Phragmites australis could maintain higher evapotranspiration rates under natural water levels.The evapotranspiration,in other words,might be the main water consumer,but it nevertheless has little effect on water levels during water shortages.The evapotranspiration of Phragmites australis responded to the changes in groundwater levels could help researchers understand water requirements of the wetlands and establish suitable water levels for the wetlands. 相似文献
20.
荒漠下垫面陆面过程和大气边界层相互作用敏感性实验 总被引：7，自引：10，他引：7
建立了一个研究荒漠下垫面陆面物理过程与大气边界层相互作用的模式. 模拟了荒漠下垫面的土壤环境物理、地面热量通量、蒸发、蒸散及大气边界层结构特征.并对主要的环境物理参数进行了敏感性实验.结果表明,本模式能合理地模拟荒漠下垫面地表热量平衡、土壤体积含水量、地表植被蒸发散阻抗、地表水汽通量日变化和湍流交换系数、湍流动能、位温和比湿廓线等.该模式还可进一步应用于研究区域陆面物理过程与大气边界层相互作用机制,及与中尺度大气模式耦合用于区域环境生态和气候的研究. 相似文献
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