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1.
喀斯特地区春季土壤水分空间插值方法对比 总被引：1，自引：0，他引：1
以杨眉河小流域为研究区,通过土壤水分采样,选取辅助变量,采用普通克里金、协同克里金、回归克里金3种地统计学方法对土壤水分数据进行空间插值。结果表明：1）回归克里金对研究区土壤水分估算误差最小,其次为协克里金,普通克里金的误差最大;2）普通克里金生成的土壤水分表面最为平滑,而回归克里金最大程度反映了研究区实际的土壤水分空间变化;3）对于协同克里金,以湿度指数（WI）样点数据作为辅助变量的估算误差小于将WI栅格数据作为辅助变量的估算误差。总之,在可获得有效辅助变量的条件下,回归克里金对研究区土壤水分估算的效果优于协同克里金与普通克里金。 相似文献
2.
松嫩平原苏打盐渍土土壤水分特征研究 总被引：2，自引：1，他引：1
以苏打盐化草甸土和苏打碱土2 种土壤类型为研究对象,研究苏打盐渍土土壤水分特征,并对土壤水分特征曲线进行模拟。结果表明,0~40 cm土壤层,盐化草甸土总孔隙度大于50%,毛管孔隙中以0.1~1.2 mm当量孔径的粗孔隙为主,苏打碱土总孔隙度低,主要以小于0.1 mm当量孔径的细孔隙为主;0~40 cm土壤层在相同水势作用下,盐化草甸土土壤含水率明显高于苏打碱土,说明苏打碱土土壤持水能力较低。通过模型模拟,获得不同土壤层的水分特征曲线参数,模拟值与实测值相关系数均在0.9 以上,模型具有可靠性。 相似文献
3.
Landscapes of the mountainous regions in northwestern China comprise a unique pattern of vegetation,consisting of a mosaic of grassland and shrub-forest.Forests generally self-organize into ordered structures and coalesce into blocks on north-facing slopes or stripes along southeast-facing slopes,with Picea crassifolia being the most representative and dominant tree species.We investigated the tree-water status and soil-moisture dynamics at a forest site(Guantan)of the Qilian Mountains in northwest China.The 30-minute-interval measurements of tree-sap flow during the growing season of 2008 are presented,and the potential functional relations between tree transpiration and environmental factors are evaluated.Soil moisture and solar energy were identified as the most influential factors,explaining more than 70%of the variance in sap flow.Based on field measurements obtained at the forest site,a stochastic model of soil-moisture dynamics was tested;and the steady-state probability density functions(PDFs)of the long-term soil-moisture dynamics and static tree-water stress were estimated using the validated model and parameters.We found that the model reproduced measured soil moisture well,despite all the simplifying assumptions.The generated PDF of long-term soil moisture was relatively open,with middle to low average values;and the calculated density of the static tree-water stress at the forest site was largely concentrated between 0 and 0.6,suggesting a moderate water-stress situation in most cases.We argue that both water and energy are limiting factors for vegetation at the forest site.In addition,the tradeoff between reduced evapotranspiration(ET)from limited solar energy and increased soil-moisture availability may create a stressed but tolerable environment and,in turn,produce a relatively constant ecological niche favorable to Picea crassifolia growth. 相似文献
4.
Soil moisture is the key link between land hydrological and ecological processes which plays an important role in the terrestrial
water cycle. As extreme weather events have increased in recent years, the stochastic simulation of soil moisture has gradually
become the focus of ecohydrology research. Based on continuous monitoring of soil moisture data from 2008 to 2011, and historical
precipitation data from 1991 to 2011, combined with the Rodriguez-Iturbe soil moisture dynamic stochastic model, soil moisture
dynamics and its probability density function in a revegetated desert area was simulated. Results show that annual soil moisture
dynamic changes of the revegetated desert area during the growing season complied with rainfall distribution; soil moisture
probability presents a single-peak distribution in the plant rhizosphere layer (0–60 cm). The peak width in the 20 cm topsoil was
wider than in other soils, and the distribution presented the strong fluctuations and multiple aggregates. The peak widths of 40 cm
and 60 cm soil moisture probability distribution were small, which are in accordance with simulated results of the Rodriguez-
Iturbe model. This confirms that the Rodriguez-Iturbe model has good applicability and can well simulate the statistical
characteristics of soil moisture in an arid revegetated desert area. 相似文献
5.
一种改进的土壤水分微波遥感反演模型 总被引：2，自引：0，他引：2
利用微波遥感数据反演地表土壤水分有着较好的物理基础,可实现大范围土壤水分状况的遥感监测。本文基于被动微波传感器AMSR-E的X波段数据,将土壤水分值分解成基准值和日变化量两个部分,并分别建立反演模型,同时引入降雨修正因子来进一步提高土壤水分的估算精度;利用IDL语言实现了我们所研发的模型,并集成为新疆土壤水分遥感反演系统模块之一;利用Watch Dog2400与传统铝盒采样获取的新疆地面土壤水分数据,提取适合的模型经验参数,并对模型结果进行精度评价。结果表明,经改进的模型反演得到的新疆土壤水分结果比美国冰雪数据中心的土壤水分产品在精度上有显著提高:均方根误差由8.4%降低为4.25%;所研发的软件模块可为相关应用部门提供快速的大范围土壤水分监测产品。 相似文献
6.
利用微波遥感土壤水分产品监测东北地区春涝范围和程度 总被引：2，自引：0，他引：2
地表土壤水分是判断农田涝害的直接数据源,以欧洲太空局1978~2010 年微波遥感土壤水分产品、2013 年SMOS MIRAS L3 级土壤水分产品和气象站点的月降水数据为基础,结合土壤水分距平指数和土壤水分异常指数,分析2013 年东北地区春涝影响范围和严重程度。结果表明:① 东北地区以黑龙江省受涝面积最大,约11 万km2,约占黑龙江省总面积的1/4;② 比较多年的月降水数据与涝灾程度,发现冬春季节强降水是引发春涝的主要原因之一;③ 春涝的严重程度与高程呈现负相关关系,涝灾区域多集中在高程500 m以下。 相似文献
7.
半干旱区土壤湿度遥感监测方法研究 总被引：5，自引：0，他引：5
针对西北半干旱地区缺水问题,探讨了一种适合半干旱地区简便、易行的土壤湿度提取方法。该研究借鉴植被供水指数法(VSWI)和温度植被干旱指数法(TVDI)的研究思想,同时考虑到半干旱地区植被覆盖度较低,采用改进型土壤调整植被指数(MSAVI)代替NDVI,以降低土壤背景对植被指数的影响,从而对两种方法进行修正。利用改进前后的指数提取土壤湿度,对比分析表明,用修正后的指数研究该区的土壤湿度效果更好。 相似文献
8.
Rudi H. Kiefer 《The Professional geographer》1990,42(2):182-194
Soil carbon dioxide content, temperature, and moisture were measured biweekly for one year at Pigeon Mountain, GA. Levels of soil CO2 ranged from 0.04% to 2.4% and were highest during the growing season, lowest during the winter. Soil temperature correlated positively with soil CO2, accounting for 90% of CO2 variation. Soil moisture variations decreased CO2 concentration at times of high soil water content when CO2 was flushed downward, and also at times of low soil moisture content when CO2 production was inhibited. A predictive model of logistic form using 14-day means of daily actual evapotranspiration fit the data well (R2= 0.83). The model also tested well against soil CO2 data acquired in the coastal plain at Rocky Point, NC. If actual evapotranspiration rates are known, the model permits estimation of soil CO2 without preliminary field work, and can be used for studies of karst denudation, which require soil CO2 data for seasonal and regional comparison of solution rates. 相似文献
9.
10.
人工固沙植被区土壤水分动态及空间分布 总被引：6，自引：2，他引：4
土壤水分是干旱区固沙植被生长发育最主要的限制因子,了解其动态变化特征对沙区人工植被建设具有重要意义。本研究利用EnviroSMART土壤水分监测系统,于2009-2013年对宁夏沙坡头地区人工固沙植被区的土壤水分动态进行连续监测。结果表明:(1)降水对土壤水分状况及动态变化有较大的影响。土壤水分总体处于过度消耗状态,在非生长季,土壤水分没有明显的回升现象。(2)生长季初期(4-5月)为土壤水分弱消耗阶段;生长旺盛期(6-8月)为土壤水分快速消耗阶段,水分变化波动较剧烈,空间异质性最强;生长季末期(9-10月)的土壤水分处于相对稳定状态。(3)土壤水分随深度增加呈“S”形变化趋势,浅层的土壤含水量明显高于其他深度,200 cm深度土壤含水量较低且年际间变化不大(1.53%~2.10%)。湿润年份土壤水分剧烈变化的土层深度为0～100 cm,而干旱年份为0～20 cm。(4)相对于干旱年份,湿润年份的土壤含水量不但较高,而且水分变化波动较为剧烈。当土壤水分较低时,其变异性会随着土壤水分含量的增加而增加。(5)试验区灌木盖度在5年间呈下降趋势,一年生草本受降水量影响年际变化较大。受降水时空分布影响的土壤水分是沙坡头人工植被演替的重要驱动力。 相似文献
11.
Based on the measurement of L-band ground-based microwave radiometer(ELBARA-III type)in the Qinghai-Tibet Plateau and theτ-ωradiative transfer model,this research evaluated the effects of four soil dielectric models,i.e.,Wang-Schmugge,Mironov,Dobson,and Four-phase,on the L-band microwave brightness temperature simulation and soil moisture retrieval.The results show that with the same vegetation and roughness parameterization scheme,the four soil dielectric models display obvious differences in microwave brightness temperature simulation.When the soil moisture is less than 0.23 m3/m3,the simulated microwave brightness temperature in Wang-Schmugge model is significantly different from that of the other three models,with maximum differences of horizontal polarization and vertical polarization reaching 8.0 K and 4.4 K,respectively;when the soil moisture is greater than 0.23 m3/m3,the simulated microwave brightness temperature of Four-phase significantly exceeds that of the other three models;when the soil moisture is saturated,maximum differences in simulated microwave brightness temperature with horizontal polarization and vertical polarization are 6.1 K and 4.8 K respectively,and the four soil dielectric models are more variable in the microwave brightness temperature simulation with horizontal polarization than that with vertical polarization.As for the soil moisture retrieval based on the four dielectric models,the comparison study shows that,under the condition of horizontal polarization,Wang-Schmugge model can reduce the degree of retrieved soil moisture underestimating the observed soil moisture more effectively than other parameterization schemes,while under the condition of vertical polarization,the Mironov model can reduce the degree of retrieved soil moisture overestimating the observed soil moisture.Finally,based on the Wang-Schmugge model and FengYun-3C observation data,the spatial distribution of soil moisture in the study area is retrieved. 相似文献
12.
干旱人工固沙植被区土壤水分动态随机模拟 总被引：1，自引：0，他引：1
土壤水分是陆地水循环过程的关键环节,是联系陆地水文过程与生态过程的纽带。随着全球极端气候事件的频繁发生,土壤水分随机模拟逐渐成为当前生态水文学研究的热点。利用2008-2011年生长季土壤湿度连续监测数据及1991-2011年日降水资料,结合Rodriguez-Iturbe土壤水分动态随机模型,模拟了沙坡头人工植被区生长季土壤水分动态与土壤湿度概率密度函数特征。结果表明：人工固沙植被区生长季土壤水分年际变化与降雨分布一致。2008-2011年生长季植物根际层（0~60 cm）土壤湿度概率分布基本呈单峰状,20 cm处的土壤水分峰的阔度较其他土层相对土壤湿度峰较宽,并且分布也出现了一定程度的跳跃。而随着土层厚度的增加,在40 cm和60 cm的土壤水分概率分布峰的阔度也较小,与Rodriguez-Iturbe土壤水分动态随机模型模拟结果一致。说明Rodriguez-Iturbe模型在干旱人工植被区也具有很好的适用性,可以对荒漠人工植被恢复区的土壤水分统计特征进行很好的模拟,为以后干旱沙区随机生态水文模型的建立奠定基础。 相似文献
13.
利用静态暗箱-气相色谱法在植物生长旺季测算了内蒙古锡林河流域羊草草原的土壤微生物呼吸、土壤呼吸和生态系统呼吸。地温和水分是植物生长旺季呼吸最重要的影响因素。地温在水分条件适宜的情况下可以解释CO2通量的部分变化(R2 = 0.376~0.655)。土壤水分含量也可以解释土壤呼吸和生态系统呼吸的部分变化(R2 = 0.314~0.583),但基本不能解释土壤微生物呼吸的变化(R2 = 0.063)。即使在较高温度下,较低的土壤水分含量(≤ 5%) 也会显著的抑制CO2排放。长期干旱后降雨使CO2通量在高温下迅速增大。基于5 cm地温和0~10 cm土壤水分含量的双变量模型可以解释CO2通量约70%的变化。观测期间,土壤呼吸占生态系统呼吸的比例介于47.3%~72.4%之间,平均为59.4%;根呼吸占土壤呼吸的比例介于11.7%~51.7%之间,平均为20.5%。由于植物体去除引起的土壤水分含量上升可能使我们对土壤呼吸占生态系统呼吸比例的估计略微偏高,根呼吸占土壤呼吸的比例略微偏低。 相似文献
14.
土壤湿度的保持对作物生长非常重要。本文运用非静力平衡中尺度大气模式MM5,通过数值模拟的方式,分别从地气间水热交换和土壤湿度变化的角度,研究了2002年7月下旬我国西北干旱区绿洲环境在不同水量滴灌条件下的变化,从理论上找到了较适宜绿洲小气候维持的滴灌水量。结果表明:绿洲下垫面为农田时,从土壤保湿和绿洲小气候维持角度考虑,500m3·hm-2·(10d)-1的滴灌水量对7月下旬黑河流域中游绿洲是一个比较合适的灌溉量,水量过大不但造成水资源的浪费,而且对作物生长不利。500m3·hm-2·(10d)-1的灌溉水量仅为同期大水漫灌定额下限的一半和上限的1/3,间接证明了滴灌是一种高效节水的灌溉方式,可以为干旱区节约大量水资源。 相似文献
15.
甘肃旱作农业区降水对土壤水分的影响 总被引：4，自引：0，他引：4
利用甘肃旱作区35个气象站1961-2007年日降水量和13个农业气象观测站从建站到2007年逐年4-10月旬土壤重量含水率资料,分析了旱作区土壤湿度与降水量的关系。采用REOF把甘肃旱作区年降水量划分为4个气候子区域:陇东、陇中西部、陇中东部和陇南。结果表明:①在0～100 cm各层土壤中,耕作层0～30 cm土壤湿度与降水量的关系最好。②旱作区降水量和耕作层土壤湿度存在着一致的年际振荡趋势。各地土壤增湿时间与旬降水达到20 mm的时间基本一致。③耕作层土壤湿度与降水量有极显著的正相关关系,土壤湿度对降水量的敏感性随深度逐渐降低,陇中土壤湿度对降水的敏感性大于陇东南。④不同级别的降水对土壤湿度有不同的影响。不同级别降水之间,土壤湿度的差异极其显著。降水级别从“较强-强”,土壤湿度增幅最大。建立了土壤湿度与不同级别降水的关系式。 相似文献
16.
土壤墒情遥感反演与旱情诊断 总被引：1，自引：1，他引：0
土壤墒情与植被生长状况和地表温度之间存在密切联系?贑OST模型算法和单窗算法,开展了TM/ETM+多光谱数据的地表反射率、地表温度(LST)和土壤调整植被指数反演(MSAVI),分析了地表温度和植被指数的线性关系,提出了土壤墒情几何特征指数和旱情诊断函数,结合土壤含水量实测数据,建立了横山县土壤墒情遥感反演模型。实证结果表明,基于TM/ETM+数据反演的长度指数可进行旱情诊断;对土壤含水量的反演模型进行T检验,差异不显著,而基于地面温度的土壤墒情反演模型优于土壤调整植被指数反演模型。 相似文献
17.
青海湖西吉尔孟附近土壤水分研究 总被引：2，自引：0，他引：2
根据对青海湖北刚察县吉尔孟乡草地土壤含水量测定和粒度分析,研究了土壤水分变化等问题。研究区土层上部粒度成分以粗粉砂为主,下部以细砂为主。2009年该区草地土壤重力水分布深度达到了60 cm左右。土壤上部含水量丰富,下部水分严重不足。在土层约80 cm深度之下出现了中等干层和部分严重干层。该区土壤干层的发育阻隔了大气降水向地下深处的入渗,属于异常水分循环类型。该区土壤水分处于负平衡状态,指示当地的降水量并不能充分满足草原植被生长的需要。吉尔孟乡土壤蓄水量较少,易于发生生态环境的退化。 相似文献
18.
基于ASAR双极化雷达数据的半经验模型反演土壤湿度 总被引：1，自引：0，他引：1
基于ENVISAT ASAR-APP数据,利用AIEM(改进积分方程模型)模拟分析粗糙度、土壤水分对ASAR 7个入射角后向散射系数的影响.建立小人射角模式ASAR数据后向散射模型和组合粗糙度计算模型,提出小入射角模式下双极化ASAR数据土壤水分反演半经验模型.基于A1EM模拟数据进行试验,验证了该模型的合理性,且反演的土壤水分和实测土壤水分相关系数为O.92,均方根误差(RMSE)为3.98%. 相似文献
19.
Kriging方法在区域土壤水分估值中的应用 总被引：74，自引：9，他引：74
土壤水分的观测对于地表参数化的发展以及气候变化的研究有着重要的作用。本文对大尺度区域土壤水分的估值进行了尝试:采用1987年中国102个气象站点1米土层四个季节的土壤水分值作为样本,运用KRIGING方法,通过对半变异函数的计算和分析,得出了所研究7个采集日的拟合函数,发现均符合球状模型,对模型有关的参数进行了拟合。并将插值结果与距离反比法进行了对比性检验,同时给出了KRIGING方法的估值精度。检验结果表明平均相对误差和标准偏差均以距离反比法较小,以样本量较大的f时段为例对检验结果进行了深入分析。由此得出了KRIGING方法内插估值的优势和不足,简要给出了提高估值精度的可能方案。最后对中国东半部f时段的土壤水分值进行内插成图。 相似文献
20.
Based on the static opaque chamber method, the respiration rates of soil microbial respiration, soil respiration, and ecosystem respiration were measured through continuous in-situ experiments during rapid growth season in semiarid Leymus chinensis steppe in the Xilin River Basin of Inner Mongolia, China. Soil temperature and moisture were the main factor affecting respiration rates. Soil temperature can explain most CO2 efflux variations (R2=0.376–0.655) excluding data of low soil water conditions. Soil moisture can also effectively explain most of the variations of soil and ecosystem respiration (R2=0.314–0.583), but it can not explain much of the variation of microbial respiration (R2=0.063). Low soil water content (≤5%) inhibited CO2 efflux though the soil temperature was high. Rewetting the soil after a long drought resulted in substantial increases in CO2 flux at high temperature. Bivariable models based on soil temperature at 5 cm depth and soil moisture at 0–10 cm depth can explain about 70% of the variations of CO2 effluxes. The contribution of soil respiration to ecosystem respiration averaged 59.4%, ranging from 47.3% to 72.4%; the contribution of root respiration to soil respiration averaged 20.5%, ranging from 11.7% to 51.7%. The contribution of soil to ecosystem respiration was a little overestimated and root to soil respiration little underestimated because of the increased soil water content that occurred as a result of plant removal. 相似文献