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利用兴海1999--2006年4—10月的土壤水分资料,分析0～50cm土壤贮水是的年、月和旬际变化规律及垂直分布特征。结果表明：兴海县天然草地土壤贮水量年际变化振荡明显,呈多波动变化,与年降水量相关关系显著;一年中逐月土壤水分变化曲线基本呈“M”型分布,可分为春季缓慢增墒期、春夏快速增墒期、盛夏快速失墒期、秋季快速增墒期和秋末快速失墒期;土壤贮水量在20～30cm层最大,就其垂直变化而言,0—20cm为多变层,20-50cm为缓变层;土壤水分垂直剖面的季节变化按变异系数大小可分为3个阶段,土壤贮水量变异系数雨季（6—9月）大于干季。 相似文献
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甘肃省东部旱作区土壤水分变化规律的研究 总被引：13，自引：1，他引：13
甘肃省东部旱作区的气候条件，降水补给作用及作物生长发育状况的特殊性，导致土壤水分具有独特的时空分布规律，麦田２ｍ土层水分的周年变化呈一峰一谷型，可划分为旱季失墒消耗阶段和雨季蓄墒贮水阶段；其垂直变化呈“Ｓ”型，可划分为水分多变层、过渡层及稳定层。 相似文献
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陇东南旱作区土壤失墒规律初探 总被引：5，自引：0，他引：5
YAOXiaoying 《干旱气象》1999,(3)
通过试验分析,探讨了陇东南地区旱作田累积失墒规律,各土壤墒值段散逸速度,模拟了土壤水分散逸过程,得出了土壤从高墒散失水分降至低墒值所用的相对时间。即土壤重量含水率占田间持水量６０ ％ ～９０ ％ 时为最速失墒期,６０ ％ ～４０ ％ 为次速失墒期,重旱（ 占田间持水量≤４０ ％ ）时,散失同样量的水分,比从占田间持水量９０ ％ 至６０ ％ 及轻旱（ 占间持水量６０ ％ 以下） 至重旱间所需时间长１０ ～２０ 倍,为今后这方面的研究及干旱预测提供参考。 相似文献
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无有效水分补给条件下麦田旬失墒规律及其应用 总被引：2，自引：0，他引：2
为了研究麦田失墒规律，对聊城市近十几年来冬小麦生育期间一旬内既无有效降水也无灌溉条件下麦田失墒资料进行统计分析，找出麦田土壤各层次、各种初始土壤湿度状态下，旬失墒的一般规律及影响失墒的主要因子，并建立了相应的失墒方程，可用于无有效降水及灌溉条件下麦田失墒的预测，向有关部门提供预测信息。此外根据麦田失墒规律对小麦冬灌、春灌工作安排时间等问题也提出参考意见 相似文献
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黄土高原芨芨草土壤水分特征及水分利用效率研究 总被引：3，自引：0，他引：3
通过对芨芨草草地土壤水分状况及芨芨草水分利用情况进行初步分析，结果表明：芨芨草地土壤贮水量呈明显的季节变化；土壤剖面可依含水量变化分为3层，即速变层、活跃层和稳定层。芨芨草群体水分利用效率以6月份为最高，而单叶水分利用效率7月份最高，具有较强的抗旱性。 相似文献
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基于自动土壤水分观测站数据建立本地土壤水分变化模型,通过人工取土烘干法观测的实际土壤湿度数值对自动土壤水分观测站数据进行修正和校订,再由修正过的自动土壤水分观测站数据作为当日的初始湿度,通过天气预报中无降水日数或降水日期及雨量大小做出未来一段时间内的失墒或增墒的模型,再通过不同的气象条件对增、失墒进行相关订正,做出相应的土壤墒情的预报,最后根据土壤墒情预报结果对照本地的土壤干旱量级指标,从而随时做出快速准确的本地旱情预报,为各级领导组织指挥农业生产、开展人影作业、指导农民进行田间管理等活动提供及时可靠的决策依据。本文通过此模型对2012年松原地区夏季干旱情况进行预报,再通过实际土壤墒情实况进行对比,预报结果基本正确。由于人工测值有一定随机性,所以人工观测值与自动站观测数据的对比只能做为参考而不可能完全吻合。但从长期数据应用情况来看,基于土壤自动水分观测站的土壤墒情监测及干旱预报模型方便稳定,反应水分变化趋势更有连续性。 相似文献
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利用吉林省西部10个自动土壤水分观测站数据与人工取土烘干法实测土壤湿度数据,制作吉林省西部土壤墒情监测及干旱预报模型.结果表明:不同气候背景下在作物不同生育期、土壤不同深度、不同初始湿度下的土壤湿度的变化趋势大致相同,但在相同的无降水日数或降水量时,不同台站不同深度的土壤湿度变化率却有一定的差异.各站农田土壤初始湿度越大,无降水时初期墒情下降速率越明显;而土壤湿度初始值越低,则失墒速率越慢.土壤不同深度均是开始时间失墒较快,后期变化逐渐趋于减弱状态.土壤深度越深则水分变化速率越缓,降水量越大,0～50 cm土壤湿度变化曲线整体越接近一致,直到从上而下几层土壤湿度全部达到饱和.通过对2017—2019年吉林省西部玉米农田土壤湿度预报结果和实测值进行对比检验,基于自动土壤水分观测数据的吉林省西部干旱模型预报的准确率超过80％. 相似文献
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The understanding of surface spectral radiation and reflected radiation characteristics of different surfaces in different climate zones aids in the interpretation of regional surface energy transfers and the development of land surface models. This study analysed surface spectral radiation variations and corresponding surface albedo characteristics at different wavelengths as well as the relationship between 5-cm soil moisture and surface albedo on typical sunny days during the winter wheat growth period. The analysis was conducted using observational Loess Plateau winter wheat data from 2015. The results show that the ratio of atmospheric downward radiation to global radiation on typical sunny days is highest for near-infrared wavelengths, followed by visible wavelengths and ultraviolet wavelengths, with values of 57.3, 38.7 and 4.0%, respectively. The ratio of reflected spectral radiation to global radiation varies based on land surface type. The visible radiation reflected by vegetated surfaces is far less than that reflected by bare ground, with surface albedos of 0.045 and 0.27, respectively. Thus, vegetated surfaces absorb more visible radiation than bare ground. The atmospheric downward spectral radiation to global radiation diurnal variation ratios vary for near-infrared wavelengths versus visible and ultraviolet wavelengths on typical sunny days. The near-infrared wavelengths ratio is higher in the morning and evening and lower at noon. The visible and ultraviolet wavelengths ratios are lower in the morning and evening and higher at noon. Visible and ultraviolet wavelength surface albedo is affected by 5-cm soil moisture, demonstrating a significant negative correlation. Excluding near-infrared wavelengths, correlations between surface albedo and 5-cm soil moisture pass the 99% confidence test at each wavelength. The correlation with 5-cm soil moisture is more significant at shorter wavelengths. However, this study obtained surface spectral radiation characteristics that were affected by land surface vegetation coverage as well as by soil physical properties. 相似文献
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通过青海省互助县1997~2002年大气观测场和春小麦地测定的0~50 cm土壤贮水量变化规律的对比分析得出:同一气候背景下,地形地势相同的不同场地不同植被0~50 cm土壤贮水量变化特征基本一致。大气观测场11月至次年2月(一般为土壤封冻期)土壤贮水量保持在25~27 mm间,变化较平稳,6~7月处于谷值阶段,为24 mm,3月至4月初和9月处于峰值阶段,为28 mm,年变化似呈"M"形。春小麦地在土壤封冻期未测定,3月至4月初处于最大峰值阶段,为33 mm,7月处于谷值阶段,为21 mm,9月达次峰值阶段,为25 mm,年变化似呈"M"形。在同一气候背景下,大气观测场中子仪测定和春小麦地烘干法测定的0~50 cm贮水量经过相关性检验,建立回归关系式后可相互代替应用。 相似文献
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利用甘肃雨养农业区11个站点的土壤湿度资料及其相关的气象资料分析了该区域土壤水分时空变化规律、降雨量的补给和作物土壤水分状况.该区域土壤含水量自东南向西北减小, 变异系数增大.土壤水分不足区水分变化主要集中在90 cm以上, 而土壤水分严重不足区、作物生育关键期土壤水分不足区和土壤水分充足区水分变化深度可达180 cm左右.雨季降雨量对土壤水分补给率的地域变化范围为15.3%~41.7%; 补给率除受降雨量的影响外, 土壤类型也是一个重要的制约因子.除成县、临夏和西峰外, 其余各站在小麦生育期水分亏缺量均超过100 mm, 占需水量的30%~50%. 相似文献
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Trends and scales of observed soil moisture variations in China 总被引：3，自引：0，他引：3
A new soil moisture dataset from direct gravimetric measurements within the top 50-cm soil layers at 178 soil moisture stations in China covering the period 1981-1998 are used to study the long-term and seasonal trends of soil moisture variations, as well as estimate the temporal and spatial scales of soil moisture for different soil layers. Additional datasets of precipitation and temperature difference between land surface and air (TDSA) are analyzed to gain further insight into the changes of soil moisture. There are increasing trends for the top 10 cm, but decreasing trends for the top 50 cm of soil layers in most regions. Trends in precipitation appear to dominantly influence trends in soil moisture in both cases. Seasonal variation of soil moisture is mainly controlled by precipitation and evaporation, and in some regions can be affected by snow cover in winter. Timescales of soil moisture variation are roughly 1-3 months and increase with soil depth. Further influences of TDSA and precipitation on soil moisture in surface layers, rather than in deeper layers, cause this phenomenon. Seasonal variations of temporal scales for soil moisture are region-dependent and consistent in both layer depths. Spatial scales of soil moisture range from 200-600 km, with topography also having an affect on these. Spatial scales of soil moisture in plains are larger than in mountainous areas. In the former, the spatial scale of soil moisture follows the spatial patterns of precipitation and evaporation, whereas in the latter, the spatial scale is controlled by topography. 相似文献
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Relationships between surface albedo,soil thermal parameters and soil moisture in the semi-arid area of Tongyu,northeastern China 总被引：15，自引：2，他引：13
Continuous observation data collected over the whole year of 2004 on a cropland surtace m Tongyu, a senti-arid area of northeastern China （44°25＇N, 122°52＇E）, have been used to investigate the variations of surface albedo and soil thermal parameters, including heat capacity, thermal conductivity and thermal diffusivity, and their relationships to soil moisture. The diurnal variation of surface albedo appears as a U shape curve on sunny days. Surface albedo decreases with the increase of solar elevation angle, and it tends to be a constant when solar elevation angle is larger than 40°. So the daily average surface albedo was computed using the data when solar elevation angle is larger than 40° Mean daily surface albedo is found to decrease with the increase of soil moisture, showing an exponential dependence on soil moisture. The variations of soil heat capacity are small during Julian days 90 300. Compared with the heat capacity, soil thermal conductivity has very gentle variations during this period, but the soil thermal diffusivity has wide variations during the same period. The soil thermal conductivity is found to increase as a power function of soil moisture. The soil thermal diffusivity increases firstly and then decreases with the increase of soil moisture. 相似文献
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分析了欧洲空间局最近基于多颗卫星微波资料研发的ECV土壤湿度产品的季节性干湿变化,并与国家气象局提供的站点资料做了对比验证。研究发现:主动与被动遥感土壤湿度的干湿季节变化在中国东部季风区有显著的不一致性。在中国东部季风区,被动遥感土壤湿度的干湿季变化和站点观测一致,均表现出夏季是干季、冬季是湿季的特征;而主动遥感的数据则存在较大的空间差异,华北地区与被动遥感数据较为一致,华南地区则呈现夏季为湿季、冬季为干季的反位相特征。两者的不一致性说明,针对欧洲空间局开发ECV土壤湿度产品的过程,融合主动遥感和被动遥感资料,研制长序列土壤湿度产品的思路在中国东部季风区不可行。 相似文献
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干旱地区春小麦耗水量和节水措施的探讨 总被引：3，自引：0，他引：3
本文研究了春小麦耗水量与产量的关系及其耗水规律，分析了土壤湿度、耗水量对春小麦生长发育的影响。结果表明：拔节至抽穗是春小麦的水分临界期，抽穗至成熟期耗水量最多，耗水模系数最大；产量与耗水量呈二次曲线关系，适宜土壤水分下限为：出苗至拔节期为田间持水量的70％-75％，拔节至抽穗期为60％-65％、抽穗至灌浆初期为55％-60％．灌浆初期至成熟期为50％-55％，本文还对春小麦覆盖地膜的节水增产原因及效果进行了探讨，提出了黑河流域春小麦节水增产的技术措施及进一步研究的意见。 相似文献