共查询到20条相似文献，搜索用时 187 毫秒
1.
为研究乡村聚落的土壤侵蚀,在陕北榆林、绥德、延安建立观测站,于2003年对乡村聚落中的户间道路、户间空地、院落在降雨时的次径流泥沙含量、平均含沙量、次侵蚀强度及观测期降雨形成的总侵蚀强度,进行了观测与分析。其观测结果,均说明户间道路、户间空地径流平均含沙量较大,榆林为29.37g/L、29.96g/L,缓德为21.06g/L、17.53g/L、延安为54.6g/L2、9.18g/L,而院落平均径流含沙量较小,榆林、绥德、延安分别为9.47g/L、8.64g/L、14.87g/L。观测期降雨侵蚀总强度,三个观测站均以户间道路最大,分别为1142t/km2、2156.6t/km26、285.7t/km2;户间空地次之,分别为744.5t/km2、1192.6t/km2、1953.2t/km2;院落较小,分别为161.1t/km23、78.7t/km2、1274.3t/km2。说明乡村聚落土壤侵蚀不可忽视,应加强防治。 相似文献
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共和盆地沙区水分含量消长趋势评价 总被引：2，自引：0，他引：2
通过青海共和盆地流动沙丘和固定沙丘０－４０ｃｍ层水分含量的观测测定，建立了二元二次多项式回归方程，评价流动沙丘和固定沙丘在生长季期间，水分消长趋势变化，为改造和利用沙丘沙地提供可靠依据。 相似文献
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通过观测沙区两种土壤类型春小麦产量和产量构成因素(单穗粒数、单位面积穗数、千粒重)对全生育期不同灌溉量、灌溉次数和土壤含水量处理(单次灌溉量)的响应,分析该区春小麦稳产、高产的最佳经济灌溉量。结果表明:(1)干旱沙区全生育期总灌溉量、灌溉次数及土壤含水量处理与春小麦产量和产量各构成因素间有强正相关关系(P<0.01);(2)风沙土春小麦全生育期总灌溉量约为4312m3/hm2,单次灌水定额相当于30.8mm水层厚,总灌水次数约以14次最佳;(3)灌淤土春小麦全生育期总灌溉量为4590m3/hm2,单次灌水定额相当于45.9mm水层厚,总灌水次数以11次左右为宜。 相似文献
4.
利用MODIS卫星资料监测内蒙古地区大气总水汽量方法研究 总被引：1，自引：0，他引：1
由于大气可降水量在人工影响天气、天气预报、气候影响、大气辐射传输等方面都具有非常重要的作用,所以准确精细地监测水汽优为显得重要。随着卫星技术的日益发展壮大,很多地球观测技术从地基观测逐步发展成空基观测。卫星观测时空分辨率很高,而且精度也在不断地提高,逐步成为最主要的地球观测手段。文中利用GPS资料和地面湿度参量(地面水汽压、地面露点)修正了利用地面湿度参量、地理纬度和海拔高度等参量计算大气总水汽量的关系式的基础上研究建立了适合内蒙古地区的MODIS卫星近红外通道监测大气总水汽量方法。 相似文献
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近50 a天山乌鲁木齐河源1号冰川变化分析 总被引：2，自引：0，他引：2
乌鲁木齐河源1号冰川是我国监测时间最长、资料最为完备的一条冰川.1962年以来,采用5种观测方法共开展过9次地形图测量和3次乌鲁木齐河源区的航空摄影测量.通过对乌鲁木齐河源1号冰川已有观测数据的分析,结合2012年最新观测资料对该冰川近50 a的变化特征进行了深入研究.结果发现,乌鲁木齐河源1号冰川1962年和1980年的面积数据存在偏差.对原始测图重新数字化后,得到1962年和1980年该冰川面积分别为1.91 km2和1.86 km2.2012年采用GPS-RTK测量技术,对乌鲁木齐河源1号冰川进行详细的地形测绘和末端变化观测,结果显示,冰川面积为1.59 km2,其中东支和西支面积分别为1.02 km2和0.57 km2.近50 a来,该冰川退缩率为16.8％.冰川整体处于消融状态,但冰面消融程度存在显著差异.冰面坡度10°区域消融最为强烈.东支南北坡退缩普遍较强,西支北坡退缩快,东北坡面积有所增加,消融速度加快主要受气温和地形共同影响. 相似文献
7.
《干旱区研究》2021,38(4):1031-1039
利用2015-06—2016-05月新疆区域地面观测的总云量小时数据,对比分析了FY-2F/CTA与地面观测云量的相关性和一致性,开展了FY-2F云量产品在新疆区域的分析检验。结果表明:(1)FY-2F/CTA与地面人工观测总云量的相关性较好,天山以北区域(含天山山区)冬季除外。(2)FY-2F/CTA与地面人工观测总云量的一致率为51.5%,南北疆差别不大,均是夏、秋季较高,但天山以北区域冬季较低,南疆春季较低;卫星反演总云量整体比地面观测值偏低,即呈高偏弱率低偏强率分布,南疆区域偏低最为明显。(3)不同云量等级下,一致率与总云量呈反比,即晴天、少云状况下的一致率较高,多云、阴天条件下的一致率较低。(4)沙尘会降低FY-2F/CTA判识的一致率,增大其偏弱率,但是对于有、无云的判识影响不大。本研究考虑了不同季节、不同云量等级以及有无沙尘影响,对FY-2F/CTA产品进行了评估,研究结果为干旱区总云量的卫星反演及应用提供了重要参考。 相似文献
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为了掌握荒漠绿洲区春小麦的耗水规律,建立高效节水型绿洲农业,通过田间观测试验,分析了6种不同灌溉定额下春小麦的土壤含水量、耗水量、土面蒸发量以及WUE的变化特征。结果显示,不同灌水定额下,春小麦全生育期耗水量的变化范围为450mm~650mm,其中春小麦的平均蒸腾耗水量为总耗水量的81%,而平均土面蒸发量为总耗水量的19%。拔节后期~抽穗前期是春小麦需水的第一关键期,灌浆后期~成熟期是次关键期。WUE随籽粒产量先增大后减小,二者之间呈二次曲线的关系。可见,过度灌溉不利于WUE的提高,造成水资源的浪费。 相似文献
9.
我站于1982和1983两年,使用江苏省激素研究所合成的小地老虎性诱剂作发生期预测,此法较之传统的糖醋酒液诱蛾有如下优点: 1.诱蛾频率高 1983年早春系统观测31个夜晚,共93钵次,诱到小地老虎成虫有71钵次,诱蛾频率0.76;而设置于相对相同生境的糖醋酒液只有33钵次诱捕到蛾子,诱蛾频率0.35。反映出性诱剂有稳定的生物活性。 相似文献
10.
明代泾河流域洪涝灾害研究 总被引：4，自引：3，他引：1
本文通过历史文献资料的搜集、整理、分析。对明代泾河流域洪涝灾害的时间、空间特征、灾害等级序列和灾害成因进行了分析研究。结果表明:明代泾河流域洪涝灾害共发生50次,平均5.54年发生一次。明代前期和后期泾河流域洪涝灾害发生频率较低,中期较高。明代该流域洪涝灾害主要发生在上游和下游地区,中游发生较少,其中上游平凉、庆阳和下游的泾阳洪涝灾害发生最为频繁。根据统计,明代泾河流域洪涝灾害主要发生在6、7、8月。根据洪涝灾害等级序列划分,得出明代该流域二级洪涝灾害发生最多,为25次,占发生次数的50%;其次为一级洪涝灾害,共发生20次,占40%;三级特大洪涝灾害共发生5次,占总次数的10%。明代该流域洪涝灾害发生主要是由于气候和该区域的地貌、降水特征决定的,人类对生态环境的破坏加剧了该流域洪涝灾害的发生。 相似文献
11.
Dew is an important supplement water source in arid and semi-arid areas. In order to determine the dew formation on different kinds of soils associated with various shrub species and microhabitats, we performed measurement of accumulated dew formation amount and duration in October 2009 in a revegetation-stabilized arid desert ecosystem in Shapotou area, northern China. The results indicated that the accumulated dew formation amount was four times larger at open spaces as compared to under the canopy, and it was nearly twice as much under living Artemisia ordosica plants（L.A.） as compared to under living Caragana korshinskii plants（L.C.）. The opposite characteristics were found for dew duration between different microhabitats. Dew amounts at different vertical heights around the shrub stands were in the order of 50 cm above the canopy〉the canopy edge〉under the canopy. Dew amount continued to increase after dawn, and the proportion of average accumulated dew amount after dawn accounting for the average maximum amount increased from above the canopy to under the canopy. Dew formation duration after sunrise accounted for more than 50% of the total formation duration during the day time. Contrary to the distribution characteristics of dew amount, dew duration after dawn and total dew formation duration during the day time were both highest under the canopy, followed by at the canopy edge and then at 50 cm above the canopy. The portion of dew duration after dawn accounting for the total dew duration during the day time increased from above the canopy to under the canopy. From these results, we may conclude that dew availability as a supplemental water resource for improving the microhabitats in water-limited arid ecosystems is position dependent especially for the plant microhabitats at different stands layers. 相似文献
12.
Characteristics of dew events in an arid artificial oasis cropland and a sub-humid cropland in China
Dew is an important source of water which significantly influences the physiological status of vegetation and the microclimate environment. For quantifying the characteristics of dew events and analyzing the underlying mechanism of dew formation in different ecosystems, we measured, based on the flux-profile method, the amount, frequency and duration of dew events in two croplands, an arid artificial oasis cropland in Zhangye, Gansu province and a sub-humid cropland in Luancheng, Hebei province in China. The results showed that dew events were observed in a total of 69 days in Zhangye, which accounted for 59% of the growing season(from 28 May to 21 September, 2012), while 128 days in Luancheng, which accounted for 79% of the growing season(from 5 April to 13 September, 2008). The frequencies of dew events were 2.8 and 2.4 times of those of precipitation in Zhangye and Luancheng, respectively. In addition, the dew amount reached up to 9.9 and 20.2 mm in Zhangye and Luancheng, which accounted for 9.5% and 4.1% of precipitation, respectively. The average amount of dew was 0.14 and 0.16 mm/night in Zhangye and Luancheng, respectively and the duration of dew events ranged from 0.5 to 12.0 h in the two study sites. Dew amounts were associated with the gradient of atmospheric water vapor concentration and dew duration(P<0.001) in both the two sites. The result implies that dew events play a more important role in crop growth in arid areas in comparison to sub-humid areas considering the dew occurrence frequency and the amount per night. 相似文献
13.
Dew is an essential water resource for the survival and reproduction of organisms in arid and semi-arid regions. Yet estimating the dew amount and quantifying its long-term variation are challenging. In this study, we elucidate the dew amount and its long-term variation in the Kunes River Valley, Northwest China, based on the measured daily dew amount and reconstructed values (using meteorological data from 1980 to 2021), respectively. Four key results were found: (1) the daily mean dew amount was 0.05 mm during the observation period (4 July-12 August and 13 September-7 October of 2021). In 35 d of the observation period (i.e., 73% of the observation period), the daily dew amount exceeded the threshold (>0.03 mm/d) for microorganisms; (2) air temperature, relative humidity, and wind speed had significant impacts on the daily dew amount based on the relationships between the measured dew amount and meteorological variables; (3) for estimating the daily dew amount, random forest (RF) model outperformed multiple linear regression (MLR) model given its larger R2 and lower MAE and RMSE; and (4) the dew amount during June-October and in each month did not vary significantly from 1980 to the beginning of the 21st century. It then significantly decreased for about a decade, after it increased slightly from 2013 to 2021. For the whole meteorological period of 1980-2021, the dew amount decreased significantly during June-October and in July and September, and there was no significant variation in June, August, and October. Variation in the dew amount in the Kunes River Valley was mainly driven by relative humidity. This study illustrates that RF model can be used to reconstruct long-term variation in the dew amount, which provides valuable information for us to better understand the dew amount and its relationship with climate change. 相似文献
14.
Sophia RATCLIFFE 《干旱区科学》2012,4(1):11-18
Dew has been recognized for its ecological significance and has also been identified as an additional source of water in arid zones.We used factorial control experiment,under dew presence in the field,to explore photosynthetic performance,water status and growth response of desert annual herbage.Bassia dasyphylla seedlings were grown in contrasting dew treatments (dew-absent and dew-present) and different watering regimes (normal and deficient).The effects of dew on the water status and photosynthetic performance of Bassia dasyphylla,grown in a desert area of the Hexi Corridor in Northwestern China,were evaluated.The results indicated the presence of dew significantly increased relative water content (RWC) of shoots and total biomass of plants in both water regimes,and enhanced the diurnal shoot water potential and stomatal conductance in the early morning,as well as photosynthetic rate,which reached its maximum only in the water-stressed regime.The presence of dew increased aboveground growth of plants and photosynthate accumulation in leaves,but decreased the root-to-shoot ratio in both water regimes.Dew may have an important role in improving plant water status and ameliorating the adverse effects of plants exposed to prolonged drought. 相似文献
15.
毛乌素沙地凝结水动态变化及其影响因子的研究 总被引：4，自引：0，他引：4
基于2002年5~10月间运用直接称重法对毛乌素沙地臭柏(Sabina vulgaris Ant.)群落林间空地的0-1.5cm表层土壤凝结水连续观测资料,分析讨论了凝结水的日变化和季节变化特征以及影响凝结水形成的环境因子。结果表明:毛乌素沙地天然臭柏群落内各月均有凝结水发生,并且可从午后持续至翌日清晨,但各月间凝结水量和凝结持续时间有所不同。5月份凝结水持续时间最短,凝结水量也最少;而9月份凝结水持续时间最长,凝结水量也最多。影响毛乌素沙地凝结水形成的主要环境因子有风速、大气相对湿度、气-地温差及其相互作用。其中,风速与凝结量间存在较高相关性,而气温能否趋近或降至露点产生土壤凝结水是决定夜间水分凝结量的一个关键因素。 相似文献
16.
凝结水对温带荒漠一年生植物生态作用研究 总被引：4，自引：0，他引：4
选取一年生草本植物雾冰藜作为研究对象,设计有凝结水和无凝结水2个处理,每个处理又分干旱条件和人工浇水2组控制试验,研究凝结水的发生对雾冰藜的叶相对含水量、叶水势、净光合速率、气孔导度、生物量及生物量分配比例的影响。结果表明:2种土壤水分状况下凝结水的发生改善了一年生荒漠植物的叶片相对含水量。但只有在干旱条件下,凝结水的发生才显著提高了荒漠一年生植物的叶水势。只有在干旱条件下,凝结水的发生才显著提高了荒漠一年生植物的净光合速率及其最大值。凝结水对气孔导度的影响只发生在干旱条件下,而且只对上午10:00以前的气孔导度有显著影响。无论在人工浇水还是在干旱条件下,凝结水的发生均显著增加了一年生荒漠植物的生物量。但只有在干旱条件下,凝结水的发生才显著降低了一年生植物黄叶生物量。无论哪种水分处理,凝结水的发生都促进了荒漠一年生植物地上部分的生长,减少了根/茎比例,促进了光合产物在整个植株叶片中的积累,而相应减少了在茎中的分配比例。 相似文献
17.
High-resolution observations of cambial phenology and intra-annual growth dynamics are useful approaches for understanding the response of tree growth to climate and environmental change. During the past two decades, rapid socioeconomic development has increased the demand for water resources in the oases of the middle reaches of the Heihe River in northwestern China, and the lower reaches of the Heihe River have changed from a perennial river to an ephemeral stream with a decreased and degraded riparian zone. Tamarisk（Tamarix ramosissima） is the dominant shrub species of the desert riparian forest. In this study, the daily and seasonal patterns of tamarisk stem diameter growth, including the main period of tree ring formation, were examined. Observations concerning the driving forces of growth changes, along with implications for the ecology of the dendrohydrological area and management of desert riparian forests in similar arid regions, are also presented. The diurnal-seasonal activity of stem diameter and the dynamics of growth ring formation were studied using a point dendrometer and micro-coring methods during the 2012 growing season in shrub tamarisk in a desert riparian forest stand in the lower reaches of the Heihe River in Ejin Banner, Inner Mongolia of northwestern China. Generally, the variation in diurnal diameter of tamarisk was characterized by an unstable multi-peak pattern, with the cumulative stem diameter growth over the growing season following an S-shaped curve. The period from late May to early August was the main period of stem diameter growth and growth-ring formation. Among all of the hydroclimatic factors considered in this study, only groundwater depth was significantly correlated with stem diameter increment during this period. Therefore, for the dendrochronological study, the annual rings of the tamarisk can be used to reconstruct processes that determine the regional water regime, such as river runoff and fluctuations in groundwater depth. For the management of desert riparian for 相似文献
18.
利用2008年黑河流域SPOT-VEGETATION NDVI数据,采用数学统计、一元线性回归方法,对绿洲植被年内长势变化的过程、速度和幅度进行了定量分析;利用空间统计方法对各地区年内长势最佳期进行了分析.结果表明:(1)绿洲植被长势在一年中呈阶段性显著:第1-18旬(1-6月)明显上升,第19-22旬(7-8月上旬)波动,第23-36旬(8月中旬-12月)明显下降.(2)绿洲植被长势变化速度具有明显的时间差异性,第14-15旬的长势速度增加最快,第27-29旬的减少最快,而且增加和减少相当的区域略具空间一致性.(3)绿洲植被长势变化的幅度也具有明显的空间差异.绿洲核心区域年内长势变化最大,向外围依次递减.(4)各区域绿洲植被长势最佳期的出现具有差异性.总体而言以出现在第22旬(8月上旬)的区域占绝对优势,其次为第20旬和第18旬等.因此在选择遥感影像时针对全流域绿洲整体的研究可以选择8月上旬的影像,而针对局部区域可以选择6月下旬、7月中旬或9月下旬的影像. 相似文献
19.
干旱半干旱地区双垄地布覆盖对土壤水分的影响 总被引：1，自引：0，他引：1
为探明一种可替代覆盖材料的可行性,在甘肃省定西市安定区开展了为期1 a的监测试验,试验设防草地布加地膜覆垄(MB)、防草地布覆垄(DB)和裸地起垄(CK)3种处理,利用土壤水分、水势传感器分别对沟内地表下5、15 cm的土壤含水率、水势进行监测,结果表明:(1)表层5 cm土壤水分日变化呈复杂波形,受不同覆垄处理和季节性天气变化的影响显著;(2)0～20 cm土层的水分年变化主要受降雨、露水和蒸发强度的影响,表现为春冬干、夏秋湿的特点,在11月至翌年2月期间MB和DB覆垄处理土壤水分净损失量要高于CK裸地垄,而在作物生育期内(5—9月)覆垄处理土壤储水净增量为DB最大(36.35 mm)、MB次之(30.73 mm)、CK最小(16.30 mm);(3)MB和DB覆垄能明显加快雨露叠加,增加土壤水储存,而CK处理下叠加效应弱,且深层土壤对降雨不敏感,具有滞后性,但随着连续降雨的发生,表层土壤储水量加大,这种滞后性明显减弱;(4) 0～20 cm土层土壤储水量日变化幅度为夏季最大(平均1.20 mm·d~(-1)),春季次之(1.03 mm·d~(-1)),秋季最小(0.79 mm·d~(-1)),全年水分净收获总量为DB最大(24.9 mm)、MB略低(21.5 mm)、CK最小(11.4 mm)。整体而言,只用地布覆垄具有最好的集水效果,这种防草地布可多年使用,无地膜碎片化污染问题,但在无降雨时期,垄沟内因土壤水分高,其蒸发强度略高于裸地处理。 相似文献
20.
《干旱区科学》2017,(4)
Dew is an important water source for plants in arid and semi-arid regions. However, information on dew is scarce in such regions. In this study, we explored dew formation, amount, and duration of rain-fed jujube(Zizyphus jujube Mill) trees in a semi-arid loess hilly region of China(i.e., Mizhi County). The data included dew intensity and duration, relative humidity, temperature, and wind speed measured from 26 July to 23 October, 2012 and from 24 June to 17 October, 2013 using a micro-climate system(including dielectric leaf wetness sensors, VP-3 Relative Humidity/Temperature Sensor, High Resolution Rain Gauge, and Davis Cup Anemometer). The results show that atmospheric conditions of relative humidity of 78% and dew point temperature of 1°C–3°C are significantly favorable to dew formation. Compared with the rainfall, dew was characterized by high frequency, strong stability, and long duration. Furthermore, heavy dew accounted for a large proportion of the total amount. The empirical models(i.e., relative humidity model(RH model) and dew point depression model(DPD model)) for daily dew duration estimation performed well at 15-min intervals, with low errors ranging between 1.29 and 1.60 h, respectively. But it should be noted that the models should be calibrated firstly by determining the optimal thresholds of relatively humidity for RH model and dew point depression for DPD model. For rain-fed jujube trees in the semi-arid loess hilly regions of China, the optimal threshold of relative humidity was 78%, and the optimal upper and lower thresholds of dew point depression were 1°C and 5°C, respectively. The study further demonstrates that dew is an important water resource that cannot be ignored for rain-fed jujube trees and may affect water balance at regional scales. 相似文献