1976—2017年青海湖东北部地区极端降水事件变化特征分析     

晁红艳 .  张娟  陈海莲  余振邦 《中国农学通报》2020,36(2):109-116

为进一步了解高寒牧区气候变化,依据1976—2017年青海湖东北部海晏站逐日降水资料,采用百分位法确定冬、夏半年极端降雨（雪）阈值并统计极端降水事件,运用线性趋势、R/S和小波分析法分析极端降水事件变化特征、未来演变趋势及周期。结果表明：青海湖东北部地区冬、夏半年极端降水日数和极端降水量呈不显著增加趋势;冬半年极端降水强度和日最大降水量不显著增加,而夏半年不显著减小;极端降水对年降水的贡献率均以不同的速率增加,其中夏半年的极端降水对年降水的影响较大;冬半年降水日数不显著减小,而降水量显著增加,表明冬半年发生短时强降水的几率增大,夏半年的降水日数和降水量增加不明显;未来,冬半年极端降水日数增加趋势将发生转变,极端降水量与之前的变化趋势无关将继续呈现震荡性,其他各要素将持续前期的变化趋势;冬（夏）半年极端降水日数和降水量分别存在明显的周期变化特征。高寒牧区的极端降水研究对于预防短时强降水带来的雪灾、洪涝事件的发生意义重大。  相似文献   

基于遥感的干旱监测方法研究     

郝晓雷 《现代农业科技》2020,(2)

在全球变暖的气候背景下,近年来干旱频发且不断加剧,对人类的生产生活造成了严重的影响。目前,干旱监测已成为全球气候变化研究的一个热点课题。遥感技术以其客观、及时、经济、覆盖范围广、数据连续等优点,已被证明是干旱监测中最具前景的技术手段。本文基于遥感原理,介绍了归一化植被指数、温度状态指数、标准化降雨指数和标准化降雨蒸散指数等几种常见的干旱指数,综述了运用不同指数干旱监测的主要应用。最后针对目前研究中存在的问题,对今后研究的主要方向作出了展望。  相似文献   

基于GIS和迈阿密模型的全球灌溉需水量计算     

梁书民  于智媛 《干旱地区农业研究》2019,37(3):96-103

通过计算光温生产潜力、气候生产潜力、光温潜力需水量、灌溉需水量以及衍生的可持续垦殖率指标，以解决农业生产潜力、农田熟制、灌溉定额、宜农荒地垦殖适宜性评价等农业发展问题。以迈阿密模型为理论基础，利用GIS空间分析的研究方法，计算出了上述指标的高精度全球分布场，得出全球光温生产潜力为2 260×10⁸ t干物质，气候生产潜力为1 253×10⁸ t干物质，灌溉需水量总计为12 441 km³。主要结论有：热带雨林区除外，全球气候生产潜力高值区同当前农业区高度吻合，表明农田气候潜力已经被人类充分利用；在温带地区，可持续覆膜雨养垦殖率＞2/3的地区适宜开垦宜农荒地，发展雨养农业。根据迈阿密模型计算得出的灌溉需水量可作为制定农田喷灌定额的重要依据；覆膜滴灌节水效果最佳，可持续覆膜滴灌垦殖率为各种垦殖率中最大值，可作为指导宜农荒地资源开发和多熟制农业发展的主要指标。  相似文献   

基于粒子图像测速的坡面流水动力学特性   总被引：2，自引：2，他引：0  

杨坪坪  张会兰  王云琦  李瑞 《农业工程学报》2020,36(17):115-124

粒子图像测速(Particle Image Velocimetry, PIV)技术具有多点同时测量、对水流无干扰的优点,该研究利用高分辨率PIV(分辨率为64 pixels/mm),测量了7组坡面流(水深范围为0.5～1.1 cm,雷诺数范围为1 000～3 000),并测量1组深水明渠紊流作为对照,研究了流速轮廓线和修正系数、紊动强度和雷诺应力、偏态系数和峰度系数的变化规律。结果表明:1)PIV能够有效观测坡面流床面至水面的流速分布。当坡面流流态为过渡流时,流速修正系数随着雷诺数的增加呈对数增加,均值为0.77;2)对比深水明渠紊流的紊动强度,坡面流的流向紊动强度较大,而垂向紊动强度较小,且随着水深及雷诺数的增加,坡面流紊动强度逐渐与深水明渠紊流的特征吻合。深水明渠紊流中受雷诺应力影响的流体占比约80%,而坡面流中受雷诺应力影响的流体占比小于80%,随着雷诺数的增加坡面流中受雷诺应力影响的流体占比变大;3)对比深水明渠紊流的峰度系数,坡面流的峰度系数大部分大于3,表明坡面流较深水明渠紊流出现极端流速事件的概率小。PIV技术有利于实验室研究坡面水力侵蚀的力学机理机制问题。  相似文献   

基于低影响开发的校园雨水控制及效益分析     

汪星  戎贵文  孙双科  郑铁刚  胡良宇 《排灌机械工程学报》2021,39(12):1223-1229

以安徽理工大学为研究对象,应用4种低影响开发(LID)方案(植草沟、下沉式绿地、雨水罐和植草沟-下沉式绿地-雨水罐组合)构建雨洪管理模型(SWMM),模拟不同雨水重现期下各种LID方案的水文和水质性能,并评价了经济效益.结果表明:植草沟的径流削减效率最好,可延迟流量峰现时间,且能有效地削减污染负荷;除雨水罐外,另外3种LID实践方案具有良好的环境效益;从成本效益上分析,下沉式绿地和组合LID实践方案的污染物控制效果较好,但其单位削减率成本高,植草沟对污染物控制效果不理想,但其具有最低的单位削减率;若想取得较好的污染物控制效果,则需要投入更大的成本,可以采用下沉式绿地或组合LID实践方案,下沉式绿地或组合LID实践方案不仅能有效削减峰值流量,缓解城市排水管网负荷,且对污染物的削减效果较好.可为中国校园中LID实践的应用决策提供理论支持.  相似文献   

Italian ryegrass establishment by self-seeding in integrated crop-livestock systems: Effects of grazing management and crop rotation strategies     

《European Journal of Agronomy》2014

We evaluated the re-establishment of an Italian ryegrass pasture by self-seeding on a no-till integrated crop-livestock systems (ICLS) in the southern region of Brazil. This work is part of a long-term experimental protocol initiated in 2003. We tested the effects of various management practices, such as summer crop systems (soybean vs. maize–soybean rotation), stocking methods (continuous vs. rotational) and grazing intensities (low vs. moderate), on Italian ryegrass pasture establishment. In addition, we tested resilience of the system by testing pasture's ability to re-establish following a year without seed head production. The experiment consisted in the rotation, on the same area, of Italian ryegrass pasture grazed by sheep during the winter and up to the end of the grass production cycle, and soybean or soybean-maize grain crops rotation cultivated during the summer. The pasture established itself by self-seeding since 2005. Data were collected in 2011 and 2012 stocking season. The soybean summer crop, continuous stocking and low grazing intensity, all positively affected the production of reproductive tillers in 2011. Grazing intensity in 2011 strongly influenced early vegetative tiller densities (before crop harvest) in 2012. However, none of the grazing intensity or the stocking method treatments affected herbage mass at the end of pasture establishment in 2011 or 2012. On the other hand, the soybean summer crop positively affected pasture establishment, both in term of tiller densities and herbage mass at the end of pasture establishment. The removal of all seed heads in 2011 (preventing seed production) resulted in the total failure of pasture establishment in 2012. Overall, Italian ryegrass establishment by self-seeding relies on the annual replacement of the soil seed bank. This experiment demonstrated that under various stocking methods, moderate grazing intensity and maize or soybean summer crop, Italian ryegrass pasture establishment by self-seeding remains successful even when the stocking periods extended up to the end of the grass production cycle. Self-seeding with moderate grazing intensity ensures successful pasture establishment, reduces labour and costs and allows to increase the stocking period and so animal live weight gain over the grazing season.  相似文献   

延边地区烟草病毒病与气象因子关系的研究     

高玉亮  高崇  张贵峰  朴龙铁  郑成睿  崔昌范 《延边大学农学学报》2014,(1):74-77,87

为探明延边地区烟草病毒病的发病规律,为生产优质高产烟叶提供科学有效的病毒病预防措施,简要分析了延边地区2010和2011年病毒病与气象因子的关系.结果表明,延边地区进入6月份,当日平均温度高于16.0℃,烟草病毒病就可以发生.病毒病发病前10d的日平均温度高,日照时数大于6h的天数多,降雨量少的情况下,病毒病发生严重.  相似文献   

蕹菜芽苗菜对LED 光强和光质的生长响应     

赵　硕赵柯涵  陈子义章竞瑾　黄丹枫 《中国蔬菜》2019,1(6):51-57

以阔叶空心菜为试材，研究蕹菜芽苗菜对LED 光强和光质的生长响应。结果表明：绿化阶段结束时处理L₇₀₀₀RBW4∶1∶1（光强7 000 lx，红光∶蓝光∶白光为4∶1∶1）的脱壳率显著高于其他处理；光强为7 000 lx 时，3 种光质处理的蕹菜芽苗菜可食部分干质量均显著高于白光对照；光照强度过高显著影响叶绿素的累积，高光强（L₁₁₀₀₀）下的叶绿素a、叶绿素b 含量及叶绿素总量随红光比例的增加而降低，同时子叶白化现象越发明显；不同光强条件下，3 种光质处理的抗坏 血酸含量均随着红光比例的增加而降低，而可溶性糖含量处理间差异不显著；主成分分析结果表明，L₇₀₀₀RBW4∶1∶1 在本试验条件下表现最佳，是较适宜蕹菜芽苗菜工厂化生产的LED 光源配方。  相似文献   

Influences of sand cover on erosion processes of loess slopes based on rainfall simulation experiments   总被引：1，自引：0，他引：1  

ZHANG Xiang  LI Zhanbin  LI Peng  TANG Shanshan  WANG Tian  ZHANG Hui 《干旱区科学》2018,10(1):39-52

Aeolian-fluvial interplay erosion regions are subject to intense soil erosion and are of particular concern in loess areas of northwestern China.Understanding the composition,distribution,and transport processes of eroded sediments in these regions is of considerable scientific significance for controlling soil erosion.In this study,based on laboratory rainfall simulation experiments,we analyzed rainfall-induced erosion processes on sand-covered loess slopes(SS)with different sand cover patterns(including length and thickness)and uncovered loess slopes(LS)to investigate the influences of sand cover on erosion processes of loess slopes in case regions of aeolian-fluvial erosion.The grain-size curves of eroded sediments were fitted using the Weibull function.Compositions of eroded sediments under different sand cover patterns and rainfall intensities were analyzed to explore sediment transport modes of SS.The influences of sand cover amount and pattern on erosion processes of loess slopes were also discussed.The results show that sand cover on loess slopes influences the proportion of loess erosion and that the compositions of eroded sediments vary between SS and LS.Sand cover on loess slopes transforms silt erosion into sand erosion by reducing splash erosion and changing the rainfall-induced erosion processes.The percentage of eroded sand from SS in the early stage of runoff and sediment generation is always higher than that in the late stage.Sand cover on loess slopes aggravates loess erosion,not only by adding sand as additional eroded sediments but also by increasing the amount of eroded loess,compared with the loess slopes without sand cover.The influence of sand cover pattern on runoff yield and the amount of eroded sediments is larger than that of sand cover amount.Furthermore,given the same sand cover pattern,a thicker sand cover could increase sand erosion while a thinner sand cover could aggravate loess erosion.This difference explains the existence of intense erosion on slopes that are thinly covered with sand in regions where aeolian erosion and fluvial erosion interact.  相似文献   

宁南山区经济林降雨集流机理试验研究     

丁广  张维江  李娟  王旭东  马芳  姜茂付  姜瑞洋  黄艳 《水土保持通报》2020,40(3):14-19,34

[目的]探究宁夏回族自治区固原市原州区彭堡镇红梅杏经济林降雨集流渗灌系统的雨水收集能力,明确当地红梅杏经济林降雨分配特征,为降雨集流的定量研究和该地区集雨农业的发展提供科学依据。[方法]以当地红梅杏为研究对象,采用对比观测的方法,以天然降雨和人工模拟降雨相结合的方式,对红梅杏降雨集流过程进行观测与模拟。[结果] 2019年7—9月在彭堡红梅杏基地观测到的总计19场降雨数据,天然降雨中5 mm以下的降雨次数占到天然降雨总次数的83.3%,天然降雨与人工模拟降雨的相似系数为0.91,总体的集流率为61.29%,渗灌系统截留率为27.12%,林冠截留率为11.95%。[结论]试验地小降雨频率大,两种降雨方式具有较高相似性,降雨集流渗灌系统集流效率高,渗灌系统的集流量与降雨量成线性关系(R~2=0.995 5),集流率与降雨量成对数关系(R~2=0.693 9)。  相似文献