不受潮汐影响城镇圩区排涝泵站群常规调度方案优化   总被引：3，自引：0，他引：3  

刘静森  程吉林  黄勇  龚懿 《灌溉排水学报》2015,34(3)

为降低不受潮汐影响城镇圩区排涝泵站群常规调度能耗,提出了排涝总能耗最小单目标选优和圩区内(外)河水位限制多目标去劣的优化方法。为圩区排涝泵站群常规调度确定若干种典型排水条件组合,对每组排水条件,以泵站为试验因素、各泵站不同的运行规则为试验水平、不同运行规则组合下的最小运行能耗为试验结果开展正交试验;对试验结果开展正交分析获得各泵站从优到劣不同运行规则组合序列。对每组运行规则序列,根据各泵站排水能力限制,应用动态规划法可获得圩区泵站群最低排涝能耗及对应的各泵站开机方案;对最低排涝能耗排序可获得圩区泵站群优化运行方案序列,进一步应用圩区内(外)河水位限制条件可获得圩区泵站群某排水条件下最优调度方案。以上海市城区某区域为实例,阐明了优化计算全过程,优化计算结果比现行调度方案的排涝能耗至少可节省6%。  相似文献   

冰灾后南岭树木园眼蝶科物种多样性的恢复研究     

龚粤宁  陈仁利  王胜坤  谢国光  顾茂彬 《广东林业科技》2014,(3):66-69

2008年1-2月南岭遭遇百年一遏的特大雨雪冰冻灾害,给森林生态系统造成了极大的破坏,使南岭国家级自然保护区位于南岭林区海拔500～600m的树木园内林木折断、倒伏及包括昆虫在内的野生动物大量死亡,其中眼蝶科灾后（2008年）种数比灾前2年（2006-2007年）的平均值降低50％、个数降低67．12％。灾后采取及时清理枯落物等恢复措施,有利于地面新生植物的萌生、预防森林火灾和可能引发的次生病虫害。经过5a的恢复期,林分及其生物多样性同步获得恢复。冰灾后形成的林窗萌生各种植物后,改善了林分结构,使森林生态系统得到修复和重建,也使植物种类比冰灾前更为丰富,生长势旺盛;眼蝶科种数比冰灾当年增加62．5％,个数比冰灾当年增加266．67％。可见,虽然冰冻灾害对森林生态系统产生严重影响,只要恢复措施得当,灾后的生态系统会逐渐优化。  相似文献   

Effects of sea-level rise and storm-enhanced flooding on Pacific harbour seal habitat: A comparison of haul-out changes at the Russian and Eel river estuaries     

Karen Backe  Ellen Hines  Karina J. Nielsen  Doug George  Elinor Twohy  Mark Lowry 《水产资源保护:海洋与淡水生态系统》2021,31(7):1749-1759

1. Patterns and changes in the distribution of coastal marine mammals can serve as indicators of environmental change that fill critical information gaps in coastal and marine environments. Coastal habitats are particularly vulnerable to the effects of near-term sea-level rise.
2. In California, Pacific harbour seals (Phoca vitulina richardii) are a natural indicator species of coastal change because of their reliance on terrestrial habitats, abundance, distribution, and site fidelity. Pacific harbour seals are marine top predators that are easily observed while hauled out at terrestrial sites, which are essential for resting, pupping, and moulting.
3. Although increasing inundation from recent sea-level rise and storm-driven flooding has changed the Californian coastline, little is known about the effect of future sea-level rise and increased storm frequency and strength on harbour seal haulout site availability and quality in California.
4. Harbour seal habitat was modelled at two sandbar-built estuaries under a series of likely sea-level rise and storm scenarios. The model outputs suggest that, over time, habitat at both estuaries decreased with increasing sea level, and storm-enhanced water levels contributed significantly to habitat flooding. These changes reflect pressures on coastal habitats that have an impact on human and natural systems.

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北京郊区农地起沙起尘与防治的初步研究     

王升堂  邹学勇  程宏  赵延治 《水土保持研究》2007,14(2):1-3

京郊农用地土壤风蚀而发生的起沙起尘是造成北京市大气环境中、重度污染的重要原因之一.为有效地防治北京郊区农业用地的起沙起尘,在2003年和2004年对京郊不同土地利用类型地表粗糙度和起沙情况进行了多次重复的野外观测.地表粗糙度观测结果表明,不同土地利用类型地表粗糙度明显不同,即使是同一地类,地表状况不同,粗糙度也有很大差异,这为通过调整土地利用结构来防止起沙起尘提供了依据.在2 m高风速为8.6 m/s时,玉米低留茬地上观测到的输沙率高达0.597 kg/(m·h),表明在大风条件下,留荐高度过低时防风蚀作用不明显.依据上述风沙观测结果,结合北京市土地资源特点和利用现状,提出调整土地利用结构,完善平原区防护林体系,全面实行保护性耕作,硬化乡间道路等控制京郊农地起沙起尘的措施.  相似文献   

甲型流感病毒与NLRP3炎性小体激活的研究进展     

潘文亮  江宁  王松  邱世昕 《畜牧与兽医》2021,(4):132-138

甲型流感病毒(influenza A virus,IAV)对全人类的健康构成了持续性威胁,感染时会引发炎症性疾病。NOD样受体蛋白3(NOD-like receptor protein 3,NLRP3)炎性小体是一种天然免疫系统传感器,与甲型流感病毒感染引发的炎症反应相关。在宿主细胞被甲型流感病毒感染时,能够激活NLRP3炎性小体,促使pro-IL-1β和pro-IL-18剪切成熟的IL-1β和IL-18并分泌至胞外,进而引发炎症反应。研究表明,NLRP3炎性小体对于在甲型流感病毒感染期间诱导先天性免疫应答至关重要,并且由甲型流感病毒感染引发过度激活的NLRP3炎性小体与细胞因子风暴和不受控制的炎症反应有关。本文回顾了甲型流感病毒与NLRP3炎性小体之间关系的研究进展,并讨论了NLRP3炎性小体在甲型流感病毒致病机理中的保护作用和致病作用。  相似文献   

Unpaved road erosion after heavy storms in mountain areas of northern China   总被引：2，自引：0，他引：2  

《国际水土保持研究(英文)》2022,10(1):29-37

More frequent extreme rainfall events associated with global climate change cause greater challenges for soil conservation. Severe erosion occurs on many unpaved roads since these structures create important water flow paths during heavy storms. The present research aimed to investigate the intensity and influencing factors of unpaved road erosion under varied land use and management conditions (sloping cropland, terraced cropland, forest & grass). The erosion occurred in the watersheds contributing runoff water to roads after the greatest rainfall event recorded in the mountain area of northern China caused by Typhon Lekima. The research was conducted in an agricultural-forest-dominated watershed based on field investigation and UAV-based image analysis. A road erosion level classification standard was given according to the occurrence of rills, ephemeral gullies, and gullies. Significant erosion happened on 67% of the unpaved roads; 42% of them suffered moderate to severe erosion in which ephemeral gullies or gullies developed. The average erosion amount from these roads was 2280.75 t ha^-1 and was significantly influenced by the watershed land use type and management. The dominant factor governing unpaved road erosion associated with terraced cropland was vegetation coverage on roads. Drainage area was the most important factor for road erosion in sloping cropland and forest & grass land, and road gradient was also a critical factor. Terraces, and forest & grass in drainage areas significantly reduced unpaved road erosion by 85% and, 47%, respectively, compared to sloping cropland. More integrated measures should be used to prevent unpaved road erosion. The results of this research can be applied to road protection against erosion in heavy storms.  相似文献   

Landscape Fragmentation and Ice Storm Damage in Eastern Ontario Forests     

J.?Pasher  D.?J.?KingEmail author 《Landscape Ecology》2006,21(4):477-483

With return times between 20 and 100 years, ice storms are a primary disturbance type for temperate forests of eastern North America. Many studies have been conducted at the forest patch and plot scales to examine relations between damage and variables describing site, composition and structure. This paper presents results from a landscape scale study of fragmentation relations with damage in eastern Ontario forests. Data previously collected for two independent and spatially non-overlapping patch level damage studies were used. A Generalized Linear Model (GLM) was used to analyse relations between damage and fragmentation metrics representing patch isolation, edge density, and the relative size and distribution of patches in the landscape. The metrics were applied using spatial extents of 1 × 1 km and 4 × 4 km, following analyses of the variability of numbers of patches and of the lacunarity of forest patterns over a range of extents. The results showed that patch isolation, as measured by the mean Euclidean distance between patches (ENN) was significantly related to damage.  相似文献   

Characteristics of air pollution events over Hotan Prefecture at the southwestern edge of Taklimakan Desert,China     

LI Jingxin  WANG Shigong  CHU Jinhua  WANG Jiaxin  LI Xu  YUE Man  SHANG Kezheng 《干旱区科学》2018,10(5):686-700

Hotan Prefecture is located at the southwestern edge of Taklimakan Desert, the world's largest shifting sand desert, of China. The desert is one of the main sources for frequent sand-dust weather events which strongly affect the air quality of Hotan Prefecture. Although this region is characterized by the highest annual mean PM_(10) concentration values that are routinely recorded by environmental monitoring stations across China, both this phenomenon and its underlying causes have not been adequately addressed in previous researches. Reliable pollutant PM_(10) data are currently retrieved using a tapered element oscillating microbalance(TEOM) 1400 a, a direct real-time monitor, while additional concentration values including for PM_(2.5), sulfur dioxide(SO_2), nitrogen dioxide(NO_2), carbon monoxide(CO) and ozone(O_3) have been collected in recent years by the Hotan Environmental Monitoring Station. Based on these data, this paper presents a comparison of the influences of different kinds of sand-dust weather events on PM10(or PM_(2.5)) as well as the concentrations of other gaseous pollutants in Hotan Prefecture. It is revealed that the highest monthly average PM10 concentrations are observed in the spring because of the frequent occurrence of three distinct kinds of sand-dust weather events at this time, including dust storms, blowing dust and floating dust. The floating dust makes the most significant contribution to PM_(10)(or PM_(2.5)) concentration in this region, a result that differs from eastern Chinese cities where the heaviest PM_(10) pollution occurs usually in winter and air pollution results from the excess emission of local anthropogenic pollutants. It is also shown that PM_(10) concentration varies within typical dust storms. PM_(10) concentrations vary among 20 dust storm events within Hotan Prefecture, and the hourly mean concentrations tend to sharply increase initially then slowly decreasing over time. Data collected from cities in eastern China show the opposite with the hourly mean PM_(10)(or PM_(2.5)) concentration tending to slowly increase then sharply decrease during heavy air pollution due to the excess emission of local anthropogenic pollutants. It is also found that the concentration of gaseous pollutants during sand-dust weather events tends to be lower than those cases under clear sky conditions. This indicates that these dust events effectively remove and rapidly diffuse gaseous pollutants. The analysis also shows that the concentration of SO_2 decreases gradually at the onset of all three kinds of sand-dust weather events because of rapidly increasing wind velocity and the development of favorable atmospheric conditions for diffusion. In contrast, changes in O_3 and NO_2 concentrations conformed to the opposite pattern during all three kinds of sand-dust weather events within this region, implying the inter transformation of these gas species during these events.  相似文献   

海平面上升叠加风暴潮风险下城市景观系统脆弱性评估：以广州为例          下载免费PDF全文

陈崇贤  方言  刘京一 《华中农业大学学报》2023,42(4):53-63

为系统评估海平面上升叠加风暴潮风险对城市不同类型景观的影响，以珠三角沿海城市广州市为研究区域，基于该地区土地利用和社会经济等数据，构建“敏感性-适应性”脆弱性评估框架，针对近期（2030年）、中期（2050年）和远期（2100年）3个不同时期海平面上升叠加风暴潮风险情景下广州城市景观系统的脆弱性特征进行评估。结果显示：从淹没范围和经济损失来看，未来不同风险情景下受淹没面积最大的是农业景观、公园绿地与湿地景观，而经济损失最为严重的是工业景观和商业与公共服务景观。从整体脆弱性空间分布来看，近期景观脆弱性较高的区域主要集中在广州中部的荔湾区、白云区和黄浦区，到中期和远期阶段，广州中部的海珠区景观脆弱性风险逐渐加剧。从各类景观脆弱性空间分布来看，与交通景观、居住区景观等其他各类景观相比，近期农业景观脆弱性程度偏高的区域最多，主要集中在广州南部的番禺区和南沙区；到中期和远期阶段，各类景观的脆弱性风险都有不同程度的加剧，其中，公园绿地与湿地景观脆弱性程度变化较为显著。研究结果表明，未来可以根据不同景观系统的脆弱性程度和空间分布特征，通过提升防御性设施建设、实施适应性技术以及加强合理利用土地等应对策略来降低该地区的受灾风险。  相似文献   

山东临朐2019年“8·10”特大暴雨水土保持调查   总被引：2，自引：0，他引：2       下载免费PDF全文

林祚顶  刘宝元  丛佩娟  焦菊英  王春梅  党维勤  邢先双 《水土保持学报》2021,35(1):149-153

2019年8月10日6时至12日6时,受台风“利奇马”影响,山东淄博、东营、潍坊等地区发生特大暴雨天气,造成了严重的水土流失灾害。暴雨发生后,水利部水土保持监测中心组织调查人员,运用现代技术手段对暴雨中心典型小流域进行了系统、全面的水土保持实地调查。结果表明:(1)本次特大暴雨降雨量为570.6 mm,最大24 h降雨507.6 mm,均超过历史记录;(2)本次暴雨造成严重水土流失灾害,典型小流域水蚀模数达9741 t/km^2,是多年平均值的2.4倍,梯田损毁率达5.96%,河道淤积厚度达10~30 cm,近1/3生产道路完全损毁,引起了严重的重力侵蚀,多处发生滑坡、泥石流;(3)通过对比小流域调查发现,高林草覆盖和重点工程治理分别可削减洪峰模数79%和36%,降低水蚀模数分别达80%和54%;重点治理小流域道路损毁比例减少23.9%,梯田损毁减少40.4%,重力侵蚀减少40%以上。调查摸清了本次特大暴雨径流输沙特征、土壤侵蚀状况、水土流失成灾情况、水土保持措施效益等,初步形成了科学的暴雨水土流失调查方法体系,为今后暴雨水土保持调查制度的建立提供了良好基础。  相似文献