Soil erosion and pollutant transport during rainfall-runoff processes     

Zhiguo He  Haoxuan Weng  Hao-Che Ho  Qihua Ran  Miaohua Mao 《Water Resources》2014,41(5):604-611

The pollutant from land surface applied to agricultural chemicals is one of the major sources of contamination in water bodies. The pollutant transport within a watershed is profoundly influenced by the rainfall-runoff processes, especially the associated upland erosion and sediment transport processes because most of pollutant can be dissolved into water or attached to the soil particles. A set of soil experiments in laboratory was conducted in this paper to investigate the impacts of upland erosion and sediment transport on pollutant loads. The soil utilized for the experiments was the silty sand collected from Loess Plateau, China; and ammonium bicarbonate was applied on the soil surface as the pollutant source. Runoff discharge, soil loss, and ammonia- and nitrate-nitrogen concentrations were measured to establish the relationships which can help the numerical model to predict the pollutant losses coupled with upland soil erosion during the rain-fall-runoff processes. The experimental results indicate the ammonia-nitrogen concentration in runoff reaches the peak at the initial stage of the overland flow generation, and quickly decreases and approaches to the steady state. The ammonia-nitrogen transported by the soil loss also makes contributions to the nitrogen loss; and its amount mainly depends on the soil transport rate. The ammonia-nitrogen dissolved in overland flow is dominant due to the strong aqueous solution of ammonium bicarbonate during the first storm right after its application.  相似文献   

充气截排水渗流与变形耦合数值模拟     

陈永珍  吴斌  杨帆  吴纲  翁杨 《吉林大学学报(地球科学版)》2019,49(2):485-492

为了探究坡体充气时土体渗流与变形之间的变化规律,利用有限元软件建立厚12m、长100m的二维边坡模型,进行渗流-变形的非完全耦合数值模拟,得到对坡体采取充气截排水方法降低地下水位时坡体内充气非饱和区的形成过程,以及坡体表面土体竖向位移的变化过程。结果表明:一个完整稳定的非饱和区形成过程可分为充气初始阶段、非饱和区扩大水位抬升阶段、不稳定两相流阶段和非饱和区稳定阶段,充气压力过大或过小都无法形成稳定完整的非饱和区;当充气压力为100kPa时,坡体表面土体的竖向位移均随时间呈现先增大后减小的规律,与土体中非饱和区的发展具有一定的协同性;不同充气压力下,偏向充气点上游的坡体表面土体竖向位移随充气压力的增大而增大,偏向充气点下游的坡体表面土体竖向位移的变化具有不确定性。  相似文献   

海外潮人文学刍论     

翁奕波 《吉林地质》2009,(4)

语言是文学的工具,海外华文文学就是以其使用工具之文字国别来划分的。海外潮人文学作为海外华文文学大家庭的一分子,在文字国别上,选取的也主要是"用华文作为表达工具而创作的文学",但它与海外华人文学一样,并不排除用其他国别文字作为表达工具。从文化人类学的事业考察,海外潮人文学与海外华人文学注重的都是其海外华人这一创作主体,是具有中华文化传统和海外各国各地区文化特色的海外华人。而海外华文文学则不限制创作主体的人类文化种属。海外潮人文学是海外华人文学的一部分,与海外华文文学一样,都是大中华文化圈里催生出来的文学。略为区别的是,它是由一种地域范畴的人文现象——潮人文化产生的,是中华大文化圈里的潮人文化催生出来的一种"类族群文学"。  相似文献   

广东一次补充型冷空气过程分析     

翁向宇  毛绍荣 《广东气象》2001,(4):1-3

本文通过对2001年1月的一次强冷空气过程分析，总结出在500hPa南槽北脊高低纬反位相配置形势下，不利于冷空气南下越时南岭，低层冷空气只能在南岭北侧堆积，但当冷空气堆积到南岭两侧温差超过10℃以上，南岭以北的冷空气积聚已达临界值，一次不太强的冷空气补充也会使冷空气冲破南岭屏障，这时影响广东的冷空气已经是前几次叠加，强度明显加强。  相似文献   

The mechanism of barrier river reaches in the middle and lower Yangtze River     

Xingying You  Jinwu Tang  Xiaofeng Zhang  Weiguo Hou  Yunping Yang  Zhaohua Sun  Zhaohui Weng 《地理学报(英文版)》2017,27(10):1249-1267

Alluvial channel has always adjusted itself to the equilibrium state of sediment transport after it was artificially or naturally disturbed. How to maintain the equilibrium state of sediment transport and keep the river regime stable has always been the concerns of fluvial geomorphologists. The channel in the middle and lower reaches of the Yangtze River is characterized by the staggered distribution of the bifurcated river and the single-thread river. The change of river regime is more violently in the bifurcated river than in the single-thread river. Whether the adjustment of the river regime in the bifurcated river can pass through the single-thread river and propagate to the downstream reaches affects the stabilities of the overall river regime. Studies show that the barrier river reach can block the upstream channel adjustment from propagating to the downstream reaches; therefore, it plays a key role in stabilizing the river regime. This study investigates 34 single-thread river reaches in the middle and lower reaches of the Yangtze River. On the basis of the systematic summarization of the fluvial process of the middle and lower reaches of the Yangtze River, the control factors of barrier river reach are summarized and extracted: the planar morphology of single-thread and meandering; with no flow deflecting node distributed in the upper or middle part of the river reach; the hydraulic geometric coefficient is less than 4; the longitudinal gradient is greater than 12‰, the clay content of the concave bank is greater than 9.5%, and the median diameter of the bed sediment is greater than 0.158 mm. From the Navier-Stokes equation, the calculation formula of the bending radius of flow dynamic axis is deduced, and then the roles of these control factors on restricting the migration of the flow dynamic axis and the formation of the barrier river reach are analyzed. The barrier river reach is considered as such when the ratio of the migration force of the flow dynamic axis to the constraint force of the channel boundary is less than 1 under different flow levels. The mechanism of the barrier river reach is such that even when the upstream river regime adjusts, the channel boundary of this reach can always constrain the migration amplitude of the flow dynamic axis and centralize the planar position of the main stream line under different upstream river regime conditions, providing a relatively stable incoming flow conditions for the downstream reaches, thereby blocking the upstream river regime adjustment from propagating to the downstream reaches.  相似文献   

单台多震和达法研究山西地区的波速比变化特征     

翁钊强  梁向军  吴昊昱  刘林飞  李丽 《中国地震研究》2015,29(4):514-526

基于山西数字地震台网2001年1月～2014年10月ML≥2.0地震震相到时数据,利用单台多震和达法计算山西地区波速比,并结合2010年3次MS≥4.5地震探讨地震前后波速比的变化特征。结果表明,在3次地震前远台波速比异常出现时间较早,为震前6个月至1年;而近台波速比异常出现时间相对较晚,为震前10天至2个月不等,因此可通过远台、近台所围限的范围来缩小地震预测地点。东山台计算结果表明,发震时刻残差大小会影响波速比变化细节,因此在实际应用中,应首先确定每个台站发震时刻的残差阈值,以确保波速比计算结果的科学性和稳定性。  相似文献   

河北省滨海旅游发展动力系统的因子分析   总被引：1，自引：0，他引：1  

翁钢民  贾苗苗  徐晓娜 《地域研究与开发》2010,29(1)

河北省滨海旅游在全省旅游业中占有重要地位。了解有哪些因素在推动河北省滨海旅游的发展,这些因素以何种组织关联构成一个动力系统,是确定河北省滨海旅游未来发展战略的必然要求。通过对河北省滨海旅游发展现状的分析,探讨其滨海旅游发展的动力系统,运用因子分析法对该省滨海旅游发展动力因子进行量化计算,根据计算结果对提取的主因子进行解释并提出相关建议,以期推动河北省滨海旅游的科学发展。  相似文献   

TOVS资料的变分处理方法在青藏高原地区的数值试验   总被引：16，自引：2，他引：14  

翁永辉  徐祥德 《大气科学》1999,23(6):703-712

首次在测站稀少的高原地区引入经变分技术处理的TOVS资料,使用MM5数值模式对高原地区降水数值预报难点进行了研究。探讨了解决高原地区测站少、数值预报模式初始场信息误差大的技术关键问题,提出了采用TOVS资料在高原地区增加初始场信息的构思。数值试验结果表明,应用变分法处理后的TOVS资料,可显著地提高高原初始场信息的可靠性。考虑夏季高原地区是对流多发区特点,本文采用非静力MM5模式,并在模式初始场中增加了TOVS资料,弥补了测站稀少的高原地区使用非静力模式的不足之处。研究结果表明,本文采用的TOVS资料技术方案可能是高原区域数值模式降水预报的有效途径,并为开拓卫星资料的应用领域提供了技术思路与理论分析依据。  相似文献   

基于三峡秭归井水位和GNSS观测特征的地震活动性研究     

翁骋  王杰  鲁小飞  涂先新  吴海波  林俊 《中国地震》2023,39(2):325-333

三峡水库蓄水后,秭归盆地内部仙女山断裂北端邻近区域内发生多次3.5级以上地震,该地区的地震活动备受关注。本研究分析了该区域秭归井动水位的变化、水化学特征以及同期GNSS形变数据,结果显示:①秭归井水位的快速变化主要受该区域构造应力变化的影响,前期以拉张应力为主,后期区域应力变为挤压状态;②GNSS应变场特征显示面膨胀率高值区位于三峡库区周边及其南部,极高值区恰好位于仙女山断裂北部,且GNSS时间序列与秭归井水位的涨落存在较好的同步性;③2020年10月初开始的震群与该地区持续6个月的挤压状态有关,表明研究区应力积累已经超过岩层抗剪强度,岩层发生破裂。  相似文献   

环烷酸对淡水微藻生理生化特征的影响     

林治豪  张焕新  唐学玺  王影 《海洋与湖沼》2023,54(1):87-97

环烷酸是高酸原油的主要污染组分,对水生生态系统造成潜在威胁。在不同浓度环烷酸处理下对两种模式淡水微藻——莱茵衣藻(Chlamydomonas reinhardtii)和小球藻(Chlorella vulgaris)进行了96 h的连续培养,研究了环烷酸胁迫对两种淡水微藻种群及生理生化特征的影响,旨在为水生生态系统中环烷酸污染的生态风险预测与规避提供前瞻性的研究资料。研究结果表明,低浓度环烷酸(0.5～4 mg/L)会刺激淡水微藻的种群增长,而高浓度环烷酸(8～16 mg/L)会抑制淡水微藻的种群增长,造成急性毒性损伤。低浓度环烷酸处理下两种微藻叶绿素a含量上升,脂质积累,高浓度环烷酸处理下两种微藻叶绿素a含量下降而多糖含量上升,推测环烷酸剂量可能会影响淡水微藻能量存储方式。两种微藻在环烷酸胁迫下均会受到氧化损伤,造成活性氧(reactive oxygen species,ROS)含量上升,两种微藻抗氧化酶超氧化物歧化酶(superoxide dismutase,SOD)和过氧化氢酶(catalase,CAT)对环烷酸处理具有种属差异;高浓度环烷酸对淡水微藻的急性损伤具有时间效应,毒性随...  相似文献