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1.
滞后补给权函数:降雨补给潜水滞后性处理方法 总被引:16,自引:0,他引:16
陈崇希 《水文地质工程地质》1998,25(6):22-24
本文分析了当前数值模型中处理降雨入渗补给潜水方法中存在的问题,提出一种能刻画滞后补给且使用方便的方法-滞后补给权函数法。 相似文献
2.
本文记述了一件产自辽宁锦州义县早白垩世九佛堂组燕鸟 (Yanornis)化石的新标本。研究标本不但自身保存非常精美 ,而且其嘴里还完整地保存了它捕获的最后一件猎物——吉南鱼 (Jinanichthys longi-cephalus)。该标本的研究 ,不仅对燕鸟的生存环境、生活习性、捕食类型等研究提供了直接的证据 ,而且对于探讨辽西热河生物群中脊椎动物的“集群死亡”的原因也具有重要的意义 相似文献
3.
Land subsidence caused by groundwater exploitation in Suzhou City,China 总被引:10,自引:2,他引:10
Suzhou City, located at the lower reaches of the Yangtze River in southeastern Jiangsu Province, is one of the few cities
in China which suffer from severe ground settlement. A research project was carried out to investigate this problem. Geological
and hydrogeological studies show that there is a multi-layered aquifer system with three distinct, soft mud layers of marine
and lagoonal origins. An examination of historical records of groundwater extraction, water levels, and ground settlement
shows that the ground subsidence is associated with the continuously increasing groundwater extraction in the deep, confined
aquifer. It is believed that the consolidation of the soft mud layers, especially the third layer which is thick and close
to the main pumped aquifer, contributes to the ground settlement. A three-dimensional finite difference numerical model representing
the multi-layered aquifer system was developed to study the ground settlement in response to groundwater extraction. By calibrating
the model with both the measured groundwater level and ground settlement, the aquifer parameters were estimated. The model
outputs fit reasonably well with the observed results, which indicates that the numerical model can reproduce the dynamic
processes of both groundwater flow and soil consolidation. The hydraulic conductivity of the third mud layer near the center
of the ground settlement has been reduced by over 30% in the last 14 years. The gradual deterioration in the hydraulic conductivity
of the mud may have significant adverse effect on the sustainable groundwater resource of the deep confined aquifer, since
the recharge from the shallow aquifers through the mud layer is the only source of water to the deep aquifer. An analysis
of the spatial distributions of groundwater drawdown and ground settlement shows that the area with maximum drawdown is not
necessarily the area with maximum ground settlement due to the occurrence of the soft mud layer. A simple reallocation in
pumping rates on the basis of the spatial distribution of the thick mud layer could significantly reduce the ground settlement.
Electronic Publication 相似文献
5.
2D Coupled 3D:A New Numerical Model forDual-Structured-Aquifer System¥ChenChongxi;FangShuzhen;LinMin(FacultyofEnvironmentalSc... 相似文献
6.
YUAN Chongxi 《《地质学报》英文版》2008,82(1):48-55
Sapeornithidae is a basal pygostylian family of Early Cretaceous primitive birds, in which only one genus and species, Sapeornis chaoyangensis, was reported before. This paper deals with a new genus and species of this family, Didactylornis jii gen. et sp. nov., which was unearthed from the Early Cretaceous Jiufotang Formation in western Liaoning. According to our phylogenetic analyses, both Didactylornis gen. nov. and Sapeornis form a sister group, which is basal to the clade formed by Confuciusornis and all the more derived birds, and more closely related to the short-tailed pygostylian birds than to the long-tailed avialian birds. The early history of pygostylian birds is poorly documented except for the studies of Confuciusornis and Sapeornis. The discovery ofDidactylornisjii gen. et sp. nov. adds the new material for the study on the early evolution of birds. 相似文献
7.
KOBAYASHI Yoshitsugu 《《地质学报》英文版》2005,79(6):766-769
The cross-section and surface structures of wing membranes from the ctenochasmatid pterosaur Beipiaopterus chenianus were observed through a scanning electron microscope (SEM). The results show that the wing membrane contains a high density of blood vessels, implying strong thermoregulatory function, similar to that of a bat wing membrane. This is the first comparison of the microstmctures of pterosaur wing membranes with those of the modem bat. It is inferred that a bat-like physiology exists, at least in relatively small pterosaurs suggesting that these pterosaurs were warm-blooded, active fliers. 相似文献
8.
New Tapejarid Pterosaur from Western Liaoning, China 总被引:5,自引:1,他引:5
Lü Junchang YUAN Chongxi Institute of Geology Chinese Academy of Geological Sciences Beijing E-mail: tmcpl@yahoo.com 《《地质学报》英文版》2005,79(4):453-458
A new tapejarid pterosaur Huaxiapterus jii gen. et sp. nov. is erected based on a nearly complete skeleton with a skull. The skull morphology of Huaxiapterus jii gen. et sp. nov. appears transitional between the skulls of Sinopterus and Tapejara. The skull morphology (low crest) of Huaxiapterusjii indicates that Huaxiapterus is more closely related to Sinopterus than to Tapejara, which has a high crest. The relatively long and shallow skull of Sinopterus indicates that it is a primitive form. Huaxiapterus is more derived than Sinopterus but more primitive than Tapejara. 相似文献
9.
再论道虎沟生物群的时代 总被引:14,自引:1,他引:14
内蒙古宁城道虎沟地区的晚中生代地层十分发育,产状平缓,主要为一套产有丰富动、植物化石的凝灰质泥岩和粉砂岩,并夹有数层火山岩。从区域上来看,在西台子一带主要为早白垩世义县组的地层,产有丰富的热河生物群的化石,常见者有鱼类Lycoptera davidi,Peipiaosteus pani,Yanosteus longidorsalis,Protopsephurus liui和鸟类Confuciusornis anctus;但在道虎沟—小西沟一带主要为中—晚侏罗世髫髻山组的地层,产有丰富的道虎沟生物群的化石,常见者有蝾螈Jeholotriton paradoxus和Chunerpeton tianyiensis,翼龙Jeholopterus ningchengensis和Pterorhynchus wellnhoferi,手盗龙类Scansorio pteryxheilmanni和(?)Pedopenna daohugouensis[本文对Xu等(2005)描述的道虎沟足羽龙(Pedopennad aohugouensis)的原始产地存有疑义],昆虫Mesobaetis sibirica,Mesoneta antiqua,Rhipidoblattina(Canaliblatta)hebeiensis,Brunneus haifanggouensis,Palaeontinodes haifanggouensis等,叶肢介Euestheria zilu jingensis,E.haifanggouensis,E.jingyuanensis和E.1uanpingensis,植物Cladophleln's(Osmunda?)sp.,Anomozamites angulatus,A.(Trymia?)sp.,Cycadolepissp.,Gmkgotes sp.,Pityospermus sp.,Pityocladus sp.,Zamitesgigas,Yanliaoiasmensis和Coniopteris burejem括等。根据区域地质构造、地层分布、生物群特征和地质年代学资料分析,笔者确信道虎沟生物群的时代为中—晚侏罗世(卡洛夫阶—牛津阶),根本不可能将其归于早白垩世热河生物群。 相似文献
10.
本文简要回顾了蜀兽类哺乳动物的研究历史,论述了在哺乳动物牙齿演化和中生代陆相地层对比研究中的科学意义。粗壮假碾磨齿兽的发现有力地支持了哺乳动物中“三磨楔齿形臼齿趋同演化”的假设,并再一次以直接的化石证据表明内蒙古宁城道虎沟地区含蜀兽类化石地层的时代为中侏罗世。 相似文献