宽甸县水土流失灾害与防治对策     

张瑛 《国土资源》1999,(4)

宽甸县处于新构造运动强烈上升区,境内峰峦叠嶂,山势陡峻,沟深谷狭,暴雨频繁,地质环境十分脆弱;加之森林大量砍伐,陡坡开荒严重,垦植指数过高,超载养蚕放牧,滥采乱挖猖獗,使生态环境遭到严重破坏,水土流失程度日益加剧。严重的水土流失,导致水库淤积,河道堵塞,土层变薄,地力下降,洪水泛滥,灾害频繁,给国民经济和社会发展造成巨大损失。本文阐述了宽甸山区水土流失的形成因素和危害现状,并因地制宜提出了水土流失灾害的防治对策  相似文献   

Factors and processes of permanent gully evolution in a Mediterranean marly environment (Cape Bon,Tunisia)     

A. El Khalili  H. Habaeib  J. M. Lamachère 《水文科学杂志》2013,58(7):1519-1531

Abstract

Gully erosion is considered to be one of the most important soil erosion processes in Mediterranean marly environments, but its actual contribution to total soil loss is still under discussion. The objectives of this paper are: (a) to acquire the distributed value of erosion rate in a permanent gully developed on a marly substratum in a Mediterranean environment; and (b) to quantify the key factors responsible for the spatial and temporal differences in erosion rates observed within the gully. A permanent gully located in Cap Bon (northeastern Tunisia) has been intensively and regularly monitored over a 7-year period with electronic survey equipment (total station) to give five field topographic surveys, as well as hydrological measurements at the gully outlet. The net soil loss for the 7-year period comprised a denudation of 51 m³ of sediment on the gully bank slopes, which corresponds to a mean soil loss of 61 m³ ha^?1 year^?1 or 6.1 mm year^?1. Denudation was observed on bed units with a slope gradient greater than 20%, while the remainder showed deposition. By confirming the factors involved in gully evolution, and by refining the statistical link between factors and erosion rates within the gully, the results provide important information to predict gully erosion rates in Mediterranean marly environments.

Editor Z.W. Kundzewicz; Associate editor G. Mahé

Citation El Khalili, A., Raclot, D., Habaieb, H., and Lamachère, J.M., 2013. Factors and processes of permanent gully evolution in a Mediterranean marly environment (Cape Bon, Tunisia). Hydrological Sciences Journal, 58 (7), 1519–1531.  相似文献   

墨西哥湾南部晚侏罗纪主力烃源岩的形成条件   总被引：3，自引：0，他引：3  

龚建明  文丽  李慧君  王文娟  杨传胜 《海洋地质前沿》2010,26(3)

通过对墨西哥湾不同时代可采储量的分布特征和油源对比资料的分析认为,晚侏罗纪烃源岩是墨西哥湾南部最主要的烃源岩。资料显示,晚侏罗纪优质烃源岩形成的主控因素是稳定的构造和沉积条件以及超咸的还原环境,其中,"世界顶级"的晚侏罗纪提塘阶烃源岩主要形成于超咸的碳酸盐岩和/或蒸发岩沉积环境,属半深海还原环境,有机质以藻类为主,推测烃源岩中的有机质可能与极端干旱气候条件下的藻类勃发有关。  相似文献   

Gene flow and demographic history of the mangrove crab Neosarmatium meinerti: A case study from the western Indian Ocean     

Lapo Ragionieri  Stefano Cannicci  Christoph D. Schubart  Sara Fratini 《Estuarine, Coastal and Shelf Science》2010

Most marine organisms are characterized by at least one planktonic phase during their life history, potentially allowing interconnection of populations separated by several hundred kilometers. For many years, the idea that marine species are genetically homogenous throughout their range of distribution, due to passive larval transport, has been a paradigm. Nowadays, a growing number of studies underline the existence of boundaries in the marine realm and highlight how larval dispersal is a complex process depending on biotic as well as abiotic factors. Marine fragmented habitats, such as atolls, mangroves and estuaries, are optimal systems for investigating the marine dispersion process under a metapopulation approach, since populations can be geographically defined a priori as opposed to those occupying open marine environments. Within this frame, the present paper investigates the population genetic structure and the demographic history of the mangrove crab Neosarmatium meinerti within the western Indian Ocean by partial sequences of the mitochondrial DNA cytochrome oxidase subunit I. A total of 167 specimens were sampled from six mangrove sites distributed along the East African coast, from Kenya to South Africa, also including a mangrove forest located on Mahé Island, Seychelles. A sharp genetic break between the mainland and the Seychelles is recorded, revealing the existence of two historically distinct groups that can be defined as independent evolutionary units. Gene flow along the East African coast appears to be high enough to form a single metapopulation, probably by means of stepping stone populations. Otherwise, this mainland metapopulation is currently under expansion through a gradual moving front from the subtropical toward the equatorial populations.  相似文献   

漓江流域水环境综合治理对策     

成官文 《南方国土资源》1999,12(2):27-30

文章概述了漓江流域水环境现状，分析了存在的主要问题，阐明了流域水灾频繁、水环境污染的成因，指出了流域森林结构欠合理，调蓄能力不足，导致了流域洪涝、干旱频繁，枯水期长，水资源短缺；流域生活与生产排污，造成枯水期水污染。因而需进行深入的科学研究、绿化、兴修水利工程、实施节水技术、严格管理、科学调配水资源等综合举措，实现流域的可持续发展。  相似文献   

EXERCISE IN DOWNSCALING ON SEA SURFACE TEMPERATURE ALONG CHINESE COAST     

练树民  王凯  崔茂常  EduardoZorita 《中国海洋湖沼学报》2000,18(2)

ＩＮＴＲＯＤＵＣＴＩＯＮＴｈｅｍｏｎｓｏｏｎｈａｓａｃｉｒｃｕｌａｔｉｏｎｆｅａｔｕｒｅｔｈａｔｉｓｐｌａｎｅｔａｒｙｉｎｓｃａｌｅａｎｄａｎｉｄｅｎｔｉｆｉａｂｌｅｓｉｇｎａｌｒｅｇａｒｄｉｎｇｉｔｓｓｕｂｓｅｑｕｅｎｔｉｎｔｅｎｓｉｔｙｓｏｍｅｎｉｎｅｍｏｎｔｈｓｐｒｉｏｒｔｏｔｈｅａｃｔｉｖｅｓｔａｇｅｏｆｔｈｅｓｕｍｍｅｒｍｏｎｓｏｏｎ(ＷｅｂｓｔｅｒａｎｄＹａｎｇ,1992).Ｆｕｒｔｈｅｒｍｏｒｅ,ｔｈｅｍａｇｎｉｔｕｄｅｏｆｔｈｅｍｏｎｓｏｏｎｖａｒｉａｂｉｌｉｔｙｉｓｓｕｂｓｔａｎｔｉａ…  相似文献   

21世纪全球油气资源形势和海上多波地震技术展望     

朱光明  李庆春  王玉贵 《地球科学与环境学报》2000,22(1)

首先综述了现在对全球油气资源量的估计和对 2 1世纪全球油气资源发展形势的预测。表明2 1世纪全球油气资源不会枯竭。未来 10 0年 ,不是世界上有没有油气可供开采 ,而是环境允不允许和在多大程度上允许以及用多大的成本开采的问题。在所有情况下 ,技术进步都起着关键的作用。然后从油气勘探角度对技术进步中的一项主要技术———多分量地震的历史、现状和发展作了评述 ,并结合国家 86 3项目关于海上多波地震技术研究的状况提出了进一步实施的设想  相似文献   

Tertiary coal geology and stratigraphy of the Port Phillip Basin,Victoria     

G. R. Holdgate  S. J. Gallagher  M. W. Wallace 《Australian Journal of Earth Sciences》2013,60(3):437-453

Results from coal‐exploration drilling in the onshore part of the Port Phillip Basin, Victoria, have established stratigraphic and age correlations of the Lower Miocene Werribee Formation brown coal deposits at Bacchus Marsh to similar brown coals at Altona. The coal deposits occur in a northwest‐southeast structural depression (the Parwan Trough) that appears to be a southeast continuation of the Ballan Graben. Recent drilling for potential coal‐bed methane in the trough has provided new data on the deeper stratigraphy not penetrated by earlier drilling, including recognition of an Upper Cretaceous to Eocene Yaloak Formation coal‐bearing interval, similar to the Anglesea area, Ballan Graben and Lal Lal Basin. Up to 200 m of coal‐bearing sediment and minor volcanics underlie the Miocene coal measures. A marine facies transition takes place between the Miocene coal swamps of the Parwan Trough, through barrier sands west of Werribee, to carbonate facies near Geelong. To the south beneath Port Phillip Bay, a similar transition probably occurs between coal swamps of the Parwan Trough and fully marine carbonate environments of the contiguous Sorrento Graben. The palaeogeographical reconstructions suggest a similar coal‐to‐carbonate facies transition as in the adjacent onshore Gippsland Basin.  相似文献   

青岛市水环境问题及防治对策     

刘建霞  董怡熹 《山东国土资源》1999,(2)

青岛是我国缺水城市之一。但本已紧缺的水资源却存在着水质污染、开采漏斗、海（咸）水入侵及高氟水等一系列水环境问题。文中分析了其发生原因、危害程度及发展趋势，并提出了综合治理建议。  相似文献   

Marine hazards in coastal areas and human action against them—A case study of the Changjiang River estuaries and Qiantang River     

Chen Ji-yu  Li Dao-ji  Yao Yan-ming  Li Jun  Jin Wen-hua 《中国海洋湖沼学报》1999,17(2):143-153

China's eastern coastal area marine hazards (storm surge, erosion and deposition by tidal currents and seawater intrusion) and the history, present situation, experiences and problems of inhabitants in their fight against marine hazards are discussed in this paper, which also suggests counter-measures against, and scientific and rational management of, coastal area marine hazards in order to protect the coastal and estuarine ecosystems.  相似文献