The influence of neo-tectonics on river patterns in Bangladesh; a preliminary study based on Landsat MSS imagery     

Seijmonsbergen  A.C. 《Geologie en Mijnbouw》1998,77(2):129-135

Bangladesh is part of the active foredeep depression south of the Himalayan collision zone, bordering the Indian plate. Seismic activity is common both in the mountain chain and in the Ganga plain reaching into the basin of the Bay of Bengal and forming the counterpart of the uplifted Himalayan chain. Erosion, sedimentation, river migration and transport within the Jamuna (Brahmaputra) river system are therefore not only controlled by processes on the Earth's surface, but are also the result of a balance between fast and continuing deposition versus geological subsidence and uplift. An attempt is made to correlate the behaviour of the Jamuna river to neo-tectonic movements, as interpreted from Landsat MSS imagery using available literature. From the imagery, covering the period 1976 to 1987, supervised and unsupervised classifications of bands 5 and 7 were made. The 1978 and 1986 images revealed the most useful classifications and yielded pronounced differences in colour variation for visual interpretations of geological lineaments and terrain units. The Jamuna riverbed can be divided into compartments, limited by faults.  相似文献   

滩槽流量分别演算法进行汾河下游河段洪水预报     

陈阆笙  曹建业 《水文》1998,(1):33-38

汾河下游柴庄以下河段由于受人为和处在然等多种因素影响,河道发生持续淤积,过水能力大幅度降低,使河道行洪特点发生很大变化,正常洪水预报方法失效。  相似文献   

吐鲁番坳陷西山窑组富煤的河流沉积与储集层的成岩作用研究   总被引：3，自引：0，他引：3  

刘林玉  柳益群  李文厚 《沉积与特提斯地质》1998,18(4):9-16

吐鲁番坳陷西山窑组（Ｊ２ｘ）发育一套含煤的陆相沉积地层,本文根据钻井资料进行研究认为这套地层属于曲流河沉积,并进一步划分出河道沙坝和漫滩沼泽等沉积类型。煤层形成于漫滩沼泽沉积环境。曲流河道砂体是主要的油气储集体。位于坳陷东南抠的曲流带河道砂岩复合体是储集砂岩最发育的地区。储集砂岩类型主要为矿物成熟度较低的岩屑砂岩和长石岩屑砂岩。坳东南区复合体河道砂岩以长石岩屑岩为主,而坳陷北区河道砂岩以岩屑砂岩为  相似文献   

西北地区侏罗系的三角洲沉积   总被引：16，自引：0，他引：16  

李文厚  赵文智 《地质论评》1998,44(1):63-69

西北地区侏罗广泛发育扇三角洲,辫状河三角洲和曲流河三角洲相沉积,其中扇三角洲与陡倾的盆地边缘有关,盆地的沉降速率大于沉积率,沉积层序为加积型,并以沉积物重力流和无河道片流区同搬运的沉积短斩泄荷为特征,辫状河三角洲与不很陡的盆地边缘梯度有关,其沉积速率大于盆地的沉降速率,沉积层序为进积型,并以河道径流广泛发育为特征,曲流河三角洲与缓坡陷型构造边界有关,并具有以河流作用为主,湖泊作用的辅的特征,３种三  相似文献   

Distribution and fractionation of heavy metals in the surface sediments of the Ganges- Brahmaputra-Meghna river system in the Bengal basin   总被引：1，自引：0，他引：1  

Dilip K. Datta  V. Subramanian 《Environmental Geology》1998,36(1-2):93-101

 The lower Ganges-Brahmaputra-Meghna (G-B-M) drainage basin occupies the total Bengal Basin, which is one of the unique basins of the world because of its location and size, density of population, and catastrophic deposition of sediments. The increased heavy metal concentration in the 63 m fraction of surface sediments shows similarity among major segments of the G-B-M system in the basin, which reflects the homogenization of lithologic and chemical diversity of the greater denudation regime by the river processes. The differences in heavy metal concentation in the lower G-B-M system with that of its upper and middle counterpart is mainly related to the contrast between Himalayan rivers and the other major South Asian rivers, and may be due to the geological differences of their denudation regime. Heavy metals in the Lower G-B-M system have an affinity towards the clay fraction of the sediments. The correlation matix of heavy metals in the lower Brahmaputra and Meghna suggests the importance of Fe-Mn oxyhydroxides in their accumulations. Iron, Ti and Mn are higher in the Meghna main channel, Zn is higher in the Meghna tributaries, and Cr is higher in both the Brahmaputra and Meghna compared to the value for standard shale. The enrichment factor is ≤1 for most of the metals except Mn which is relatively higher in the Meghna and lower Ganges main channels. The geoaccumulation index (I_geo) for most of the heavy metals lies below grade zero, suggesting unpolluted sediment quality. The lower Ganges system shows relatively higher concentration in the nondetrital fraction of heavy metals, probably due to the presence of petroleum refinery, industrial and mining effluents, and agricultural runoff in the drainage basin. The relative uniformity in concentration of heavy metals in vertical profiles may be due to the uniformity in sediment grain size and catastrophic deposition of sediments, where the time period represented by the vertical sediment column is not enough to reflect the cultural accumulation of heavy metals. The Bengal basin thus represents a relatively unperturbed alluvial basin with regards to heavy metal pollution. Received: 21 July 1997 · Accepted: 13 October 1997  相似文献   

铁法盆地阜新组网结河沉积   总被引：5，自引：1，他引：4  

王宇林 《沉积学报》1998,16(2):87-91

铁法盆地为晚中生代半地堑式断陷盆地,阜新组的网结河沉积发育于断裂盆缘内侧冲积扇至湖缘三角洲之间的湖退进积体系域。大量的钻孔和矿井地质资料详尽揭示了网结河道相、河岸相及湿地相的特征,其中,泥石流沉积是网结河道相的一种特殊的成因类型。在有关各成因地层单元中,以网结河沉积体系的繁盛发育为主体,以网结河沉积体系的衰退并伴随大面积泥炭沼泽化而结束。盆缘断裂活动比较活跃、盆地沉降速率大、沉积充填速率高、河道坡降小是网结河发育的重要条件。  相似文献   

内陆河流域生态环境的空间分异特征   总被引：19，自引：3，他引：16  

王根绪  程国栋 《地理科学》1998,18(4):355-361

分析研究了内陆河流域气候条件,植被生态,土壤环境及水环境质量等生态环境要素的空间变异特征,探讨了流域不同地带的生态环境功能。结果表明：干旱内陆河流域气候条件,尤其是水热条件和地貌特征是植被生态,土壤环境及水环境形成与分异最主要的控制性因素,几大环境要素之间相互联系,相互制经久形成内陆流域生态环境空间带规律和生态系统功能在空间不同地带上的显著差异性,认识这种分带规律与不同区域的生态功能,是合理开发的  相似文献   

西北干旱区水资源转化与开发利用模型   总被引：13，自引：0，他引：13  

曲耀光  马世敏 《中国沙漠》1998,18(4):299-307

干旱地区的内陆河发源于山区,在山前平原地区受干旱气候、地质地貌结构和岩性的影响,地表水与地下水之间具有大数量转化的特点。根据水量平衡原理,通过对西北干旱区内陆河流域山前平原地区河水、地下水、泉水相互转化机制的研究和分析,建立了模拟与计算相结合,兼有预测性质的水资源转化与开发利用模型。模型概念明确,形式简单,所需资料容易获得。在新疆乌鲁木齐河流域实际应用结果表明,模拟的流域最大可能引水量和水资源净可利用量,都远比现状实际引水量和水资源净利用量小得多,水资源开发利用明显过度,每年超采地下水１．２×１０８ｍ３,与当地水文地质部门计算结果非常一致,效果较好。另外,模型预测结果还表明,对于处在完成地表水与地下水联合开发利用阶段的,类似乌鲁木齐河流域的内陆河流域来说,可用水资源的开发已达到极限,再采用传统的提高地表渠系利用率的方法,已不可能增加流域的可用水资源量。这不仅从理论上解决了,水利和水文地质部门长期以来有关地表水和地下水到底如何开发才算合理的争论;也证实了,这样做的结果不但在经济上得不偿失,而且将破坏流域已建有的地下水开采和供水系统,有可能造成更大的经济、社会和生态损失。  相似文献   

Modelling Spatial Patterns of Overbank Sedimentation on Embanked Floodplains   总被引：2，自引：0，他引：2  

Hans Middelkoop  & Marcel van der Perk 《Geografiska Annaler: Series A, Physical Geography》1998,80(2):95-109

This paper presents a GIS-based mathematical model for the simulation of floodplain sedimentation. The model comprises two components: (1) the existing hydrodynamic WAQUA model that calculates two-dimensional water flow patterns; and (2) the SEDIFLUX model that calculates deposition of sediment based on a simple mass balance concept with a limited number of model parameters. The models were applied to simulate floodplain sediment deposition over river reaches of several kilometres in length. The SEDIFLUX model has been calibrated and validated using interpolated raster maps of sediment deposition observed after the large magnitude December 1993 flood on the embanked floodplain of the lower river Rhine in the Netherlands. The model appeared to be an adequate tool to predict patterns of sediment deposition as the product of the complex interaction among river discharge and sediment concentration, floodplain topography, and the resulting water flow patterns during various discharge levels. In the investigated areas, the resulting annual average sedimentation rates varied between 0.5 mm/year and 4.0 mm/year. The role of the most important mechanisms governing the spatial patterns of overbank deposition, i.e. inundation frequency, sediment load, floodplain topography and its influence on the flow patterns over the floodplain, are discussed.  相似文献   

流域地貌系统定量研究的新指标   总被引：6，自引：3，他引：3  

王协康  方铎 《山地学报》1998,(1)

简要介绍了分形基本理论,着重讨论了流域地貌系统定量研究的指标．水系分维的计算方法,水系分维区域划分原则及其应用含义．  相似文献