共查询到19条相似文献，搜索用时 156 毫秒
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印度水资源年利用总量为188.2万立方米。河水径流量时间和空间分布不平衡,总径流量的三分之二集中在三大河流(发源于喜马拉雅山的印度河、恒河和布拉马普特拉河)流域。仅一条恒河其径流量就几乎等于整个印度半岛部分的径流量。印度大部分河流有雨水补给,因此其最大和最小流量相差数千倍,很难以进行水利工程建设。 相似文献
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基于事件数据的雅鲁藏布江-布拉马普特拉河国际河流安全分析 总被引：3，自引：0，他引：3
雅鲁藏布江-布拉马普特拉河是我国重要的国际河流,近年的水电开发活动,使其日益成为国内外国际河流研究关注的热点。本文基于国际关系研究中常用的事件分析方法,在构建事件数据库的基础上,从事件类型、涉及国别、事件频率、影响程度四方面进行分析,结果表明：水资源分配问题是雅江流域主要问题;中国在雅江国际河流问题上与下游国家的联系主要以与印度或孟加拉国的双边联系为主;随着时间的推移,雅江冲突与合作事件的频率都表现出增加的趋势;雅江围绕国际河流的国际关系局势大致可分为4个阶段：60年代的平稳阶段、70年代的紧张阶段、80年代的沉寂阶段、90年代后的持续关注阶段。 相似文献
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恒河是印度北部的大河,自远古以来一直是印度教徒的圣河。其大部流程为宽阔、缓慢的水流。恒河源出喜马拉雅山南麓加姆尔的甘戈特力(实为塔婆万高原,说法不同的原因是印度对恒河源头说 相似文献
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基于全球恐怖主义数据库（GTD）和南亚恐怖主义门户网站（SATP）所收录的印度暴力袭击事件数据,借助统计分析和核密度分析法,对1980—2017年印度暴力袭击事件时空演变及其驱动机制进行分析。结果表明：印度国内的暴力袭击事件频发,1980年以来呈现出波动上升态势。从空间上看,印度国内的暴力袭击事件具有自西到东、从北到南以及由边境地区向内地发展的扩散特点,展现出局部集中、面上扩散的发展趋势;呈现出以西北部的查馍-克什米尔地区和旁遮普邦、东北部的阿萨姆邦和曼尼普尔邦、中部的恰蒂斯格尔邦和东部的贾坎德邦、比哈尔邦和西孟加拉邦为主的四大集聚中心;形成以印度河上游—恒河—布拉马普特拉河一线为横轴,东高止山脉及其北部山区为纵轴的“T”字形空间格局。印度暴力袭击事件的时空演变受到身份认同、经济问题、历史问题和利益诉求等多方面因素的影响,通过宗教极端主义组织、民族分离主义组织、武装革命主义组织推动以及行动主体之间的互相作用,推动了暴力袭击事件的时空演变。要从根本上解决印度国内暴力袭击事件频发的态势,需要从政治、经济、宗教、社会等多方面进行综合施策。 相似文献
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挠力河流域龙头桥水库对坝址下游湿地水文过程影响分析 总被引：3，自引：0，他引：3
在调查挠力河流域龙头桥水库的设计参数和运行方式的基础上,利用宝清和菜咀子两个水文站实测的水位和流量等观测数据,研究了龙头桥水库建设与运行对坝址下游(宝清水文站和菜咀子水文站之间)湿地的水文过程影响。龙头桥水库对坝址下游湿地水文过程的影响主要为:①使湿地径流量季节性变化幅度减小;②使河流湿地冰封期连底冻现象发生频率增加,特别是从1999年开始,出现了4月份河流连底冻现象,并且1999~2006年期间12月份河流连底冻现象的发生频率高达87.5%;③减少了进入湿地的径流总量;④使河流湿地的地表水位下降;⑤减少了河流湿地的地下水补充量;⑥水库对湿地水文过程影响带来了一些负面生态效应,如进入湿地的营养物质减少,湿地生物的越冬环境受到破坏等。建议在每年4月、9~12月期间,龙头桥水库增加向下游的放水量,并保证水流流量不小于3 m3/s;减少挠力河流域上游水田种植面积,将水库在灌溉和发电方面的功能主要转换为防洪和下游湿地生态水量调节。 相似文献
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水电开发对河流水沙特性影响的综合评价方法 总被引：5，自引：1，他引：4
选取已连续25 年大规模水电开发的澜沧江为研究对象,建立了河流水沙特性受影响程度评价指标体系及指标回归还原模型,并采用层次分析法和因子分析法相结合的赋权方法确定指标权重;借鉴“边际效益”原理,结合基于河流水沙自然变幅确立的指标评价标准,建立了各指标受影响程度定量评价模型。利用所建立的方法与模型,综合定量评价了澜沧江水沙特性的受影响程度,结果表明：澜沧江水电开发以来(1986-2007 年),河流水沙特性总体受影响程度等级为很小的年数占72.7%,为较小的年数占18.2%,为一般的年数占9.1%,输沙受影响程度远大于径流;水沙特性受影响的变化过程呈“U”形,其主要原因是在漫湾水电站运行与大朝山水电站建设并存期,库区拦沙作用与电站施工增沙作用使输沙趋于平衡。本研究,为后续相关研究提供方法借鉴,为评估水电开发对澜沧江水沙特性影响提供新的依据。 相似文献
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黑河流域典型区土地利用格局变化及影响比较 总被引：28，自引：4，他引：24
在黑河流域选择两个典型区域进行土地利用变化的空间差异与影响的对比研究,利用20世纪60年代以来的三期遥感数据,通过定量表征指标体系,对比分析了两个区域不同空间土地利用格局变化和土地利用类型变化的分异特征,定量评价了土地利用变化对不同区域绿洲系统的稳定性和水资源空间分配的影响。结果表明：过去35年来两个对比区域不同的土地利用格局变化,形成了显著的绿洲沿河流的溯源迁移和以基于下游老绿洲的渐进性绿洲外围拓展两种不同模式,前者导致流域水资源过度集中消耗于流域上游和源区,中下游水资源可利用量急剧减少,在35年间下游荒漠化土地增加了85.1%,灌溉绿洲萎缩了25.5%;后者则不同,水资源利用量的空间配置在区域下游具有小幅度集中,区域绿洲系统整体的稳定性较高。从流域整体的水土相互关系出发,合理规划干旱内陆流域土地利用模式和空间土地资源配置,对于促进流域整体的可持续发展具有重要意义。 相似文献
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Shanghai is a megacity that increasingly relies on water drawn from the Yangtze River estuary. During periods of low flow, water in the estuary can become too saline for use in city water supplies. River flow is measured at the Datong gauging station 680 km upstream from the river mouth. Several existing and planned river water extractions are located below Datong, including the Eastern Route of the South-North Water Diversion Project (ERP). The effect of these extractions on discharge into the estuary and the associated salinity levels may be significant, even though the extractions are not reflected in the discharge at Datong. We estimate the effects of these downstream extractions on water discharge into the estuary (rather than at Datong), particularly the critical discharge level below which salinity compromises water security in Shanghai. Our results show that the ERP will cause the discharge into the estuary to fall below critical levels between December and February in dry years and January to February in normal years. Future water transfer projects along the lower Yangtze River will further compound the problem. Maintaining Shanghai's water security is therefore a significant challenge for China's water resource management institutions. 相似文献
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通过对有关项目研究成果的分析，总结了新疆流域水资源分配模拟系统设计的基本原理与方法。其中对模拟模型的建立、模拟系统的结构与各子模块的功能及寻求合理分水方案的方法进行了详细分析与说明。 相似文献
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J.N. Sarma 《Geomorphology》2005,70(3-4):226
The Brahmaputra River finds its origin in the Chema Yundung glacier of Tibet and flows through India and Bangladesh. The slope of the river decreases suddenly in front of the Himalayas and results in the deposition of sediment and a braided channel pattern. It flows through Assam, India, along a valley comprising its own Recent alluvium. In Assam the basin receives 300 cm mean annual rainfall, 66–85% of which occurs in the monsoon period from June through September. Mean annual discharge at Pandu for 1955–1990 is 16,682.24 m3 s− 1. Average monthly discharge is highest in July (19%) and lowest in February (2%). Most hydrographs exhibit multiple flood peaks occurring at different times from June to September. The mean annual suspended sediment load is 402 million tons and average monthly sediment discharge is highest in June (19.05%) and lowest in January (1.02%). The bed load at Pandu was found to be 5–15% of the total load of the river. Three kinds of major geomorphic units are found in the basin. The river bed of the Brahmaputra shows four topographic levels, with increasing height and vegetation. The single first order primary channels of this braided river split into two or more smaller second order channels separated by bars and islands. The second order channels are of three kinds. The maximum length and width of the bars in the area under study are 18.43 km and 6.17 km, respectively. The Brahmaputra channel is characterised by mid-channel bars, side bars, tributary mouth bars and unit bars. The geometry of meandering tributary rivers shows that the relationship between meander wavelength and bend radius is most linear. The Brahmaputra had been undergoing overall aggradation by about 16 cm during 1971 to 1979. The channel of the Brahmaputra River has been migrating because of channel widening and avulsion. The meandering tributaries change because of neck cut-off and progressive shifting at the meander bends. The braiding index of the Brahmaputra has been increasing from 6.11 in 1912–1928 to 8.33 in 1996. During the twentieth century, the total amount of bank area lost from erosion was 868 km2. Maximum rate of shift of the north bank to south resulting in erosion was 227.5 m/year and maximum rate of shift of the south bank to north resulting in accretion was 331.56 m/year. Shear failure of upper bank and liquefaction of clayey-silt materials are two main causes of bank erosion. 相似文献
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长江中游马口-田家镇河段40年来河道演变 总被引：2，自引：1，他引：1
Quantitative analysis was performed on the filling-scouring process for the river reach within Makou and Tianjiazhen, the middle Yangtze River with the help of GIS and DEM techniques. The research results indicate that the river reach between Makou and Tianjiazhen was dominated by the scouring process, and the magnitude of scouring is increasing over time. The intensity of scouring process is more in the deep and narrower river reach than shallower and wider ones. The river reach in the Makou and Tianjiazhen river knot is in fre-quent scouring and filling process, however the river reach upper to the Makou and lower to the Tianjiazhen river knot is in moderate scouring and filling process. The river reach just upstream or downstream to the river knot (e.g. Makou and Tianjiazhen river knot in this research) is dominated by filling process and the river reach in the river knot is dominated by the scouring process. Research results indicate no changes in the boundary of the river but the scouring and the filling magnitude in specific river channel is strong. The filling and the scouring process of the study river reach is greatly impacted by the sediments and water from the upstream of the study river reach. The construction of the Three Gorges Dam just upstream to Yichang will cause further decrease of the release of the sediment load to the middle and the lower Yangtze River basin, which will further intensify the scouring process of the river channel in the study river reach. 相似文献
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长江中游马口-田家镇河段40 年来河道演变 总被引：2，自引：0，他引：2
运用地理信息系统(GIS) 与数字高程模型(DEM) 分析了马口-田家镇河段1963 年、1972 年与2002 年河道地形数据, 较为系统地研究了该河段过去40 年冲淤时空变化。研究结 果认为, 1972 年与1963 相比冲刷量达到789.9 hm3, 冲刷面积为39.7×104 m2; 2002 年与1963 年相比冲刷量达到1196.5 hm3, 冲刷面积为59.4×104 m2; 2002 年与1972 年相比冲刷量 达到960 hm3, 冲刷面积为54.3×104 m2。由以上结果认为, 马口-田家镇河段近40 年来以冲刷为主; 河道冲淤变化以马口卡口与田家镇卡口等窄深河段最为剧烈, 宽浅河段与顺直河 段冲淤变化较为和缓, 冲淤变化幅度不大; 卡口上、下端以淤积过程为主, 而卡口顶冲水流的顶弯部位以冲刷过程为主。研究河段冲淤变化受上游来水来沙条件影响很大, 对未来三峡工程建成后, 三峡大坝下游来水来沙以及研究河段冲淤变化的影响研究提供借鉴。 相似文献
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Joy Sanyal Priyanka Dasgupta Shinjiro Kanae 《Singapore journal of tropical geography》2020,41(2):284-298
Dam-related downstream adjustments of riverbeds are normally investigated by analysing the trend in sediment supply and high flow events during the pre- and post-dam periods. The required data for existing predictive models is not measured at river gauges, which limits the application of these tools. We derived the frequency of sediment-transporting streamflow events (T*) and upstream sediment supply (S*) in the pre- and post-dam periods with widely available gauged records and predicted changes in the downstream riverbed by adapting an existing model. Ten gauging stations in the Godavari River Basin, India, located downstream of dams, were chosen as study sites. Annually surveyed cross-sections at each site validated the accuracy of the predicted dam-related downstream changes. Then, a regression equation (R2 = 0.75) was established between T*/S* (independent variable) and changes in the downstream bed elevation (dependent variable) for the Godavari Basin. We recommended that similar local empirical equations be formulated for larger river basins. Models of large-scale rainfall-runoff and sediment transport processes that can account for the influence of dams, such as the Soil & Water Assessment Tool, can be paired with the proposed regression equation to estimate dam-related downstream erosion and deposition with globally available data. 相似文献
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《Basin Research》2018,30(2):302-320
The Holocene stratigraphy of Sylhet basin, a tectonically influenced sub‐basin within the Ganges‐Brahmaputra‐Meghna delta (GMBD), provides evidence for autogenic and allogenic controls on fluvial system behaviour. Using Holocene lithology and stratigraphic architecture from a dense borehole network, patterns of bypass‐dominated and extraction‐enhanced modes of sediment transport and deposition have been reconstructed. During a ~3‐kyr mid‐Holocene occupation of Sylhet basin by the Brahmaputra River, water and sediment were initially (~7.5–6.0 ka) routed along the basin's western margin, where limited downstream facies changes reflect minimal mass extraction and bypass‐dominated transport to the basin outlet. Sediment‐dispersal patterns became increasingly depositional ~6.0–5.5 ka with the activation of a large (~2250 km2) splay that prograded towards the basin centre while maintaining continued bypass along the western pathway. Beginning ~5.0 ka, a second splay system constructed an even larger (~3800 km2) lobe into the most distal portions of the basin along the Shillong foredeep. This evolution from a bypass‐dominated system to one of enhanced mass extraction is well reflected in (i) the rapid downstream fining of deposited sand and (ii) a change in facies from amalgamated channel deposits to mixed sands and muds within discrete depositional lobes. The persistence of sediment bypass suggests that seasonal flooding of the basin by local runoff exerts a hydrologic barrier to overbank flow and is thus a principal control on river path selection. This control is evidenced by (i) repeated, long‐term preference for occupying a course along the basin margin rather than a steeper path to the basin centre and (ii) the persistence of an under‐filled, topographically low basin despite sediment load sufficient to fill the basin within a few hundred years. The progradation of two 10–20‐m thick, sandy mega‐splays into the basin interior reflects an alternative mode of sediment dispersal that appears to have operated only in the mid‐Holocene (~6.0–4.0 ka) during a regional weakening of the summer monsoon. The reduced water budget at that time would have lowered seasonal water levels in the basin, temporarily lessening the hydrologic barrier effect and facilitating splay development into the basin interior. Overall, these results place basin hydrology as a first‐order control on fluvial system behaviour, strongly modifying the perceived dominance of tectonic subsidence. Such coupling of subsidence, fluvial dynamics and local hydrology have been explored through tank experiments and modelling; this field study demonstrates that complex, emergent behaviours can also scale to the world's largest fluvial system. 相似文献
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Quantitative analysis was performed on the filling-scouring process for the river reach within Makou and Tianjiazhen, the middle Yangtze River with the help of GIS and DEM techniques. The research results indicate that the river reach between Makou and Tianjiaz-hen was dominated by the scouring process, and the magnitude of scouring is increasing over time. The intensity of scouring process is more in the deep and narrower river reach than shallower and wider ones. The river reach in the Makou and Tianjiazhen river knot is in fre-quent scouring and filling process, however the river reach upper to the Makou and lower to the Tianjiazhen river knot is in moderate scouring and filling process. The river reach just upstream or downstream to the river knot (e.g. Makou and Tianjiazhen river knot in this re-search) is dominated by filling process and the river reach in the river knot is dominated by the scouring process. Research results indicate no changes in the boundary of the river but the scouring and the filling magnitude in specific river channel is strong. The filling and the scouring process of the study river reach is greatly impacted by the sediments and water from the upstream of the study river reach. The construction of the Three Gorges Dam just up-stream to Yichang will cause further decrease of the release of the sediment load to the mid-dle and the lower Yangtze River basin, which will further intensify the scouring process of the river channel in the study river reach. 相似文献