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1.
黑河“97”分水方案适应性分析 总被引：2，自引：0，他引：2
黑河"97"分水方案自2000年实施以来,流入下游水量明显增加,缓解了下游生态环境恶化趋势,但在丰水年难以完成分水指标,其适应性受到各方关注。本文在分析"97"分水方案的技术特点及背景条件变化对分水方案适应性影响的基础上,通过构建黑河水资源配置模拟模型,对分水方案在不同需水条件和黄藏寺水库建成运行后长系列年(1958-2012年)实施情况进行了模拟,分析评价了黑河"97"分水方案的适应性。研究表明,由于分水方案制定和实施前后黑河经济社会、水系连通性等背景条件发生了较大变化,在现状工程和需水条件下,不能完成"97"分水方案的分水要求;在中游退耕至2000年水平和黄藏寺水库建成的情况下,虽然可以完成"97"分水方案的分水要求,但仍存在地下水超采情况,因此,基于20世纪80年代中期黑河经济社会和1955-1986年水文条件的"97"分水方案与黑河流域现状存在一定的不适应性。 相似文献
2.
研究黄河和滹沱河对季节河化的适应性调整，发现季节化程度较高的滹沱河下游河床断面和平面形态调整幅度不大，而河床的糙率成倍增加造成下游的小水大灾现象；黄河下游近年流量减小，不断断流，主槽淤积，虽然河槽断面形态在游荡段变得更窄深，但主槽明显变小、变窄、变高，构成下游近年出现的小水大灾现象的主要原因。 相似文献
3.
根据黄河下游7个控制断面的深泓高程、平均河底高程、滩槽高差及过水断面面积的历年变化,可以看出黄河下游河道的萎缩过程,大型水利工程的运用及引黄灌溉加速了下游河道的淤积和萎缩。 相似文献
4.
基于二元水循环的河流生态需水水量与水质综合评价方法——以辽河流域为例 总被引：11，自引：0，他引：11
通过考虑水的自然循环与水在人类活动影响下的循环 (二元水循环),后者包括水资源开发利用率、耗水率、污水排放浓度影响,探讨了二元水循环下河流生态需水“质”与“量”的综合评价,以区别以往仅从自然水循环 (一元) 出发评价河流生态需水的缺陷。建立了二元水循环下的河流生态需水的水量与水质计算方法,并确定了河流生态需水的“质”与“量”的评价标准,实现了河流生态需水水量与水质的综合评价。以辽河流域为例进行实证分析,计算了一元水循环下西辽河、东辽河、辽河干流、浑太河、东北沿黄渤海诸河等水资源分区的河流生态需水,分别占径流的39.3%、63.0%、43.9%、43.3%、43.5%,采用Tennant推荐流量及等级进行评价,结果是：除西辽河属于“中”等级外,东辽河、浑太河、辽河干流、东北沿黄诸河等均在“好”等级以上,东辽河达到“极好”等级。与之对应的二元水循环下的河流生态需水比例分别是57.5%、74.1%、60.8%、60.3%、60.4%,综合评价结果显示：从水量角度评价,西辽河不能达到生态需水“量”的标准,其余能够达标,从水质角度评价,西辽河、浑太河、辽河干流、东北沿黄诸河等均不能够达到“质”的标准,东辽河可以达标。从“量”与“质”相结合的角度评价,仅有东辽河可以达标。因此,水质状况是决定辽河流域河流生态需水是否满足生态系统需求的主要问题。 相似文献
5.
Esperanza Muñoz‐Salinas Miguel Castillo 《Geografiska Annaler: Series A, Physical Geography》2013,95(2):171-183
This study explores the main factors controlling sediment and water discharge in the Santiago and Pánuco Rivers, the two largest rivers of central Mexico. Both Santiago and Pánuco Rivers are sourced in the Central Plateau of Mexico and flow in an opposite direction. Santiago River flows over a tectonically active margin draining to the Pacific Ocean, and Pánuco River flows into the passive margin of the Gulf of Mexico. Mean annual and monthly values of suspended sediment load and water discharge spanning around 50 years were used to evaluate sediment load and water discharge in these two rivers. Our findings indicated that Santiago River delivers to the ocean around 45% more sediment than Pánuco River. However, we found that Santiago River has about half the water discharge of Pánuco River. The high river gradient along Santiago River is likely to enhance the net erosion and sediment transport capacity. Water discharge at Pánuco Basin is higher than in Santiago Basin because the annual rainfall is higher for the former. The difference in sediment and water discharge for both rivers are also related to El Niño Southern Oscillation events. Our results indicated that water discharge in Santiago River increases during El Niño and La Niña events. In contrast, Pánuco River is mostly affected by La Niña events. 相似文献
6.
Flow and form in rehabilitation of large-river ecosystems: An example from the Lower Missouri River 总被引：2，自引：0，他引：2
On large, intensively engineered rivers like the Lower Missouri, the template of the physical habitat is determined by the nearly independent interaction of channel form and flow regime. We evaluated the interaction between flow and form by modeling four combinations of modern and historical channel form and modern and historical flow regimes. The analysis used shallow, slow water (shallow-water habitat, SWH, defined as depths between 0 and 1.5 m, and current velocities between 0 and 0.75 m/s) as an indicator of habitat that has been lost on many intensively engineered rivers and one that is thought to be especially important in rearing of young fishes. Two-dimensional hydrodynamic models for modern and historical channels of the Lower Missouri River at Hermann, Missouri, indicate substantial differences between the two channels in total availability and spatial characteristics of SWH. In the modern channel, SWH is maximized at extremely low flows and in overbank flows, whereas the historical channel had substantially more SWH at all discharges and SWH increased with increasing discharge. The historical channel form produced 3–7 times the SWH area of the modern channel regardless of flow regime. The effect of flow regime is evident in increased within-year SWH variability with the natural flow regime, including significant seasonal peaks of SWH associated with spring flooding. Comparison with other reaches along the Lower Missouri River indicates that a) channel form is the dominant control of the availability of habitat even in reaches where the hydrograph is more intensively altered, and b) rehabilitation projects that move toward the historical condition can be successful in increasing topographic diversity and thereby decreasing sensitivity of the availability of habitat to flow regime. The relative efficacy of managing flow and form in creating SWH is useful information toward achieving socially acceptable rehabilitation of the ecosystem in large river systems. 相似文献
7.
Jiongxin Xu 《Geomorphology》2004,57(3-4):321-330
Through an analysis of data collected from the Yellow River and its tributaries on the Loess Plateau of China, the phenomenon of double-thresholds in scour–fill processes of wide-range water-sediment two-phase flows has been shown. Thresholds located in non-hyperconcentrated flows may be called the lower threshold, and that in hyperconcentrated flows the upper threshold. This double-threshold phenomenon leads to complicated sediment transport behavior of heavily sediment-laden rivers. With an increase in suspended sediment concentration, the channel sediment delivery ratio increases initially and becomes higher than 1, followed by a decrease and finally becomes lower than 1 again.Controlled by the double-thresholds in the scour–fill processes, channel adjustment of the lower Yellow River is non-linear and complex. When the suspended concentrations were lower than the lower threshold or higher than the upper threshold, scour or bed downcutting was the dominant channel-forming process. Channel shape tends to be narrower and deeper, and the channel thalweg became more sinuous. When the suspended concentrations lay between the lower and upper thresholds, deposition of sediment was the dominant channel-forming process; channel shape tended to be shallower and wider, and channel thalweg became less sinuous. 相似文献
8.
现在的洪泽湖和淮河中游河道不断淤高,致使淮河中游洪涝不断。入洪泽湖后淮河水主要流入长江。而苏北北部地区需要水,因入海泥沙数量太少而致海岸侵蚀问题不能根本解决,那里需要淮河的泥沙。为改变这种不合理的格局。在洪泽湖北岸和浅水区开挖与洪泽湖分离的河道,连接完成远期工程的淮河入海水道和拓宽、挖深的淮沭河—北六塘河—新沂河水道,使淮河水沙只经过这两条水道到达黄海,改变淮河水沙不合理的资源分配。新水道路程短,比降大,使洪泽湖和淮河中游河道不再淤高,并将进一步使淮河中游水道刷深,减轻淮河中游洪涝灾害,并为洪泽湖湖底高程降低创造条件。通过分析现在淮河的输沙量、输沙模数,与历史时期和其他流域对比,认为连云港至射阳河口这段海岸将改变为北部稳定,南部缓慢进积,形成新的淮河三角洲,彻底解决苏北海岸侵蚀问题。 相似文献
9.
人为季节性河流的初步研究 总被引：14，自引：3，他引：11
由于人类引水量的激增,我国北方的一些天然常流河频繁断流,已经成为季节性河流。文中提出了人为季节河的概念,在分析天然常流河与天然季节河的形成条件的基础上,查明了人为季节河形成的敏感带和在这种敏感带中,常流河向季节河转化的条件。 相似文献
10.
河流健康理论初探 总被引：27，自引：1，他引：26
健康河流是指在相应一定时期其社会功能与自然功能和谐并能够均衡发挥的河流, 其标志是具有良好的水质、水沙流畅的河床与可维系的河流生态系统。河流健康的指示性因子应是能够基本反映河流自然功能的因子, 包括河床形态、水质、河流生态和河川基流, 但因子的种类和数量因河而异, 其量化标准的确定则要充分考虑河流自然功能和社会功能均衡发挥 的需要和河流水情背景条件的变化。河流健康的核心是有相应足够而洁净的河川径流, 因此 保障河流一定的环境流量对维护河流健康十分重要。人类过多抽取河川径流和开发水电、不当地调控洪水和泥沙、过多向河流排污和过多改变关键物种栖息地水流环境的活动, 均会对河流健康造成严重伤害。本文以黄河为例, 对河流健康指标和低限健康指标的确定方法进行了阐述。 相似文献
11.
宽变幅水沙两相流的冲淤双临界现象及其地貌学意义 总被引：3，自引：1，他引：3
通过黄土高原一些河流资料的分析，发现了宽变幅水沙两相流冲淤过程中的2个临界值，位于非高含水流区域中的临界点，可称之为冲淤下临界；位于高含沙水流区域中的临界点，可称之为冲淤上临界，水沙两相流冲淤的双临界现象，对珩多沙河流河道泥沙的输移有重要意义，随着含沙量的增大，排沙比先减小而后增大，2次与代表排沙比等于1的直线相交，这2个交点即分别对应于挟沙水流冲淤的下临界和上临界，运用所揭示的水沙两相流冲淤过程的双临界现象，可以对冲积河流河型的形成进行新的解释，以我国近百条冲积河流的资料为基础，点绘了年均悬移质输沙率与年均流量的关系，并以不同的符号来区分弯曲河型、游荡河型和高含沙曲流河型。结果表明，上述3种河型可以很好于被代表特征含沙量分别为C=60kg/m^3和C=3.3kg/m^3的2条直线所区分，这2个特征含沙量反映了河道水沙两相流冲淤的上、下临界值。 相似文献
12.
Sanjeev Joshi 《自然地理学》2018,39(2):140-165
Changes in channel morphology provide relevant insights into sediment transport and deposition in alluvial river systems. This study assessed three to four decades of morphological changes at seven locations along a 327-km reach of the Lower Mississippi River (LMR) to better understand channel adjustment processes of this large alluvial river. The assessment included analysis of three cross-sectional areas at each location during the period 1992–2013, as well as analysis of the changes in river stage and maximum surface slopes under four flow conditions over the last three to four decades . We found that the first 20–25 km LMR reach below its diversion to the Atchafalaya River and the reach from 80 to 140 km experienced significant riverbed aggradation, while the reach in between (i.e. from 20 to 80 km) experienced riverbed degradation. The lower 187-km reach (i.e. from 140 to 327 km) showed negligible sediment trapping. These findings may have relevant implications for management of river sediment diversions along the LMR and other large alluvial rivers in the world. 相似文献
13.
Ding Dengshan Bao Haosheng Department of Urban Resources Sciences Nanjing University Nanjing People''s Republic of China 《地理学报(英文版)》1997,(4)
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14.
基于二元水循环的河流生态需水水量与水质综合评价方法——以辽河流域为例 总被引：1，自引：0，他引：1
In this article the meaning of the quantity and quality of environmental flows of river in dualistic water cycle is discussed,and compared with the meaning of unitary water cycle. Based on the analysis of the relationship between environmental flows of river re-quirements,the efficiency of water resource usage,the consumption coefficient,and the concentration of waste water elimination,the water quantity and water quality calculation method of the environmental flows of river requirements in dualistic water cycle is developed,and the criteria for environmental flows of river requirements are established,and therefore the water quantity-quality combined evaluation of natural river flows requirements are realized. Taking the Liaohe River as a model,the environmental flows of river requirements for Xiliao River,Dongliao River,mainstream Liaohe River,Huntai River and northeast rivers along the coasts of the Yellow and Bohai seas in unitary water cycle are calculated,each taking up 39.3%,63.0%,43.9%,43.3% and 43.5% of runoff respectively. Evaluated according to Tennant recommended flow,the results show that: except Xiliao River is "median",the rest are all upon "good",the Dongliao River is even "very good". The corresponding results in dualistic water cycle are that,the proportion of natural flows for each river is 57.5%,74.1%,60.8%,60.3% and 60.4%; while the combined evaluation results show that: considering "quantity",except Xiliao River,the rest rivers can all achieve the "quantity" criteria of the en-vironmental flows of river requirements,but if considering the aspect of "quality",only Dongliao River can reach the "quality" standard. By water quantity-quality combined evalua-tion method,only Dongliao River can achieve the criteria. So the water quality is the main factor that determines whether the environmental flows can meet the river ecosystem de-mands. 相似文献
15.
Geomorphic effects of floods are a function of several controlling factors, such as magnitude, frequency, rate of sediment movement, flood power, duration of effective flows, sequence of events and the channel geometry. In this paper, these measures of effectiveness have been evaluated for the monsoon-dominated, flood-controlled and incised Tapi River, India by defining four flow categories: low flows, moderate flows, floods and large floods. Ratios between effectiveness parameters of moderate flows on one hand and the floods, large floods and maximum floods on the other, were computed to understand the relative importance of moderate and large flows. In addition to this, stream-power graphs for large floods were constructed, and the changes in channel form were analyzed by using multi-date cross-sections. The results of the study indicate that the morphological characteristics of the bedrock as well as the alluvial channels of the monsoonal and incised Tapi River are maintained by large-magnitude, but low frequency floods that occur at long intervals. Because the channel is incised the effectiveness of large flows is accentuated. The incised channel form enhances the role of large floods by reducing the width–depth ratio, and by increasing the velocity as well as the energy per unit area. The low and moderate flows are superior to high-magnitude flows, only in terms of suspended sediment transport and frequency of occurrence. Another conclusion is that the suspended sediment carried by flows may not be the most appropriate criterion for measuring the geomorphic effectiveness of flows, particularly for monsoonal rivers. 相似文献
16.
In this article the meaning of the quantity and quality of environmental flows of river in dualistic water cycle is discussed, and compared with the meaning of unitary water cycle. Based on the analysis of the relationship between environmental flows of river re-quirements, the efficiency of water resource usage, the consumption coefficient, and the concentration of waste water elimination, the water quantity and water quality calculation method of the environmental flows of river requirements in dualistic water cycle is developed, and the criteria for environmental flows of river requirements are established, and therefore the water quantity-quality combined evaluation of natural river flows requirements are realized. Taking the Liaohe River as a model, the environmental flows of river requirements for Xiliao River, Dongliao River, mainstream Liaohe River, Huntai River and northeast rivers along the coasts of the Yellow and Bohai seas in unitary water cycle are calculated, each taking up 39.3%, 63.0%, 43.9%, 43.3% and 43.5% of runoff respectively. Evaluated according to Tennant recommended flow, the results show that: except Xiliao River is “median”, the rest are all upon “good”, the Dongliao River is even “very good”. The corresponding results in dualistic water cycle are that, the proportion of natural flows for each river is 57.5%, 74.1%, 60.8%, 60.3% and 60.4%; while the combined evaluation results show that: considering “quantity”, except Xiliao River, the rest rivers can all achieve the “quantity” criteria of the en-vironmental flows of river requirements, but if considering the aspect of “quality”, only Dongliao River can reach the “quality” standard. By water quantity-quality combined evalua-tion method, only Dongliao River can achieve the criteria. So the water quality is the main factor that determines whether the environmental flows can meet the river ecosystem de-mands. 相似文献
17.
18.
近年来,国际上和国内相继出现了一个流行的说法:由于中东水资源短缺和人口迅速增长,各国间水资源矛盾日趋尖锐,因而很可能在不久的将来因争夺水资源而爆发战争。该种说法值得商榷。对两河流域和有关各国的水资源现状和近年来该地区地缘政治的一些方面进行了具体分析,指出:有关各国的水资源并不十分短缺,而且存在着节水的巨大潜力；有关各国将会在水资源上继续采取合作和妥协的态度,不会使矛盾激化到为此而发生战争的程度。 相似文献
19.
黄河流域环境对水资源开发承受力的思考 总被引：8，自引：0，他引：8
根据黄河1919－1999年系列水沙资料，系统分析了其下游水沙变化时空过程，揭示了其发生断流原因及由此引发的环境问题，模拟了不同历史时期水情条件下环境用水需求量，并对如何提高黄河水资源开发承受能力，如何满足其环境用水提出看法。 相似文献
20.
《The Australian geographer》1995,26(1):71-86
The upper Nepean River has been progressively regulated for water supply to Sydney and Wollongong since 1886 by the Upper Nepean Water Supply Scheme which consists of four large dams, two small dams and two diversion weirs. Secular rainfall changes produced periods of high rainfall and large floods (flood‐dominated regimes) between 1857 and 1900 and 1947 and the present, and an intervening period (1901–46) of low rainfall and small floods (drought‐dominated regime). Upstream impoundment and flow regulation significantly reduced flood magnitudes for most return periods during both types of flood regimes. The probability distribution of mean daily flows was also changed significantly by flow regulation such that during the drought‐dominated regime, the high and low frequency flows were reduced substantially but the moderate frequency flows were increased due to dam releases; the change from a regulated drought‐dominated regime to a regulated flood‐ dominated regime resulted in a substantial increase in discharge for most durations; and increased water diversions to Wollongong during the current flood‐dominated regime produced a marked downward shift in the whole flow duration curve. Nepean Dam reduced downstream suspended sediment yields by two orders of magnitude because it traps in excess of 99 per cent of the inflowing suspended sediment load. Streamflow releases are urgently required from the two diversion weirs to improve downstream water quality and to ensure the viability of the resident ‘potentially threatened’ eastern Macquarie perch (Macquaria nov. sp.). 相似文献