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1.
The blocking or reversing effect of the downstream trunk river on its tributary lakes is an essential aspect of river-lake hydraulics.To measure how and the extent to which a trunk river can influence its tributary lakes,we made a case study in Changjiang River and one of its tributary lakes,Lake East Dongting(Lake ED)during a 35-year study period(1980–2014).Specifically,we investigated Lake ED’s discharge ability into Changjiang River using stage-discharge relationship curves,and hence the changes of the lake discharge ability under different hydrologic conditions of the Changjiang River.The results show that (1) the Changjiang River does exert a huge impact on the water regimes of Lake ED.And this impact varies seasonally.A variation of 3000in Changjiang River’s runoff would change the lake water level by about 1.1 min dry seasons,by 0.4 min wet seasons,and by 0.6 m during severe summer floods.(2)Changes in the Changjiang River runoff triggered by the Three Gorges Dam since 2003 have led to dramatic water regime variations in Lake ED.Other factors,including reduction of lake inflow and the lake bed erosion,also exacerbated the water regime variations in Lake ED. 相似文献
2.
1TheYellowRiverBasinThe Yellow River, with a drainage area of 752,000 km2 and a length of 5,464 km, is the second largest river in China (Figure 1). This river, recognized as the cradle of Chinese civilization, is one of the most complicated and challenging rivers in the world in terms of erosion and sedimentation control, flood defense, and water resource management. The river basin is mostly arid and semi-arid, with a long-term average annual runoff depth of 77 mm and a mean annual input … 相似文献
3.
Ⅰ.Losatlon and Historical Development Chukiang or “the winding river” was a castle-like town which was originaIly surrounded by a wall.(Fig. 2)it is situated on the upper part of the Peikiang at the iunction of the Teheng and Wu Riwrs, and is on the crossroad both by land and water (Fig. 1). The city was developed as 相似文献
4.
C.W.Wen 《地理学报(英文版)》1948,(1)
Ⅰ.Losatlon and Historical Development Chukiang or “the winding river” was a castle-like town which was originaIly surrounded by a wall.(Fig. 2)it is situated on the upper part of the Peikiang at the iunction of the Teheng and Wu Riwrs, and is on the crossroad both by land and water (Fig. 1). The city was developed as 相似文献
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6.
西藏冻融侵蚀的分级和评价 总被引：4，自引：0，他引：4
Freeze-thaw erosion is the third largest soil erosion type after water erosion and wind erosion. Restricted by many factors, few researches on freeze-thaw erosion have so far been done at home and abroad, especially those on the assessment method of freeze-thaw erosion. Based on the comprehensive analysis of impact factors of free-thaw erosion, this paper chooses six indexes, including the annual temperature range, annual precipitation, slope, aspect, vegetation and soil, to build the model for relative classification of freeze-thaw erosion using weighted and additive methods, and realizes the relative classification of the freeze-thaw erosion in Tibet with the support of GIS software. Then a synthetic assessment of freeze-thaw erosion in Tibet has been carried out according to the relative classification result. The result shows that the distribution of freeze-thaw eroded area is very extensive in Tibet, accounting for 55.3% of the total local land area; the spatial differentiation of freeze-thaw erosion with different intensities is obvious; and the difference in distribution among different regions is also obvious. 相似文献
7.
ZulkifliNasution MashhorMansor 《湿地科学》2004,2(2):104-109
Situated at an elevation of 905 m above sea level in the Province of North Sumatra, Lake Toba and its surrounding landscapes are regarded as a natural heritage in a certain extent, as a quoted national treasure. Unfortunately degradation of the land and water resources in the watershed along Lake Toba is taking place at an alarming and totally unacceptable rate. The quality of the lake is partly depended on input the quality of the rivers. When compared to the control area the water quality that influenced by the piggeries are highly polluted. It can be concluded that the Salbe River at the downstream of the piggeries has been polluted and apparently it is a serious problem to the catchment area management. It should be noted that the polluted river would influence the water quality of the Lake Toba. Based on calculation, the permissible BOD5 according to B- river standard is 238 mg/L, it means the river still in B standard but the condition and quality are decreasing continuously. Following the Indonesian health standard the permissible BOD is - 461 mg/L. It means BOD in the river should be reduced 461 mg/L or clean program is needed. 相似文献
8.
Soil erosion by wind means the soil particles are eroded and transported by wind. Fine particles of soil are transported as suspended load and may travel much greater distances than the coarse coarse materials do which are transported as creep and saltation. The finest particles and chemical microsome constitute the aerosol which can even keep for several years in atmosphere from descending. Wind erosion is a serious problem in many parts of the world. In China, up to 2400 km2 of land is dese… 相似文献
9.
Fluvial diversity in relation to valley setting in the source region of the Yangtze and Yellow Rivers 总被引：3，自引：3，他引：0
Guo-an Yu Le Liu Zhiwei Li Yanfu Li Heqing Huang Gary Brierley Brendon Blue Zhaoyin Wang Baozhu Pan 《地理学报(英文版)》2013,23(5):817-832
The spatial distribution of valley setting （laterally-unconfined, partly-confined, or confined） and fluvial morphology in the source region of the Yangtze and Yellow Rivers is contrasted and analyzed. The source region of the Yangtze River is divided into 3 broad sections （I, II and III） based on valley setting and channel gradient, with the upstream and downstream sections being characterized by confined （some reaches partly-confined） valleys while the middle section is characterized with wide and shallow, laterally-unconfined valleys. Gorges are prominent in sections I and III, while braided channel patterns dominate section II. By contrast, the source region of the Yellow River is divided into 5 broad sections （sections I-V） based on valley characteristics and channel gradient. Sections I, II and IV are alluvial reaches with mainly laterally-unconfined （some short reaches partly-confined） valleys. Sections III and V are mainly confined or partly-confined. Greater morphological diversity is evident in the source region of the Yellow River relative to the upper Yangtze River. This includes braided, anabranching, anastomosing, meandering and straight alluvial patterns, with gorges in confined reaches. The macro-relief （elevation, gradient, aspect, valley alignment and confinement） of the region, linked directly to tectonic movement of the Qinghai-Tibet Plateau, tied to climatic, hydrologic and biotic considerations, are primary controls upon the patterns of river diversity in the region. 相似文献
10.
In this study, data measured from 1955–2016 were analysed to study the relationship between the water level and river channel geometry adjustment in the downstream of the Three Gorges Dam(TGD) after the impoundment of the dam. The results highlight the following facts:(1) for the same flow, the low water level decreased, flood water level changed little, lowest water level increased, and highest water level decreased at the hydrological stations in the downstream of the dam;(2) the distribution of erosion and deposition along the river channel changed from "erosion at channels and deposition at bankfulls" to "erosion at both channels and bankfulls;" the ratio of low-water channel erosion to bankfull channel erosion was 95.5% from October 2002 to October 2015, with variations between different impoundment stages;(3) the low water level decrease slowed down during the channel erosion in the Upper Jingjiang reach and reaches upstream but sped up in the Lower Jingjiang reach and reaches downstream; measures should be taken to prevent the decrease in the channel water level;(4) erosion was the basis for channel dimension upscaling in the middle reaches of the Yangtze River; the low water level decrease was smaller than the thalweg decline; both channel water depth and width increased under the combined effects of channel and waterway regulations; and(5) the geometry of the channels above bankfulls did not significantly change; however, the comprehensive channel resistance increased under the combined effects of riverbed coarsening, beach vegetation, and human activities; as a result, the flood water level increased markedly and moderate flood to high water level phenomena occurred, which should be considered. The Three Gorges Reservoir effectively enhances the flood defense capacity of the middle and lower reaches of the Yangtze River; however, the superposition effect of tributary floods cannot be ruled out. 相似文献
11.
LI Xusheng YANG Dayuan KE Xiankun ZHOU Lufu CHEN Deji YANG Tianmin XUE Guofu 《地理学报》2003,13(4):507-512
This paper describes valley bottom troughs of the Changjiang River and infers the geomorphologic development of troughs. Based on the morphology of the troughs, the following conclusions are drawn. (1) The deep troughs on the Three Gorges valley bottom are formed by river downcutting along the structural zones on the background of regional tectonic uplift at about 40-30 ka BP. (2) When river downcutting occurred in the river bed of Changjiang, the jets current (particularly eddy current) with a large number of pebbles ground and eroded the valley bottom, resulting in trough formation and deepening. Meanwhile, water currents with gravels and pebbles eroded the bank and the left wall of No.76 trough as well as the right wall of No.77 trough by striking, scouring, horizontal and vertical grinding. (3) The depth of the trough is mainly determined by the intensity of the water current and the consistency of bedrock against erosion, and is not controlled by the altitude of the sea level as the base level of erosion. 相似文献
12.
长江三峡坝区河谷深槽的地貌特征及其成因 总被引：10，自引：0，他引：10
通过实地观察，分析三峡工程坝区河谷深槽的地貌特征，并在此基础上，对三峡深槽的成因及其发育年代进行探讨，结果表明：（1）三峡坝区河谷深槽是在三峡地区构造抬升过程中，水流顺构造裂隙强裂侵蚀下切而形成的；对深槽堆积物中朽木进行的14C测年表明，三峡深槽的深切侵蚀大约发生在30－40ka BP;(2)三峡深槽的向下深切主要是急流（特别是漩流）携带岩砾对槽底进行研磨，掏蚀作用形成的；三峡坝区坝上深槽中的岩礁和左壁以及坝下深槽的右壁还受到急流携带岩砾的撞击、冲蚀、磨蚀和下沉流的垂向磨蚀作用；坝下深槽的左壁则是发育了深槽之后，由槽壁岩石的减压张裂及其水下的坍塌而拓展形成的；（3）深槽的平面延伸受到纵向裂隙构造的控制，最容易发生强烈深切的位置，则受到横向裂隙与纵向裂隙的受切部位控制；深槽中的深潭向下深切所能达到的深度，主要与局部水势的变化及床底岩石抗蚀强度的差异有关，其深度不受海面高度的限制。 相似文献
13.
Seismic framework and the Holocene morphological evolution of the Changjiang River mouth, China 总被引：2，自引：0，他引：2
Acoustic profiling in combination with coring has been used to examine the recent evolution of river mouth of the Changjiang. Two acoustic facies are present. Petrologic, radiometric and seismic analyses show that the upper facies I of 10–20 m thick fine sand and silt represents the sandy shoals of late Holocene age in the distributary, and the 5–20 m thick lower facies II of fine-grained silty clay with abundant marine microfossils represents the mid-Holocene prodelta facies deposited as fillings in the former large estuarine valley of late Pleistocene to early Holocene origin. Rapid accumulation during the Holocene has led to some instability of unconsolidated sedimentary strata in the distributary, such as strata collapse and mud diaper formation. The existence of large cross beddings, such as tabular and trough stratification in facies I identifies the sediment transport as predominantly bed load, driven by runoff and tidal currents. Two sets of discrete flood-ebb flow troughs, oriented NW and SE reflect controls by tidal waves generated from the sea and the superimposition of runoff and ebb flows. Symmetrical sand waves that appear at the northern trough of one of the distributaries also indicate the balancing sediment dynamics between runoff-ebb and flood currents, whereas the asymmetrical ones in the southern trough indicate superimposed sedimentation by runoff and ebb flows. A large quantity of sediment has been deposited in the slack water region between the discrete flood and ebb flows to form sandy shoals — the principal mechanism of the evolution of estuarine islands in the Holocene Changjiang mouth. The morphology of the extended river mouth to the southeast possibly indicates an external driving force, such as the Coriolis Effect, NW-prevailing wind and longshore currents. 相似文献
14.
科尔沁沙地西部响水河河水与其河岸相互作用的初步研究 总被引：1，自引：1，他引：0
近年来,半干旱地区的风水相互作用正成为风沙地貌研究的新热点,为探讨科尔沁沙地西部响水河河水与其河岸间的相互作用,通过对科尔沁沙地西部响水河的3个典型河段的6个断面的断面形态、流速进行现场实测,同步采集了31个水样,然后在室内对其泥沙含量进行测试,并推算断面流量。结果表明：由南向北3个河段瞬时流量和泥沙含量呈递增的趋势,集水效应十分明显;该河丰水期水量较为丰沛,河流与河岸间的相互作用明显且活跃,主要存在河水掏蚀河岸陡坡等5种相互作用的方式;当下风向陡岸弯道的法线方向与当地盛行风向一致时,气流发生明显汇聚,侵蚀加强,形成风蚀槽,且当风蚀槽接近谷底时,又为曲流的摆动创造了有利条件;河流受到沙丘前移的压迫与下风向河谷陡坡的阻挡,曲流较为发育但不完美,属于非自由曲流。 相似文献
15.
Channel morphology and its impact on flood passage, the Tianjiazhen reach of the middle Yangtze River 总被引：1，自引：0，他引：1
The Tianjiazhen reach of the middle Yangtze is about 8 km long, and characterized by a narrow river width of 650 m and local water depth of > 90 m in deep inner troughs, of which about 60 m is below the mean sea level. The troughs in the channel of such a large river are associated with regional tectonics and local lithology. The channel configuration plays a critical role in modifying the height and duration of river floods and erosion of the riverbed. The formation of the troughs in the bed of the Yangtze is considered to be controlled by sets of NW–SE-oriented neotectonic fault zones, in which some segments consist of highly folded thick Triassic limestone crossed by the Yangtze River. Several limestone hills, currently located next to the river channel, serve as nodes that create large vortices in the river, thereby accelerating downcutting on the riverbed composed of limestone highly susceptible to physical corrosion and chemical dissolution. Hydrological records indicate that the nodal hills and channel configuration at Tianjiazhen do not impact on normal flow discharges but discharges > 50,000 m3s− 1 are slowed down for 2–3 days. Catastrophic floods are held up for even longer periods. These inevitably result in elevated flood stages upstream of prolonged duration, affecting large cities such as Wuhan and a very large number of people. 相似文献
16.
西安地区灞河河谷土壤侵蚀量研究 总被引：1，自引：1，他引：0
以野外调查测量与河谷侵蚀历史资料为依据,研究了灞河河谷土壤总侵蚀量和各阶段侵蚀量,并提出了非对称型河谷区与对称型河谷区的土壤侵蚀量计算公式。结果表明,灞河发育的5级阶地与河漫滩代表灞河发育以来共经历了6个明显的侵蚀阶段,各阶段侵蚀量均存在差别,从老到新,第一、三侵蚀阶段侵蚀强,第二、四、五阶段及河漫滩代表的侵蚀阶段侵蚀弱。河流侧向迁移造成的侵蚀量大于垂直下切产生的侵蚀量。蓝田县城附近57.3 km2范围内侵蚀总量约为6.5 km3。文中提出的计算河谷土壤侵蚀量的计算公式不仅适用于灞河河谷区,而且也适用于其他河谷区。这项研究对河谷区土壤侵蚀总量和分阶段侵蚀量的计算以及查明侵蚀强度变化规律有重要意义。 相似文献
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螺髻山地处青藏高原东南缘,是确切存在第四纪古冰川遗迹的典型山地之一,该区冰川地貌演化对于研究环境变化具有重要的科学意义。螺髻山东坡清水沟保存两套古冰川槽谷,分别为上槽谷和下槽谷,其中下槽谷保存完整,而上槽谷在3450~3600 m的阴坡部分出现缺失。采用野外地貌调查与模型分析相结合的方法,对冰川槽谷地貌进行分析,结果表明:清水沟槽谷的抛物线模型中,|A|值在1.3101~15.2064 之间变动,B 值变化于0.9695~3.2965 之间,且随着海拔由高到低,都存在着先变小后变大的规律,A、B值同时反映出在海拔3450~3600 m处冰川槽谷的演化不符合常态。分析认为岩性差异和河流溯源侵蚀是影响上槽谷形态的主要原因。对保存在清水沟上下槽谷内的高、低侧碛进行ESR年代测定,结果显示:高侧碛形成于58-84 ka BP左右的末次冰期早期,对应深海氧同位素4 阶段(MIS4);低侧碛形成于13-17 ka BP,属于于全球末次冰盛期晚期的产物。两次冰川作用分别塑造出两套冰川槽谷,即在末次冰期早期冰川作用形成上槽谷,末次冰期晚期形成下槽谷。 相似文献
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The blocking or reversing effect of the downstream trunk river on its tributary lakes is an essential aspect of river-lake hydraulics. To measure how and the extent to which a trunk river can influence its tributary lakes, we made a case study in Changjiang River and one of its tributary lakes, Lake East Dongting (Lake ED) during a 35-year study period (1980–2014). Specifically, we investigated Lake ED’s discharge ability into Changjiang River using stage-discharge relationship curves, and hence the changes of the lake discharge ability under different hydrologic conditions of the Changjiang River. The results show that (1) the Changjiang River does exert a huge impact on the water regimes of Lake ED. And this impact varies seasonally. A variation of 3000 m3/s in Changjiang River’s runoff would change the lake water level by about 1.1 m in dry seasons, by 0.4 m in wet seasons, and by 0.6 m during severe summer floods. (2) Changes in the Changjiang River runoff triggered by the Three Gorges Dam since 2003 have led to dramatic water regime variations in Lake ED. Other factors, including reduction of lake inflow and the lake bed erosion, also exacerbated the water regime variations in Lake ED. 相似文献
20.
云南东川地区层状地貌面的成因 总被引：1，自引：1，他引：1
在东川地区的山地及小江河谷的两侧山麓上部，分布着不同高度和不同规模的层状地貌面，对其成因仍有不同的认识。分歧主要表现在两个方面：一是高原隆升之前的初始地貌面是否是准平原型夷平面；二是山顶面之下的梯级层状地貌面的成因。本文从以下几个方面对上述问题进行讨论：(1)层状地貌面的地貌特征及其与侵蚀河谷体系的关系；(2)层状地貌面上堆积物的性质；(3)层状地貌面与断裂构造水平展布的关系；(4)相邻层状地貌面的空间过渡关系；(5)区域构造演化背景。作者认为在云贵高原抬升过程中，东川地区以挤压穹起隆升变形为主。不同海拔高度的层状地貌面具有多成因特性。山顶面及局部高原面是高原隆升之前古夷平面的残留。并遭到后期强烈的侵蚀改造。目前，尚缺乏足够证据证明高原隆升之前的古夷平面为准平原型夷平面。小江河谷两侧的梯级层状地貌面是侵蚀或剥蚀面，它们形成于高原隆升及初始地貌面解体之后，其梯级空间分布特征与区域性的阶段隆升有关。 相似文献