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1.
通过野外调查及试验对堰塞坝的稳定和裂点的发育进行研究,发现堰塞坝的稳定性主要取决于泄洪道内阶梯-深潭系统的发育程度SP和坝体上游洪峰的水流能量P.堰塞坝的保存与溃决情况采用保留的坝高比进行定量描述,对于洪峰流量小于30 m3/s山区河流,保留坝高比与SP呈线性相关;洪峰流量大于30 m3/s(＜ 30000m3/s)时,河道稳定所需的最小河床结构强度SP随着单宽水流能量P的增加而增大.堰塞坝泄洪道内不发育阶梯-深潭系统或发育程度较低的坝体,SP值小于稳定河床最小的阻力强度,将会发生下切、溯源冲刷并引起溃坝.保留的堰塞坝在泥沙淤积和水流的长期作用下会形成裂点,对河床下切起到控制作用,降低再次发生滑坡的风险.大型裂点能改变河床演变和河流地貌,连续堰塞坝形成的裂点能长期保存并形成优美的自然景观,创造良好的河流生态环境. 相似文献
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涌浪规模对冰碛湖溃决的影响实验 总被引：2，自引：0，他引：2
随着全球气候变暖,冰碛湖溃决灾害频发,冰碛湖溃决的触发机理研究成为关注点,其中由于冰(雪)崩坠湖触发的涌浪冲蚀破坏是冰碛湖溃决的主要因素。为探索研究涌浪诱发冰湖溃决的动力过程,设计了一套水槽系统进行模拟实验,探讨冰(雪)崩塌入湖诱发涌浪溃坝的发展过程及溃决流量特征,分析不同涌浪规模对溃坝形成机制的影响。结果表明:1.涌浪是冰碛湖坝体溃决的直接触发因素,在首浪及后续周期性折返涌浪的作用下坝体溃口逐渐形成,其后随着水势能增大,在下蚀、溯源侵蚀和侧蚀的共同作用下,坝体侵蚀率迅速加大,洪峰流量出现在这个阶段;2.涌浪规模越大,首浪对坝顶的侵蚀越充分,涌浪对坝体的侵蚀越迅速,坝体剖面形态线越稀疏。由于静水位不变条件下侧蚀作用更强烈,溃口的最终宽度较静水位改变的情形大;3.静水位改变的情形下,首浪漫溢形成极大规模的初始流量Q0,并且首浪规模越大,初始流量Q0也就越大。洪峰流量Qm出现在坝体溃决初期,涌浪规模越大,洪峰流量Qm出现时间越早。 相似文献
3.
通过土石坝溃决的特征,建立了土石坝体溃决模型,并预测溃口流量过程和溃口拓展过程。模型溃口假定为梯形,且在坝体溃决过程中底宽和溃口边坡不发生变化。根据水量平衡和坝体物质守恒,模拟溃口的拓展过程;溃口水力过程用宽顶堰流表示,并使用经验公式计算溃口不同水头条件下的冲蚀量。针对这些差分方程为隐性格式,难以直接求解,提出了特殊的迭代解法,且较少的迭代次数即可收敛。通过模型对四川北川唐家山堰塞湖的溃决过程进行了反演,结果显示:坝体溃决相关参数包括溃决持续时间,溃决峰值流量和出现时刻、坝体最终几何形状以及堰塞湖溃决排出总水量,当计算参数选择合理时,预测值与实测值比较吻合。从模拟计算结果来看,模型预测具有一定的可行性,可以为堰塞坝的安全预警和应急处置提供数据支持。 相似文献
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"5·12"汶川地震堰塞湖应急处置措施的讨论——以唐家山堰塞湖为例 总被引：2，自引：1，他引：1
堰塞湖是地震诱发的次生灾害类型之一.唐家山堰塞湖是"5·12"汶川地震造成的规模最大、潜在威胁最严重的堰塞湖,水利部组织了唐家山堰塞湖应急处置,成功降低了该堰塞湖风险,未造成新的人员伤亡.从该堰塞湖溢流的流量过程曲线和对北川县城的影响来看,还有值得改进的地方.经初步分析,提出改进措施:1.变梯形过流断面为复式断面;2.增大设计纵比降;3.保护泄流槽的进、出口,控制沟道下切速度;4.抛掷人工结构体控制沟床下切速度.为了避免自然排泄的不利影响,提出"人工可控排泄"处理堰塞湖.希望这些措施在以后类似堰塞湖应急处置中能够被参考,最大限度减少灾害损失,减少防灾减灾的社会、经济成本. 相似文献
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《山地学报》2016,(2)
红石岩堰塞湖是2014-08-03鲁甸地震诱发形成的大型堰塞湖,由红石岩崩塌堵断牛栏江形成。红石岩堰塞坝坝高约96 m,堆积体总方量约1 200×10~4m~3,湖区满库库容为2.6×10~8m~3。从红石岩堰塞湖形成的背景条件,以及堰塞湖对坝址所在流域构成的潜在灾害链效应,评估堰塞湖的溃决危险程度。同时根据可能的溃决形式分析,采用1/3和1/2溃决模式对堰塞湖溃坝洪水估算,得到两种工况条件下的峰值流量分别为:Q_p≈(1.3~1.5)×10~4m~3/s和Q_p≈(2.2~2.8)×10~4m~3/s,远超过坝址处500 a一遇的牛栏江暴雨洪水,并在此基础上对下游演进过程的洪水进行估算。认为红石岩堰塞湖在后期整治中仍存在库岸稳定、堰塞坝稳定和鱼类生态破坏等问题,应引起关注。 相似文献
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受青藏高原新生代快速隆升和河流的快速下切影响,在我国西南山区高山峡谷、高地应力场、频繁的地震活动、暴雨及人类活动等内外动力作用下,河谷地段常形成暴雨诱发滑坡→堵江→堰塞湖灾害链。2012-08-31,四川喜德县遭遇200 a一遇的特大暴雨,日最大降雨量达149.2 mm。热柯依达乡上游1.5 km处发生大型碎屑岩滑坡,体积为520×104m3,堵河形成堰塞坝。堰塞湖水位上升28.6 m,库容量达120×104m3,威胁下游9个乡镇与县城约1.29万人的生命财产安全。基于对滑坡及堰塞坝的工程地质测绘,分析了滑坡的平面、空间形态,滑坡体、堰塞坝的物质结构、变形破坏特征。研究了滑坡运动过程的地质力学模式,推导出本构方程。主要认识有:1.滑坡体物质主要分为散体、层状碎裂、层状块裂结构。2.滑坡失稳运动地质模式为:强降雨诱发滑体产生后退式拉裂蠕滑启动;在岩体裂隙中静水压力和动水压力作用下,和前缘良好临空条件结合,产生高速滑动,凌空飞行;受河谷、对岸山体阻挡,急速停止,解体、破碎,堆积于河谷,堵断河流形成堰塞体。3.滑坡启动失稳力学模式主要为潜水和承压含水层混合模式。天然工况下稳定性系数为1.18,处于基本稳定状态;暴雨工况下为0.92,失稳破坏。推导出滑坡短程飞行、碎屑流运动本构方程。4.堰塞坝整体稳定性好,发生管涌或流土溃决的可能性小,主要以"漫顶"模式逐级冲刷破坏。 相似文献
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《山地学报》2015,(6)
针对松散物质异常丰富孕灾环境条件下泥石流的形成过程和泥沙来源,设计了人工降雨条件下泥石流形成试验,主要获得以下结果:1.震后孕灾环境条件下泥石流的形成首先需要细颗粒的起动,然后夹杂大颗粒运动,径流量快速增加,并伴随着沟道堵塞-溃决现象,形成阵性泥石流;此后随着细颗粒的迁移,沟道粗化现象严重,泥石流现象逐渐消失。2.坡面首先对降雨开始响应,发生崩塌形成堰塞体,对沟道侵蚀产生较大影响,并伴随着坝体松散物质溃决向下游迁移。3.泥石流的泥沙主要来源于沟道中下游,其次是沟道中上游和源头坡面,三处的泥沙来源占到70%以上。4.土体对降雨的响应明显,孔隙水压力和含水量在不同时间段和不同部位变化曲线具有明显差异,并出现一定的波动特征,其不仅受到降雨的影响,同时对土体细颗粒含量和土体结构也有明显响应。5.细颗粒在泥石流的形成过程中扮演者非常重要的角色,其位移和汇集均对流域地形的演化和泥石流的形成产生影响。在泥石流形成预报时,应考虑土体细颗粒含量,不同的细颗粒含量其泥石流起动时临界含水量和孔隙水压力差异较大。 相似文献
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岩溶流域水文模型研究进展 总被引：6，自引：0，他引：6
岩溶地区含水介质结构的多重性和岩溶地貌形态的高度复杂性,使岩溶系统的水文效应和水资源的评价与预测一直都成为水文研究的重点和难点.在岩溶含水介质特点和岩溶水文形成过程的基础上,本文着重评述了黑箱模型、概念性模型、物理性模型和分布式水文模型在岩溶水文模拟中的应用.其中黑箱模型包括基于核函数的算法、回归模型、人工神经网络和小波分析;概念性模型包括蓄泄模型和流量过程线衰减函数;物理性模型主要包括达西定律、Darcy-Weisbach方程、有限元法和等效连续多孔介质;分布式水文模型主要是SWMM模型,并分别对各类模型的概念、方法、应用效果以及存在的优缺点等进行了分析.最后指出了研究中存在的一些不足,并就岩溶流域水文模拟的进一步研究提出了相应的建议,这对于解决岩溶区的水资源可持续利用问题有重要意义. 相似文献
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粤东北山区不同土地利用类型红壤团聚体及其有机碳分布特征 总被引：1，自引：1，他引：0
以天然常绿阔叶林地、柚果园、茶园、人工桉树林地和旱地为研究对象,采用野外调查和室内实验分析相结合的方法,研究了粤东北山区红壤团聚体及其有机碳的分布特征.结果表明:①研究区5种土地利用类型红壤各级风干团聚体占总团聚体的比例均为粒径＞5 mm的最大,阔叶林地各级风干团聚体含量基本上高于其他土地利用类型.湿筛后,阔叶林地和果园土壤团聚体水稳性较好,表土层粒径＞ 0.25 mm的水稳性团聚体含量均在70％以上;而茶园、桉树林和旱地各土层土壤水稳性团聚体明显减少,结构体破坏率高.②不同粒级红壤团聚体有机碳含量在不同土地类型有明显差异,总体上表现为阔叶林地最高,果园次之,早地与桉树林地最低.随土层增加团聚体有机碳含量呈逐渐减小趋势,阔叶林地团聚体有机碳含量垂直变化最大,减幅达46.25％;桉树林地和旱地减幅最小,分别为29.58％和12.54％.③不同粒径团聚体的百分含量与其有机碳含量之间存在线形关系,阔叶林地和果园土壤＞5 mm、5～2 mm团聚体与其有机碳含量之间呈高度或显著正相关.茶园、桉树林地和旱地则较小粒径的团聚体与其有机碳含量之间呈高度或显著正相关.地带性森林植被的营造和保护有利于土壤团聚体的形成以及土壤有机碳的积累与稳定. 相似文献
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准噶尔无叶豆的地理分布、群落学特征及生物生态学特性 总被引：3，自引：1，他引：2
准噶尔无叶豆(Eremosparton songoricum（Litv.）Vass.)是国家级保护植物。对该植物地理分布、群落特征及生物生态学特性进行的研究表明:①准噶尔无叶豆分布区和生态幅狭窄,在我国仅斑块状分布于新疆古尔班通古特沙漠腹地局部地段及沙漠东南缘的部分流动沙地上;②群落中包含植物14科33属37种,可划分为7个地理区系成分,其中,温带分布型属占75.76%。依据群落组成及外貌,划分为5个群丛,主要特点为:不表现为显著的景观植被,且小面积出现;结构简单,层次单调,植物组成均系适沙和耐沙的种类;整个群落以先锋性为特征。此外,群落不稳定,有逐步被其他类型的、相对稳定的群落所替代的趋势,具有时空分布的“暂时性”;③具有“花多果少”的果实产量格局,2005年结实率为(15.36±2.16) %。呈“水泡状”或“干瘪状”的种子比率达(16.2±2.31)％,虫蛀率达(16.92±2.69)%;④种子向幼苗转化率低。依靠超强的水平根茎克隆能力来扩展种群空间。经综合分析,认为准噶尔无叶豆对生境高度专一,人为干扰破坏所带来的生境丧失将使该种受胁状态加剧。对该物种进行保护首先应加强现有生境的就地保护,减少人为破坏;其次,积极开展迁地保护生物学研究,建立苗圃,营造人工种群。 相似文献
11.
The Bunger Hills in East Antarctica occupy a land area of approximately 400 km2. They have been exposed by Holocene retreat of the Antarctic ice sheet and its outlet glaciers. The accompanying sea level rise flooded the marine inlets that now separate the northern islands and peninsulas from the major part of the hills. During deglaciation the continental ice sheet margin retreated south‐eastwards with several temporary halts, during which ice‐dammed lakes were formed in some valleys. These lakes were maintained long enough to permit formation of beaches of sand and gravel, and for the erosion of shore platforms and low cliffs in bedrock. Around the western end of Fish Tail Bay impressive shoreline features 20 m above sea level define a former ice‐dammed lake that was 5.5 km long. A similar 7 km long former ice‐dammed lake was formed at Lake Dolgoe. The more extensive and deeper glacial lake is revealed by well‐developed and preserved shoreline features cut at 29 m which is 16 m above present lake level. In addition, several small ice‐dammed lakes existed temporarily near Lake Shchel and in the valley to the west. Lake Fish Tail existed more than 6,900 14C years ago and Lake Shchel probably more than 6,680 14C years ago. It is inferred that the shore platforms and beaches were formed by lake ice and wave action over considerable periods when the lakes were impounded by steep cold ice margins. There appears to have been a balance between meltwater input and evaporative loss from the lakes in the cold dry continental climate. There is no evidence for rapid lake level fluctuations, and there was very little input of clastic sediment. This resulted in poor development of deltaic and rhythmically laminated lake floor deposits. It is suggested that such deposits are more characteristic of ice‐dammed lakes formed in association with wet‐based temperate ice than those associated with dry‐based polar ice. 相似文献
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JOHN F. SHRODER JR BRANDON J. WEIHS 《Geografiska Annaler: Series A, Physical Geography》2010,92(4):469-483
Lake Shewa in northeastern Badakhshan, Afghanistan, was dammed sometime in antiquity when a large rock avalanche (sturzstrom) from the fault‐shattered and strongly weathered Archean gneisses of the Zirnokh peaks to the north moved into the Arakht River valley. This rock avalanche dammed up the river and its tributaries to a dam thickness of c. 400 m, producing a 12‐km‐long lake that is as much as 270 m deep, leaving c. 80 m of freeboard to the top of the dam. At least four separate instances of slope failure have been mapped at the site of the landslide dam, as well as a rock glacier, using remotely sensed data, historical maps, and Google Earth?. Spring seepage through the dam face has caused several recent subsidiary debris slides, which if continued at a large enough scale for long enough, or with additional seismicity from the active strike‐slip faults that cross beneath the landslide dam, could threaten its integrity. Otherwise the clean water that emerges from the dam face could be the source of an unvarying mini‐hydroelectric power source, in addition to the agricultural irrigation that it provides at the present time. 相似文献
14.
中昆仑山阿什库勒盆地地貌与第四纪环境问题 总被引：8，自引：0，他引：8
本文论述了阿什库勒盆地的地貌和沉积物的发育等问题。认为:(1)阿什库勒盆地的火山锥至少有11座,1号火山1951年不可能有岩浆喷发,火山泥石流体是不存在的;(2)黄土物质是全新世风积物,戈壁荒漠是其物源区;(3)阿什库勒湖与乌鲁克库勒湖均是火山堰塞湖,前者是18kaB.P.前熔岩流阻塞盆地东部出口而成;后者则是6.5kaB.P.新期火山喷发物拦截阿什库勒湖的部分水域所致。 相似文献
15.
青藏高原东南缘干热河谷中广泛发育黄土或黄土状土,是解读中国西南季风、干热河谷环境演变与高原隆升关系的良好载体,但目前尚无关于其成因、形成时代和古气候意义的系统研究。通过对金沙江干热河谷华弹段中黄土状土的空间分布、粒度特征、化学风化指数以及沉积速率的分析,发现该区黄土状土拔河越高,粒径越小,沉积速率越低;结合前人物源示踪研究成果,证实黄土状土来源于金沙江谷底的河漫滩沉积和古堰塞湖沉积,局地山谷风环流为其提供搬运动力。磁性地层学分析显示黄土状土地层全为正极性,剖面中未出现B/M界线,结合光释光测年结果,确定金沙江干热河谷华弹段中的黄土状土形成于中更新世中期以来。通过与同河段的古堰塞湖沉积形成时代进行对比,发现黄土状土的形成时代稍晚于同河段古堰塞湖相沉积大量堆积的时代。金沙江河谷中黄土状土与古堰塞湖相沉积在时空上的紧密关联性表明,滑坡堰塞事件控制着金沙江干热河谷中黄土状土物源的丰富程度,是影响金沙江深切河谷中黄土状土形成与沉积过程的主要因素。黄土状土的粒度与化学风化指数结果表明358 ka BP以来,该段河谷中古环境气候发生过明显冷干-暖湿波动,并在冰期-间冰期尺度上响应全球气候变化。 相似文献
16.
Kwadwo Owusu Maame Asiwah Nkansah 《Geografisk tidskrift / udgivet af Bestyrelsen for Det Kongelige danske geografiske selskab》2017,117(1):1-10
Construction of dams affects the livelihoods of the population living along the dammed river. There is a need for more studies to guide dam development policies and management to safeguard the livelihoods of local river users. This paper examines the effects of dams on the socio-economic livelihoods of downstream communities by drawing on the Kpong Dam in Ghana constructed from 1979 to 1982 with the goal of supplying energy and for irrigation purposes. Primary data were collected in resettled and non-resettled downstream communities using a mixed-research approach. This case study highlights how the Kpong Dam has affected the downstream river-dependent population whose livelihoods, particularly farming and fishing revolved around the seasonal flow regimes of the Volta River. Our study challenges the general perception that dams increase agricultural production by illustrating that developing ancillary facilities such as irrigation schemes as part of dam projects can enhance all-year-round agricultural production to improve food and income security of downstream households only when constraints such as lack of farm inputs are addressed. To safeguard livelihoods and limit the social impacts of dams, compensation schemes and alternative livelihood activities should be designed to include resettled and non-resettled communities along the downstream areas affected by dam projects. 相似文献
17.
《Norsk geografisk tidsskrift. Norwegian journal of geography》2012,66(3-4):122-149
Glacier dammed lakes may have their outflow over a bedrock threshold like other lakes, or they may flow on the surface or below the damming ice. In the former case the lake, over some considerable period, has a constant maximum level with marked shore lines corresponding to the threshold. But when the level is determined by the ice dam, the conditions are unstable. The level of the lake will then to a certain extent vary in step with the glacier, and never remain at a certain level for any length of time. The normal behaviour of such a lake will be a moderately fast rise of the water level, dependent upon the supply, until a certain critical level is reached, whereupon drainage is rapid. Such is also to some extent the case with the type of lake first mentioned, if the height of the pass is situated near to the critical level for drainage. 相似文献
18.
Per Klingbjer 《Geografiska Annaler: Series A, Physical Geography》2004,86(2):169-179
An ice‐dammed lake at the margin of the glacier Sälkaglaciären, in the Kebnekaise Mountains in northern Sweden, drained suddenly in July 2003 producing a flood with a measured peak discharge of 9.5±0.25 m3s‐1. The total lake volume of 4.55×105 million3 drained within two days. The hydrograph of this event is characteristic of a jökulhlaup controlled by a single basal ice tunnel that enlarges due to melting. The jökulhlaup had an exponential rise to a peak discharge, and following the peak, a very steep fall in discharge as the water supply to the drainage system ceased. A similar jökulhlaup was observed in August 1990 with an estimated release of 8.05×105 m3 water. Jökulhlaups at Sälkaglaciären are recurring events and have been indirectly observed since the 1950s. 相似文献
19.
堰塞湖的水文特征过程对于库区洪水宏观调控、预报预警、安全防治等具有重要意义。为了及时掌握萨雷兹堰塞湖水文特征和历史演化过程,本文基于密集时间序列遥感数据,综合调查全面系统地分析了1972—2019年帕米尔高原萨雷兹堰塞湖的水文特征以及时空变化过程;并通过“面积-水位”关系模型重建了1972—2019年萨雷兹堰塞湖的历史水位面积演变时序过程;在此基础上采取M-K趋势和突变检验分析了水文变化特征。研究结果表明：① 萨雷兹堰塞湖水位总体上呈现波动性显著上升趋势,这种波动趋势主要表现为年内波动和高位震荡,但振幅在逐年减小。② 萨雷兹堰塞湖水文时序演化过程在2013年前后出现了一个突变拐点,面积水位变化特征表现为由原来的缓慢增加转变到加速上升。③ 1972—2019萨雷兹堰塞湖面积和水位关系模型为：y=-0.1003x2+18.181x+2440,（R2=0.63,P<0.05,双尾）。结合流域气象、径流以及相关文献数据分析得出萨雷兹堰塞湖的水文特征年内/际波动直接受穆尔加布河径流补给量的影响;区域冰川积雪加速消融带来的河道径流补给量增加是近年来面积水位加速上升的主要原因。 相似文献
20.
On 10th Oct.and 3rd Nov.2018,two successive landslides occurred in the Jinsha River catchment at Baige Village,Tibet Autonomous Region,China.The landslides blocked the major river and formed the barrier lake,which finally caused the huge flood disaster loss.The hillslope at Baige landslide site has been still deforming after the 2018 slidings,which is likely to fail and block the Jinsha River again in the future.Therefore the investigation of 2018 flood disaster at the Baige landslide is of a great significance to provide a classic case for flood assessment and early warning for the future disaster.The detailed survey revealed that the outstanding inundations induced bank collapse disasters upstream the Baige landslide dams,and the field investigations and hydrological simulation suggested that the downstream of the Baige landslide were seriously flooded due to the two periods of the outburst floods.On these bases,the early warning process of potential outburst floods at the Baige landslide was advised,which contains four stages:Outburst Flood Simulating Stage,Outburst Flood Fore-casting Stage,Emergency Plan and Emergency Evacuation Stage.The study offers a con-ceptual model for the mitigation of landslides and flood disasters in the high-relief mountain-ous region in Tibet. 相似文献