金沙江“11·3”白格堰塞湖溃决洪水事件在奔子栏—石鼓段的地貌作用和沉积特征     

苏怀  史正涛  董铭  叶燎原  叶蕾 《地学前缘》2021,28(2):202-210

古堰塞湖溃决洪水事件的重建是当前地学研究的热点问题之一,寻找足够的可参考的现代溃决洪水事件案例是顺利开展这项工作的基础。2018年11月13日发生在金沙江干流的白格堰塞湖超万年一遇的溃决洪水事件(学术界称之为“11·3”白格堰塞湖溃决洪水事件)就是一个难得的样本。这次溃决事件发生在枯水期,洪峰完全由溃决洪水产生,没有叠加其他来源,对评估流域地貌和沉积体系对堰塞溃决事件的响应有很好的参考价值。本文以溃决洪水事件受灾最为严重的奔子栏—石鼓段为研究区,通过详细的野外调查和初步的水力学估算发现“11·3”白格堰塞湖溃决洪水事件在奔子栏—石鼓段的地貌作用主要表现为洪水淹没区的岸坡塌岸和沉积物堆积,未发现明显的基岩侵蚀。沉积物主要由分选良好的具水平纹层的砂组成。受金沙江较低的河床比降影响,洪水产生的基底剪切应力较弱在27~142 N/m²,不能悬浮和搬运直径5 cm以上的砾石,也不能产生明显的磨蚀和冲(撞)击作用。在发生塌岸的部分段落,洪水沉积物中有砾石坠入,甚至会出现类似浊流沉积的层序。这些现象的发现对深入理解堰塞湖溃决洪水的复杂地貌过程和沉积特征有重要参考意义。  相似文献   

基于暴雨内涝模型的天津市西青区中小河流暴雨洪涝灾害评估     

陈靖  高强  李培彦  解以扬  王秀俊  刘志杰  韩玥 《气象科技》2019,47(1):147-153

利用ARCGIS对天津市西青区的高精度地理信息数据、排水设施和排水方式进行预处理,以西青区下垫面和明渠河道的水流运动为模拟对象,建立天津市西青区中小河流暴雨洪涝仿真模型。以区内14条二级河道的水位变化作为模型的动态侧边界条件,针对2016年7月20日的大暴雨过程,设计了4个模拟方案,对河道高水位及暴雨造成的洪涝淹没过程进行评估,并将模拟结果与实际调查内涝灾情进行对比,结果表明,模型可以较客观地反映暴雨和河道水位变化对城镇造成的内涝灾害情况。  相似文献   

气候变化情景下澜沧江流域极端洪水事件研究   总被引：1，自引：0，他引：1  

王书霞  张利平  李意  佘敦先 《气候变化研究进展》2019,15(1):23-32

以澜沧江流域为研究对象,基于ISIMIP2b协议中提供的GFDL-ESM2M、HadGEM2-ES、IPSL-CM5A-LR、MIROC5这4种全球气候模式,通过4种模式的输出数据耦合VIC模型,分析4种模式在历史时期（1961—2005年)对洪峰洪量极值(年最大洪峰流量、3 d最大洪量)、极端洪水的模拟能力,比较RCR2.6和RCP6.0两种情景下未来时期（2021—2050年)年均径流量较基准期（1971—2000年)的变化情况,并结合P-III型分布曲线预估了澜沧江流域在两种情景下未来时期极端洪水的强度变化情况。结果表明：VIC模型在该流域能够较好地模拟极端洪水;HadGEM2-ES和MIROC5两种气候模式的输出数据在澜沧江流域有较好的径流模拟适用性;在RCP2.6情景下,澜沧江流域未来时期年均径流量没有明显变化,可能会有略微的增加,而在RCP6.0情景下,未来时期年均径流量有较大可能增加;澜沧江流域未来时期极端洪水较基准期,在RCP2.6情景下无明显变化,而在RCP6.0情景下,洪峰、洪量增加的可能性较大,极端洪水频率和强度也较大可能增加。  相似文献   

2017年江西汛期设区市城区暴雨回波特征分析   总被引：3，自引：3，他引：0  

邓虹霞  智海  马中元  张瑛  何文 《气象科学》2019,39(2):274-284

使用江西WebGIS雷达拼图和自动站雨量、雷电监测、强天气监测等数据,以及MICAPS常规天气图资料,对2017年3—7月江西汛期11个设区市26次城区暴雨过程的雷达回波特征进行分析。结果表明:2017年江西汛期共出现52日暴雨过程,其中江西11个设区市所在地城区出现26次暴雨。在这26次城区暴雨个例中,有23次伴随出现短时强降水,有3次降水比较均匀。暴雨维持时间长短不一,最长的有15 h,最短只有3 h,平均是10 h。有5次出现大风天气,21次没有大风出现。雷达回波特征主要有3种:块状(强单体、超级单体)、带状(飑线、回波带)、絮状(絮带、絮团)。这3种回波形态特征,出现率最高的是絮状回波,即比较宽、嵌有中等强度的对流单体絮带状回波带,强度40～55 dBz,出现16次,概率62%;其次是窄而长、紧密排列由强单体组成的飑线回波带,强度50～60 dBz,出现8次,概率30%;块状(强单体、超级单体)回波强度最强,中心强度达到60～70 dBz,出现2次,概率8%。  相似文献   

疏勒河流域极端水文事件对极端气候的响应     

程玉菲  程文举  胡想全  金彦兆 《高原气象》2019,38(3):583-592

为了明确疏勒河流域极端水文事件对极端气候事件的响应关系,选取疏勒河流域内及其周边的托勒、敦煌、瓜州、玉门、酒泉、马鬃山等气象站点的气温、降水和蒸发的日值数据,昌马堡水文站的日径流数据,通过趋势分析、滑动平均、主成分分析等方法,分析疏勒河流域极端气候指数、极端水文事件的年际变化规律以及影响极端水文事件的因素,并明确该流域极端洪水年内分布特征。结果表明:疏勒河流域年际气温升高趋势明显,降水量呈波动变化,增加趋势不明显,而蒸发量呈下降的变化趋势。表征高温的极端气温指数呈显著上升趋势,表征低温的极端气温指数呈显著下降趋势,说明疏勒河流域气温增幅明显。极端降水指数呈显著的增加趋势。该流域极端洪水事件和频次呈上升趋势,而极端枯水事件和频次呈下降趋势。极端洪水事件主要受控于极端降水事件,特别是极端降水总量,极端高温事件对极端洪水总量的增加也有影响,而极端枯水事件主要受控于极端低温事件。此外,2000-2016年年最大洪峰流量出现的时间有由8月向7月转变的趋势。  相似文献   

内蒙古东南部暴雨洪涝灾害风险评估与区划——以通辽市为例     

李思慧 《内蒙古气象》2019,(1):23-28

文章选取通辽市各气象站点气象数据、基础地理信息数据、历史灾情数据、第二次土地调查数据及相关社会经济等统计数据,基于自然灾害风险原理,利用数理统计、层次分析法及空间叠加分析等方法,提出了通辽市暴雨洪涝灾害风险评价指标体系,得到通辽市暴雨洪涝灾害风险评估空间分布图。结果表明:高风险区主要分布在通辽市北部山区、中东部地区及偏南部地区,包括扎鲁特旗鲁北镇、科尔沁区、科左中旗东南部及库伦旗东南部;而科左后旗大部地区易形成由短时强降水引发的洪涝,为次高风险区;低风险区及次低风险区主要分布在通辽市中部、西南部地区,包括开鲁县、奈曼旗北部、科左中旗西部。  相似文献   

OUTBURST FLOODS FROM GLACIER-DAMMED LAKES: THE EFFECT OF MODE OF LAKE DRAINAGE ON FLOOD MAGNITUDE     

JOSEPH S. WALDER  JOHN E. COSTA 《地球表面变化过程与地形》1996,21(8):701-723

Published accounts of outburst floods from glacier-dammed lakes show that a significant number of such floods are associated not with drainage through a tunnel incised into the basal ice—the process generally assumed—but rather with ice-marginal drainage, mechanical failure of part of the ice dam, or both. Non-tunnel floods are strongly correlated with formation of an ice dam by a glacier advancing from a tributary drainage into either a main river valley or a pre-existing body of water (lake or fiord). For a given lake volume, non-tunnel floods tend to have significantly higher peak discharges than tunnel-drainage floods. Statistical analysis of data for floods associated with subglacial tunnels yields the following empirical relation between lake volume V and peak discharge Q_p : Q_p = 46V^0.66 (r² = 0.70), when Q_p is expressed in metres per second and V in millions of cubic metres. This updates the so-called Clague–Mathews relation. For non-tunnel floods, the analogous relation is Q_p = 1100V^0.44 (r² = 0.58). The latter relation is close to one found by Costa (1988) for failure of constructed earthen dams. This closeness is probably not coincidental but rather reflects similarities in modes of dam failure and lake drainage. We develop a simple physical model of the breach-widening process for non-tunnel floods, assuming that (1) the rate of breach widening is controlled by melting of the ice, (2) outflow from the lake is regulated by the hydraulic condition of critical flow where water enters the breach, and (3) the effect of lake temperature may be dealt with as done by Clarke (1982). Calculations based on the model simulate quite well outbursts from Lake George, Alaska. Dimensional analysis leads to two approximations of the form Q_p ∝ V^qf(h_i, θ₀), where q = 0.5 to 0.6, h_i is initial lake depth, θ₀ is lake temperature, and the form of f (h_i, θ₀) depends on the relative importance of viscous dissipation and the lake's thermal energy in determining the rate of breach opening. These expressions, along with the regression relations, should prove useful for assessing the probable magnitude of breach-type outburst floods.  相似文献   

ANALYTICAL HAYAMI SOLUTION FOR THE DIFFUSIVE WAVE FLOOD ROUTING PROBLEM WITH LATERAL INFLOW     

ROGER MOUSSA 《水文研究》1996,10(9):1209-1227

The diffusive wave equation is generally used in flood routing in rivers. The two parameters of the equation, celerity and diffusivity, are usually taken as functions of the discharge. If these two parameters can be assumed to be constant without lateral inflow, the diffusive wave equation may have an analytical solution: the Hayami model. A general analytical method, based on ‘Hayami’s hypothesis, is developed here which resolves the diffusive wave flood routing equation with lateral inflow or outflow uniformly distributed over a channel reach. Flood routing parameters are then identified using observed inflow and outflow and the Hayami model used to simulate outflow. Two examples are discussed. Firstly, the prediction of the hydrograph at a downstream section on the basis of a knowledge of the hydrograph at an upstream section and the lateral inflow. The second example concerns lateral inflow identification between an upstream and a downstream section on the basis of a knowledge of hydrographs at the upstream and downstream sections. The new general Hayami model was applied to flood routing simulation and for lateral inflow identification of the River Allier in France. The major advantages of the method relate to computer simulation, real-time forecasting and control applications in examples where numerical instabilities, in the solution of the partial differential equations must be avoided.  相似文献   

FLOOD MODELLING WITH GIS-DERIVED DISTRIBUTED UNIT HYDROGRAPHS     

I. MUZIK 《水文研究》1996,10(10):1401-1409

The concept of a spatially distributed unit hydrograph is based on the fact that the unit hydrograph can be derived from the time–area curve of a watershed by the S-curve method. The time–area diagram is a graph of cumulative drainage area contributing to discharge at the watershed outlet within a specified time of travel. Accurate determination of the time–area diagram is made possible by using a GIS. The GIS is used to describe the connectivity of the links in the watershed flow network and to calculate distances and travel times to the watershed outlet for various points within the watershed. Overland flow travel times are calculated by the kinematic wave equation for time to equilibrium; channel flow times are based on the Manning and continuity equations. To account for channel storage, travel times for channel reaches are increased by a percentage depending on the channel reach length and geometry. With GIS capability for rainfall mapping, the assumption of a uniform spatial rainfall distribution is no longer necessary; hence the term, spatially distributed unit hydrograph. An example of the application for the Waiparous Creek in the Alberta Foothills is given. IDRISI is used to develop a simple digital elevation model of the 229 km² watershed, using 1 km × 1 km grid cells. A grid of flow directions is developed and used to create an equivalent channel network. Excess rainfall for each 1 km × 1 km cell is individually computed by the Soil Conservation Service (SCS) runoff curve method and routed through the equivalent channel network to obtain the time–area curve. The derived unit hydrograph gave excellent results in simulating an observed flood hydrograph. The distributed unit hydrograph is no longer a lumped model, since it accounts for internal distribution of rainfall and runoff. It is derived for a watershed without the need for observed rainfall and discharge data, because it is essentially a geomorphoclimatic approach. As such, it allows the derivation of watershed responses (hydrographs) to inputs of various magnitudes, thus eliminating the assumption of proportionality of input and output if needed. The superposition of outputs is retained in simulating flood hydrographs by convolution, since it has been shown that some non-linear systems satisfy the principle of superposition. The distributed unit hydrograph appears to be a very promising rainfall runoff model based on GIS technology.  相似文献   

广州市南沙区万顷沙网河区排涝调蓄演算研究     

刘树锋  刘一休  杨晨  陈记臣  谭丹  沈学明 《亚热带资源与环境学报》2021,16(1):1-8

快速城市化进程改变了城市地区原有下垫面,不透水层面积增加,暴雨期间汇流时间缩短,洪峰流量加大,进而导致城市内涝加剧,严重影响城市的防洪安全.本研究以广州市南沙区万顷沙网河区为研究对象,基于水量平衡的调蓄演算方法,对研究区域蓄排设施的规模进行分析;构建MIKE11一维网河模型,对涝区水情进行模拟,校核排涝工程规模,并对工...  相似文献