Dam-break flood simulation under various likely scenarios and mapping using GIS: Case of a proposed dam on River Yamuna, India

The precision modeling of dam break floods can lead to formulation of proper emergency action plan to minimize flood impacts within the economic lifetime of the assets.Application of GIS techniques in integration with hydrological modeling for mapping of the flood inundated areas can play a momentous role in further minimizing the risk and likely damages.In the present study,dam break analysis using DAMBRK model was performed under various likely scenarios.Probable Maximum Flood (PMF)calculated for a return period of 1000 years using deterministic approach was adopted for dam break analysis of the proposed dam under various combinations of breach dimensions.The available downstream river cross-sections data sets were used as input in the model to generate the downstream flood profile.Dam break flow depths generated by the DAMBRK model under various combinations of structural failure are subsequently plotted on Digital Elevation Model(DEM)of the downstream of dam site to map the likely affected area.The simulation results reveals that in one particular case the flood without dam may be more intense if a rainfall of significant intensity takes place.     

Effects of spillway types on debris flow trajectory and scour behind a sabo dam

Debris flows are one of the common natural hazards in mountainous areas. They often cause devastating damage to the lives and property of local people. The sabo dam construction along a debris flow valley is considered to be a useful method for hazard mitigation. Previous work has concentrated on the different types of sabo dams such as close-type sabo dam, open-type sabo dam. However, little attention has been paid to the spillway structure of sabo dam. In the paper, a new type of spillway structure with lateral contraction was proposed. Debris flow patterns under four different spillway structures were investigated. The projection theory was employed to predict trajectory of debris flow out from the spillway and to estimate the incident angle and terminal velocity before it plunged into the scour hole behind the sabo dam. The results indicated that the estimated data were in good agreement with the experimental ones. The discrepancy between the estimated and experimental values of main parameters remained below 21.82% (relative error). Additionally, the effects of debris flow scales under different spillway structures were considered to study the scour law. Although the debris flow pattern and scour law behind the sabo dam under different operating conditions was analyzed in this paper, further study on the scour mechanism and the maximum scour depth estimation based on scour theory is still required in the future.     

Influence of dietary probiotic Bacillus TC22 and Prebiotic fructooligosaccharide on growth, immune responses and disease resistance against Vibrio splendidus infection in sea cucumber Apostichopus japonicus

The effects of probiotic Bacillus TC22 (isolated from intestine of infected sea cucumber) and prebiotic fructooligosaccharide (FOS) on growth, immunity and disease resistance in sea cucumber Apostichopus japonicus were studied. Six experimental diets were formulated with combinations of three levels of TC22 (0, 107 and 109 CFU g-1 diet) and two levels of FOS (0 and 0.5%) in a 3 × 2 factorial experiment. At the end of the 8-week feeding trial,animals were challenged by injecting Vibrio splendidus. The results revealed that the specific growth rates (SGR) of sea cucumbers were not affected by TC22 and FOS, or the interaction between TC22 and FOS (P > 0.05). However,there were significant interactions between TC22 and FOS for immune response and disease resistance in sea cucumbers (P < 0.05). When sea cucumbers were fed with TC22 at 109 CFU g?1 feed and 0.5% FOS alone or in combination, the phagocytosis, respiratory burst and phenoloxidase activity of sea cucumber coelomocytes were significantly enhanced;the disease resistance against V. splendidus infection was also increased significantly (P < 0.05).However, dietary combination of TC22 at 109 CFU g-1 diet and 0.5% FOS did not yield significantly higher efficiency than either TC22 at 109 CFU g-1 diet or 0.5% FOS used alone (P > 0.05). Therefore, further studies should examine the effects of combinations of other levels of FOS(> 0.5% or < 0.5%) and TC22 on the immunity and disease resistance of sea cucumbers.     

济南市东湖水库地质灾害预测

济南市东湖水库库区不具备发生崩塌、滑坡、地面塌陷、地面沉降、泥石流、地裂缝、砂土液化的地质环境条件。水库建成使用后，可能出现坝后浸没、次生盐渍化及坝体不均匀沉降等地质灾害，应采取工程措施。     

Long-Term Effects of Docosahexaenoic Acid-Bound Phospholipids and the Combination of Docosahexaenoic Acid-Bound Triglyceride and Egg Yolk Phospholipid on Lipid Metabolism in Mice

The bioavailability of docosahexaenoic acid (DHA) and eicosapentaenoic acid (EPA) depends on their chemical forms. This study investigated the long-term effects of DHA-bound triglyceride (TG-DHA), DHA-bound phospholipid (PL-DHA), and the combination of TG-DHA and egg yolk phospholipid (Egg-PL) on lipid metabolism in mice fed with a high-fat diet (fat levels of 22.5%). Male C57BL/6J mice were fed with different formulations containing 0.5% DHA, including TG-DHA, PL-DHA, and the combination of TG-DHA and Egg-PL, for 6 weeks. Serum, hepatic, and cerebral lipid concentrations and the fatty acid compositions of the liver and brain were determined. The concentrations of serum total triglyceride (TG), total cholesterol (TC), high-density lipoprotein cholesterol (HDL-c), and hepatic TG in the PL-DHA group and the combination group were significantly lower than those in the high-fat (HF) group (P < 0.05). Atherogenic index (AI) of the PL-DHA group was significantly lower than that of the combination group (P < 0.05). Hepatic TC level in the combination group was significantly lower than that in the HF group (P < 0.05), but no significant difference was observed between the combination group and the PL-DHA group. Both the PL-DHA and the combination groups showed significantly increased DHA levels in the liver compared with the HF group (P < 0.05). However, there were no obvious increases in the cerebral DHA levels in all DHA diet groups. These results suggest that PL-DHA was superior to the combination of TG-DHA and Egg-PL in decreasing the AI. Long-term dietary supplementation with low amount of DHA (0.5%) may improve hepatic DHA levels, although cerebral DHA levels may not be enhanced.     

Influence of inflow discharge and bed erodibility on outburst flood of landslide dam

Accurate prediction of the hydrographs of outburst floods induced by landslide dam overtopping failure is necessary for hazard prevention and mitigation. In this study, flume model tests on the breaching of landslide dams were conducted. Unconsolidated soil materials with wide grain size distributions were used to construct the dam. The effects of different upstream inflow discharges and downstream bed soil erosion on the outburst peak discharge were investigated. Experimental results reveal that the whole hydrodynamic process of landslide dam breaching can be divided into three stages as defined by clear inflection points and peak discharges. The larger the inflow discharge, the shorter the time it takes to reach the peak discharge, and the larger the outburst flood peak discharge. The scale of the outburst floods was found to be amplified by the presence of an erodible bed located downstream of the landslide dam. This amplification decreases with the increase of upstream inflow. In addition, the results show that the existence of an erodible bed increases the density of the outburst flow, increasing its probability of transforming from a sediment flow to a debris flow.     

Combined action of uniform flow and oscillating flow around marine riser at low Keulegan-Carpenter number

With the increase of petroleum and gas production in deep ocean, marine risers of circular cylinder shape are widely used in the offshore oil and gas platform. In order to research the hydrodynamic performance of marine risers, the dynamic mesh technique and User-Defined Function （UDF） are used to simulate the circular cylinder motion. The motion of a transversely oscillat-ing circular cylinder in combination of uniform flow and oscillating flow is simulated. The uniform flow and oscillating flow both are in x direction. SIMPLE algorithm is used to solve the Navier-Stokes equations. The User-Defined Function is used to control the cylinder transverse vibration and the inlet flow. The lift and drag coefficient changing with time and the map of vorticity isolines at different phase angle are obtained. Force time histories are shown for uniform flow at Reynolds number （Re） of 200 and for the com-bination of uniform and oscillating flows. With the increase of amplitude of oscillating flow in combined flow, the change of lift am-plitude is not sensitive to the the change of cylinder oscillating frequency. Lift amplitude increases with the increase of oscillating flow amplitude in the combined flow, but there is no definite periodicity of the lift coefficient. The drag and inertia force coefficients change when the maximum velocity of the oscillating flow increases in the combined flow. The vortex shedding near the circular cylinder shows different characteristics.     

GNSS多系统组合PPP解算方法与成果分析

研究GPS、GLONASS和BDS三系统组合精密单点定位（PPP）,包括函数模型、对流层延迟参数和差分码偏差(DCB)参数的解算方法。利用C++语言编制3系统组合PPP程序,分析MEGX网12个连续跟踪站1周观测数据,结果表明,无电离层组合模型和非组合模型的收敛速度和定位精度相当,同一测站在不同时间的收敛速度无明显差异,但非组合模型采用先验电离层信息约束可提高定位的收敛速度。多系统组合定位能改善PDOP值,提高收敛速度和定位精度;3系统组合PPP的水平坐标精度约3 cm,高程精度约5 cm,优于3个系统单独定位或2个系统组合定位的精度;当卫星遮挡较大时,多系统PPP结果较单系统更为稳定。     

岷江上游汶川退耕还林(草)中“3S”技术的应用

遥感(RS)、全球定位系统(GPS)和地理信息系统(GIS)技术的结合能快速、准确、动态及直观地查明研究区生态环境本底状况,建立生态环境本底调查数据库,为国家政府有关部门宏观管理决策与规划提供科学依据。本文以“岷江中上游生态环境遥感综合调查与评价”项目为例2,探讨利用“3S”技术在指导汶川地区制定退耕还林(草)政策和生态环境监测管理中的应用。     

基于深度全连接神经网络的大坝变形预测研究

将深度全连接神经网络引入大坝变形预测领域,结合大坝多源监测数据的训练样本,建立基于深度全连接神经网络的大坝变形预测模型.利用几种常见的深度优化学习算法对模型进行优化训练,通过对比各损失函数的变化曲线选取最优学习算法,进一步构建基于最优学习算法的深度全连接神经网络大坝变形预测模型;最后结合大坝多源监测数据的测试样本对模型...     

黄河老宅庄控导工程改建整治方案探讨

黄河老宅庄控导工程位于鄄城县彭楼与桑庄两弯道之间,工程平面布置呈前凸弯道型,在多年河势作用下,空裆处常年靠溜,存在抄工程后路的威胁。工程改建后,能够改善该河段的河势,强化老宅庄工程的送溜能力。为此,对老宅庄控导工程进行整治提出3种可行方案,并对各方案的优缺点进行分析比选,最终确定整治的最优方案为部分拆除后退方案。     

Numerical calculation of dispersion relation for linear internal waves

With the horizontal Coriolis terms included in motion equations and the influence of compressibility of seawater on Brunt-Visl frequency considered, a numerical method of calculating the dispersion relation for linear internal waves, which is an improvement of Cai and Gan (1995), and hence Fliegel and Hunkins (1975), had been set up. For different models (Pacific model, Atlantic model and Arctic model), simulations using the three different methods were compared and the following conclusions were reached:(1) the influence of horizontal Coriolis terms on dispersion relation cannot be neglected and is connected with the direction of the wave celerity, the latitude, and the modes of the wave;(2) the effect of compressibility of seawater in stratification is not an important factor for the dispersion relation of linear internal wave, at least for those three models. With the improved method, the wavefunction curves for the Pacific model had also been built.     

Fish Assemblage Responses to a Low-head Dam Removal in the Lancang River

Dam removal is becoming an effective approach for aquatic biodiversity restoration in damming river in order to balance the aquatic ecosystem conservation with large-scale cascade damming. However, the effects of dam removal on fish communities in Asian mountainous rivers, which are dominated by Cypriniformes fishes, are still not well known. To determine whether dam removal on a mountainous river benefit restoration of fish diversity, we investigated the response of fish assemblage to dam removal using a before-after-control-impact design in two tributaries of the Lancang River(dam removal river: the Jidu River, and control river: the Fengdian River). Fish surveys were conducted one year prior to dam removal(2012) and three years(2013–2015) following dam removal. We observed rapidly and notably spatio-temporal changes in fish biodiversity metrics and assemblage structure, occurring in the Jidu River within the first year after dam removal. Overall, fish species richness, density and Shannon-Wiener diversity all increased immediately in above-and below-dam sites, and maintained a stable level in subsequent years, compared to unchanged situation in the control river. All sites in the Jidu River experienced shifts in fish composition after dam removal, with the greatest temporal changes occurred in sites below-and above-the former dam, resulting in a temporal homogenization tendency in the dam removed river. These findings suggest that dam removal can benefit the recovery of habitat conditions and fish community in Asian mountainous rivers, but the results should be further evaluated when apply to other dammed rivers since the dam age, fluvial geomorphology and situation of source populations could all affect the responses of fish assemblages.     

Global Trends in Dam Removal and Related Research: A Systematic Review Based on Associated Datasets and Bibliometric Analysis

Dam removal has been increasingly reported globally and is becoming an important approach for river management, restoration and environmental conservation in damming rivers. However, current limited knowledge of global trends in dam removal and related research may be potentially biased in terms of the geographic distribution and organisms studied. Such bias could mislead dam removal planning and management in different areas and ecological conservation for different taxa. In this study, we quantitatively and qualitatively analyzed datasets of dam removal and publications of dam removal research using bibliometric methods. A total of 1449 dam removal documents were published from 1953 to 2016. Trends, current hotspots and future directions of dam removal research were identified. The results from this study reveal that dam removal largely occurred in the North America and Europe, and most of the removed dams were small and old dams. With respect to the topic analysis, more dam removal studies should focus on the responses of a wide range of organisms, not only fish, as well as the interspecies relationships, food webs and ecosystem structures and functions. Based on our findings, we also provide some suggestions for future dam removal planning and analysis.     

Seismic deformation and seismic resistance analysis of Shapai Roller Compacted Concrete Arch Dam based on field monitoring and dynamic finite element method

Shapai Roller Compacted Concrete(RCC) Arch Dam is the highest RCC arch dam of the 20th century in the world with a maximum height of 132m,and it is the only concrete arch dam near the epicentre of Wenchuan earthquake on May 12th,2008.The seismic damage to the dam and the resistance of the dam has drawn great attention.This paper analyzed the response and resistance of the dam to the seismic wave using numerical simulations with comparison to the monitored data.The field investigation after the earthquake and analysis of insitu data record showed that there was only little variation in the opening size at the dam and foundation interface,transverse joints and inducing joints before and after the earthquake.The overall stability of the dam abutment resistance body was quite good except a little relaxation was observed.The results of the dynamic finite element method(FEM) showed that the sizes of the openings obtained from the numerical modeling are comparable with the monitored values,and the change of the opening size is in millimeter range.This study revealed that Shapai arch dam exhibited high seismic resistance and overload capacity in the Wenchuan earthquake event.The comparison of the monitored and simulated results showed that the numerical method applied in this paper well simulated the seismic response of the dam.The method could be useful in the future application on the safety evaluation of RCC dams.     

Seismic stratigraphy of the Qiongdongnan deep sea channel system,northwest South China Sea

Based on more than 4000 km 2D seismic data and seismic stratigraphic analysis, we discussed the extent and formation mechanism of the Qiongdongnan deep sea channel. The Qiongdongnan deep sea channel is a large incised channel which extends from the east boundary of the Yinggehai Basin, through the whole Qiongdongnan and the Xisha trough, and terminates in the western part of the northwest subbasin of South China Sea. It is more than 570 km long and 4–8 km wide. The chaotic (or continuous) middle (or high) a...     

Rapid geometry analysis for earthquake-induced and rainfall-induced landslide dams in Taiwan

Stability analysis of the dam is important for disaster prevention and reduction. The dam＇s geometry plays an important role in understanding its stability. This study develops a rapid landslide dam geometry assessment method for both earthquake-induced and rainfall-induced landslide dams based on nine real cases collected in Chinese Taipei and 214 cases collected worldwide. For simplification purposes, a landslide dam is classified into triangular or trapezoidal. The rapid landslide dam geometry assessment method in this paper uses only satellite maps and the topographic maps to get landslide area, and then analyze the dam geometry. These maps are used to evaluate the area of the landslide and the slope of the river bed. Based on the evaluation information, the proposed method can calculate dam height, the length of the dam, and the angles of the dam in both upstream and downstream directions. These geometry parameters of a landslide dam provide important information for further dam stability analysis. The proposed methodology is applied to a real landslide dam case at Hsiaolin Village. The result shows that the proposed method can be used to assess the landslide dam geometry.     

基于SSA-Adam-BP神经网络模型的堰塞坝稳定性预测

现有的堰塞坝稳定性预测模型多为线性模型,无法充分考虑堰塞坝稳定性与其形态特征和水域条件之间的复杂非线性关系。鉴于此,结合反向传播神经网络模型和樽海鞘优化算法,提出了一种新型的堰塞坝稳定性预测模型SSA-Adam-BP。该模型通过网格搜索法选取确定模型结构的最佳超参数组合,进而利用交叉验证和绘制ROC曲线的方式分别对采用不同优化算法的模型进行评估。使用开源数据库中的全球153例堰塞坝数据对模型的实际应用进行了说明及验证。与传统线性模型的对比表明神经网络模型预测准确率较高,具有较低的误报率。将SSA与Adam优化算法结合提高了BP模型的全局搜索能力,其平均交叉验证准确率达到了91.73%,能够使用较少的参数实现对堰塞坝稳定性快速准确的预测。SSA-Adam-BP模型对近年来典型工程的稳定性能够准确预测,具有一定的实用性和系统平台推广应用价值。     

Analysis on dam-breaking mode of Tangjiashan barrier dam in Beichuan county

Tangjiashan landslide is a typical high-speed consequent landslide of medium-steep dip angle. This landslide triggered by earthquake took place in about semi-minute. The relative sliding displacement is 900 meters, so average sliding speed is about 30 meters per second. The longitudinal length of barrier dam which is formed by high-speed landslide along river is 803.4 meters; and maximum width crossing river is 611.8 meters. And its volume is estimated about 20.37 million steres. Through detailed geological investigation of the barrier dam, together with early geological information before earthquake, geological structures of the barrier dam and its stability of upstream and downstream slopes are studied when water level reaches different elevations in condition of continual after shocks with seismic intensity of 7 or 8 Richter scale. On this basis, dam-breaking mode of barrier dam is discussed deeply. Thereby, analytic results provide significant guidance and advices to front headquarters of Tangjiashan barrier dam, so that some proper engineering measures can be implemented and flood discharge can be carried out well.     

滑坡堰塞坝堆积形态影响因素离散元分析

滑坡是形成堰塞坝的最主要原因,在地震、降雨、冰雪融水等作用下均可形成滑坡堰塞坝,而滑坡堰塞坝的堆积形态、范围等对评价堰塞坝的稳定性有着重要的影响。通过离散元方法(DEM),系统分析了三维条件下滑动距离、滑面出口宽度、滑面倾角、河床倾角、河谷形状对堰塞坝堆积形态的影响。研究结果表明：滑动距离和出口宽度对坝体高度影响最大;随出口宽度和坡面倾角的增加,坝长和坝宽分别呈线性增大和减小趋势;滑动距离可以有效控制滑体速度,进而影响堆积角大小;河床倾角主要影响坝长;对坝高、坝长、上下游绝对倾角正切值和堆积角正切值进行回归分析表明,数学模型契合程度高,说明其形态可以预测;引入2个参数λ和χ,对堰塞坝堆积特征进行了描述;河谷形状的影响主要体现在随着河谷底部宽度的增大,滑体爬高爬坡能力增强。研究成果对根据实际地形预测滑坡堰塞坝堆积形态进而评估坝体的安全性具有重要意义,可以为进一步开展堰塞湖溃决研究提供一定的参考。