Barrier Dam Research Articles

Centrifugal model tests and numerical simulations for barrier dam break due to overtopping

The present study focuses on the breaching process and failure of barrier dams due to overtopping. In this work, a series of centrifugal model tests is presented to examine the failure mechanisms of landslide dams. Based on the experimental results, failure process and mechanism of barrier dam due to overtopping are analyzed and further verified by simulating the experimental overtopping failure process. The results indicate that the barrier dam will develop during the entire process of overtopping in the width direction, whereas the breach will cease to develop at an early stage in the depth direction because of the large particles that accumulate on the downstream slope. Moreover, headcut erosion can be clearly observed in the first two stages of overtopping, and coarsening on the downstream slope occurs in the last stage of overtopping. Thus, the bottom part of the barrier dam can survive after dam breaching and full dam failure becomes relatively rare for a barrier dam. Furthermore, the remaining breach would be smaller than that of a homogeneous cohesive dam under the same conditions.

Centrifugal Model Test on the Failure Mechanism of Barrier Dam Overtopping

In order to study the failure mechanism of barrier dam overtopping, centrifugal model tests of dam failure were conducted in this research. A calculation method of rectangular weir flow in the centrifugal field was derived. The process and mechanism of barrier dam overtopping were intensively analyzed. They were further verified by the breach flow curve and the development curve of the breach top width acquired from model tests. Results showed that the barrier dam breach developed during the entire process of overtopping in the width direction. The development of the barrier dam breach in the depth direction, however, ceased at an earlier time on account of the large particles accumulated in the downstream slope. Moreover, coarsening in the downstream slope could be clearly observed in the last stage of overtopping. Thus, it was concluded that the bottom part of the barrier dam could survive after dam breaching and that a full dam failure is relatively rare for a barrier dam. Furthermore, the size of the remaining breach would be less than that of a homogeneous earth dam under the same conditions.

Formation mechanism and movement processes of the Aizigou paleolandslide, Jinsha River, China

The Aizigou paleolandslide is a large basalt landslide in the Liucheng section of the Lower Jinsha River, southwestern Sichuan Province, China. Geological investigation and interpretation of remote sensing imagery, in addition to experiments, numerical simulation, and geochronological dating were used to determine the formation and movement of the landslide. Four factors were critical: a substantial height difference between the landslide shearing surface and the foot of the slope; multiple structural defects within the rock mass; a tuff intercalation in the basaltic series with long-term softening due to surface water and groundwater; and seismic activity. The kinematic behavior of the landslide was simulated using a 3-D discrete element model (3DEC), with four stages: (1) Seismic waves in the upper part of the slope were amplified by the mountain topography. When the vibrational energy exceeded the strength of the rock mass, the landslide formed, with deformation and failure by sliding and fracture. (2) Landslide materials with a volume of approximately 3.82 × 108 m3 slid at high speed from a high position, before colliding with the mountainside on the right bank of Aizi Valley. (3) The high-speed debris flow then moved 3 km downstream in Aizi Valley. (4) Landslide materials with a volume of 2.72 × 108 m3 blocked Jinsha River. A lake formed behind the barrier dam; its backwater region reached 75 km upstream. Optically stimulated luminescence dating of the lake sediments suggested that the landslide occurred about 25,000 years ago.

Breach mechanism and numerical modeling of barrier dam due to overtopping failure

As a production of natural process, the barrier dam has its own features, and is easily to fail due to overtopping. Based on the breach mechanism revealed by small-scale model tests and the draining case of Tangjiashan Barrier Lake, a numerical breach model for barrier dam due to overtopping failure is put forward. In terms of the geometrical characteristics, physical and mechanical properties of barrier dam, a unified approach is developed to model the evolution of breaches in the dam crest and downstream slope, as well as the morphological change of the barrier dam in streamwise. Furthermore, different failure modes, such as one- and two-sided erosion, incomplete and base erosion are taken into account. The draining of Tangjiashan Barrier Lake is adopted to testify the present model, and the comparison of measured and calculated results indicates the rationality of the present model with the relative errors are less than 10% for peak discharge, final breach widths, and time to peak; in addition, the calculated breach discharge hydrograph and the changing process of water level are in accord with the measured data. The sensitivity analysis shows that the residual dam height after breaching and soil erodibility affect the breach flow prediction of the barrier dam significantly, whereas the one- or two-sided breach mode is less sensitive.

Failure mechanisms and characteristics of the 2016 catastrophic rockslide at Su village, Lishui, China

This paper describes a recent large rockslide, which occurred at Su village in Lishui, Zhejiang Province, China, on September 28, 2016. In the past decade, a vegetation-free deformed surface was clearly visible and frequent rockfalls were noticed. Due to strong sustained rainfall, approximately 0.4 million m3 of granite blocks rapidly descended from the upper part of the hillside. The mass rushed into the V-shaped valley resulting in the formation of a barrier dam and dammed lake. The catastrophic rockslide caused 27 deaths and more than 20 houses were destroyed. The evolutionary process before the rockslide is clearly captured by high-resolution remote sensing images and photos. Video of the rockslide and field investigations show entrainment of superficial material in the middle and lower parts of the slope.

Foliation impact on the dynamic properties of selected samples of the barrier dam site Prvonek: Right side

The 'Prvonek' dam was built in tight asymmetric Banjska river valley about 100 meters downstream from the river Gradasnica. Barrier at the dam site built predominantly slate series of high crystallinity Vranjska Banja, alternately layered double mica, gneiss, leptinolite and micaschist. For the construction of this place were carried out extensive field and laboratory geotechnical investigations. Part of laboratory geotechnical investigations related to the testing of dynamic properties in the perpendicular and parallel direction to the foliation of gneiss and micashist samples on the right side. The aim of investigations is definition of anisotropy tested dynamic parameters.

Mitigation planning based on the prediction of river blocking by a typical large-scale debris flow in the Wenchuan earthquake area

Due to scale amplification resulting from the blocking-bursting process associated with landslide dams in debris flow catchments, many of large-scale debris flows that occurred as a result of the Wenchuan earthquake blocked the main rivers and resulted in catastrophic dam-breaking floods. To decrease the damage caused by dam-breaking floods, mitigation works should be applied in debris flow gullies. Currently, few studies focus on how to determine the key parameters concerning the scale of debris flows (i.e., peak discharge and total volume) that need to be controlled for mitigation planning considering downstream objects affected by the flow. The Xiaojia debris flow is described and analyzed as a typical large-scale case from the Yingxiu area. A back-calculation method and numerical simulation were proposed for mitigation planning in Xiaojia gully based on predictions of river blocking. First, the maximum peak flood discharge that did not endanger the town of Yingxiu was calculated. Then, the permissible blockage from a debris flow was determined based on the back-calculation of a dam-breaking flood. Finally, the scale of the largest permissible debris flow was obtained for use in mitigation plans based on numerical simulations. The calculations showed that the peak discharge of a flood that would not endanger Yingxiu should be <1496.48 m3/s. Accordingly, based on the 1/3 and 1/2 breach modes, the permissible blocking height of a debris flow barrier dam should not exceed 43.09 and 31.64 m, respectively. The total volume and peak discharge of a single debris flow event should be controlled to not exceed 70.59 × 104 m3 and 784.59 m3/s for the 1/3 breach mode and 45.21 × 104 m3 and 551.77 m3/s for the 1/2 breach mode. Based on these determinations of the key debris flow parameters, the simulation results indicate that debris flow damage can be decreased to an acceptable level to ensure the safety of Yingxiu downstream by the implementation of two check dams in the downstream channel and a deposition works on the debris fan.

Three-Dimensional Dynamic Visual Simulation of Slope Instability of Barrier Landslide

The sliding movement of barrier landslide is a complex and dynamic process, because of the great effect of seismic action and huge surge. Adopting NURBS-TIN-BRep hybrid data structure and integrating with multi-source geological data, 3D geological model of the Tangjiashan quake dam was rebuild. The instability mechanism of the landslide was analyzed. Applying visualization technology, the whole formation process of the barrier dam, the production and development process of surge were fully and realistically displayed. These results above can help the engineering personnel to understand the whole condition of the Tangjiashan barrier dam. These research can provide some technical support for comprehensive governance scheme.

Development and Application of Spatial Analysis and Management System of Dammed Lake Based on 3D GIS

Using Skyline and GIS technology, true three-dimensional scene of the Wenchuan earthquake is built in the area affected by the "5.12" earthquake in Sichuan is. And then the system development and model structures are done by the application development software of Visual Studio 2005. The decision analysis platform is built including the functions of the dynamic monitoring based on remote sensing for dammed lake, the lake recognition and feature extraction for dammed lake (rapid identification, the calculation of barrier dam, storage capacity calculation), submergence analysis (upstream submerged analysis, downstream image evaluation), and the function of disaster assessment and risk assessment. It can provide support for the Monitoring, and Early-Warning and aid decision-making for dammed lake.

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

Tangjiashan landslide is a typical highspeed 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.

Draining Tangjiashan Barrier Lake after Wenchuan Earthquake and the flood propagation after the dam break

Tangjiashan Barrier Lake is one of the largest barrier lakes caused by the Wenchuan Earthquake. Its risk analysis, emergency plan and effect of the emergency plan are introduced in this paper. The dam height of Tangjiashan Barrier Dam is about 105 m, and the reservoir storage capacity is 3.2×108 m3. When the dam broke the flood peak were estimated to be larger than 48000 m3/s, which might cause a enormous disaster to the downstream cities and residents. A discharge channel with 13 m deep and 8 m wide was drug, so that the water may flow out of the lake before the dam breaks. As a result, the drainage and risk mitigation project are successful. During the drainage process, the flood peak was about 6500 m3/s, and about 1.6×108 m3 of water was drained off and the residual reservoir capacity was only 8.97×107 m3. A new channel with average width 100 m was formed, which can bear floods of 200 years frequency. The successful experience and the collected data can be used to deal with the similar natural disasters in future.

Simulation of dam breach development for emergency treatment of the Tangjiashan Quake Lake in China

The Tangjiashan Quake Lake is the largest quake lake triggered by the 5.12 Wenchuan Earthquake that happened on May 12, 2008 in China, posing high risk of catastrophic flash flood hazards to downstream human life and properties. A physics-based numerical simulation approach is proposed for real-time prediction of dam breach development of the Tangjiashan Quake Lake in the case of emergency treatment. Bed erosion and lateral development of the dam breach are represented through accounting for the underlying physics including selective sediment transport and gravitational collapse. Conceptualized breach erosion model that involves few parameters enables quick calibration based on the monitored hydrological data in emergency analysis where fully geotechnical information about the barrier dam is not available. The process of dam breach development is found to be nonlinear in cascades due to the combined effects of headcutting and bank collapse. The agreement between the simulation results and the observed data shows the applicability of the present approach for emergency analysis of quake lakes. Limitations will arise in the situation where the soil composition of barrier dam is significantly inhomogeneous. Incorporation of circular arc failure for cohesive soil and lateral seepage in bank slope will also enhance its applicability to complex situations.

Dependable Water Supplies from Valley Alluvium in Arid Regions

Reliable sources of high-quality water for domestic use are much needed in arid regions. Valley alluvium, coarse sand and gravel deposited by streams and rivers, provides an ideal storage medium for water in many regions of the world. However, river sediments will not accumulate in a valley without a natural or artificial barrier to slow the water. Sediments will deposit upstream of a barrier dam and form an alluvial deposit of relatively well-sorted material. The alluvium then acts as both an underground water-supply reservoir and a water filter, yielding a constant flow of high-quality water. Trap dams that store water in alluvial sediments and slowly release the filtered water represent an appropriate and inexpensive technology for combating desertification and mitigating the effects of drought at the community level. Small trap dams may be built as a community project using local materials and local labor.

The engineering geological characteristics of lake sediments in the Yuanshan area, Ilan City, Taiwan

The paper describes a study of the sedimentology and some engineering parameters related to the geological characteristics of the lake sediments which formed behind a barrier dam in a suburb of Ilan City, north east Taiwan. It is concluded that the variation in engineering parameters is strongly influenced by the proportion of diatoms present.

Relation Between Concentrations of Polycyclic Aromatic Hydrocarbons, Grain Size, and Organic Matter Content in Lake Ketelmeer (The Netherlands)

The relation between concentrations of polycyclic aromatic hydrocarbons (PAH), organic carbon (Corg) content and grain size in a sediment sample from the Ketelmeer (the Netherlands) was investigated. Before 1932 the area from where samples were taken was part of the inland sea called the Zuiderzee. Since the closure by a barrier dam (the Afsluitdijk), the Ketelmeer basin is a shallow fresh water lake which receives approximately 10 % of the total discharge of the river Rhine and thus forms an important sedimentation area for this river: heavy metals, pesticides, polychlorobiphenyls (PCB) and PAH are deposited in this area. Underneath the approximately 45 cm thick silty sediment layer deposited after 1932, there is a salt water clay deposit. Two samples, one at a depth of 0-30 cm and one at 40-120 cm, were taken from a core that was collected in November 1996. The samples were separated into eight size fractions ( 63 gm) in the clay and silt range, using sieves and split-flow lateral transport thin separation cell fractionation (SPLITT). The top layer consists of 28 % (< 2 gin) and 63 % silt (2-63 gm); the fraction larger than 63 gm makes up only 9 % of the sediment, from which 95 % is in the range 63-200 gm. In all fractions, C-org content and PAH concentrations were measured. Organic carbon contents vary from 6 % in the top layer to 10 % in the bottom layer. Determination of PAH was carried out by a soxhlet extraction with an acetone-hexane mixture followed by ana lys i s with High Pressure L iqu id Chromatography (HPLC) with fluorenscence detection. Eight of the 16 parental PAH identified by the World Health Organisa t ion and the U.S. Environmental Protection Agency were measured, i.e. phenanthrene, anthracene, fluoranthene, benzo(b)f luoranthene, benzo(k)fluoranthene, b e n z o ( a ) p y r e n e , b e n z o ( g h i ) p e r y l e n e and Indeno(123cd)pyrene. Total PAH concentrations vary from 9.5 mg/kg in the top layer (0-30 cm) to 22.2 mg/kg in the bottom layer with a recovery of 80 to 100 % (reliability of the measured values was tested by measuring a blank and the reference material 1941 NIST). PAH concentrations and C-org content, both expressed as the amount of substance per gram of a specific fraction, were found to be the highest in the coarsest fraction; this can be attributed to the presence of plant fragments. Among the various size fractions (except the coarsest fraction), no major differences in both C-org content and PAH concentrations exist. PAH concentrations and C-org content show a positive, approximately linear, correlation indicating that PAH behave like many other hydrophobic organic substances. In terms of relative abundances (i.e. the amount of a substance relative to the total amount in the sample), PAH concentrations and C-org content were found to be the highest in the finest fraction (< 0.5 gm) because of the relatively large contribution of this fraction to the total sediment. Concentration distributions of each of the eight PAH-compounds is essentially the same. Normalisation of all concentrations to the total surface area, calculated on the basis of the assumption of spherical particles, indicates that specific surface area is not the major factor in controlling the PAH level in the sediment. Instead, texture (pore structure and size) seems to be more important.

Evaluation of Atlantic salmon parr responses to habitat improvement structures in an experimental channel in Newfoundland, Canada

Distributional patterns and microhabitat selection of Atlantic salmon (Salmo salar) parr were investigated in relation to habitat improvement structures in a controlled flow experiment channel at Noel Paul's Brook, Newfoundland. The channel consisted of six replicates, each containing three randomly arranged treatments. Each replicate included a control treatment with no habitat modification, a mid-channel treatment with a boulder cluster and low-head barrier dam, and a stream bank treatment with undercut banks and wing deflectors. The influence of size class, density, discharge and diurnal/nocturnal differences on microhabitat selection were evaluated. Results showed that the mid-channel treatment did not serve its purpose at lower discharges (0.032–0.063 m3 s−1), and as a result was not the treatment of choice. However, as the discharge increased (0.13 m3 s−1), more salmon took up residence in this treatment. In all experiments, greater depths were selected in the stream bank treatment, and salmon parr in the mid-channel treatment consistently selected positions closer to cover. Larger parr preferred greater depths and were found closer to the improvement structures. Benthic and drifting food availability were also estimated, and results showed that ‘funnelling effects’ of the drift were created near the structures. This study indicates that these structures have the potential to create favourable feeding sites, and provide the necessary physical characteristics required by salmon parr. © 1998 John Wiley & Sons, Ltd.

Mediterranean sub-bottom giant Messinian salt as a precipitite

We question the widely held view that the sub-Mediterranean giant salt is anevaporite deposited in a dessicated deep basin (Hsu model). Instead we suggest it to be aprecipitite (new word, as the termevaporite tends to beg the question) precipitated within a deep water saturated brine (Schmalz model). We question the validity of supposed dessication indicators (mud cracks, stromatolites, etc.). One is reminded of the 1950’s when submarine canyons and deep sea sand were falsely interpreted to mean ocean basins had dried up. Remarkable hypothesis require extraordinary proof! Precipitation better accounts for the usual draping (rather than ponding) of the salt strata, their apparent deposition on young oceanic crust, general lack of erosional redepositional unconformities and interposed beds with deep water fauna. The repeated (ca. 12 times) absolute blocking at the Gibraltar portal by tectonism of a flow equivalent to several Amazons defies the geomorphic principle that river cutting overpowers tectonic uplift. In isolated large arid basins, (e.g. Caspian Sea, Aral Sea, Dead Sea, Great Salt Lake) complete dessication, which requires zero precipitation and zero inflow, is an asymptotic end point never achievable in reality. Ground water hydrologic regimes and a paleo-Nile which flowed in from tropical rain forest are additional problems. Recent deposition (1983–85) of 4 cm of halite in the Dead Sea provides an actualistic example of precipitation. Undirectional inflow through a coral reef barrier dam at the Gibraltar portal is offered as possibly causing brine saturation in the Mediterranean 5 Ma.

Changes in Biotic Integrity of a River in North-Central Tennessee

Abstract Fish species composition and index of biotic integrity of Roaring River, Tennessee, were assessed in 1972 and 1986. During the intervening years, a fish barrier dam was constructed in the river, heavy gravel dredging occurred, and the watershed was disturbed by bridge construction, highway construction, and poor agricultural practices. Species composition changes and a general decline in index values reflected these instream and watershed disturbances. Deliberate and inadvertent introductions of new fish species also contributed to these changes. There was a general decline in number of native species, a loss of intolerant species in the lower reaches, and a general increase in tolerant species. There was also an increase in number of introduced species in the lower reaches, and a general increase in percentage of the population consisting of introduced species.

Abundance of Spawning Pacific Salmon in Two Lake Superior Streams, 1981–1987

We examined, by mark and recapture procedures, the abundance of Pacific salmon entering two Lake Superior tributaries to spawn between 1981 and 1987. In 1987, abundance of pink salmon in the Carp and Pancake rivers declined to 50 and 25%, respectively, of that observed in 1981. In contrast, abundance estimates and catch records indicated that coho and chinook salmon had increased since 1981. The construction of a lowhead barrier dam on the Carp River in 1983/84 allowed passage of coho and chinook but precluded passage by pink salmon. Construction of the barrier dam did not appear to be the major cause for changes in abundance of pink salmon. Most mature pink salmon (>50% of total abundance) entered the spawning streams during a 2-week period following either onshore wind or a heavy rainfall. We submit that it is premature to suggest a lake-wide decline in pink salmon abundance.

Role of Physical Barriers in the Control of Sea Lamprey (Petromyzon marinus)

Mechanical and electromechanical barriers played a significant role in the initial attempts to control sea lamprey (Petromyzon marinus) populations in the upper Great Lakes. More recently electromechanical weirs have been used to assess the relative abundance of spawning-run sea lampreys in Lake Superior. Development of an integrated control approach to sea lamprey control has stimulated an ongoing research program to define structural and/or velocity criteria that can be used to design barrier dams that block spawning runs of sea lamprey.Key words: sea lamprey, Petromyzon marinus; physical barriers, burst swimming speed, barrier dam criteria