The need for paleoflood investigations on the American reach of the Red River of the North

Over the past century, the Red River of the North has been the least stationary river in the continental United States. In Canada, historical and paleoenvironmental evidence indicates severe floods were common during the early 1800s, with the record ce 1826 flood having an estimated peak discharge 50% higher than the second-most severe flood ever observed. Unfortunately, the recorded history of flooding upstream in the United States does not begin until seven decades after this event. If 1826 was an equally exceptional flood on American reach of the river, then current flood-frequency curves for the river underestimate significantly the risks posed by future flooding. Alternatively, if the American stretch did not produce a major flood in 1826, then the recent spate of flooding that has occurred over the past two decades is exceptional within the context of the past 200 years. Communities in the Fargo-Moorhead metropolitan area are building a 58-km long, $2.75 billion (USD) diversion channel that would redirect floodwaters westward around the two cities before returning it to the main channel. Because this and other infrastructure in North Dakota and Minnesota is intended to provide protection against low-probability, high-magnitude floods, new paleoflood investigations in the region would help local, state, and federal policy-makers better understand the true flood threats posed by the Red River of the North.

Evaluation of the Open Diversion Channel Capacity on Margatiga Dam Construction Project using 6D BIM Analysis

The Margatiga Dam is designed to combine a gravity concrete dam and rockfill with an upright core. In the Margatiga Dam Project, river diversion is carried out in 2 stages. Stage 1 through a trapezoidal open channel with discharge plan of Q10 years approximately 789.10 m3/second and stage 2 with the diversion discharge of Q25 years approximately 976.90 m3/second. During construction, the stage 1 diversion channel is built with a capacity that exceeds the planned design due to the very high water level fluctuations. Moreover, an evaluation is needed regarding the annual plan discharge that passes through stage 1. The Evaluation is based on data from the desk study and 6D BIM analysis. Based on the analysis, the water level is at elevation +19.50. The discharge through the diversion channel on this stage is 884.69 m3/second; this discharge exceeds the planned discharge design for diversion channel stage 1 with an annual Q10 discharge of approximately 789.10 m3/second.

Valveless Piezoelectric Pump with Reverse Diversion Channel

In order to reduce backflow and improve output performance, a valveless piezoelectric pump with a reverse diversion channel was produced. The channel was designed based on the structure of the Tesla valve, which has no moving parts and can produce a high-pressure drop during reverse flow. Therefore, this special flowing channel can reduce the backflow of a valveless piezoelectric pump, which has the characteristic of one-way conduction. This work first revealed the relationship between the main structural parameters of the Tesla valve and the kinetic energy difference of liquid. Then, by using simulation software, the structure was verified to have the characteristics of effective suppression of the backflow of valveless piezoelectric pumps. Through setting multiple simulations, some important parameters that include the optimal height between the straight channels (H), the optimal angle (α) between the straight channel and the inclined channel, as well as the optimal radius (R) of the channel were confirmed. Finally, a series of prototypes were fabricated to test the output performance of this valveless piezoelectric pump. Comparing the experimental results, the optimal parameters of the Tesla valve were determined. The results suggest that when the parameters of the Tesla valve were H = 8 mm, α = 30°, and R = 3.4 mm, the output performance of this piezoelectric pump became best, which had a maximum flow rate of 79.26 mL/min with a piezoelectric actuator diameter of 35 mm, an applied voltage of 350 Vp-p, and a frequency of 28 Hz. The effect of this structure in reducing the return flow can be applied to fields such as agricultural irrigation.

Perencanaan Sistem Penyaliran dan Pemompaan pada Tambang Terbuka di PT X Desa Tegalega, Kecamatan Cigudeg Kabupaten Bogor, Provinsi Jawa Barat

PT X is a mining company with open pit mining methods for andesite rocks. The implementation of open pit methods is inseparable from the problem of inclusion water of rainfall and groundwater seepage into the mining area (pit). This can lead to disruption of mining activities if not handled properly. In this case to cope with the incoming water at Pit in PT X requires some study. It deals with the large number of pumps needed to tackle the incoming water each day.The purpose of the research is to overcome the potential of water entering the Pit, by making diversion channels and to overcome water that already inside the Pit is handled by making sump and pumping system.The data used are 2014-2018 rainfall data, topographic maps, mine progress maps, land use maps, water velocity data, temperature and humidity data and soil condition and land conservation data. Pit has 4 Catchment Areas with each divided into 3 namely Catchment Area PIT, Catchment Area A, Catcthment Area B, Catcthment Area C with a total area of 26,28 Ha. The water runoff plan during the 10 years period. From these data the reults obtained amounted to 50,35 m3/day. Water discharge that enters from inside and outside the pit with a total discharge of 0,94 m3 /sec. Based on data that obtained the ways to prevent water entering the mining area can be minimized by creating a diversion channel. The first diversion channel made for prevent water entering the mining area that comes from Catchment Area A, the diversion channel made along 569 m from 300–270 mals. The second one made for prevent water from Catchment Area C with total length 756 m from 290–130 mals. So that the incoming water debit becomes as much as 0,53 m3/sec. Sump is place at an elevation 115 masl, volume of sump is 7.900 m3 with dimensions of surface length 43 m, surface width 50 m, the base length of the is 36 m, and the depth of 4 meters can accommodate the total volume of water. The pump used is a MFC 180 , with a total of 2 unit pump, the pumping hours are adjusted based on the incoming water debit per month. The highest pumping hour in November was 15.2 hours with a debit of 12,403.63 m3 / day and the lowest in May was 6 hours with a discharge of 4,896.17 m3 / day. Abstrak. PT X merupakan salah satu perusahaan pertambangan dengan menggunakan Sistem Tambang Terbuka dengan tipe Quarry untuk batuan andesit. Akan tetapi belum tersedianya sistem penyaliran tambang menyebabkan terjadinya banjir pada lokasi penambangan, sehingga mengganggu kegiatan penambangan terutama pada musim penghujan. Tujuan dilakukan penelitian adalah untuk menanggulangi potensi air yang masuk ke pit , maka dilakukan penanggulangan air dari luar pit dengan membuat saluran pengalihan dan penanggulangan air yang masuk ke dalam pit dengan sistem pemompaan dan kolam penampungan.Data yang digunakan merupakan data curah hujan tahun 2014-2018, peta topografi, peta kemajuan tambang, peta tataguna lahan, data kecepatan air, suhu dan kelembaban dan data kondisi tanah dan konservasi lahan. Pit memiliki 4 Catchment Area dengan masing-masing dibagi menjadi 4 yaitu Catchment Area PIT, Catchment Area A, Catchment Area B, Catchment Area C dengan total luasan sebesar 26,28 Ha. Curah hujan rencana dengan data curah hujan selama 10 tahun periode 2014-2018. Hasilnya adalah curah hujan rencana maksimum sebesar 50,35 mm/hari. Debit air yang masuk adalah dari dalam pit dan luar pit dengan total debit sebanyak 0,94 m3/detik. Dari hasil penelitian, saluran pengalihan dibuat pada dua lokasi yaitu untuk menangani Catchment Area A dengan total panjang saluran 569 m pada elevasi 300 -270 dan untuk menangani Catchment Area C dengan panjang 756 m pada elevasi 290 - 130. Sehingga debit air yang masuk menjadi sebanyak 0,53 m3/detik.Kolam penampungan dibuat dengan volume 7.900 m3,dengan dimensi panjang atas 43 dan panjang bawah 36 m, dengan lebar 50 m dan ketinggian 4 m. Pompa yang digunakan adalah 2 unit pompa Multiflow 180 dengan jam pemompaan disesuaikan berdasarkan debit air yang masuk perbulannya. Jam pemompaan tertinggi pada bulan November yaitu 15,2 jam dengan debit 12.403,63 m3/hari dan yang paling rendah pada bulan Mei yaitu 6 jam dengan debit 4.896,17 m3/hari.

Red River Structure physical model study : bulkhead testing

The US Army Corps of Engineers, St. Paul District, and its non-federal sponsors are designing and constructing a flood risk management project that will reduce the risk of flooding in the Fargo-Moorhead metropolitan area. There is a 30-mile long diversion channel around the west side of the city of Fargo, as well as a staging area that will be formed upstream of a 20-mile long dam (referred to as the Southern Embankment) that collectively includes an earthen embankment with three gated structures: the Diversion Inlet Structure, the Wild Rice River Structure, and the Red River Structure (RRS). A physical model has been constructed and analyzed to assess the hydraulic conditions near and at the RRS for verification of the structure’s flow capacity as well as optimization of design features for the structure. This report describes the modeling techniques and instrumentation used in the investigation and details the evaluation of the forces exerted on the proposed bulkheads during emergency operations for the RRS.

Effect of a Submerged Vane-Field on the Flow Pattern of a Movable Bed Channel with a 90° Lateral Diversion

This laboratory study focused on the effect of a submerged vane-field on the flow pattern and bed morphology near and inside the entrance reach of a movable bed 90° lateral diversion. The system was modelled under live bed conditions for a water discharge ratio of ≈0.2. Two experiments were run until bed equilibrium was reached: with and without a vane-field installed close to the diversion entrance to control the transfer of sediments into the diversion channel. The equilibrium bed morphology and the associated 3D flow field were measured in great detail. The bed load diverted into the diversion was reduced by approximately one quarter due to the action of the vane-field. The vanes prevented the formation of the diversion vortex in the main channel, upstream of the diversion’s entrance, thus contributing to that decrease. They also created a main channel vortex that started at the most upstream vanes and further decreased the amount of bed load entering the diversion. The flow separation zone inside the diversion was larger with vanes, but conveyance was balanced through a slightly deeper scour trench therein. The flow structures described were confirmed through the measurements of the turbulent kinetic energy.

Large scale filed experiment on the landslide dam breaching

<p>Landslide dam breaching is the one of focus topics in the geophysical flows. The frequency of occurrence of landslide dam increases due to earthquake, climate change and mans activities in recent years. Once the dam breaks, it would trigger extreme flood downstream. A field experiment on landslide dam breach has been carried out on a small mountain river in Mianzhu, Sichuan Province, China from 23 November to 29 December, which aims to reveal impact of different diversion channel types on the dam breaching process as well as the resulting flood. The dam is of 4m high, 10~15m wide. the length of the dam crest is 5m, upstream downstream slopes of the dam are 1:2 and 1:5. Results show division channel can reduce the peak flood discharge obviously. The pilot vertical fall can trigger earlier back erosion and thus peak discharge appears earlier with smaller magnitude.</p>

Reducing bubble generation and sweepdown effect on a research vessel with a moonpool

Some research vessels set moonpools for sonars installation. The moonpool provides a relatively good working environment for sonar in a harsh marine environment. At the same time, other acoustic detection equipment are installed along the ship bottom behind the moonpool. Due to the exist of the sonar with a variable cross-section, the number of bubbles generated in the moonpool increases. The bubbles generated in the moonpool expel and flow along the vessel bottom to the stern, which leads to the sweepdown effect. The performance of the sonar and other acoustic detection equipment degrades by the bubbles around. However, the research on reducing bubble generation in the moonpool and sweepdown effects is rare. So in present paper the reduction effects of damping devices such as the flange and choke deck on the bubble generation in the moonpool are investigated experimentally. Then, in order to reduce the sweepdown effects of bubbles on the ship bottom, three other damping devices which are double flaps, diversion channel and wedge are investigated. It can be seen that through reducing the area of bubble leakage in the moonpool the distribution position of bubbles can be effectively restricted and the width and thickness of the bubbles reduce.