Hydraulic Structures (Engineering)

The local scour around bridge piers is one of the most common causes of bridge failures. Many equations have been proposed for determination. Most of these equations have a reliability and are used for design, were developed when the pier located within straight reaches for both flume and field studies. However, few studies have been conducted on bridge pier located within the curved channel. A laboratory work was conducted to measure the local scour which is formed around single circular pier fixed at each 30 o of the bend while adopting three different diameters. The results show that the maximum depth of scour and the maximum extents (i.e., length and width) of scour hole, and maximum modification factor due to bend have occurred when the pier is located at sector 90 o of the bend. The results also show that the diameter has a significant effect on scour phenomenon.

The feature and configuration of culvert entrance beside the aspect ratio (span/rise) have a key role in determining the hydraulic performance of culver. The conveyance along with the permitted height of head water can be determined mainly by the effect of the entrance factors on it. The present study aim to investigate the entrance feature and configuration on the hydraulic performance of culvert operated at inlet control for both unsubmerged and submerged entrance. Different aspect ratios with just head wall of square edges entrance have been tested experimentally by a wide range conditions to perform both unsubmerged and submerged flow. However, a new shape of inlet transition structure that proposed by Howes et al., 2010 have been adopted as the inlet approach to achieve a gradual contraction of stream lines before entrance. The results showed that improvement in performance through adoption of the actual measurements of contraction coefficients which leads to extract a new practical equations and design charts. However, the traditional limitations of the zone between unsubmerged and submerged flow at the entrance were developed through using a new shape of the inlet transition as the approach section to square edges entrance.A culvert is a structure through which storm water is drained from one side of an embankment to the other. There are two aspects to the design of a culvert; the first is the hydraulic aspect at which the culvert should be able to convey the design discharge with water level on the upstream side as low as possible, whereas the second is the structural aspect. The hydraulic aspect deals with the flow feature through culvert, it may be under inlet or outlet control. Inlet control occurs when the culvert barrel is capable to convey more flow than the inlet will accept, at which the control section is located just inside the entrance, and the hydraulic characteristics downstream this section do not affect the culvert capacity. The flow rate depends only on size and shape of the cross section (aspect ratio) and the entrance conditions (such as square edged or splayed, etc.) (Dasika, 1995). However, the outlet control flow occurs when the culvert barrel is not capable to convey as much flow as the inlet opening will accept. At this feature of flow the control section is located at the barrel exit or further downstream. When achieving the outlet

In this study the effect of upstream face slope of a trapezoidal broad-crested weir on discharge coefficient and water surface profile was investigated using the laboratory models. The velocity and pressure distribution profile were determined. The location of the critical section above the weir was specified. The dimensions of flow separation zone were also measured for different upstream face slopes. The results showed that decreasing the upstream face slope prevents development of separation zone. In this case, the flow was passed through the weir more regularly and the water surface and pressure drop were decreased. Decreasing the upstream face slope to 210, increased the discharge coefficient up to 10% and reduced the separation relative length and height up to 80% and 95% respectively.

Монголын говийн бүсэд уул уурхай, үйлдвэржилтийн хөгжил эрс нэмэгдэн үүнийг даган сууршлын бүсүүд шинээр бий болж хүн амын хүрээгээ тэлсээр байна. Өсөн нэмэгдэх усны хэрэгцээтэй уялдан гадаргын усны нөөц багатай говийн бүсэд он удаан жил тогтсон гүний усыг авч хэрэглэх нь тэр бүр техникийн төгс шийдэл биш гэдгийг эрдэмтэд тэмдэглэсээр байна. Иймд бүс нутаг хооронд ус шилжүүлэн ашиглах хэд хэдэн төслийн нэг болох Орхоны УЦС нь Говийн бүсэд чухал үүрэг гүйцэтгэх ба бүс нутгийн эрчим хүчний асуудал мөн усны дутагдлын асуудлаас гарах боломжийг бий болгоно. Боомт бүхий усан цахилгаан станцын гол судлагдахуун нь усан сангийн ажиллагаа байдаг. Усан сангийн ажиллагаа болон түүний характеристик нь тухайн голын гидрологийн үндсэн параметрүүдээс хамаарна. Энэхүү усан сангийн урьдчилсан судалгааны ажлыг HEC-ResSIM программ ашиглан гүйцэтгэсэн ба загварчлалын үр дүнд усан сангийн үйл ажиллагааны горим, түүний үндсэн характеристик, эрчим хүч үйлдвэрлэх боломж, байгаль орчинд нөлөөлөх байдлыг судалж цаашид хийх судалгааны ажлын чиглэлийг тодорхойлсон болно. Судалгааны дүнд усан сангийн бага эзэлхүүнийг 1128м, ХТТ-ний хэлбэлзэл 1145-1162м, эрчим хүч үйлдвэрлэх дүрмийг усан сангийн дүүргэлтээс хамаарахаар тохируулахад говьд шаардлагатай усны хэмжээг тасралтгүй хангаж /2.27м3/с - ээс 2.8м3/с хүртэл тасралтгүй хангах, 4м3/с хүртэл 2 хоногийн тасралттай өгөх/, багадаа 5МВт, дунджаар 14.35МВт эрчим хүч үйлдвэрлэх, станцын фактор дунджаар 0.41-тэй ашигтай горимд тохирлоо гэж дүгнэж байна.

In this research, an experimental study was conducted to determine the maximum length and maximum length of the scour hole downstream for the combined structures, comprising of weir and gate. Sixty models were designed and that were divided into four groups. Each model is a composite weir consisting of two geometric shapes and three types of gates, which are rectangular, semi-circular and triangular in shape. Multiple factors were studied to find out the effect of changing geometry for both weir and gate, discharge flowing in the flume and particle size of bed material on the dimensions of scour hole. The experiments were conducted in a laboratory channel which is built of blocks and concrete. The total length of the flume is (18 m), width of (1 m) and (1 m) deep. The laboratory models were installed 7 m away from the main gate which controls running of the water from the main reservoir into the flume.
First, the calibration process was performed to identify the actual discharge values that pass through the flume, then three hundred experiments were conducted by using different values of discharges within the flume on the basis of this change. The water depth was varied upstream and downstream for combined structure to examine the hydraulic performance and to measure the discharge coefficient for each model; this is considered as being one of the studied factors within the dimensional analysis of the variables to derive the empirical formulas for calculating the dimensions of scour hole. Twelve relationships were developed by using the dimensional analysis and IBM SPSS 21 program to calculate the discharge coefficient; higher values for coefficients of determination (R2) have been achieved. Six hundred experiments were conducted thereafter in order to derive equations to find depth and length of the scour hole generated in the sand floor spreading as a layer of 30 cm in thickness for a distance of 4 m downstream for combined structure.  Two samples of sand were used in the experiments with different median sizes of particles (d50), the first is 0.7 mm and the second is 1 mm.
The dimensional analysis was later employed to derive twelve nonlinear relationships based on π theorem and IBM SPSS 21 program, to calculate the dimensionless scour depth (SD/d50). Additional twelve nonlinear relationships were derived to calculate the dimensionless  length of scour (SL/d50) depending on the laboratory results of each of the relative discharge (Qr), Froude number in terms of mean size of bed material particle (Frd), non-dimensional difference head between upstream and downstream of combined structure  (HD/d50), dimensionless distance between the lower edge of the weir and the upper edge of the gate (y3/d50), dimensionless head over the crest of compound weir (h/d50), and the discharge coefficient (Cd). Higher values of the determination coefficients (R2) were obtained.
The maximum depth (SD) and length (SL) of the scour hole values were recorded in the second group models in general and particular, these values increase in models with semi-circular gate when compared with the other models with a rectangular and triangular gates. The maximum value of scour depth (SD) is 27.7 cm and maximum value of scour length (SL) was 205 cm recorded at model no. 25 with d50 equal to 0.7 mm with maximum values of affecting parameters. The minimum depth (SD) and length (SL) of the scour hole values were recorded in the fourth group models in general and particular, these values decrease in models with triangular gate when compared with the other models with a rectangular and semi-circular gates The minimum value of scour depth (SD) was 8.5 cm and minimum value of scour length (SL) is 75 cm recorded at model no. 56 with d50 equal to 1 mm with minimum values of affecting parameters.

The forced hydraulic jump characteristics were studied experimentally using different configurations of a standard USBR baffle blocks. Each configuration was tested under Froude numbers ranged between 2.27 to 9.2 at which the hydraulic jump located within a description of oscillating and steady jump. Two groups of baffle block models were adopted. The first group installed at one row with two blockage ratios, whereas the second group consisted of two rows; the first was fixed at a specified location after sluice gate, while the second has been installed at three different distance ratio. During each test, the sequent depth and the transverse velocity distribution were measured. The results showed that the sequent depths for all configurations were less than the sequent depth of a classical jump. Among all configurations undertaken, the greater reduction of sequent depth was 30%. The new experimental formula was developed for determining the sequent depth ratio in term of the initial Froude number for this configuration which gives the better performance. The comparisons were also made with the previous relevant studies to show the reliability of the configurations undertaken. The analysis of the experimental results concluded that; when using two rows configuration of standard USBR baffle blocks with a blockage ratio 50% and 37.5%, respectively, and at a specified distances the best performance could be achieved by reducing the sequent depth beside the velocity become nearly uniformly distributed across the width of the basin.

The current study focus on the effect of using stepped gabion weir in a laboratory
channel on the hydraulic jump distance which form at its toe. A series of 175 operation tests and
25 laboratory experiments were conducted by using a laboratory flume 10 m long, 0.3 m wide,
and 0.5 m deep. The tested gabions had different five lengths 0.72 m, 0.84 m, 0.96 m, 1.08 m,
and 1.20 m respectively, and the material used to fill the gabions was natural quarry mono graded
gravel in five different sample sizes of diameters ranged between (09.5-14.0) mm, (14.0-19.0)
mm, (19.0-25.0) mm, (25.0-37.5) mm, and (37.5-50.0) mm. The operation flow rate values
ranged between 2.33*10-3 to 50.00*10-3 m3/s/m. Dimensional analysis was used to generate
dimensionless parameters, and correlated them using the Buckingham Pi-Theorem. The results
of this study showed that the hydraulic jump distance increases by increasing the flow rate value,
but increasing the values of both of the gravel sample used and the total length of the weir have
an undular effect on the hydraulic jump distance.

In this research, a study was conducted experimentally to investigate the scour hole dimensions downstream the combined structures which consist of weir and gate. Twelve models have been designed and every model is formed from composite weir consists of two geometric shapes and three types of gates which are rectangular, semi-circular and triangular in shape, where multi factors were studied to find out the effect of changing geometry for both weir and gate, discharge flowing in the flume and particle size of bed material on the dimensions of scour hole. The experiments was conducted in a laboratory channel was constructed from blocks and concrete with length of 18 m, 1 m width and 1 m depth. The laboratory models were installed after 7 m from the main gate which is controlling the passage of water from the main reservoir into the flume. At the beginning, the calibration process was conducted to identify the actual discharge values that pass in the flume, then experiments were conducted to calculate the discharge coefficient for each model, which represents one of the studied factors within the dimensional analysis of the variables to derive the empirical formulas to calculate the dimensions of scour hole. Then the experiments were conducted in order to derive formulas to investigate the depth and length of the scour hole which formed in the sand floor spreading as a layer of 30 cm in thickness for a distance 4 m downstream combined structure. Two samples of sand were used in the experiments with different median size of particles (d50), the first of 0.7 mm and the second of 1 mm. Using the dimensional analysis by π theorem and IBM SPSS 21 program, Four nonlinear relationships were derived to calculate the dimensionless scour depth (SD / d50) and another four nonlinear relationships calculates the dimensionless length of scour (SL / d50) depending on the laboratory results for each of the relative discharge (Qr), Froude number in terms of mean size of particle of bed material (Frd), non-dimensional difference head between upstream and downstream of combined structure (HD / d50), dimensionless distance between the lower edge of the weir and the upper edge of the gate (y3 / d50), dimensionless head over the crest of compound weir (h/d50) and the discharge coefficient (Cd), where the resulted determination coefficients (R2) from these relationships were good.

Hydraulics is a topic in applied science and engineering dealing with the mechanical properties of liquids or fluids. At a very basic level, hydraulics is the liquid version of pneumatic. Fluid mechanics provides the theoretical foundation for hydraulics, which focuses on the engineering uses of fluid properties. In fluid power, hydraulics are used for the generation, control, and transmission of power by the use of pressurized liquids. Hydraulic topics range through some part of science and most of engineering modules, and cover concepts such as pipe flow, dam design, fluids and fluid control circuitry, pumps, turbines, hydro power, computational fluid dynamics, flow measurement, river channel behavior and erosion.Free surface hydraulics is the branch of hydraulics dealing with free surface flow, such as occurring in rivers, canals, lakes, estuaries and seas. Its sub-field open channel flow studies the flow in open channels.

Flow unsteadiness in flood events has a significant effect on the structure of the flow field and motion of sediment particles, thereby affecting dispersion of pollutants and river ecology. The aim of the present article was to evaluate state-of-the-art research efforts concerning flow characteristics and sediment transport in unsteady flow condition. The paper is organized in four sections: The first section deals with the unsteady parameters which affect sediment transport. In the second section, the flow characteristics in unsteady open channel flow are presented. Different studies showed that the flow characteristics which affect sediment transport including velocity distribution or shear stress during passage of a hydrograph differ from steady flow condition. In addition, measurements during passage of a hydrograph show that turbulence intensity is generally larger in the rising limb of the hyd-rograph rather than in the falling limb. This causes the peak of sediment load and pollutants occur during the rising limb of the storm hydrograph. The third and forth sections deal with bed load and suspended load in unsteady flow condition, respectively. Studies show that the methods which are based on steady flow conditions generally underestimate the sediment transport rates in unsteady flows. The larger the unsteadiness, the bigger is the difference. Finally, with considering different findings from previous studies, suggestions are presented for further research.

In this research, water surface profile, piezometric head distribution and energy dissipation (E/E 0)%, were studied over a stepped spillway of semicircular crest.Different types of stepped spillway were used. Three types of d/s slope of the spillway (α=V: H=1:0.75, 1:1 and 1:125) were used and three number of steppes (N s = 3, 5 and 7) for every slope. Seventy two experiments were performed in a laboratory horizontal channel of 12 m length, 0.5 m width and 0.45 m depth for a wide range of discharge. The experimental results of the study on stepped spillway show that an increases in (d 0 /d c) and (L/d c) value causes an increase in (E/E 0)%, and an increases intheroughness Froude number(F*) and number of steps (N s)value causes decreasing in (E/E 1)% value for all stepped models. An empirical equation was established for calculating the dissipation energy.

The stability of glover leaf coffer dam in two soil cases
(dry and wet) and two positions (neutral and longitudinal), with
nonlinear finite element analysis has been used in this study to
predict the load deflection behavior of cellular cell cofferdam under
lateral load. Series of laboratory tests have been carried out on one
(single) glover-leaf cofferdam cells of different width to height ratio
(b/H) (0.75, 0.85, 1.0) with three types of soil fill (sand passing sieve
No.4, river sand, subbase).
In finite element analysis, AN SYS(version 12.1) computer
program with combination of CivilFEM was used, eight-node solid
element SOLID 45 has been used to model filling with river sand
soil and the same element for steel sheet pile and foundation, by
using glue technique to model of steel sheet pile of cofferdam, the
load applied on the one third of the cell cofferdam height and full
Newton-Raphson method is used for the nonlinear solution algorithm
and the results are compared with experimental data.
The results expressed that the cells fill with wet subbase were
more stable against sliding and overturning at different (b/H) ratio
and the cells that put on the longitudinal direction was more stable
against sliding and overturning at different (b/H) ratio than the cells
with neutral direction. Also, the results obtained using the finite
element models show a good agreement with the experimental data.
The difference between the numerical ultimate loads and the
corresponding experimental ultimate loads is in the range between
(0-6.9)%.

Abstract
Flood estimation is necessary to design hydraulic structures and to quantify structures failure risk. Most of the methods used for design flood estimation in Mozambique were developed in the late 1960s. Furthermore, collecting hydrological data in east Africa is a big challenge; few data are available in literature for Mozambique. Pegram (2004) proposed new approaches which are applied in this project. Annual rainfall database is analyzed, adjusted and used to assess peak discharges of 198 catchments in Mozambique. In addition, hydraulic structures (bridges and box culverts) are designed along Mueda-Negomano national road of about 170 km.
Key words: Mozambique, hydrological models, sizing, box culvert, bridge.
Résumé
L’estimation des crues de projet est nécessaire pour concevoir les ouvrages hydrauliques et pour quantifier leur risque d'échec. La plupart des méthodes utilisées pour l'estimation des crues de projet au Mozambique ont été développés dans les années 1960. En outre, la collecte de données hydrologiques en Afrique de l'Est est un grand défi; peu de données sont disponibles dans la littérature au Mozambique. Pegram (2004) a proposé de nouvelles approches qui sont appliquées dans ce projet. Une base de données de précipitations annuelles est analysée, ajustée et utilisée pour déterminer les débits de pointe de 198 bassins versants au Mozambique. En outre, les structures hydrauliques (ponts et ponceaux) sont conçues tout au long la route nationale Mueda-Negomano sur environ 170 km.
Mots clés : Mozambique, modèles hydrologiques, dimensionnement, dalot, pont.
ملخص
ان من الضروري القيام بعملية تقدير تخطيط الفيضانات خلال تصميم المنشآت المائية وتحديد مخاطرها من الفشل.
تم تطوير معظم الطرق المستخدمة في تقديرتخطيط الفيضانات في الموزامبيق في أواخرالستينات.بالإضافة إلى ذلك, فإن
جمع البيانات المائية في شرق أفريقيا يمثل تحديا كبيرا؛ فالبيانات المتوفرة في المراجع عن الموزامبيق هي قليلة جدا . قام
العالم بغرام في سنة 4002 بإقتراح منهجيات جديدة وقد تم تطبيقها في هذا المشروع.ووقع الإعتماد على قاعدة بيانات
الأمطار السنوية، حيث تم تحليلها و تعديلها للحصول على ذروة التدفق في مائة و ثمانية وتسعين ) 891 ( حوضا للصرف
في الموزمبيق.وقد تم أيضا تصميم المنشآت المائية)الجسور والقنوات( على طول الطريق
الكلمات المفاتيح : الموزامبيق, نماذج هيدرو لوجية, تصميم, قناة, جسر̣
الوطنية موادا - نقمونو على في الموزمبيق.وقد تم أيضا تصميم المنشآت المائية)الجسور والقنوات( على طول الطريق
حوالي 071 ك م

In this research, a laboratory study of hydraulic jump properties was conducted by making small semicircular rough elements, which covered the stilling basin floor downstream of spillway. The objective of this research was to introduce and make a comparison of roughed bed hydraulic jump stilling basin by using semicircular rough elements. To reach such an idea, a new expression was first developed for sequent depth and hydraulic jump length. Then, hydraulic jumps were conducted on a bed of prismatic roughness elements in a rectangular flume in order to investigate the jump effect on the characteristics of stilling basin. The rough elements are positioned on the bed of the flume downstream of an Ogee spillway in such a way that the incoming water jet is just skimming above the elements' top surface. Each rough element shape was tested under different Froude numbers, ranging from 4 to 11. In each test, the water surface profile, the roller length and the jump length were measured. The experimental results showed that the presence of a rough element increases the shear force and consequently reduces the jump length and the sequent depth of flow. Comparison of the results with those of previous studies showed that using beds roughed with semicircular shaped elements can decrease the length of the stilling basin by 56% of any regular basin and the sequent depth of the jump by 25% of a comparable one occurring on a smooth bed. Also, the average value of energy dissipation was computed and found to range between 68.1% and 60.4% of stilling basin of type I developed by Peterka (1978).

The Kut Barrage is one of the most important hydraulic structures in Iraq, which is in
place to regulate the flow from the Tigris River and distribute it between Graf River, Dujelah
Channel, Dalmch Channels, and other irrigation projects. The barrage includes 56 sluice gates,
each 6 m wide, which control the discharge of the Tigris River at the individual locations.
According to observations and measurements, about 90% of the flow at the downstream has been
modular (free flow) within the last five years. In the present study, a trial was attempted to
calibrate some universal formulas that would offer a reliable means of determining the discharge
under gates such as those presented by Rajaratnam and Subramanya, Swamme, and Ferro, which
would make them suitable for Kut Barrage discharge calculation over a wide range of scenarios
in terms of gate openings. A recent formula presented by Maatooq for canal operation was also
adopted in order to test whether it was appropriate for application under the flow and geometric
boundary conditions of the Kut Barrage. The available data was also used to extract an empirical
equation for the coefficient of discharge used for calibration. A total of 221 measurements taken
at the head at upstream, nine different gate openings, and at the discharges were employed for
calibration, and 28 data points taken at six different gate openings were adopted for verification.
The determined discharges using the calibrated formulas show good agreement with the
measurements with the coefficient, R2 ranging between 0.874 using Rajaratnam and Subramanya
and 0.880 using Maatooq.

Seepage under hydraulic structures is very impor-tant in designing of such structures and if it is not considered, the whole structure may fail due to both effects of uplift pressure and piping phenomenon. 1 Up to now, a number of authors have investigated seepage problems through and under hydraulic structures, both numerically and analytically. Validation of numerical models is often done by field observations, where there are no experimental data available. To verify numerical models for practical purposes, an accurate record of ...

The aim of the present study is to indicate the drag coefficient, pressure distribution
and flow types on unconventional types of angularly cutted baffle blocks and compare the
results with standard baffle blocks by using the Fluent program depending and the
experimental results to achieve that.
Values of the drag coefficient for different baffle blocks in this study were found in
terms of the primary Froude numbers. Results indicated that values of the drag coefficient
for the vertically cutted blocks were less than the horizontally cutted baffle blocks in the
same flow conditions. Also, maximum values of applied pressures on the surface of the
vertically cutted baffle blocks were less than on other models which makes them more
better than others.

This paper present nonlinear finite element analysis to predict the load deflection behavior of circular cell cofferdam under lateral load by using ANSYS (ANalysis SYStem) (version 12.1) computer program, eight-node solid element (SOLID 65) has been used to model the concrete cofferdam and (line search on) method is used for the nonlinear solution algorithm. In this study circular concrete cofferdam with width to height ratio (D/H) = 1.0 on concrete foundation and another case circular concrete cofferdam on concrete foundation with (0.4 from the height of the cell) concrete berm was analyzed. Also in this work the fractured cracking or crushing types of fracture occurred at concrete elements are indicated as circles located at sampling points inside the elements, each integration point of a brick element can crack in up to three different planes. The first crack occurred at an integration point is shown with a red circle outline, the second crack is presented with a green circle outline, and the third crack is shown with a blue circle outline. The cracks were occurred around the place of applied load (at one third of the cell height) and the crush which represented by octahedron outline occurred at the place of applied load. From numerical analysis found that using (0.4H) concrete berm reduce the displacement by about (34.22%).

Flip buckets are a common configuration for side channel spillways. Similar to other spillways, the flip bucket or ski jump has its disadvantages, among which the scour hole downstream due to the flip bucket jet is the most important. The structure safety and stability may be influenced by the scour holes generated at the downstream side of bucket type energy dissipators. This study has employed an experimental model in order to examine the sediment scour created at the end of flip bucket energy dissipators at various flow rates and tail water depths. A total of 45 experiments were performed under different conditions. The experimental invistigation was conducted at the hydraulic laboratory of Shahid Chamran University in Iran. The main objective of this research was to identify the maximum depth of sediment scour () and the maximum distance of sediment scour hole () from the structures. The results showed that the maximum depth of scour and its distance from the structure increased by increasing discharge. The results of experimental models show that, at the downstream depths () of 0.2 and 0.3 m, the stack was formed by the scouring at the upstream side of the hole, and at a depth of 0.1 m, this stack was transferred to the area after the scour hole. This could be explained by the fact that at downstream depths of 0.2 and 0.3 m, the rolling flow moved from the bottom upwards in the opposite direction of the water flow and sequestrated the sediments upstream. According to Equation Mean Absolute Relative Error (MARE) proposed relation based on laboratory studies has MARE of about 34.2%.

In the present study, a laboratory work has been done to measure the local scour at equilibrium state which is formed around single oblong pier fixed at the center of the section located each 30° of 180°-bend. The results show that the maximum depth of scour and the maximum extents (i.e., length and width) of scour hole and maximum Modification factor due to bend for local scour occurs when pier located at sector 90° of the bend. With increasing angle of attack for the pier in this sector the depth of scour increase linearly and the width of scour hole increased accordingly. However, an appreciable effect is also recorded with the direction of the angle of attack relative to the inner and outer bank, where the scour depth was larger with the pier skew towards the inner bank than that recorded when it skewed towards the outer bank.

Earth-fill dam safety and stability control during service period is important at the view point of economics and social security. Monitoring is very important to control dam security, to compare real action with predicted planning and to make good experience and opportunity for future planning. In this paper, water pore pressure and settlements in different parts of Sattarkhan dam during service period was studied. So at first, according to instrument data installed in the body of dam, calibration of numerical model done and by doing back analysis real properties of materials of dam defined. Then by using the calibrated model, pore water pressures and settlements of dam studied. Analysis carried out by Flac2D Finite Difference software. The constitutive model used was Mohr-Coulomb at the state of plane strain. Results showed that dam will be safe during service period at the view point of hydro-mechanical behaviour. Finally, stability of dam studied from the view of rapid depletion of the reservoir, which results showed safety conditions.

The present study investigates the effect of using stepped gabion weir in a laboratory channel on the distance of the hydraulic jump. A set of 25 laboratory experiments and 175 operation tests were conducted using a laboratory flume with dimensions 10 m long by 0.3 m wide, and 0.5 m high. The tested gabion weir had different five possible lengths 0.88 m, 0.96 m, 1.04m, 1.12 m, and 1.20 m, and the filling material used was natural quarry mono graded gravel in five different sample sizes of average equivalent diameter 11.75 mm, 16.50 mm, 22.00 mm, 31.25 mm, and 43.75 mm. Operation discharge values ranged between 0.7 to 15.0 l/s. The data set was subject to dimensional analysis to generate dimensionless groups, and correlated using the Buckingham Pi-Theorem. The results of this study showed that in case of direct representation between the parameters, the distance of hydraulic jump has a direct relationship with discharge but both the gravel sample used and the overall length of the weir give an undular behaviour with its increment. While using of dimensional representation shows that both the gravel sample and weir length have an inverse relationship with the distance of the hydraulic jump. Many trials have been made to formulate the best equation which combine the studied parameters with good agreement.

Anhand von chronikalischen Berichten, Stadtrechnungen, archäologischen Befunden und Literatur gelang es erstmals, 25 einzelne Hochwasserereignisse der Saane in Freiburg i. Ü. von 1387 bis 1570 zu identifizieren, zu rekonstruieren und zusammenzutragen. Sie verteilen sich über 22 Jahre im Zeitraum von 1387 bis 1570; davon eines im 14., vierzehn im 15. und zehn im 16. Jahrhundert. Über die Erhebung der Arbeits- und Kostenaufwände für wasserbauliche Reparaturen, welche die Schäden an Brücken und Wehren erforderten, konnten 20 Hochwasser gemäss ihrer ökonomischen Intensität in einer vierstufigen Skala semiquantitativ klassifiziert werden. Die vier schwersten Hochwasser 1387, 1445, 1480 und 1481 werden als extrem bezeichnet, da sie verschiedene Infrastrukturen in und am Wasser praktisch völlig zerstörten.
Zur Erstellung der chronikalischen Hochwasserreihe wurden die in Chroniken und Literatur genannten Daten in den halbjährlichen Seckelmeisterrechnungen, welche 1402 einsetzen, sowie in weiteren Rechnungsbeständen überprüft. Damit wurde eine in der historischen Hochwasserforschung bisher kaum verwendete Quellengattung neu erschlossen. Erfasst wurden dabei häufige leichte bis seltene extreme Hochwasser, wobei die Reihe nur bezüglich der extremen Ereignisse durchgehend homogen ist. Für das 15. Jahrhundert konnten auch die schweren Ereignisse lückenlos erfasst werden. Zur sachgerechten Verwendung der Rechnungsinhalte musste vorgängig die Rechnungsführung der Baufinanzierung detailliert aufgearbeitet werden. Aufgrund der inhomogenen Quellenlage wurde das 16. Jahrhundert in allen nachfolgend beschriebenen Bereichen weniger umfassend aufgearbeitet als das 15.
Die vornehmlich kulturgeschichtliche Untersuchung der Hochwasser fokussiert auf die kommunale Organisation der Hochwasserabwehr und jene der Hochwasserbewältigung im Bereich des Wasserbaus. Dabei gelang es, die frühneuzeitliche Brücken- und Wehrlandschaft an der Saane zu rekonstruieren und dabei den Bau der Neustadtmauer 1385-1392 in seinen Etappen nachzuvollziehen. Zusätzlich wurden die Wassermengen historisch-hydrologisch abgeschätzt: Die Scheitelwasserstände der acht grössten Ereignisse wurden über topografische Angaben in den Chroniken und archäologische Befunde approximativ rekonstruiert und vor dem Hintergrund der jeweiligen zeitgenössischen Gerinne- und Ufertopografie der entsprechenden Flussabschnitte interpretiert. Diese bewerteten Höhenkoten können weiterführend für die Quantifizierung der Spitzenabflüsse verwendet werden. Allerdings dürften lediglich die Ergebnisse für 1566 die tatsächlichen Scheitelwasserstände mit 541,33 m ü.M. für die Neustadt und 537,46 m ü.M. für die Untere Matte einigermassen gut annähern.

Contemporary analytical and computational techniques enable the researcher to define interaction between varying flow rates, varying volumes of filling water and the deformation and stresses occurring in the structural components of a hydraulic structure. This study aims to describe and create visualisations, under selected operating conditions, of displacements, deformations and stresses of a hydraulic structure resulting from loads generated by hydraulic conditions in standard components of the structure. A sample analysis was carried out for the Niedów earthen dam on the Witka River that failed in 2010 due to a disastrous inflow. The scope of this analysis covers the components of the spillway section: the spillway monolith, the dissipation basin slab and the flip bucket. The results of analytical work and visualisations are shown using the Flow3D software program. Streszczenie Współczesne techniki analiz i obliczeń pozwalają na określenie wzajemnej interakcji pomiędzy zmienną wielkością przepływu i napełnienia a odkształceniem i naprężeniem, występującymi w elementach kon-strukcyjnych obiektu hydrotechnicznego. Tematem proponowanego artykułu, dla wybranych warunków pracy obiektu hydrotechnicznego, jest opis i wizualizacja przemieszczeń, odkształceń oraz naprężeń będą-cych konsekwencją obciążeń generowanych warunkami hydraulicznymi dla typowych elementów obiektu hydrotechnicznego. Przykład analizy został opracowany dla zapory ziemnej Niedów na rzece Witce, która uległa awarii w 2010 roku wskutek katastrofalnego dopływu. Zakres analizy obejmuje elementy sekcji prze-lewowej: monolit przelewu, płyta niecki wypadowej oraz szykany. Wyniki analiz i wizualizacje są prezento-wane z wykorzystaniem oprogramowania Flow3D.

The current study focus on the effect of using stepped gabion weir in a laboratory channel on the hydraulic jump distance which form at its toe. A series of 175 operation tests and 25 laboratory experiments were conducted by using a laboratory flume 10 m long, 0.3 m wide, and 0.5 m deep. The tested gabions had different five lengths 0.72 m, 0.84 m, 0.96 m, 1.08 m, and 1.20 m respectively, and the material used to fill the gabions was natural quarry mono graded gravel in five different sample sizes of diameters ranged between (09.5-14.0) mm, (14.0-19.0) mm, (19.0-25.0) mm, (25.0-37.5) mm, and (37.5-50.0) mm. The operation flow rate values ranged between 2.33*10-3 to 50.00*10-3 m3/s/m. Dimensional analysis was used to generate dimensionless parameters, and correlated them using the Buckingham Pi-Theorem. The results of this study showed that the hydraulic jump distance increases by increasing the flow rate value, but increasing the values of both of the gravel sample used and the total length of the weir have an undular effect on the hydraulic jump distance.

In hydraulic structures design, using cutoff walls is essential to reduce and control the resultant uplift force (U), seepage discharge (Q), and exit hydraulic gradient (i). This research investigates the effectiveness of inclined double cutoff walls under hydraulic structures, considering the influence of depths, locations, and inclination angles of the upstream and downstream cutoff walls by using Finite Element Method (FEM). The results confirmed that installing a deeper cutoff wall on the downstream reduces the exit gradient even further. In the case of the cutoff walls located in the upstream and downstream ends, the exit gradient will be less than when the cutoff walls are installed at a closer distance. Increasing the inclination angle of downstream cutoff wall has a major impact on exit gradient reduction. Embedment of cutoff walls in the upstream and downstream ends with right angles and equal depths reduces the seepage discharge more than other cases.

— In this research, a study was conducted experimentally to investigate the scour hole dimensions downstream the combined structures which consist from weir and gate. Twelve models have been designed and every model is formed from composite weir consists of two geometric shapes and three types of gates which are rectangular, semi-circular and triangular in shape, where multi factors were studied to find out the effect of changing geometry for both weir and gate, discharge flowing in the flume and particle size of bed material on the dimensions of scour hole. The experiments was conducted in a laboratory channel was constructed from blocks and concrete with length of 18 m, 1 m width and depth of 1 m, where the laboratory models were installed after 7 m from the main gate which is controlling the passage of water from the main reservoir into the flume. At the beginning, the calibration process was conducted to identify the actual discharge values that pass in the flume, then experiments were conducted to calculate the discharge coefficient for each model, which represents one of the studied factors within the dimensional analysis of the variables to derive the empirical formulas to calculate the dimensions of scour hole. Then the experiments were conducted in order to derive formulas to investigate the depth and length of the scour hole which formed in the sand floor spreading as a layer of 30 cm in thickness for a distance 4 m downstream combined structure. Two samples of sand were used in the experiments with different median size of particles (d50), the first of 0.7 mm and the second of 1 mm. Using the dimensional analysis by π theorem and IBM SPSS 21 program, Four nonlinear relationships were derived to calculate the dimensionless scour depth (SD / d50) and another four nonlinear relationships calculates the dimensionless length of scour (SL / d50) depending on the laboratory results for each of the relative discharge (Qr), Froude number in terms of mean size of particle of bed material (Frd), non-dimensional difference head between upstream and downstream of combined structure (HD / d50), dimensionless distance between the lower edge of the weir and the upper edge of the gate (y3 / d50), dimensionless head over the crest of compound weir (h/d50) and the discharge coefficient (Cd), where the resulted determination coefficients (R2) from these relationships were good.

Flip buckets are a common configuration for side channel spillways. Similar to other spillways, the flip bucket or ski jump has its disadvantages, among which the scour hole downstream due to the flip bucket jet is the most important. The structure safety and stability may be influenced by the scour holes generated at the downstream side of bucket type energy dissipators. This study has employed an experimental model in order to examine the sediment scour created at the end of flip bucket energy dissipators at various flow rates and tail water depths. A total of 45 experiments were performed under different conditions. The experimental invistigation was conducted at the hydraulic laboratory of Shahid Chamran University in Iran. The main objective of this research was to identify the maximum depth of sediment scour () and the maximum distance of sediment scour hole () from the structures. The results showed that the maximum depth of scour and its distance from the structure increased...

When the sheet pile is used as the reservoir wall or retains the action of saturated fills and cuts for construction works, it will be certain that the seepage occurs from the back side (retained side) to the working place (opposite side). Often, the rate of seepage and its quantity in homogenous strata depends mainly on the permeability of soil. However, the presence of cavity certainly has a direct impact on trend, steady time, and the quantity of seepage. The present study considered a preliminary attempt to measure this impact through physical model. Eighteen model tests are conducted to study the effect of different locations and diameters (size) of single cavity on the seepage problem when it is presented at upstream side (back side) of the sheet pile wall. Period of completion every model test ranged from four to seven days. The start time of seepage when the water began to flow from the downstream side (working place) ranged between 13min and 26min, which depended on the location of cavity and its size. However, the results show that the quantities of seepage generally increase with the smallest size of a cavity and with the farthest horizontal distance from the sheet pile. The maximum quantity has been recorded when the cavity is located at the same level of sheet pile end.

The local scour around bridge piers is one of the most common causes of bridge failures. Many equations have been proposed for determination. Most of these equations have a reliability and are used for design, were developed when the pier located within straight reaches for both flume and field studies. However, few studies have been conducted on bridge pier located within the curved channel. A laboratory work was conducted to measure the local scour which is formed around single circular pier fixed at each 30 o of the bend while adopting three different diameters. The results show that the maximum depth of scour and the maximum extents (i.e., length and width) of scour hole, and maximum modification factor due to bend have occurred when the pier is located at sector 90 o of the bend. The results also show that the diameter has a significant effect on scour phenomenon.

This study was undertaken to evaluate the hydraulic
performance of stilling basin with unusual shapes of baffle
blocks. Seven groups of baffle blocks were selected for this
purpose , these blocks were cut within a different forms, three
of these groups were cut with angle (15º, 30º, 45º)
horizontally. Another three groups were cut with the same
above angles, but vertically. The seventh group was cut with
semi-cylindrical section (shown from side view). For a
comparison, standard trapezoidal baffle blocks were used.
Dimensional analysis technique was used to obtain
the dimensionless parameters of hydraulic performance of the
cutting baffle blocks and the drag force applied on these
blocks. Laboratory experiments were carried out on one
raw of the cutting baffle blocks for each model. The results
indicated that the cutting baffle blocks are generally better than
the standard blocks in dissipation of a hydraulic energy and
reduction of a hydraulic jump length, but a ratio of drag force
applied on cutting baffle blocks was greater than this ratio on
the standard blocks. For the same flow conditions and angle of
cut, the baffle blocks of vertically cutting gave a better
results for energy dissipation and reduction in the length of the
hydraulic jump than the baffle blocks of horizontally cutting,
but the drag force applied on the baffle blocks with a vertically
cutting was greater than applied on a blocks with horizontally
cutting. Also, the results indicated that an agreement in the
hydraulic performance between the baffle blocks which were
cut at (45º) vertically and the baffle blocks of semi-cylindrical
cutting. The cutting baffle blocks gives a greater value of the
energy dissipation which was (80.62%) than the standard
blocks and greater value of reduction in the hydraulic jump
length which was(37.5%),also these blocks gives maximum
increase of the drag force ratio which was (97%) greater than its
value on the standard baffle blocks.

In this research, a study was conducted experimentally to investigate the scour hole dimensions downstream the combined structures which consist from weir and gate. Twelve models have been designed and every model is formed from composite weir consists of two geometric shapes and three types of gates which are rectangular, semicircular and triangular in shape, where multi factors were studied to find out the effect of changing geometry for both weir and gate, discharge flowing in the flume and particle size of bed material on the dimensions of scour hole. The experiments was conducted in a laboratory channel was constructed from blocks and concrete with length of 18 m, 1 m width and depth of 1 m, where the laboratory models were installed after 7 m from the main gate which is controlling the passage of water from the main reservoir into the flume. At the beginning, the calibration process was conducted to identify the actual discharge values that pass in the flume, then experiments ...

The forced hydraulic jump characteristics were studied experimentally using different configurations of a standard USBR baffle blocks. Each configuration was tested under Froude numbers ranged between 2.27 to 9.2 at which the hydraulic jump located within a description of oscillating and steady jump. Two groups of baffle block models were adopted. The first group installed at one row with two blockage ratios, whereas the second group consisted of two rows; the first was fixed at a specified location after sluice gate, while the second has been installed at three different distance ratio. During each test, the sequent depth and the transverse velocity distribution were measured. The results showed that the sequent depths for all configurations were less than the sequent depth of a classical jump. Among all configurations undertaken, the greater reduction of sequent depth was 30%. The new experimental formula was developed for determining the sequent depth ratio in term of the initial...

In hydraulic structures design, using cutoff walls is essential to reduce and control the resultant uplift force (U), seepage discharge (Q), and exit hydraulic gradient (i). This research investigates the effectiveness of inclined double cutoff walls under hydraulic structures, considering the influence of depths, locations, and inclination angles of the upstream and downstream cutoff walls by using Finite Element Method (FEM). The results confirmed that installing a deeper cutoff wall on the downstream reduces the exit gradient even further. In the case of the cutoff walls located in the upstream and downstream ends, the exit gradient will be less than when the cutoff walls are installed at a closer distance. Increasing the inclination angle of downstream cutoff wall has a major impact on exit gradient reduction. Embedment of cutoff walls in the upstream and downstream ends with right angles and equal depths reduces the seepage discharge more than other cases.

The construction of spillway with steps represents
an efficient technique to decrease the energy of water that flows
over it. Steps shape, or geometry of the spillway, has a significant
effect on the residual energy at the toe of the spillway. In this
study, a traditional stepped spillway model designed with six
steps of 5cm height, 5cm length, and 30cm width. The stepped
spillway model modified twice by curving the horizontal treads
using sectors of PVC pipe with 7.5cm diameter. The first
modification done by curving the treads up to make convex
treads with height of 1.1cm and the second modification was done
by curving the treads down to make-concaved treads with depth
of 1.1cm. Eleven tests carried out for the three cases with flow
rates varied from 0.64l/s to 24.95l/s. The experimental results
showed that the discharge affected reversely on the energy
dissipation, and the concaved treads case produced higher
dissipation than the horizontal and the convex cases. The energy
dissipation for concaved treads case ranged from 48.84 to
87.82%, 41.38 to 84.08% for convex treads case and 34.93 to
78.23% for horizontal treads case. In addition, the total energy
dissipation produced by the spillway and hydraulic jump
together, for concaved treads case ranged from 62.51 to 94.38%,
convex treads case from 60.74 to 93.81%, and horizontal treads
from 59.64 to 93.25%. The other relation that noted were the
decrease of Froude number at the toe, with the increase of flow
rate, and concaved treads case produced lower values of Fr than
the other two cases. In addition, the values of y2/y1, conjugate
depths of the hydraulic jump, decreased with the increase of flow
rates, and concaved treads case produced lower values of y2/y1
than the other two cases.

This study aims to investigate the effect of single cavity when it presence at a specific location within the homogenous soil, on the behavior of seepage and uplift pressure under a hydraulic structure. The results are analyzed to introduce deterministic formulae for calculating the amount of seepage and the uplift pressure head. The work was done in three stages by using experimental investigation; the first stage includes 36 models of 75mm in diameter cavity, while the second and the third stages includes eight models for each with 100mm and 34mm diameter of cavity, respectively. The results shows that, when the cavity presence at the left side its impact was positive on the seepage behavior. While the influence was changed to a negative impact when the cavity presence at the right side, except at some specific locations. The statistical software has been employed to generate the two deterministic formulae, and the results of multiple regressions are checked by statistical indices for the purpose of recognizing the reliability of the proposed formulae.

Inlet and outlet keys are the main two components of piano key weir. Understanding the phenomena of flow over these two components is an important factor in the design of this structure. In this article, 2D investigation into the velocity and pressure distributions of the flow over individual inlet and outlet keys under different discharges has been performed using CFD technique. Analysis of the results provided information about the critical areas that should be taken into account when designing the PKW structure.

Eddies that result from the flow separation in abrupt expansion transition structures lead to serious problems in the bed and sides of the downstream channel. The head loss produced through expansion, on the other hand, is important as it affects the downstream stage. This study has been conducted for subcritical flow to develop the hydraulic performance of an abrupt outlet transition. The aim of this study is to keep the head losses at lower stages and achieve a uniform velocity distribution across the width at the end of transition downstream (in the transverse direction) by spreading the flow laterally. A new baffle column model that has not been previously investigated was adopted and installed at a specific location to be a dispenser inside the transition. This model is semi-circular in shape convex against the flow, by which the flow spreads and distributes across the width with highly regularity and uniformity. At the same time, this shape keeps the head losses at a minimum stage. The results of this attempt proved that it has considerable advantages both hydraulically and economically over using a flared wall transition. The results have indicated that the uniformity in local velocity distribution across the width has increased, a shorter length of transition has been achieved, and no more head loss than that occurs at plain abrupt transition.