Dr. Harinarayan Tiwari | IIT Roorkee (original) (raw)

Papers by Dr. Harinarayan Tiwari

Discharge and sediment in rivers have multidimensional aspects due to association of hydrology as... more Discharge and sediment in rivers have multidimensional aspects due to association of hydrology as well as hydraulics. Discharge and sediment time series data collected from field & which represents the fundamental existent scenario. Mathematical exploration extracts features form existing time series data and its probabilistic uncertainty analysis can be extrapolated for future prediction. Artificial Neural Network models & Maximum Likelihood Estimator techniques was applied for probabilistic uncertainty analysis of discharge and sediment time series. Discharge was found to be more an uncertain and complex phenomenon with respect to sediment. In discharge and sediment time series analysis maximum minimum ratio has a significant role to decide its extent of uncertainty.

Arabian Journal for Science and Engineering, 2016

ISH Journal of Hydraulic Engineering, 2016

Ain Shams Engineering Journal, 2015

Modeling Earth Systems and Environment, 2015

Journal of Applied Water Engineering and Research, 2015

ISH Journal of Hydraulic Engineering, 2015

The present study identifies the pattern of near bed RMS velocity in the approach flow of Piano K... more The present study identifies the pattern of near bed RMS velocity in the approach flow of
Piano Key Weir (PKW) using 3D near-bottom velocities measured by Acoustic Doppler Velocimeter
(ADV). Further, Three methods of stress estimation were evaluated using ADV: (1) Reynolds Stress
approach (2) Turbulent Kinetic Energy & (3) Modified Turbulent Kinetic Energy. The experimental results
demonstrate that the estimation of bed shear stress is considerably affected by the presence of the hydraulic
structure. The turbulent kinetic energy method was the most consistent and appears most promising for
further development. Results also show that as the structural influence is getting decreased; MTKE yielded
similar result to as of TKE. Results encourage future use of the ADV in near hydraulic structure but also
favour the use of several methods according to their applicability to estimate flow hydraulics.

Dams whose collapse could cause loss of life or huge assets damage are considered to survive a pr... more Dams whose collapse could cause loss of life or huge assets damage are considered to survive a probable maximum flood (PMF),
but the PMF in various locations has been amplified at regular intervals, resulting in spillways that no longer convene the
proposed norms. Spillway rehabilitation is required for lots of dams in India; in order to get better hydraulic competence.
Catastrophe in Uttarakhand (June 2013) necessitates the research aspect of spillway rehabilitation. Increasing specific flow form
hydraulic structures is one of the thought of spillway rehabilitation. Labyrinth weir may be used for amplifying specific flows of
existing spillway. Sediment trapping behind Labyrinth weir might be one of the disadvantages for river with high sediment flow.
The Piano Key Weir (PKW), ramped type Labyrinth weir is a hydraulically attractive alternative to linear overflow weirs,
increasing the unit discharge for similar heads and spillway widths. This advantage allows operating dam reservoirs on an
increased level and provides thereby an enhanced retention volume. It is a result of the non-linear nature of PKW being folded
back and forth to make repeated cycles or keys. This type of weir is particularly suitable for sites where topographic conditions
limit the extent of its width. Together with its high discharge capacity for low heads, this geometry makes these weirs interesting
in spillway rehabilitation. This paper investigates the recent developments to improve hydraulic competence of spillways. Head
reduction over crest can improve efficiency as well as reduce submergence. This study shows that for increasing discharge, head
reduction with respect to conventional rectangular weir is reducing but reduction was found above seventy percent for all the
experiments

This research paper focuses on the need of turbulence, instruments reliable to capture turbulence... more This research paper focuses on the need of
turbulence, instruments reliable to capture turbulence,
different turbulence parameters and some advance
methodology which can decompose various turbulence
structures at different levels near hydraulic structures.
Small-scale turbulence research has valid prospects in open
channel flow. The relevance of the study is amplified as we
introduce any hydraulic structure in the channel which
disturbs the natural flow and creates discontinuity. To recover
this discontinuity, the piano key weir (PKW) might
be used with sloped keys. Constraints of empirical results
in the vicinity of PKW necessitate extensive laboratory
experiments with fair and reliable instrumentation techniques.
Acoustic Doppler velocimeter was established to be
best suited within range of some limitations using principal
component analysis. Wavelet analysis is proposed to decompose
the underlying turbulence structure in a better
way.

Piano Key Weirs are more efficient than the traditional Labyrinth weir and Piano Key Weirs can be... more Piano Key Weirs are more efficient than the traditional Labyrinth weir and Piano Key Weirs can be an interesting solution for increasing the active storage of reservoir or for improving the safety of dam during extreme flood. This technology helps to reduce the reservoir sedimentation. It will also help in minimizing the sub-mergence effect. Flushing is vital for the preservation of long-term storage in reservoirs. However, downstream impacts such as turbidity act as a constraint in the planning and operation of sediment flushing. Physics especially about turbulence phenomena will be helpful to decide the design criteria. Turbulent mixing is an important process controlling the descent rate, water mass modification and volume transport. Under stable conditions dissipation essentially balances shear production, while turbulent transport and buoyant production are of secondary importance. Under unstable conditions, dissipation slightly exceeds the total production, and energy is also lost at a substantial rate due to upward export by the turbulence. Theoretical analysis and prediction of turbulence has been problem of fluid dynamics due to random or chaotic nature of turbulence phenomena. Because of this unpredictability, it has been usual to work with the time averaged forms of the governing equations, which inevitably results in terms involving higher order correlations of fluctuating quantities of flow variables. Turbulence is a very complex phenomenon so near PKW occurrence need extensive laboratory experiment and analysis of these results through some statistics will be reliable. This paper deals with issues, gaps and scope of statistical turbulence study near PKW.

Turbulence by its handiwork immeasurably enriches the lives of even those who cannot comprehend i... more Turbulence by its handiwork immeasurably enriches the lives of even those who cannot comprehend its mysteries. In turbulent flow the speed of the fluid at a point is continuously undergoing
changes in both magnitude and direction. Flow parameters are complicated to envisage near any
hydraulic structures like Piano Key Weir until small scale time fluctuating turbulent nature of flows is clearly understood. Theoretical analysis and prediction of turbulence has been problem of fluid dynamics due to random or chaotic nature of turbulence phenomena. Without the recognition of turbulence
structure near any hydraulic structures like Piano Key Weir, it is impossible to properly understand the processes happening during the flow of water. Important issues regarding turbulence, development, methodology, gaps and scope for Piano Key Weir has been discussed in this paper.

Flow velocity of alluvial channel is an area of intense research due to its complexity of nature.... more Flow velocity of alluvial channel is an area of intense research due to its complexity of nature.
The dependability of velocity on multiple factors viz., bed characteristics, discharge, channel
topography (slope), flow depth etc., makes it more difficult to estimate. Velocity is directly
related to flow resistance. Both Manning’s and Chezy’s equations which are being used
worldwide for velocity calculations, gives a single value (mean velocity) and do not generate
depth wise variation in velocity. Moreover, these equations have been derived for rigid beds
only. In alluvial channel flow, sediment movement at bed as well as in suspension has significant
influence on velocity variation. Validity of log-law distribution of velocity in vertical section is
studied in this thesis and comparison of their numerical coefficients for different localized bed
condition is made. It is found that numerical coefficient values depend on relative roughness
(Rr) and Hari’s Number (Ph). A simple relationship between flow & fluid characteristics and
velocity of flow is proposed to be established, which could be used for study of vertical
movement of sediment in alluvial channels. Accordingly, a non-linear empirical equation is
developed with a satisfactory coefficient of regression of 0.786. In this equation, velocity is
related to relative depth, flow depth, shear velocity, discharge and representative bed size. Study
of shear velocity which depends on turbulence motion needs an in depth knowledge of
turbulence strength and sweep-ejection motion. As per literature, sweep-ejection is the main
contributor to Reynolds’s stress. Analysis of results of experiments shows that Reynolds’s stress
is evenly distributed for sandy bed. As such, in sandy bed condition the calculation of shear
velocity parameter may be taken as the function of hydraulic radius and slope for whole depth. In
the case where the bed representative size is increased, distribution of Reynolds’s stress gets
randomness. The shear velocity in the coarser bed case is not only the function of hydraulic
radius and slope but also it varies significantly with depth. Quadrant distribution of velocity
gives the variation in contribution of velocity to generate shear. Percentage distribution of first
and fourth quadrant look like a wine cup which is wider in the case of sandy bed and gets
narrower as the representative bed size is increased. It is also an indication of increasing
randomness throughout the depth as representative bed size increased.

We are in the decay where water is important as well as complex concern of our day to day life. R... more We are in the decay where water is important as well as complex concern of our day to
day life. River is the main source of surface water. It’s merely essential to figure out the
issues that will affect the river changes for successful river management. Due to
enormously uncertain spatial; temporal multidimensional characteristic of river change
it’s very difficult to give exact theoretical concept to address this issue. There is inherent
contradiction that what the basis for river management is; since property of river change
cannot be explained and expressed by single factor. Therefore, river changes scenario
should have to realize as dynamic process. Integrated assessment of physical and
socioeconomic scales in rivers changes improve our understanding and provide greater
potential for long-term persistence of river management and it will require a conceptual
framework. A successful development of conceptual framework should provide a basis for
multi-disciplinary researcher with very diverse goals for river changes to come together
in support of better river management. To see regularity in the behavior of river change,
it is necessary to prepare a conceptual framework. In this paper an attempt has been
made to prepare the conceptual framework of river changes to get more to Trans
disciplinary research.

Insufficient spillway capacity has been the cause of one-third of all dam failures. An innovative... more Insufficient spillway capacity has been the cause of one-third of all dam failures.
An innovative and effective way of increasing the spillway capacity is to use a Labyrinth weir in
the modified form of PKW having range of specific flow from 3 to 1000m3/s/m. As the flow
approaches towards the PKWeir, it was observed that the Z-component of the velocity of water in
lower levels increases which enhances the flushing capacity. One of the important observations is
that with decrease in discharge from higher flow to medium flow; Z component velocity is getting
lowered by about 14 percent. Increase in discharge from lower to medium flow Z component
velocity is getting increased by about 40 percent. It indicates that at lower discharge, upward
velocity component is appreciably more which may be helpful for significant amount of sediment
suspension at lower discharge also. For flood flow, it was found that there has been reduction of
around 25–30% of submergence depth with respect to ogee spillway. Induced flow characteristics
near PKW and tractive stress exertion by flowing water in the inlet cell are capable to flush out
even the coarser sand particles.

Ganga River, downstream Vikramshila Setu (Bhagalpur, Bihar), is shifting towards its right bank w... more Ganga River, downstream Vikramshila Setu (Bhagalpur,
Bihar), is shifting towards its right bank with great effect.
Right bank of Ganga is densely populated and has many
important structures. In last ten years, riverbank of the Ganga
downstream of the bridge was changed by more than 1000 m.
Due to the right bank shifting of Ganga; Bhagalpur city under
risk of submergence in flood seasons. Bank protection
strategies are required immediately at this place. Form the
study of satellite image of 1988 and 2006 using ARC-GIS, it
was found that there is significant amount of bank shifting
occurred during this period. In Bhagalpur, major city
population residing on right bank of Ganga, so right bank of
Ganga is the main area of concern in this particular study.
USGS images (1988 and 2006) analysis clearly indicates that in
upstream of Vikramshila Setu; right bank Ganga is almost
intact. Downstream of Vikramshila Setu was getting more
erosion than upstream. Rate of erosion was found to be more in
between 2003 & 2011 in comparison with 1988 & 2006 satellite
image study. Contribution of bridge (Commissioned in 2001) to
downstream erosion cannot be ignored directly. At the point
around 3.5 km downstream of Vikramshila Setu 1100 m
erosion in past 8 years (2003-2011) with respect to 720 m
erosion in previous 18 years(1988-2006). Rate of erosion was
determined more than twice.

Rate of sediment transport is critical to understand, which gives the idea how rivers work. Chang... more Rate of sediment transport is critical to understand, which gives the idea how rivers work. Change in the river bed elevation due to sediment transport and hydraulic structure depend on distance of river reach from hydraulic structure. All rivers are full of sediments: a river, in effect, can be considered a body of flowing sediments. An understanding of the behavior of sediment discharge relationship in a reservoir is necessary for effective reservoir and basin management.

Lacey’s equation is often used to find out the scour depth in rivers in India. Lacey’s regime for... more Lacey’s equation is often used to find out the scour depth in rivers in India. Lacey’s regime formula
(1930) was developed on the basis of limited field data from irrigation canals in Punjab Province having
discharge ranges from 0.70 to 173 m3/s. The total scour at a highway crossing is comprised of three
mechanisms: long-term aggradation-degradation, contraction of reach, and local scours at piers and
abutments. In the present study, HEC-RAS model is used to estimate the bridge scour for the Ganges
road bridge and it is then compared with Lacey’s formula. Apparently, more realistic results are
obtained by HEC-RAS model as it considers more related factors as angle of attack, bed conditions,
shape of piers, flow concentrations, flow depth and Froude No. as against discharge intensity and silt
factor considered in case of Lacey’s equation. Comparative study is carried out for different angles of
attack and restricted flow condition near the bridge site. From the restriction of waterway by 3.6 km to
2 km, abutment scour and contraction scour change 1.6 times and 3.9 times respectively. So, the
waterway has significant role for the bridge foundation design. By changing angle of attack by 5 °, the
change in pier scour is 10%.

Free-flow spillways are simpler and safer than gated ones, but the low specific flow of their tra... more Free-flow spillways are simpler and safer than gated ones, but the low specific flow of their
traditional shapes requires high spilling nappe depths and thus huge losses of storage (100
x 109m3 worldwide). A newly evolved shape of free-flow spillway (the "Piano Key weir")
has the potential to increase the specific flow as high as fourfold at lower discharges. It
could substantially increase, at low cost, the safety and the storage and/or the flood control
efficiency of many existing as well as new dams. It is thus very advantageous to increase the
specific flow as much as possible. Some tens of existing spillways have been designed
accordingly as vertical walls on a flat bottom, with a trapezoidal labyrinth layout which is
much longer than the spillway length (often four times). They usually double the specific
flow of an Ogee Spillway. Piano-Key Weir derives its name from its plan-form shape which
looks like a ‘piano-key’. It is configured as polygonal walls such as to provide a much
longer crest length than the conventional ogee spillways.

Arabian Journal for Science and Engineering, 2016

ISH Journal of Hydraulic Engineering, 2016

Ain Shams Engineering Journal, 2015

Modeling Earth Systems and Environment, 2015

Journal of Applied Water Engineering and Research, 2015

ISH Journal of Hydraulic Engineering, 2015