Transcript Hirakud Reservoir - CivilDigital.com

Flood Routing By Reservoir
Presented By:
Prafulla Pokhara
Poornima Vashishtha
Om Prakash
Pankaj Khatri
2008 UCE 157
2008 UCE 422
2008 UCE 420
2008 UCE 421
SAFETY INSPECTION OF DAMS
 The dams are national property – constructed for
the development of the national economy and in
which large investments and other resources have
been deployed.
 The safety of the dam is a very important aspect
for safeguarding the national investment and the
benefits derived by the nation from the project.
 In addition, an unsafe dam constitutes a hazard to
human life and property in the downstream
reaches.
CLASSIFICATION OF DAMS
Dams should be classified in accordance with size and
hazard potential in order to formulate a basis for
selecting dams.
The height of the dam is established with respect to
the maximum storage potential measured from the
natural bed of the stream or watercourse at the
downstream toe of the barrier.
Size classification may be determined by either
storage or height, whichever gives the large size
category.
SIZE CLASSIFICATION
CATEGORY
Minor
Medium
Major
STORAGE
(hectare meters)
>6 and <125
>125 and <6250
>6250
HEIGHT
(meters)
>8 and <12
>12 and <30
>30
SELECTION OF DAMS TO BE INVESTIGATED
 The selection of dams to be investigated should be
based upon an assessment of existing developments in
flood hazard area. Those dams possessing a hazard
potential classified high or significant.
 Inspection priorities within each category may be
developed from a consideration of factors such as size
classification and age of the dam,the population size in
the downstream flood area, and potential
developments anticipated in flood hazard areas.
INVESTIGATION
 Purpose:The primary purpose of the Phase I investigation
programme is to identify expeditiously those dams which
may pose hazards to human life or property.
 Scope:The investigation will develop an assessment of
the general condition with respect to safety of the project
based upon available data and a visual inspection,
determines any need for emergency measures and
conclude if additional studies, investigation and
analyses are necessary and warranted.
 Based upon the findings of the review of engineering
data and the visual inspection, an evaluation will be made
of the general condition of the dam, including where
possible the assessment of the hydraulic and hydrologic
capabilities and the structural stability
 Engineering Data: To aid in evaluating the adequacy of
hydraulic and hydrologic capabilities and stability of the
dam.
 Field Inspections:Particular attention should be given to
detecting evidence of leakage, erosion, seepage, excessive
wetness or slushiness in the areas downstream of dam,
presence of sand boils, change in water table conditions
downstream, slope instability, undue settlement,
displacement, tilting, cracking, deterioration and
improper functioning of drains and relief wells.
EVALUATION OF STRUCTURAL STABILITY
Design and construction data
Operating records
Post construction changes
Seismic stability
Various flood routing Strategies:
(i) Inter-Basin water transfer assessment
(Ganga & Brahmaputra Basins)
(ii) Flood Management by Reservoir in Pakistan
(Tarbela & Mangla Reservoir)
(iii)Extended Muskingum method for flood routing
(Hirakud Reservoir)
1.Use of Geoinformatics for InterBasin water transfer assessment
An Interlinking of Ganga and Brahmaputra
River basin
Why we NEED it ?
India is a large sub-continent and, as a result, the
challenges it faces are also on a large scale.
Uneven distribution of rain.
Drought in some parts of the country and floods in
others.
The Indian river system:Divided into two parts
1) Himalayan component:- the sources of which are the
glaciers of the Himalayas and the monsoon rains.
2) Peninsular component:-consisting of water mainly from
the monsoon rains.
 There is surplus water in the Himalayan component and
partial deficit in the peninsular component.
 Especially during the dry season,resulting in inundation
of agricultural land in areas with high precipitation and
water scarcity and crop failure in areas with low
precipitation.
Methodology
 Based on the problems , aims, the data available, and
technological know-how and its implementation.
 Various methods can be used to identify possible
locations for dams and reservoirs , and to determine
the best route of canals.
 The choice of method depends on the drainage
characteristics and the terrain, as well as the
technology appropriate for a particular environment.
How it is done?
Procedure divided into 3 stages:
Stage-1
 Deals with the terrain analysis (TA) required for
reservoir location .
Thematic maps were generated from remote
sensing data and a multi criteria analysis was
undertaken using the thematic information to
identify possible dam and reservoir sites.
Cont…
Stage-2
Deals with the estimation of reservoir storage
capacity.
In which data were used as the input for an iterative
numerical propagation method .
To determine the spatial extent of the reservoir and
factors related to reservoir capacity.
Cont…
Stage-3
Concerned with identifying the best route for
canals to transport the water from the
reservoirs.
With the ultimate aim of joining the new
canal to the existing canal system between
the Teesta & Mahananda basins.
Limitations of the Methodology
 The terrain analysis and multi criteria analysis included only
some of the factors affecting site selection such as slope,
drainage, geomorphology, geology , structure and land use
regarding physical suitability and village location and
transport networks regarding Socioeconomic suitability.
 In reality, other factors such as the kind of drainage,
drainage discharge, soil type and soil character would be
required in the multi criteria assessment.
 The data used as the input for elevation had a resolution of
90 m and were taken from a global data set useful for
preliminary assessments of possible reservoir locations.
 But when considering specific potential reservoir locations,
high-resolution elevation data are essential as the data may
underestimate slope steepness
Cont…
 Neither the slope nor the condition of the terrain was
considered in detail when determining the most suitable route
of the link canal.
 The assessment of the utilization of the water made available
was based on certain assumptions regarding water transfer and
reservoir capacity.
 The actual availability in the study area was not determined.
 The transfer volume was also assumed and only irrigation and
human consumption were considered.But In reality , the water
will also be used for other purposes.
2.Flood Management by Reservoir in Pakistan
Introduction:
 Tarbela Reservoir across river Indus and Mangla Reservoir across river
Jhelum are two large reservoirs. Tarbela reservoir is about 850 km
upstream of Mithan Kot. Four major tributary rivers join river Indus as
a combined river below Panjnad Barrage.
 A flood wave from downstream Tarbela is likely to take 9 days to reach
MithanKot. Mangla reservoir is about 315 km upstream of the
confluence of river Jhelum with river Chenab above Trimmu within 3.5
days.
 Vulnerable population and structures exist a few kilometres
downstream Mangla which may be hit by a flood in a short time.
Therefore, flood management through Mangla Reservoir is a very
sensitive issue in view of short lead time and enormous possible
damage.
 In case of severe floods like 1992 flood there is a possibility of
reducing the Mangla Reservoir outflow from 8500 to 11500
cumecs by pre-releasing the stored volume or delaying the
release by storing the inflow hydrograph.
 However such decisions can’t be made without considering the
flood hydrograph at Marala Barrage ,flood waves from
downstream Mangla Reservoir.Near Trimmu Barrage from
Mangla Reservoir must include combined model of Jhelum and
Chenab rivers.
Meteorological Aspects
 Floods in Mangla catchment of river Jhelum and catchment of
river Chenab occur due to monsoon depressions emerging
from Bay of Bengal which travel to Rajasthan in India before
moving to these catchments.
 For Mangla catchment it is possible to make one day rainfall
forecast when the weather system starts moving from
Rajasthan or an alert can be given 2 to 3 days earlier.
Hydraulic Aspects
 The flood waves in river Jhelum and river Chenab join at about
5 km upstream Trimmu Barrage. In such a case the resulting
flood peak may exceed the capacity of Trimmu Barrage which is
18300 cumecs endanger life and property in the flooded areas.
 The flood hydrograph downstream Mangla Reservoir along
with the flood hydrograph at Marala Barrage should be routed
through the combined hydrodynamic models of river Chenab
and river Jhelum to pre-assess the flood situation at Trimmu.
Procedure used to ensure proper reservoir operation
During the real time operation the following procedure should
be used to ensure proper reservoir operation at Mangla
Reservoir to avoid synchronization of flood at Trimmu Barrage.
1. Meteorological tracking of weather system as it originates
from Bay of Bengal.
2. Quantitative rainfall forecast/measurement on Mangla
Reservoir catchment.
3. The forecast/measured rainfall will be used to compute the
inflow hydrograph at Mangla Reservoir using the rainfall-runoff
models.
4. The computed inflow hydrograph at Mangla Reservoir should be routed
using the reservoir routing model. If the outflow from the reservoir
exceeds the 14000 cumecs then different operational scenarios of Mangla
Reservoir may be formulated and reservoir routing can be carried out.
5. The outflow hydrograph at Mangla Reservoir (boundary condition of
river Jhelum branch of hydrodynamic model) should be routed along with
the real time flood hydrograph at Marala Barrage (boundary condition of
river Chenab branch of hydrodynamic model).
6.Verify the flood hydrographs at intermediate stations to ascertain the
peak discharges will not endanger their safety .Compare the peak
discharge at Trimmu Barrage with the capacity of Trimmu Barrage.
7.If flood hydrograph at Trimmu Barrage exceeds its capacity go back to
step 4 to formulate a new scenario at downstream Mangla Reservoir by
reservoir operation and repeat steps 5 and 6. Repeat until acceptable
situation at Trimmu is achieved.
Conclusions
 Large storage volume is available in Mangla Reservoir can be
utilized efficiently only if a proper decision support system is
available. outflow scenarios should be formulated using the
reservoir routing modules in which the maximum Mangla
release is limited to avoid damage.
 The time of concentration of flood peaks at Mangla Reservoir
and Marala Barrage are similar and travel in almost same
time to point of confluence i.e. damage at Trimmu and
downstream in river Chenab. Therefore it is essential that
any Mangla release scenario should be checked for possible
discharge.
 With outflow hydrograph from Marala Barrage by channel
routing use combined hydrodynamic flow model of river
Jhelum and river Chenab.
3.Extended Muskingum method for flood routing:
 The factors causing floods at flood control station are :
(i)The release of water for power and spill from reservoir,
(ii)Measured inflow to the river from tributaries between the
reservoir and the flood control station and
(iii) Unmeasured lateral flow from the intermediate catchment
 Extended Muskingum method comprises with multiple
inflows & single outflow
 So this method has the ability to account for the lateral
inflows also.
Hirakud Reservoir:
 Hirakud reservoir, is situated in Mahanadi basin, Orissa,
India. Area of the basin is 1,41,600 sqkm.
 Mahanadi river originates in Raipur district of Madhya
Pradesh After a run of 450 km from its starting point, the
Hirakud dam was built across the river.
 The multipurpose Hirakud reservoir is utilized mainly for
three purposes, flood control, irrigation, and hydropower
production in that order of priorities.
 Hirakud dam is expected to control flood in coastal delta
area by limiting the flow at Naraj flow measuring station
to be within 25,500 cumecs.
 The 320 km long reach of river between Hirakud reservoir
and Naraj is treated in this study for flood routing. Flood data
from 1992 to 1995 are considered for the purpose.
 The outflow from the reservoir is the combination of the
spill from the reservoir and the release for power. This outflow
is measured at the dam.
 Two tributaries, Ong and Tel, join Mahanadi river on the
downstream of Hirakud reservoir and their flow is
measured at Salebhat & Kantamal station.
 Because the confluence points of these two tributaries with
Mahanadi river are quite close, compared to the length of
river, so the flow at Sukma ,Salebhat, Kantamal stations
are combined and termed as d/s catchment contribution.
 The difference between inflow into the reach and outflow
from the reach, i.e., flow at Naraj, constitutes the lateral
flow into the routing reach.
 It is observed that the unmeasured lateral flow varies
widely from one flood to other. This is not having any
specific ratio to the volume of inflow or volume of outflow.
 The floods are classified into two categories.
(i) Both outflow from reservoir and d/s catchment
contribution influence the pattern of flow at Naraj and
(ii) Only outflow from reservoir has the influence on the flow.
 It is proposed to evaluate the performance of gate
operation once in 24 h, 18 h, 12 h, and 6 h to find out the
effect of these variations on the predicted flow at Naraj .
Conclusion of this method:
 It is observed that mean relative error in
computation of flow decreases systematically with
decrease in routing interval, both for calibration and
testing phase.
 In addition, it is also observed that the flows
predicted by Muskingum method are less than the
observed flows .
 So extended Muskingum method can be explored
for similar reservoir configuration such as Hirakud
reservoir system.
Research on New techniques of river flow
measurement on flood condition:
1.Hand held Radar
The difference in the frequency between the transmitted &
reflected signal is proportional to the speed of water surface.
2.Acoustic Doppler Current Profiler(ADCP):
 ADCP transmits sound bursts into water & measure the
reflected signal from particles suspended in the water
column.
 The frequency shift between the transmitted & reflected
sound (Doppler Shift) is used to compute the particle
velocity.
References:
1.K.H.V. Durga Rao ,V. Bhanumurthy , P.S. Roy ,2009 .Application of Satellite - based
Rainfall Products and SRTM DEM in Hydrological Modelling of Brahmaputra Basin
.Indian soc. remote sens. (december 2009) 37:587–600.
2. Niladri Gupta, Petter Pilesjo, and Ben Maathuis, 2009. Use of Geoinformatics for Inter
-Basin Water Transfer Assessment . ISSN 0097-8078, Water Resources, 2010, Vol. 37,
No. 5, pp. 623–637.
3. Dr. shahbaz khan. Decision support system for reservoir operation to manage severe
floods in Pakistan, National Engineering service of Pakistan pvt. Ltd.,576.
4. D. Nagesh Kumar , Falguni Baliarsingh , K. Srinivasa Raju ,2011.Extended Muskingum
method for flood routing. Hydro-environment Research 5(2011) 127-135.
5. Government of India manual on Guidelines for Safety Inspection of Dams.