hydrologic safety

7/25/2019 Hydrologic Safety

1/54

1

Workshop on Dam safety Management

29-30 September, 201129-30 September, 2011

HYDROLOGIC SAFETY OF DAMS I IDIAby

Bhopal Singh

Director, Hydrology(S)C!"#$% &$"# C'SS'!


2/54

Outline of the Presentation

Intro!"#t$on

Des$gn F%oo! Est$mat$on

Dam Safety &rogram $n In!$a

Re'$e( of Des$gn F%oo! Cr$ter$a

Genera% O"t#ome of Des$gn F%oo! Re'$e(

St"!$es

&reparat$on of &M& At%ases

Impa#t of C%$mate Change on Des$gn

F%oo!2


3/54

3

2.4% of Worlds Land Area

4% of Worlds Fresh Water Resources

16% of Worlds Poulation

IDIA


4/54

4

Water A'a$%a)$%$ty * IDIA

Tota% "t$%$+a)%e (ater reso"r#esTota% "t$%$+a)%e (ater reso"r#es

,,-. /CM,,-. /CM

Gro"n! WaterGro"n! Water

0.. /CM0.. /CM

*re+ently meet+ the demand bt i+ nadeate .or.tre demand

S"rfa#e (aterS"rfa#e (ater

123 /CM123 /CM

C"rrent "t$%$+at$onC"rrent "t$%$+at$on

of SWof SW

03. /CM 4 156 703. /CM 4 156 7

C"rrent "t$%$+at$onC"rrent "t$%$+at$on

Of GWOf GW

-., /CM 48567-., /CM 48567

Tota% (ater a'a$%a)$%$tyTota% (ater a'a$%a)$%$ty

,512 /CM,512 /CM

Tota% &re#$p$tat$onTota% &re#$p$tat$on

0333 /CM0333 /CM


5/54

!

Spat$a% 9ar$at$on of Ra$nfa%% $n IDIA

mm

A"era#e ,:,;3

$a. ,,:333 &herraun'i

$in. ,33 Western

Ra'asthan

Preciitation durin# (une to )ete*+er 3,,, -&$


6/54

6

Tempora% 9ar$at$on of Ra$nfa%%

All India


7/54

R$'er /as$ns of In!$a


8/54

/

0 -&$

,< &re &%an = ,8


9/54

&er Cap$ta Storage


10/54

eed for Re"ie of 5drolo#ic )afet of 7a*s

8hus9 hile there is an o+"ious need to constructstora#e da*s as the la an i*ortant role in the

ater resources de"elo*ent of the nation9 there $s

a%so the nee! of ens"r$ng the safety an! %ong %$fe of

the !ams a%rea!y #onstr"#te!and ta:in# due safetcare of da*s under construction or +ein# lanned

As er failure data on lar#e da*s collected +

;&OL79 #lo+all near%y .86 of !ams ha'e fa$%e!

!"e to #a"ses re%ate! to $na!e?"ate sp$%%(ay

#apa#$ty and therefore9 this +eco*es a *a'or concern

in 7a* )afet Pro#ra**e

1,


11/54

eed for Re"ie of 5drolo#ic )afet of 7a*s

A+out , ercent of da*s are *ore than to decade old Old da*s ere desi#ned +ased on hate"er infor*ationuire thin:in# on the hdrolo#ic safet of old da*s.

11


12/54

Design Flood

7esi#n Flood is one of the :e 5drolo#ical

inuts

A+solute flood rotection ? unrealistic

Flood corresondin# to a tolera+le ris: to +e

adoted

Flood ith :non ris: is called desi#n flood


13/54

Classification of Dams

4As per IS=,,--.*,2587

C%ass$f$#at$on Gross Storage Hy!ra"%$#

Hea!

Sma%% 3


14/54

Design Flood for Safety of Dams

4As per /IS=,,--. * ,2587

Dam

Classification

Inflow Design Flood

Small 100 Yr RP

Medium SPF

Large PMF


15/54

Stan!ar! &roe#t F%oo! 4S&F7 is defined as the flood that

*a +e eected fro* the most se'ere #om)$nat$on of#r$t$#a% meteoro%og$#a% an! hy!ro%og$#a% #on!$t$ons that

are reasona)%y #hara#ter$st$#s of the reg$on under

>uestion. 8hus o+"iousl its co*utation ecludes rare

e"ent under its ur"ie. &ro)a)%e MaB$m"m F%oo! 4&MF7 is the flood that *a

+e eected fro* the *ost se"ere co*+ination of critical

*eteorolo#ical and hdrolo#ical conditions that are

reasona+l ossi+le in the re#ion under >uestion and iseected to denote a flood that can occur9 +ut is not li:el

to +e eceeded. P$F is co*uted + usin# Pro+a+le

*ai*u* reciitation 0P$P as the inut stor*.

1!


16/54

4/IS=,,--. * ,2587 Floods of lar#er or s*aller *a#nitudes *a also

+e used if the ha@ards in"ol"ed is hi#h or lo.

8he rele"ant ara*eters to +e considered in'ud#in# the ha@ard in addition to the si@e ould

+e 7istance to and location of the hu*an

ha+itations on the donstrea* afterconsiderin# the li:el future de"elo*ents

$ai*u* hdraulic caacit of the

donstrea* channel at the le"el at hich

catastrohic da*a#e is not eected.

Incororation of !a"ard inselecting Design Flood


17/54

Incororation of !a"ard inselecting Design Flood

For *ore i*ortant ro'ects da* +rea:

studies *a +e done as an aid to the

'ud#*ent in decidin# hether P$F needsto +e used.

Where the studies or 'ud#*ent indicate an

i**inent dan#er to resent or future hu*ansettle*ents9 the P$F should +e used.

1


18/54

RE9IEW OF DESIG FLOOD

CRITERIA

1/


19/54

International Agencies/ ICOLD

Definition of Large Dams

If Height of dam > 15m ht(measured from the lowest portion ofthe general foundation area to the crest)

If Height of dam lies in between 10m to 15m

It complies with at least one of the following conditions:

i.Length of the crest of dam 500m

ii.Capacity of reservoir formed by the dam is not less than 1 MCMiii.Maximum flood discharge dealt by the dam is not less than 2000m3/s

iv.The dam had specially difficult foundation problem

v.The dam is of unusual design

Design Criteria for Large Dams

As a general rule, ICOLD recommends thatdesign floods shall bePMF.

Ref: ICOLD, 1984; ICOLD, 1992

di i /


20/54

2,

Leading Countries/ UK

Category Con+eence o. dam

breach

!ormal de+ign

+tandard

inimm

+tandard i.

o/ertoppingtolerable

A Endangers lives in a

community

PMF 10000 year flood

B Endangers lives of

individuals or

Causes extensive

damage

10000 year flood 1000 year flood

C Negligible ris to life and

limited damage

1000 year flood 1!0 year flood

" No ris to life and very

limited additional flood

damage

1!0 year flood 1!0 year flood

di C i / S


21/54

21

Haard potential Sie cla++ Spillay de+ign

.lood#ig$

%oss of life &robable

Environmental' economic and

lifeline losses ex&ected

A PMF

B PMF

C 1() PMF to PMF

" 100 yr* to 1() PMF

Moderate

No loss of life ex&ected

Environmental' economic and

lifeline losses ex&ected

A PMF

B 1() PMF to PMF

C 100 yr* to 1() PMF

%o+

No loss of life ex&ected

%o+ or limited environmental'

economic and lifeline losses

A 1() PMF to PMF

B 100 yr* to 1() PMF

C !0 yr* to 100 yr*

Leading Countries/ USA


22/54

Rankof

Proje

ct

Storage

Capac

ity of

Reser

voir

(106

m3)

Flood Prevention WaterLogging

control

Irrigation

WaterSupply

WaterPower

Cities and

industrial

regions

Farml

and

(103

ha)

Draining

Water logged

Area (103ha)

Irrigati

on

Area

(103

ha)

Cities &

Mines

Installe

d

Capacit

y (MW)

I >

10000

Very

Important

>333 >133.3 >100 Very

Important

>750

II 10000

-100

Important 333-

67

133.3-40 100-

33.3

Important 750-

250

III 100-

10

Moderately

important

67-20 40-10 33.3-

3.3

Moderately

important

250-25

IV 10-1.0 Less

important

20-3.3 10-2.0 3.3-0.3 Less

important

25-0.5

V


23/54

Rank of Project Grade of Permanent Structures Grade of

Temporary

structuresMain Structures Less Important

one

I 1 3 4II 2 3 4

III 3 4 5

IV 4 5 5

V 5 5 -

Leading Countries/ China continues

Grading of Permanent and Temporary Structures


24/54

Leading Countries/ China

Grade 1 2 3 4 5

Embankment dams 10000 or PMF 2000 1000 500 200 Return

PeriodConcrete dams etc 5000 1000 500 200 100

Design flood criteria for permanent

structures


25/54

In Japan, when the dam is constructed or reconstructed, the inflow

design floods for a concrete dam must be taken on the largest value

among the following three discharges:

i. 200-year flood at the dam site;

ii. maximum experienced flood discharge at the dam site and

iii. maximum flood discharge that can be expected at the dam site

based on the maximum experienced flood discharge in thebasins with similar hydrological conditions or climate.

For an embankment dam, the design flood should be specified to be1.2 times of the relevant values for a concrete dam (JICE, 2000). Thereturn period of the design flood for an embankment dam is actually

equivalent to 1000 years or more.

Leading Countries/ Japan

Ref : Structural standards for river protective Facilities (Cabinet Order) on the basis of River Law


26/54

ee! for Re'$e( of Des$gn Cr$ter$a

8he idesread ractice internationall is to associate thedesi#n inflo for da* safet assess*ent ith the otential

conse>uences donstrea* of the structure in the e"ent of its

failure.

;n *ost countries9 the desi#n inflo for a safet assess*ent

hich should +e assed ithout failure of the da* is related to

the ro+a+le *ai*u* flood 0P$F9 +ut the silla caacit

*a +e set for a loer inflo

8he classification and criteria laid don in the ;ndian standards

are +ased on hi#hest safet standards and co*ara+le to safetstandards of "arious countries.

5oe"er9 the inclusion of >uantitati"e ha@ard assess*ent in

hdrolo#ic desi#n criteria elicitl *a also +e desira+le.

26


27/54

Type of Dam Parameters for Determining

the type of Dam

Design Flood

Storage Height

Large > 60 MCM > 30 m PMF

Intermediate 10-60 MCM (12-30 ) m SPF

Small 0.5-10 MCM ( 7.5-12) m 100 Year Flood

Indian Standard

Design Flood Criteria as per BIS : 11223 -1985

Floods of lar#er or s*aller *a#nitudes *a also +e used if the ha@ardsin"ol"ed is hi#h or lo. 8he rele"ant ara*eters to +e considered in

'ud#in# the ha@ard in addition to the si@e ould +e 7istance to and location of the hu*an ha+itations on the

donstrea* after considerin# the li:el future de"elo*ents $ai*u* hdraulic caacit of the donstrea* channel at

the le"el at hich catastrohic da*a#e is not eected.


28/54

7esi#n Flood Aroaches


29/54

7esi#n Flood Bsti*ation

Carious *ethods co**onl e*loed for

desi#n flood esti*ation are

B*irical flood for*ulae

Bn"eloin# cur"es

Flood fre>uenc analsis

5dro=*eteorolo#ical aroach


30/54

7esi#n Flood Bsti*ation

B*irical *ethods

B*irical For*ulae

D R"es For*ula E&A2


31/54

Current Practices

The metho!s )ase! on emp$r$#a% form"%ae an! en'e%op$ng #"r'es are

not s"ggeste! for the est$mat$on of !es$gn f%oo! for the !es$gn of !ams

an! they may at the most )e "se! for gett$ng a f$rst han! est$mate of

!es$gn f%oo! peakT&>T

4Des$gn F%oo! Hy!rograph7

I&>T

4&MS or S&S or ret"rn per$o!

storm7

!ydro$meteorological %roac&

In the hy!ro*

meteoro%og$#a% metho!:

attempt $s ma!e to

ana%yse the #a"sat$'e

fa#tors respons$)%e for the

pro!"#t$on of se'ere

f%oo!suac of silla caacit9relaation of the so*e a*+ient conditions *a +e

considered on *erit of each case.

34

id li f i i d l i l f


35/54

Juidelines for 7eter*inin# 5drolo#ical )afet

of Bistin# 7a*s

For eistin# da*s9 i*in#e*ent le"el to +e considered can +eloer than for ne da*s9 after ta:in# into account a ractica+le

schedule of fillin#

For eistin# da*s9 here a flood forecastin# ossi+ilities eist

and ha"e +een ro"ed in the field9 a reasona+le re=deletion *aalso +e alloed9 althou#h this is not alloa+le for ne da*s

For eistin# da*s9 here #ate *aintenance is "er satisfactor9

and after *a:in# sure of stand+ arran#e*ents9 the desi#n

conditions one of the #ate failure *a not +e considered.

Relaation of free +oard and clearance

8hese could +e relaed on case to case +asis. A roerl desi#ned

solid araet all *a +e considered for the free +oard.

3!


36/54

&r$or$t$sat$on for mo!$f$#at$on of eB$st$ng

!ams for greater safety

8he etent of inade>uac of the silla caacit *a +e

classified accordin# to the folloin#=

8he *ai*u* inflo flood that can +e assed throu#h the

da* ith the relaed a*+ient conditions9 eressed as a

roortion of the inflo desi#n flood.

8he li:el effect of the inflo desi#n flood on the safet of

the da*9 i.e. hether the da* has reasona+le chance of not

failin# under such a flood.

8he ris: associated ith the failure of da*

36


37/54

DAM SAFETY &ROGRAM

DSAR& 7a* )afet Assurance and Reha+ilitation Pro'ect as

ta:en u for i*le*entation ith the World -an:

assistance in 11 and as co*leted in 1.

A+out !! da*s ere re"ieed under the da* safetro#ra**e9 5ira:ud 0Orissa and Jhandhi )a#ar Pro'ect

0$P +ein# to *ain da*s hose hdrolo#ic caa+ilities

ere thorou#hl ea*ined.

For*ulation and use of a nu*+er of #uidelines on 7a*)afet9 rearation of Pro+a+le $ai*u* Preciitation

0P$P Atlases + &W& for a nu*+er of +asins ere

uni>ue achie"e*ents of the ro'ect.

3

Dam Reha)$%$tat$on an! Impro'ement


38/54

Dam Reha)$%$tat$on an! Impro'ement

&roe#t

As follo u of 7)ARP9 a ne ro'ect titled H7a* Reha+ilitation and;*ro"e*ent Pro'ectI 07R;P has +een initiated ith the hel of World -an:in fi"e states "i@. &hhattis#arh9 erala9 $adha Pradesh9 Orissa and 8a*il

adu.

Out of a total of 14/ lar#e da*s in these fi"e articiatin# states9 the 7R;P

co"ers 24 lar#e da*s.

8he +road o+'ecti"es of 7R;P are to stren#then and further consolidate theinstitutional fra*eor: of 7a* )afet Assurance in &W& and the

articiatin# )tates9 to carr out detailed safet re"ie of identified da*s and

ta:e u *easures for i*ro"in# their safet.

8he #uidelines for safet of da*s includin# hdrolo#ic safet shall also +e

re"ieed. 8he hdrolo#ical re"ie are to +e carried out for all the identified da*s. 8his

tas: of has alread +een initiated and desi#n flood re"ie of a nu*+er of

ro'ects ha"e +een carried out.

3/

JBBRAL OM8&O$B OF 7B);J FLOO7


39/54


RBC;BW )8M7;B)

Re"ie desi#n flood studies of a nu*+er of

ro'ects ha"e +een carried out + &entral

Water &o**ission in association ithstates.

8he re"ised inflo desi#n floods is

#enerall found to +e hi#her than ori#inaldesi#n flood for *ost of the old da*s.

3


40/54

4,


41/54

41


42/54

42


43/54

43



44/54


RBC;BW )8M7;B)

8he *ain reason for such a si#nificant increase in desi#n flood of old da*s can+e attri+uted to the fact that desi#n floods for old da*s ere *ainl +ased on

e*irical for*ulae ithout *uch suort of hdro *eteorolo#ical data

a"aila+le at that ti*e.

8he concet of hdro *eteorolo#ical aroach for esti*atin# desi#n flood

ic:ed u in late se"enties onl. B"en the desi#n flood studies for *a'or da*s

ere +ased on flood fre>uenc analsis 0 1,,, ear flood etc. 8he ro+le* of increased desi#n flood is found to +e *ore acute in case of

s*all


45/54


RBC;BW )8M7;B)

Once the re"ie desi#n flood is found to +e si#nificantl

hi#her9 ade>uac of silla caacit needs to +e

thorou#hl re"ieed.

8he relaation of the a*+ient conditions as discussed a+o"e*a +e considered on *erit of each case.

When it is found that the re"ised desi#n flood hdro#rah9

e"en ith relaation of the a*+ient conditions cannot still

+e routed throu#h the silla ithout encroachin# into thefree +oard9 then "arious structural and non structural

*easures *a +e used to *a:e the da* hdrolo#icall

safe.

4!

i


46/54

Aroriate $easures

8he aroriate solution to +e adoted ill "ar fro* case to case and

folloin# list of alternati"es is not ehausti"e and are onl for

ea*le.

Au#*entin# the eistin# silla caacit throu#h addition of *ore

silla +as

Pro"ision of +reachin# sections or fuse lu#s.

;ncreasin# the free +oard a+o"e FRL of the da* + ro"ision of

araets

Bsta+lishin# earl flood arnin# sste*

;ncreasin# the flood stora#e + loerin# the conser"ation stora#e le"elA suita+le alternati"e is to +e chosen + considerin# the "arious

otions that are feasi+le and or:in# out the relati"e +enefit cost

scenario

46

Bff t f JLOF


47/54

Bffect of JLOF 8here ha"e +een nu*+er of #lacier la:e out+urst floods in the recent

ti*es.

8he i*act of cli*ate chan#e on #lacial la:es is li:el to further

accentuate the associated ris: ith JLOF.

8he effect of JLOF is to +e considered on the inflo desi#n flood to +e

adoted for a da*.

8he rocess in"ol"es identification of otentiall dan#erous #lacial la:es

+ased on records of ast e"ents9 field o+ser"ation9 #eo=*orholo#ical and#eotechnical characteristics of la:es.

Recentl &entral Water &o**ission in association ith R)& has ta:en

u *ain# of #lacier la:es in 5i*alaan re#ion. 8he ro'ect includes

rearation of in"entor of #lacial la:es


48/54

&RE&ARATIO OF &M& ATLASES

Assess*ent of desi#n stor* heto#rah for*s the :e co*onent in the

desi#n flood stud of an ro'ect. 8he stor* studies re>uire not onlrofessional eertise +ut also lar#e a*ount of stor* data +ase in and around

the catch*ent


49/54

&RE&ARATIO OF &M& ATLASES

o the or: of rearation of the P$P Atlases for the

re*ainin# +asins na*el Jan#a -asin and -rah*autra-asin has +een ta:en u in N;th lan + &W&.

;n addition to the a+o"e to +asins9 the or: of udation

of P$P Atlases for the ri"er +asins reared in under

7)ARP 0)i ri"er +asins in nineties has also +een ta:enu.

8he a+o"e or: is scheduled to +e co*leted + Octo+er9

2,13.

8he P$P atlases not onl hel in >uic: initial esti*ate ofdesi#n stor*0P$P


50/54

ee! for &")%$# A(areness

5drolo# is a data +ased science and therefore9 ith i*ro"e*ent in

data +ase9 results of studies are +ound to differ. Further ith i*ro"ed :noled#e of hdrolo#ic rocesses and +etter

tools of analsis9 *ore relia+le esti*ation of )PF


51/54

Impa#t of C%$mate Change on Des$gn F%oo!

An i*ortant concern in hdrolo#ical rediction is that the li:el cli*ate chan#e 9 ill lead

to chan#es in flood fre>uenc and *a#nitude.

&urrent infor*ation on the effects of cli*ate chan#e contains considera+le co*leit anduncertaint hich recludes *a:in# fir* assess*ent of the chan#es in flood *a#nitude and

fre>uenc.

)tudies in re#ard to cli*ate chan#es scenarios redict that the fre>uencies of floods *a

increase and floods of sa*e *a#nitude +eco*e *ore fre>uent

;n ational Water $ission 7ocu*ent9 2,,/ of $OWR9 it is *entioned that it ould +e

difficult to 'ud#e 9 at resent9 ho the esti*ation of the P$P


52/54

Strengthen$ng Data Co%%e#t$on et(ork

8he desi#n floods of a lar#e nu*+er of ro'ects ha"e +een re"ieed9 hoe"er

the efforts on data collection is co**onl found lac:in#. B"en after 3,=4,

ears functionin# of a ro'ect9 the re>uisite data such as short inter"al

concurrent rainfall and runoff data 9 instantaneous flood ea:s9 )RRJ data etc

are hardl a"aila+le for an ro'ect.

As >uantit and >ualit of re>uisite hdro=*eteorolo#ical data for* the "er

+asis of an hdrolo#ical re"ie9 it is etre*el i*ortant to esta+lish

ade>uate data collection netor: for e"er ro'ect and re#ularl collect and

*aintain the data roerl. 8he eistin# *eteorolo#ical hdrolo#ical o+ser"ations netor: is

inade>uate articularl in 5i*alaan re#ion. At hi#her altitudes 0a+o"e 3,,,

*sl9 the data a"aila+ilit is "er oor.

8here is a need of stren#thenin# the data collection netor: and efforts not

onl + central a#encies such as &W&9 ;$7 etc. +ut also + ro'ect

authorities.

8he hdro=*eteorolo#ical data collection netor: is roosed to +e

stren#thened si#nificantl durin# 12th lan. ;t is lanned to increase the 5O

netor: of &W& fro* resent // stations to a+out 2/,, stations.

!2

&onclusion


53/54

&onclusion 8he tas: of hdrolo#ic safet of da*s needs to +e ta:en "er seriousl and

rofessionall + da* authorities.

;n the case of da*s ith inade>uate sillas9 certain relaations inassu*tions


54/54

hydrologic safety

Documents