CHAPTER 2Hydrology

7/23/2019 CHAPTER 2Hydrology

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CHAPTER 2 HYDRO-METEOROLOGICAL RECORD

2.1 Climate

2.1.1 General

The climate of the Solo River Basin is tropical and is subject to the tropical

monsoon. The south-west to north-west winds prevail from November to April in

ordinary year and they bring rainy season to the river basin. hile in the period

from !uly to "ctober# the basin area is dried up by the south and south-east

monsoon.

The monthly average temperature is about $%.& ' and it slightly fluctuates from

the minimum daily average temperature of (%

' to the ma)imum daily averageof *+ '. The monthly average relative humidity is about ,,.& through a year.

The ma)imum daily average wind velocity is .$ m/s# whereas the daily average

wind velocity in the basin is (.0 m/s. 1onthly average evaporation rate over the

basin is &.** mm/day.

2.1.2 Available data

There are (2 meteorological stations scattered in the Solo River Basin. The

observation wor3s is operated and managed by several agencies such as 4BS#

541A# 6ast !ava 7rrigation Service 86!7S9# 7ndonesian Navy and 7ndonesian Air

:orce. The available meteorological station for each sub-basin is as the following.

a9 ;pper Solo River Basin < , stations

b9 =ower Solo River Basin < * stations

c9 1adiun River Basin < $ stations

d9 >rindulu River Basin < ( stations

e9 =among River Basin < ( stations

f9 "utside of Basin 8Surabaya9 < ( stations

The oldest 4anasan station has a period of operation since (%$. 1ost of the

stations have duration period of the record from (+( up to ( with some

interrupted data record. The list of meteorological stations and its operating

agencies# elevation and record period is shown in Table $.(.

1eteo-hydrological data used for this study was collected from 4BS and 7rrigation

Services# and also ta3en from previous ater Resources 5evelopment 4roject

reports. The meteo-hydrological data used to analy?e the climate in the basin are

collected from & stations in the Solo River basin i.e.# Sura3arta 84abelan9# 1adiun#

Bojonegoro and Surabaya.

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The monthly mean climate data for above four stations is presented in Table $.$.

The availability of meteorological data record for each station and the location of

the stations are presented on :ig. $.( and :ig. $.$ respectively.

2.1.3 Temerat!re

The monthly average temperature is about $%.& ' and it slightly fluctuates from

the minimum monthly average temperature of $,.2 ' and the ma)imum monthly

average of $+.& '. The monthly average temperature is high in the rainy season

81arch through 1ay and September through 5ecember9 and low in the dry season

8!anuary through 1arch and !une through August9. The daily temperature is

fluctuates from the minimum temperature of (*.$ ' to the ma)imum of *+.% '.

The monthly average temperature is summari?ed in the table and also graphically

presented below.

Temperature 8unit < "'9

St. Name Basin ! : 1 A 1 ! ! A S " N 5 1ean

Sura3arta ;S $,., $,. $%.& $%.+ $%. $%.2 $,.2 $%.( $%., $+.* $%. $%.* $%.&

1adiun 15 $%. $+.0 $+.& $+.& $+.( $%.2 $%.0 $%.* $%.+ $+.+ $+.+ $+.2 $+.0

Bojonegoro =S $2.% $2.& $2. $%.( $,.+ $,.0 $2.* $2. $,.+ $%.% $%. $,.2 $,.&

Surabaya - $%.( $%.( $%., $+.0 $+.0 $%.2 $%.( $%.$ $+.( $+. $+.+ $%.% $%.+

Average $,.+ $,. $%.* $%.+ $%.% $%.( $,.2 $,. $%., $+.& $+.* $%.2 $%.&

2.1." Relative H!midit#

The monthly average relative humidity is about ,,.& through a year. The

ma)imum monthly average relative humidity in Solo River basin is %(.$ # while

the minimum is ,0.$ . The humidity is naturally relatively higher in the rainy

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1"NT = AC6RA>6 R6=AT7C6 ;1757T 7N B.S"=" R7C6R BAS7N

22.0

,0.0

,2.0

%0.0

%2.0

!an

:e

b

1ar

Apr

1ay

!un

!ul

Aug

Sep

"c

t

Nov

5ec

;1757TB8-

9

1"NT = AC6RA>6 T6146RAT;R6 7N T6 B. S"=" R7C6R BAS7N

$2.2

$,.0

$,.2

$%.0

$%.2

$+.0

$+.2

$.0

!an

:e

b

1ar

Apr

1ay

!un

!ul

Aug

Sep

"c

t

Nov

5ec

T6146RAT;R68"

'9


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season 8!anuary through 1ay and November through 5ecember9 and lower in the

dry season 8!une through "ctober9. The monthly pattern of relative humidity

follows the pattern of rainfall# increasing during the rainy season and decreasing

during the dry season as graphically shown below.

Relative umidity 8unit < 9


Sura3arta ;S %%.2 %%. %2.( %&.+ %&.$ %*.* %(.& ,.$ ,+., ,+.+ %$.+ %2.$ %*.$

1adiun 15 2$., 2*.( 2(.+ 2$.* &.$ &,.* &2.2 &*.* &0.% &$.2 &2., 2(.2 &%.

Bojonegoro =S %$.( %0.% ,.% %$. %(. %(.0 ,+.2 ,&.$ ,2.& ,*., ,,.$ %(.2 ,.0

Surabaya - +$.2 +$. +$.( +0.( %%. %,.* %*.2 ,., ,,.0 ,,.0 %(.% %.0 %2.,

Average %(.$ %(.$ ,.% %0.0 ,+.* ,,.% ,&.% ,(., ,0.$ ,0.$ ,&.( ,.* ,,.&

2.1.$ %!n&'ine D!rati(n

The sunshine duration data record at Sura3arta is available from (%, to (%+.

The daily sunshine duration at Sura3arta is slightly varies from (0.& to ((.* hours

per day throughout the year.

Sunshine 5uration 8unit < hours/day9


Sura3arta ;S (0.% (0.& (0.% ((.0 (0.+ (0., ((.0 ((.( ((.$ ((.* (0., (0.% (0.+

1adiun 15 - - - - - - - - - - - - -

Bojonegoro =S - - - - - - - - - - - - -

Surabaya - - - - - - - - - - - - - -

Average (0.% (0.& (0.% ((.0 (0.+ (0., ((.0 ((.( ((.$ ((.* (0., (0.% (0.+

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1"NT= AC6RA>6 S;NS7N6 5;RAT 7"N AT S;RA@ARTA

(0.0

(0.2

((.0

((.2

($.0

!an

:eb

1ar

Apr

1ay

!un

!ul

Aug

Sep

"ct

Nov

5ec

S;NS7N65;RAT7"N

8";RS/5AB9


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2.1.) *ind +el(,it#

The average wind velocity in the basin is (.& m/s throughout the year. 1a)imum

average wind velocity in Solo basin is (.+ m/s# while the minimum is (.( m/s.

ind Celocity 8unit < m/s9


Sura3arta ;S $.0* $.0+ (.% (.* (.0 $.0( $.$ $.+ *.&0 *.( $.,$ $.** $.&0

1adiun 15 0.2( 0.+* 0.2& 0.2( 0.&* 0.2$ 0.2, 0.%* 0.+0 0.,% 0.%+ 0.2+ 0.,$

Bojonegoro =S (.0% 0.% (.0+ 0.+ (.0+ (.00 (.$* (.&$ (.$, (.(+ (.0, 0. (.(0

Surabaya - - - - - - - - - - - - - -

Average

(.$0 (.$ (.( (.(( (.(* (.(+ (.*, (.%( (.+$ (.,+ (.& (.*0 1.3

2.1. Eva(rati(n

1onthly average evaporation rate over the basin is &.* mm/day. The evaporation

is naturally relatively higher in the dry season 8!uly through November9 and lower

in the wet season 85ecember through !une9. The monthly average evaporation rate

is summari?ed in the table and graphically presented below.

6vaporation 8unit < mm/day9

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0.0

0.2

(.0

(.2

$.0

!an

:eb

1ar

Apr

1ay

!un

!ul

Aug

Sep

"ct

Nov

5ec

C6="'7TB8m/sec9

1"NT = AC6RA>6 6CA4"RAT7"N 7N B. S"=" R7C6R BAS7N

0.0

(.0

$.0

*.0

&.0

2.0

,.0

!an

:eb

1ar

Apr

1ay

!un

!ul

Aug

Sep

"ct

Nov

5ec

6CA4"RAT7"N8mm/day9


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Sura3arta ;S $.2( $.&% *.(0 *.&+ *.20 *.%( *.* &.2* &.+$ &.,0 *.%, *.(& *.,*

1adiun 15 *.(0 $.* *.*( *.2$ &.(* &.(+ &.* &.% 2.&2 2.*0 *.+, *.*+ &.0&

Bojonegoro =S *.* *.* &.0* &.(% &.0& &.(0 &.&+ 2.&0 2.%$ 2.%( &.,& &.(( &.&*

Surabaya - &.2 &.(+ &.2% &.&* &.+& &.2$ 2.( ,.(( ,.,$ %.00 2.+( &.,2 2.$(

Average *.&0 *.$& *.%2 *.0 &.(* &.(* &.20 2.$2 2.,2 2.,, &.2( *.+$ &.**

2.2 Rainall

2.2.1 General

The continuous long-term rainfall data for a time period of $2 years in the studyarea is needed for estimating both of low flow through simulation model and flood

flows with varies of return period. :urther# it is highly e)pected that the runoff

data should be of high accuracy because the water balance analysis in the study

area is highly dependent on the reliability of available runoff data.

The annual mean rainfall distribution in the ;pper Solo# 1adiun# =ower Solo and

in the whole Bengawan Solo River basin is analy?ed based on data recorded at

selected $% rainfall stations of the period from (%2 to (. The annual mean

rainfall for the ;pper Solo# 1adiun# =ower Solo and in the whole Bengawan SoloRiver basin are $#(,2 mm# (#%( mm# (#,% mm and (#$+ mm respectively. The

monthly distribution of annual rainfall for each basin is graphically presented as

below. The annual mean rainfall distribution for each sub-basin in the '514

Study area is shown in the following table.

Avera/e

8 unit < mm 9

Basin ! : 1 A 1 ! ! A S " N 5 Annual

;pper Solo *%+ *2% *($ $0 ((, %+ * *( &$ ((% $(0 $%, $#(,2

=ower Solo $%& $*, $20 (,, +, 2 *, $$ *% ++ (+$ $&* (#,%

1adiun *$$ $( $0 $$+ (0& %2 *% $( ** $(* $2+ (#%(

hole B.

Solo Average

*$& $& $+* (, (0( %0 *+ $2 *+ (0( ( $2 (#$+

North 'oastal $, (+ ($ ($ $ ,0 && ( *0 %* (&+ $* (#&*

South 'oastal *,$ *0$ $2 ($ 0 +0 &( $% &* ((, $(( $+& $#0&*

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=among *(& $2% $*( (2% %% 2( *( + *2 %0 (2* $,* (#,&%

2.2.2 Available Data

The rainfall data are available from a number of sources# the primary one being

the 7rrigation Services and another sources are belong to the 4BS and B1>

offices which operates rainfall monitoring stations in the Solo River basin.

There are *%& rainfall gauges scattered in the Bengawan Solo River Basin# consist

of +0 stations located in the =ower Solo# $$& stations and %0 stations are located

in the ;pper Solo and the 1adiun river basin respectively. These rainfall gauge

stations consists of 2( automatic gauges and *$* ordinary gauges. 1ost of the

ordinary gauge stations have duration period of the record since (2$. The period

of recording for the daily record at ordinary gauges is over &+ years# whereas the

record period of rainfall at automatic gauges are started after (%0.

The resume of available rainfall station in the Bengawan Solo River Basin is

summari?ed below.

Re&!me ( Rainall %tati(n& Availabilit#

A/en,# 0( ( &tati(n

L(er %(l( er %(l( Madi!n T(tal

6!7S 22 2+ ($$

'!7S 0 (,& * (,%

4BS (+ $0 + &,

'!7S/B1> , $2 0 *(

B1> 0 & ( 2

541A 0 ( 0 (

"thers ( ( 0 $

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M(nt'l# Di&trib!ti(n ( Mean Ann!al Rainall in t'e 0(rt' C(a&tal3 %(!t' C(a&tal

and t'e Lam(n/ 4a&in

0

20

(0 0

(2 0

$0 0

$2 0

*0 0

*2 0

&0 0

!an :eb 1ar Apr 1ay !un !ul Aug Sep "ct Nov 5ec

Rain.allDet'5mm6 North 'oastal

South 'oastal

=among

M(nt'l# Di&trib!ti(n ( Mean Ann!al Rainall in t'e 4. %(l( River 4a&in

0

20

(0 0

(2 0

$0 0

$2 0

*0 0

*2 0

&0 0


Rain.allDet'5mm6

;pp er Solo

=ower Solo

1adiun


7/19

T(tal 78 22" 8 3"

Ga!/e T#e 0( ( &tati(n

L(er %(l( er %(l( Madi!n T(tal

Automatic (% $2 2(

"rdinary ,* ( ,( *$*

T(tal 78 22" 8 3"

4BS < 4roye3 Bengawan Solo

'!7S < 'entral !ava 7rrigation Service

6!7S < 6ast !ava 7rrigation Service

B1> < Badan 1eteorologi dan >eofisi3a 81eteorological and >eophysical Service9

541A < 5ire3torat 4enyelidi3an 1asalah Air 87nstitute of ydraulic 6ngineering9

Another rainfall data also collected for stations in the South 'oastal# =among and

North 'oastal basins from the same sources as the Solo River basin. There are $0

ordinary and automatic rainfall gauge stations located in the South 'oastal basin#

($ stations belong to the 6!7S and the remaining stations belong to the 4BS. The

period of record for some stations is from (,* up to (. 7n the =among basin#

there are , ordinary rainfall gauge stations belong to the 6!7S# * stations have a

record period from (2 to ( and the remaining stations from (2 to (0. 7n

the North 'oastal basin# there are (* ordinary rainfall stations belong to the 6!7S

with record period from (2$ to ( and only ( 8one9 4BS automatic rainfall

station has been installed in (%*.

Almost of the rainfall stations belong to 7rrigation "ffice has the longer record

period than the others# these stations have a period of the record since (2$. The

availability of daily record data also longer if compare to the other sources. So far#

the available daily rainfall data record in the 4BS "ffice have a short period# themost rainfall data still in continuous chart form. 'onsidering this reason# almost of

the daily rainfall data for further analysis is ta3en from the 7rrigation "ffice.

The list of rainfall station in '514 Study area and its operating agencies#

elevation of gauges# period of recording is presented in Table $.* and also the

availability of data record are shown in :ig. $.*.

2.2.3 Di&trib!ti(n ( Rainall

An isohyetal map of annual mean rainfall has been developed by "T'A# !apan for

Survey and Study for the 5evelopment of Solo River Basin in (%&. As seen in

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the isohyetal map# annual mean rainfall tends to decrease towards the north and

east in the =ower Solo and the North 'oastal. The annual mean rainfall in the

=ower Solo basin varies from (#%20 mm in northern and eastern area and

increasing to $#$20 mm in the southern area. Rainfall is higher in the south-west

of the basin# with mean annual rainfall varying from (#%20 mm in the valley to

*#000 mm in the mountain area of ilis# =awu and 1erapi. The isohyetal map of

annual mean rainfall is shown on :ig. $.&.

2.3 River *ater Level

2.3.1 General

The measurement of river water level had been carried out in many places along

the Solo River and its tributaries and also in the >rindulu and the =among River.

Two methods i.e.# ordinary staff gauge and Automatic ater =evel Recorder

8A=R9 are commonly used to measure the stage of water surface. The staff

gauge are usually read three times per day in the morning# afternoon and evening#

and the average of these three values is applied as daily water level record. :or

special cases as flood# the water level also recorded out of above three times

reading. The stage data record of A=R is presented in the form of a plot of stage

against continuous time 3nown as stage hydrograph. 5etail information about the

River ater =evel gauge stations is presented in 5ata Boo3 Anne) No. ( R64"RT No. (


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stations in the >rindulu and =orog River and ( 8one9 station in the =among River

were collected.

The detail river water level data availability in the ;pper Solo# =ower Solo and

1adiun River are presented on :ig. $.2# :ig. $., and :ig. $.% respectively. Thewater level station list and its operation agencies# period of operation# ?ero gauge

elevation and gauge type are presented in Table $. Table $.2 and Table $., for

the ;pper Solo# =ower Solo and 1adiun River respectively. The location of River

ater =evel Stations is presented on :ig. $. e)cept the 8nine9 stations for high

water level in 1adiun River. The daily river water level record at major stations is

graphically presented on :ig. $.(0.

The resume of the water level station availability# agencies and gauge type is

summari?ed below.

*ater Level %tati(n in t'e %(l( River and it& Trib!tarie&

0( A/en,# er %(l( L(er %(l( Madi!n T(tal

( 4BS $, ** $2 +&

$ 4BS/BT45AS $ 0 0 $

* 4BS/'!7S/6!7S ( ( 0 $

& 541A * 2 (

2 541A/'!7S/6!7S $ 0 0 $

, 4;. Solo ( 0 0 (

% '!7S/6!7S ( (& 2 $0

T(tal 3) $3 31 128

0( Ga!/e T#e er %(l( L(er %(l( Madi!n T(tal

( Staff >auge $& *0 $& %+

$ Automatic/Staff >auge ($ (+ % *%

* Automatic 0 2 0 2

T(tal 3) $3 31 128

4BS < 4roye3 Bengawan Solo

'!7S < 'entral !ava 7rrigation Service

6!7S < 6ast !ava 7rrigation Service

541A < 5ire3torat 4enyelidi3an 1asalah Air 87nstitute of ydraulic 6ngineering9

BT45AS < Balai Te3nologi 4engelolaan 5aerah Aliran Sungai 87nstitute of atershed

1anagement9

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4;.Solo < 4e3erjaan ;mum Solo 84ublic or3 of Solo9

7n the South 'oastal River Basin# there are * water level station installed by 4BS

along the >rindulu River at >unungsari# Arjowinangun and 4acitan and ( 8one9station installed in 4onggo3 River at Semanten. There is only ( 8one9 water level

station available in the =among River installed by 4BS at Boboh. The water level

data availability in the >rindulu and =among River is presented on :ig. $.+.

:rom the water level data schedule# sometimes the chart is interrupted due to

lac3ing of data record. This lac3 data is mainly due to some reason such as

a9 the staff gauge or A=R is bro3en

b9 the location of gauge is moved to other place

c9 missing of the data record# etc.

The water level observation is usually carried out by local person to read the staff

gauge or to replace the chart paper for the A=R. "ccasionally# the observer does

not come to the gauge location due to many reasons so that they only imagine the

water level as their e)perience. Another problem was found out for limited range

of the staff gauge# so that if the range is e)ceeded the observer can not read the

water level and the value of data recorded out of staff gauge range is not correct.

2." Di&,'ar/e Mea&!rement Ratin/ C!rve and R!n( Re,(rd

2.".1 General

The data of major stations of $2 water level gauges from the total of ($0 gauge

stations in the Bengawan Solo River and its tributaries# and in the other basins was

collected as previously discussed in sub-section of river water level.

7n this study# the discharge-rating curve for each station were determined by

e)amining the accuracy of the collected rating curves and constructed discharge

rating curve by '514 study team in case of the curve is not available. The daily

mean discharge was estimated by converting the water level to the discharge using

the constructed rating curve.

2.".2 Available Data

The discharge measurement had been carried out at (0* locations along the

Bengawan Solo River and its tributaries. The discharge was measured at *&

locations along the ;pper Solo# $ locations in the 1adiun and &0 locations in the

=ower Solo basins by several agencies such as 4BS# 541A# 6!7S and '!7S from

(,+ for the oldest station to (. 7n the South 'oastal basin area# there are 2

8five9 stations of discharge measurement along the >rindulu and the =orog River.

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"nly ( 8one9 station is available in the =among River# and no discharge

measurement is available in the North 'oastal basin area.

The discharge measurement data of major stations were collected for flow

analysis. :or the above measurement data# the discharge-rating curve had beenconstructed by 4BS to convert the water level data to runoff so far.

7n the Solo River basin# daily discharge data is available at *2 stations along the

main stem and tributaries# consists of ( stations in the ;pper Solo River# %

stations in the 1adiun River and stations in the =ower Solo. Same as water level

record# this daily discharge data is also owned by several agencies such as 4BS#

541A# 6!7S and '!7S. The availability of data and its period of record# operating

agencies for each station is presented as barchart in :ig. $.((.

2.".3 Di&,'ar/e Mea&!rement Data

The discharge measurement data records have been collected together with water

level record from the same sources. The name of major station list and its period

of record and number of observation along the Bengawan Solo River and the

tributaries are tabulated below.

Di&,'ar/e Mea&!rement Re,(rd in t'eer %(l( River at Ma9(r %tati(n&

0( %tati(n Peri(d ( 0( (

Re,(rd Ob&ervati(n

er %(l(

( Ngrembang (+0 D (2 (&

$ Sembu3an (+( D(+% $&

* Ngadipuro (+ D(2 ,+

& !uranggempal (%2 D(+2 &2

2 4aseban (%+ D(+2 $2

, !arum (%% D(2 ($0

% Serenan (++ D(& %+

+ Tegalgondo (+* D(+2 $

4eren (% D(0 ,+

(0 !urug (, D( $,,

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(( >rompol (++ D(+ (%

($ 1ung3ung (++ D(+ $(

(* @enatan (++ D(+ (2

(& @ajangan (%2 D(2

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Di&,'ar/e Mea&!rement Re,(rd in t'eL(er %(l( River at Ma9(r %tati(n&


Re,(rd Ob&ervati(n

L(er %(l(

( Napel (%$- (2 *$

$ 'epu (,+- (, (+(

* Bojonegoro (%% D(, (+,

& Babat (%2 D( (%

2 Brang3al (+% D(2 ,&

Di&,'ar/e Mea&!rement Re,(rd in t'eMadi!n River at Ma9(r %tati(n&


Re,(rd Ob&ervati(n

Madi!n

( Se3ayu (%2- (2 (,$

$ A.ani (%*- (2 ((0

* @etonggo (+( D(2 (%&

& inongo (++ D(2 ,&

2 Badegan (+0 D(+2 +(

, Ngindeng (+2 &*

2."." Ratin/ C!rve

7n order to estimate the river flow discharge for a long period at major station# the

available discharge rating curve data and discharge measurement were collected

primarily from the 4BS office. The discharge measurement data at the major

station was plotted for chec3ing the reliability of the discharge-rating curve

constructed by 4BS. At some major station# the discharge-rating curve had not yet

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been constructed so far# therefor the curve is estimated by the Bengawan Solo

'514 Study Team.

The list of discharge rating curve eEuations used for converting the discharge is

shown in Table $.%. The plotted discharge rating curve and more detailinformation for each station and its eEuation are presented on :ig. $.($.

2.".$ R!n( Re,(rd

The monthly average discharge distribution are estimated at the major station such

as !urug# @ajangan along the ;pper Solo River# @etonggo in the 1adiun River#

Bojonegoro# Babat# Brang3al along the =ower Solo River and tributaries#

Arjowinangun in the South 'oastal Basin and Boboh in the =among River as the

following table and figures.

M(nt'l# Avera/e Ob&erved Di&,'ar/e at t'e Ma9(r %tati(n& 51:$-1:::6

8unit < m*/sec9

Station River ! : 1 A 1 ! ! A S " N 5

!urug ;pper Solo (+( $$( (% ((, 2* * $* ( ( *0 2+ 2

@ajangan ;pper Solo &*2 2,( &*( $,+ ($& 2 &+ $ *$ & (&& $*$

@etonggo 1adiun $*2 *0( $$0 (,( 2% *% (, + (( (& &( ++

Bojonegoro =ower Solo %,$ 0+ +0+ 2$+ $(+ (2( ,$ *& *, 2, $$, *+0

Babat =ower Solo +(+ (0$$ +,$ ,&, $% (% ((( 2, ,* (00 *0% 2(*

Brang3al @ening $ *( $ $( , 2 & $ $ * ($ $0

Arjowinangun >rindulu 2& 2( 2( * ( (* 2 , $% *&

Boboh =among *% &2 * $% % 2 * & * $$ $+

N744"N @"67 '514 Study

1arch $00( $-(& :7NA= R64"RT$%,2*&&.doc S;44"RT7N> R64"RT No. (

M(nt'l# Avera/e Ob&erved Di&,'ar/e at t'e 4. %(l( River 51:$-1:::6

0

$00

&00

,00

+00

(000

($00


Di&,'ar/e5m

3;&e,6 !urug 8;pper Solo River9

@ajangan 8;pper Solo River9

@etonggo 81adiun River9

Bojonegoro 8=ower Solo River9

Babat 8=ower Solo River9

Monthly Average Observed Discharge at the Brangkal, Arjowinangun and B oboh Stations (19!"1999#

0

(0

$0

*0

&020

,0


Discharge(m3/sec)

Brangkal ($ening %iver#

Arjowinangun (&rindulu %iver#

Boboh ('aong % iver#


15/19

The daily average discharge were estimated by applying the water level records to

the corresponding discharge rating curves for the period from (%2 to (. The

observed daily discharge hydrograph at major river water level stations are

presented on :ig. $.(*.

Similar as rainfall pattern# the pattern of monthly average runoff is higher from

November to April and relatively low in the period from 1ay to "ctober. The

ma)imum monthly average discharge is recorded in :ebruary for Bengawan Solo

River and in !anuary for tributary# >rindulu River and =among River# whereas the

minimum discharge occurs in August or September for all stations.

The average annual runoff coefficient between the basin mean annual rainfall and

observed runoff at the respective gauges was estimated to be in the range from

0.*& at A.ani station to 0.2, at @ajangan station.

The detail information of the major River ater =evel Stations such as its location

map# cross section# photo and other information are presented on :ig. $.(&.

2.$ Oerati(n Re,(rd ( Ma9(r *ater %!l# R64"RT No. (


16/19

2.$.2 *(n(/iri Re&erv(ir

The onogiri 1ultipurpose 5am is the largest e)isting storage reservoir in the

Bengawan Solo main stem and provides flood control# irrigation# domestic water

supply and hydropower generation.

There are * reservoir operational rules have been established since the beginning

of operation in (+*. 7nitially# reservoir operation rule of onogiri 1ultipurpose

5am was established by Nippon @oei 'o.# =td. in :ebruary (+&. 7n (+,# after

completion of the onogiri Second 4hase 7rrigation 4roject# the operation rule

was authori?ed by the 1inisterial 5ecree of 4ublic or3s. :or increasing water

supply capacity of the onogiri Reservoir# again the operation rule was modified

by 4BS in (*.

The monthly average outflow from the e)isting onogiri Reservoir# the rainfall at

onogiri Reservoir# the reservoir water level and monthly average of evaporation

data in the period of (+*-( is summari?ed as shown in the table below.

M(nt'l# Avera/e Data at *(n(/iri Re&erv(ir 51:73-1:::6

=an


17/19

The daily data used in the analysis was ta3en from hourly data at 0.00 a.m.#

e)cept for discharge release through the flushing gates was used hourly data. The

discharge release through weir crest was estimated by discharge rating curve

available in the 'olo eir operation manual. The discharge release through

flushing gate is calculated based on the recorded water level in front of gates and

gate opening height by applying the formula for orifice because no discharge

rating curve is available.

The monthly average discharge diverted to right and left inta3e canals and

released discharge bac3 to the river is presented in the table below.

M(nt'l# Avera/e Di&,'ar/e Re,(rd at C(l( *eir 51:7)-1:::6

8unit < m*/sec9


5/S released for

maintenance flow

*+.& 2,.0 ,$.* *(.$ 2., *.* $.2 $. *.+ %.( (*.( $(.+

=eft 'anal 7nta3e $.* $.+ $., $. $.+ $.+ $. $.% *.* $. $.+ $.2

Right 'anal 7nta3e (,.0 (*.* (,.$ (%.0 (%.0 (2.( (2.2 (2.2 (+.& (+.( (%.& (+.$

5ata source < 'olo eir operational office at site.

The 'olo eir inflow as a total of discharge diverted to the canals and discharge

released bac3 to the river is graphically presented on :ig. $.(&. together with

onogiri 5am outflow record. The monthly average discharge record at 'olo

eir is presented in Table $..

2.$." =ati *eir

The !ati eir is located in the 1adiun River provides irrigation area of ((#%&, ha.

The weir have been modified from concrete weir type to rubber dam type togetherwith e)isting + 8eight9 weirs as part of 1adiun River ;rgent :lood 'ontrol 4roject

to control the sediment transport in the 1adiun River.

The monthly discharge data record available from (,, to(( is ta3en from the

previous study on :easibility Study of 'ountermeasure Against Riverbed

=owering in the 1adiun River in ($ under the 1adiun River ;rgent :lood

'ontrol 4roject.

The monthly average inta3e discharge record is presented in Table $.(0 and the

annual average is summari?ed below.

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18/19

M(nt'l# Avera/e Di&,'ar/e Re,(rd at =ati *eir 51:))-1::16

8unit < m*/sec9


7nta3e 5ischarge&.%0 &.&, &.*+ &.*0 *.,0 $.+* $.&, (.( (.2, (.( $., &.0,

5ata source < :easibility Study of 'ountermeasure Against Riverbed =owering in the 1adiun

River in ($ under the 1adiun River ;rgent :lood 'ontrol 4roject Report.

2.) %ediment Data

2.).1 %ediment L(ad Mea&!rement Data

The data of sediment load is collected from 4BS office for data measured at (stations on Solo River and the tributaries. The period of measurement are started

in (%2 in =ower Solo and after (+0 for 1adiun and ;pper Solo. All of the

above measured data is only for suspended load# whereas the data for bed load

measurement is not available.

The list of station name and its number of measurement data and period of

measurement is shown in Table $.((# and the detail measurement data are enclosed

in the 5ata Boo3 Anne) No. ( < ydrology.

2.).2 %ediment Di&,'ar/e Ratin/ C!rve

The sediment discharge-rating curve should be prepared for the total measured

load and the measured bed-material sediment load. 5ue to the availability of

sediment data# the sediment discharge-rating curves were developed based on the

data collected from 4BS office for measured suspended load only.

The sediment discharge-rating curve may vary with time. This can be due to

change in land use management# construction of upstream reservoir that trap

sediment# channel stabili?ation wor3s that decrease ban3 erosion or river

improvement wor3s that increase river conveyance and thus sediment transport

potential.

The developed sediment discharge-rating curve are shown in Table $.(( and also

graphically presented in 5ata Boo3 Anne) No. ( < ydrology.

2.).3 %ediment Yield

The annual suspended load sediment yield is estimated by applying the above

sediment discharge-rating curve to the simulated present condition flow at the

selected stations. Assuming the bed load material is (0 of suspended load# the

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19/19

estimated average annual unit sediment yield per 3m$in the Solo River Basin is

around $#*&0 tons/3m$. The mean annual sediment transport yields were estimated

*,.+ million tons/year at Babat on the =ower Solo River# $.2 million tons/year at

@ajangan on the ;pper Solo River and (&.* million tons/year at @etonggo on The

1adiun River. The annual sediment yield for each station is as the following table.

Ann!al %ediment Yield

Ann!al Yield

4a&in 0( %tati(n Cat,'ment %!&ended L(ad 5%!&ended?18@4ed6

L(ad

Area 5m26 518)t(n&6 5t(n&;m26 518)t (n&6 5t(n&;m26

N744"N @"67 '514 Study

$ (

Documents

CHAPTER 2Hydrology