Numerical Simulation of Storm Water Sewer System With Sobek-RR-SF (Rainfall Runoff-sewer Flow). Yureana w Oki S Jurnal Skala vol 3 no 1 feb 2006 ISSN 1693-959x

8/13/2019 Numerical Simulation of Storm Water Sewer System With Sobek-RR-SF (Rainfall Runoff-sewer Flow). Yureana w O

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U/Numerical Simulation Of Storm Water Sewer System With Sobek-Rr-SfRainfall Runoff - Sewer Flow)Yureana Wijayanti, Oki Setyandito) IKajian Penggunaan Batuan Silika Sebagai Agregat Kasar Betonlsfrnari)

Pengaruh Pengawetan Dengan Sistem Pengasapan Terhadap Sifat Fisik DanMekanikBambuJauhar Fajrin, Muh. Zaenuddin)

Pengaruh Penggunaan Abu Sekam Padi Rha) Sebagai Pengganti Sebagiansemen Dengan Proporsi Fralsi Beratpada Beton Beragregat Kasar BatuanPiroklastik MerahNi Ketut Sri Astati Sukawati, Hariyadi)

Kontribusi Lempung Ekspansif Terhadap Kerusakan Ruas Jalan Banggo-DompuAgungPrabowo)

Kajian Konservasi Daerah Resapan Cekunganair Tanah Mataram-selongPropinsi Nusa Tenggara BaratDwi Winarti, S. Koesnaryo, Suyono)


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Vol.3 No. I Pebruari 2006 ISSN 1693-9s9X

SKALAIURNAL TEKMKPenangsung JawabDekan Fakultas Teknik Universitas Muhammadiyah Mataram

PenerbitFakultas Teknik Universitas Muhammadiyah Mataram

Pemimpin RedaksiNgudiyono

Wakil Pemimpin RedaksiIsfanari

AneeotaAgusPartonoWiduriY{ianti

IxraidinHiliyadi

TimAhliDwi Winarti, ST. MT. TeknikPertanrbangan-UMM Mataram)Didi S. Agustawijaya, k, M. Eng, Ph.D Teknik Geologi-UNRAM Mataram)Suryawan Murtiadi, Ir., M. Eng, Ph. D Teknik Stuktur-UNRAM Mataram)N.K. sri Astati sukawati, h., MT. Teknik Transportasi-UNMAS Denpasar)Yureana Wijayanti, ST. M.Eng. Teknik Hidro-UII Yogyakarta)

Sekretariat Jurnal Teknik SKALAFakultas Teknik Universitas Muhammadiyah MataramJIn. K.II. A. Dahlan No. 1 Pagesangan Mataram NTBTelp/Fax : 0370) 640728

e-mail: j [email protected]

SKALA JURNAL TEKNIK diterbitkan 2 dua) kali setahun pada bulan Pebruari dan Agustus.Redaksi.menerima artikel dalam bidang teknik berupa hasil penelitian,studi kepustakann maupun tulisan ilmiah terkait.


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Vol.3 No. 1 Pebruari 2006 ISSN: 1693-959X

SKALAJURNAL TEKMKDAFTAR ISI

Numerical simulation of storm water sewer system with sobek-Rr-Sf (R.infalt Ruroff- SewerFIow)(Yureana /ijayanti,m&ie )Kajian Penggunaan Batuan Silika Sebagai Agregat Kasar Beton.(Isfanari)Pengaruh Pengawetan Dengan Sistem Pengasapan Terhadap sifatFisikDan MekanikBambu(Jauhar Fajrin, Muh. Zaenuddin)Pengaruh Penggunaan Abu Sekam Padi (Rha) Sebagai Penggautisebagian scmen Dengan Proporsi Fraksi Beratpada BetonBeragregat Kasar Batuan Piroklastik Merah(I.{i Ketut Sri Astati Strkawati, Hariyadi)Kontribusi Lempung Ekspansif Terhadap Kerusakan Ruas JalanBanggo-Dompu(Agung Prabowo)Kajian Konservasi I)aerah Resapan Cekunganair Tanah Mataram-Selong Propinsi Nusa Tenggara Barat(Dwi Winarti, S, Koesnaryo, Suyono)

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l 1-18

t9-28

29-40

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IYT'IVIERICAL SIMT}LATIONOF STORM WATER SEWER SYSTEM WITIIsoBEK-RR-Sr EATNTALL Rt NOrr - SEWER FLOW)Yureanarilijayanti.), fu*rp&fa1"

'\.ecturer in Environmental Eng. Dept.. Faculty of Civil Engineering and Design,")Lecturer in civil Eng. Depart*"yJtt*ff*frgineering university of Mataram

ABSTRACTFlooding is the big problem in every urban area. Some solutions regarding sewerpipe, drainage channels that laying to accommodate the rain-fall run otT have beenmade. Yet, it is still lot accurately defined what the best solution for themanagement of floodplains is. Therefore, it is important to understand the behaviorof a sewer system and the influence of a certain combination of storage andmanagement in order to find some alternative solutions.To study flooding problems in wban area, this modeling presents the appiication ofSobek-RR-SF system for rainfell run-off and sewer flow. Sobek, rvhich is developedby WL Delft l{ydraulics, is an integrated numerical modeling package to simulatehydrodynamics of one-dimensional model. With this program, the user candetermine the level of the schematizalion. Also, it has the capability of dealing withhistorical rainfall data as well as with a user defined rain event. Water system can beschematized by nodes and branches being building blocks for the one-dimensionalschematization.The simulation shows the effect of storage in the reduction of the quantity of waterflow in a swer and the flood is not occurred. Other finding is the laying of a shortcut- -' pipe (new pipe from node 29 to node 13) to overcome the flooding there. Horvevelin laying new pipes, it is important to check the land use of that area. Morealternatives such as adding other ponds for storage, laying channels (using SOBEK-RR-CF-SF) can be done for finding the most effective and efficient solution for theflooding problern-Keywords: Sobek RR-SF, sewer system, flooding, storage

INTRODUCTIONBackgroundThe main objective of thisexperiment is to simulate the rainfallrunoff and sewer system. And thesimulation will be applied in Flavs city asa case study. This city is annually sufferedfrom flooding during the rainy season. Themap of the city can be seen in figure 1. Theprediction of the flooding cause is stilluncertain, whether from ftw heavy

rainfalls or the existing design is no longerbe able to cope with- Also the first point offlooding is unknown, although some areasare flooded-ObjectivesThe simulation must achievecuntnt standard, which is no floodingshould occur within l- years return period( in 60 minutes duration).

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Figure 1.LITERATURX, R EVIEWBasic Theory1. Delft-scheme and Calculationpoint :The computation of the waterlevels and discharge in the sobek-flownetwork is performed with the Delft-scheme. This scheme solves the continuityand momentum equation by mean of astaggered grid. In this staggered grid thervater levels are defined at the connectionnodes and calculation points, while theelischarges are defined at the intermediatereaches or reach segrnents.In general nurnerical approxi-mations must satisfy the followingrequirements:

The Map of Flavo Cityo Accurate, i.e. sufficient accuracygiven the modeling purpose.A sobek-flow model consists of a

network ofreaches connected to each otherat connection nodes. In each reach numberof calculation points can be defined. Thesecalculation points represent the spatialnumerical grid to be used in the simulation.The momentum equation and continuityequation will be solved nunerically on thisgrid, which results in the hydraulic states atthe calculation points and the reachsegments. The resulting water levels aredefined at the calculation points, while thedischarges are defined at the reachsegments (staggered grid).The locatiorr of each calculationr Robust i.e. effective or capable of point should be selected on various criteria:dealing with a wide range of . The distance between twopractical problems neighboring calculation points. Efficient i.e. efficient usc of should not be too large (for accuracycomputational resources such as and proper represenratiott of theprocessor time; physical processes);

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o The distance between twoneighboring calculation pointsshould not be too small because ofincreasing simulation time. Thesmallest distance the Delft-schenreuses is l0 meters;. The location of the calculation pointsmay be non-equidistant

Figure 2- Caiculation points2. BoundaryBoundary conditions can beapplied at the locations where the modelnetwork ends as a boundary node. In order

to solye the water-flow equations(continuity equation and momentumequation), information about the water-flow at the model boundaries should besupplicd.At each boundary, one conditionfor the water-flow should be specified. Thefollowing options are available:r Discharge (constan tabulatedfunction of time, tabulated functionof the water level);o Water level (constant, tabulatedfunction of time)In sewer systems a dead end (or beginning)of a reach can be a connection noderepresenting a manhole at the end of a pipe.In contrast to a boundary node, this nodehas storage.

3. Storage and StructureThe storage that is used in thecontinuity equations is in the Sobek-flowmodule joined to the nodes and calculationpoints. Each node has as its storage thenode storage plus the storage of half of thereach segments that are connected to thenode. Each calculation point has as itsstorage half of the reach segments oneither side of the calculation point.

In the sobek-flow modulestructure types are available:. Orificeo pumpo Weir

three

Figure 3. Storage and structure in networkBoundary nodes and halfthe reach(segments) next to this boundary do nothave any storage. Structures are defined at

reach segments.4. Bed frictionThe bed friction is the frictionbetween the flowing water and the riverbed.As such, it exerts a force on the flowingwater always in the direction opposite thewater-flow. In water courses this forcetogether with the force caused by earthgravity usually determines the flowconditions: the other forces are far lessimportant.The fourth term of the mcmentumequation is the bed-friction term:

Bed friction = solalC, RA,where:

g: Gravity acceleration 1m2/s2;Q: Discharge (m3ls)C : Chezy coefficient lmr/2/s;R = Hydraulic radius (m)As: Wetted area (m2)In this rnodeling of the Sobek-Flow module, the value of the chezycoefficient C during cornputation may bedetennined in number of input ref,erences.I use nranning (n*) number, so it will resultin chery coefficient according to:^ R"o('-_nm

Numerical Simulation Of Storm Water Sewer System With Sobek-Rr-Sf(Rainftll Runoff- Sewer Flow) (Yureana Wijayanti, Oki Setyandito)


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D030.09

0.03

0.o2

Figure 5. 'Ihe rainfall of standard event 05 and the inflow into the sewer for a flatclosed paved area of t ha.

2. EvaporationThe evaporation process is ofminor influence on the loss of rainfall. Thestorage in depressions of impervioussurfaces (e.g. closed paved areas) however,can only disappear by evaporation. Storagein depressions of pervious surfacesdisappears mostly by infiltration. Theevaporation of SOBEK-RR-SF is based onthe evaporation data of KNMI (The RoyalDutch Meteorological Institute).MethodologyTo model the behavior of a sewersystem, the following building blocks,called nodes and branches, are available:. Flow-Manhoie with Runoff Flow- Pipe with RunoffWhere the input parameters of the nodeand the branch are the same. The Rainfall-

runoffmodel is called the Runoffmodel ofFlow-Manhole and Flow-Pipe.The inflow towards the sewersystem consists of runoff from rainfall anddry weather flow. The Runoff model ofFlow-Manhole and Flow-Pipe, also calledNWRW model, describes the dry weatherflow and the transformation in time ofrainfall into runoff entering the sewersystem. The Runoff model is based on theguidelines. The processes included are:r moistening, and puddle formingo infiltration. runoffdelayFigure 6, illustrates the rainfall-runoffprocess with net to rainfall is the same asthe runoff to*'ards the selver system and iseqr:al to the rainfall minus evaporationminus infiltration minus the change ofstorage.

Sewer inflorr'

-> Hietograph I year Period

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II et ailD iail o11Figure 6. The rainfal l-runoff process

As a result of moistening andpuddte forming, part of the rainfall will bestored temporarily on t}te surface. Thisstorage is called surface storage. Thisstorage is reduced by evaporation as wellas infiltration. Different types of surfaeescan be distinguished, depending on surfacecharacteristics and slope. The modeldistinguishes four types ofsurfaces (closedpaved, open paved, roof unpaved) andthree types of slopes (area with a slope,flat, sketched flat), thus twelve differentarea types. The slope of the surface and theinfiltration capacity largely influence therainfall-runoff process.The infiltration of rainfall takesplace in the open paved areas and unpavedareas. The infiltration capacrty dependsmostly on the type of surface and moisture

condition. Other factors may also play animportant role. For example, theinfiltration capacrty of brick paths dependson the condition of the openings betweenthe bricks. The infiltration capacity of theunpaved areas depends on the vegetation,the kind of soil and the percentage ofmoisture in the subsurface. The descriptionof the infiltration of the Runoff model isbased on the formula of Horton (Table 2.Default Parameter Horton Equation).MODEL SETI]P AND RESTTLTS

As mention before, there are twokinds of modeling: Rainfall-runoffmodeling and Sewer modeling. Thereforethere will be two inputs data for eachmodeling. And both will be compute asone result.

T able 2. Default Parameter Horton ation.No Area Type RunoffType

InfiltrationCapacityMaximumrfb)

InfiltrationCapacityMinimum(fc)

Time FactorDecreasing(ka)

TimeFactorRecoveringftb)

Closed paved With a slope 0.0 0.0 0.0 0.02 Closed paved Flat 0.0 0.0 0.0 0.0) Closed paved Stetched flat 0.0 0.0 0.0 0.04 Onen oaved With a slope 2.0 0.5 3.0 0.t5 Open paved Flat 2.0 0.5 3.0 0.16 Open paved Stretched flat 2.0 0.5 3.0 0.1

Roof Witt a slooe 0.0 0.0 0.0 0.08 Roof Flat 0.0 0.0 0.0 0.09 Roof Stretched flat 0.0 0.0 0.0 0.0l0 Unpaved Wiih a slope 5.0 1.0 3.0 0.tll IJnoaved Flat 5.0 1.0 3.0 0.1t2 Unoaved Stretched flat 5.0 1.0 3.0 0.1

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Model Setupl. Rainfall dataThe rainfall of standard event 05 ischosen for the criteria of the calculationable 3. Standard Precipitation events 0Date(dd/mm/vvvv) Time(hh:mm:ss) Height(m)0t/aylg gs 00:01:00 0.01

01101/1995 00:04:00 0.01auOt/1995 00:07:00 0.020t/01/r99s 00:10:00 0.0201layt995 00:13:00 0-0501101/t995 00: l6:00 0.0501101/199s 00:20:00 0.09au0t/1995 00:23:00 0.094u01fi99s 00:25:00 0.0901/au19gs 00:28:00 4.07aual/199s 00:30:00 0.070llaut99s 00:32:00 0.0501loyt99s 00:34:00 0.05au0ut99s 00:37:00 0.04auatl1995 00:40:00 0.0401i01/199s 00:43:00 4.4372. Delay of runoffThe delay of runoffdepends on theaverage distance to the inflow location insewer system, the slope and the geometryof the catchments. The formrlla whichdescribes the runoff to the sewer system isthe formula of the rational method:Q: c.hwhere:Q::nflow into sewer

Table 4. Default

point (Return Period I year, 60 minutesoccurs and location of peak at the front).The data of standard precipitation event 05is as follows:Date(dd/mm/ww) Time(hh:mm:ss) Height(m)0 l0 /1995 00:40:00 a.a40 t0 /1995 00:43:00 0.0370 t0 /199s 00:44:00 0.0370 /a /1995 00:47:00 0.030 la /199s 00:49:00 0.030 t0 /1995 00:52:00 0.0270 /0 n995 00:55:00 0.0210 l0 /199s 00:58:00 0.020 t0 /199s 0l:01:00 0.020 l0 t1995 01:04:00 0.0180 /0 /1995 01:06:00 0.0180 t0 11995 01:08:00 0.0r0 t0 11993 01:10:00 0.0r0 l0ilr99s 01:i3:00 0.0060 l0t/199s 0l : l5:00 0_0060 lot/1995 01:18:00 0.001

c : runofffactorh : rainfall, dynamic storage oncatchmentsThe runoff factor is a function oflength, roughness and slope, Twelvedifferent area types are described in theDutch Guidelines for sewer systemscomputations, hydraulic functioning . Thetypes and default values are presented inTable 4.

5.

meters of Delav of Runoff MNo AREA TYPE RUNOFFTYPE RT]NOFFFACTOR, C SURTACESTORAGE. h

1 Closed paved With a slope 0.5 0.02 Closed oaved Flat 0.2 0.5J Closed paved Stretched flat 0.1 t.04 0oen oaved With a slooe 0.5 0.05 Open paved Flat 0.2 056 Open paved Stretched flat 0.t 1.07 Roof With a slone 0.5 0.08 Roof Flat 0.2 2.09 Roof Stretched flat 0.1 4_At0 Unpaved With a slope 0.5 2.4H Unpaved Flat 0.2 4.4t2 Unpaved Stretched flat 0.1 6.0

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An area 'with a sloPe' is an areawith a slope more than 4Yo. A sfietched flatarea is an ara with the distance to thenearest inflow point in the sewer largerthan 100 meters.

Results The result shows thal floodingoccurs &om point 20 up to point 29 ( callbe viewed on the longitudinal section,Figure 7.):

Iml WArER LEVEL NODES - 1-'l-1994 00:00:00 TLAYOE{{IF22 23: zo tt ^--*

7500.0: i' , . ,''i,.,i6 ozooo.ol . : , I,:,J.'ur*.ol . i 6l.':1^o:ssoo.o j , ,

I

5000.0 -1 : iii,.i*#'i:. :\7a500.01- - , -;.- -:;;,.i;-, :; j;.;,, ,-[--;:i-;.-+;;; +--- '-- ,;;..-i ; ,-;+;_--: --j-;ffi 4000.0 '4500.0 5000.0 5500.0 6000.0 &frn.o 7000.0 7500.0 s0m.0 8500,0 9000-0 9500'0: Figure 7. Water kvel Nodes'The flooding betwen the points are recogniznd by the hydraulic gradientposition is above the ground level:

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WATER LEVEL BRANCHES - 1-1-1994 00:00:00 FI-AV0EX.PRFDischarge .0001 I llo.ooo 0.0m 0 000 0.ooo 10.000 0 000 m3

,(,v,{V\, t)

8.0l:60 -I

4.0: , : -:'l: ::r-------ir-0 0 500.0 1000.0

(.iround Lev. \,

ri T-t-:-r-1.. : ::-ir-:---r-:-t25000 30000 3500.0 4000.0

1.0

8. Water level in sewer system

1$0.0 2000.0oo1qooTNqcNN

500{i0 s500.0 6000.0 6500.0iml

oo1oioiNldrotNl

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oooc qeorQ(oooo)f-.- O od iri+ lo @r iN Nd ld do:,o oo,N t'i'-- io m. l,N I NI:o or iN, $I o 'l o i oloLornii ,;t;i qt9i2.44

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Length

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ro olO ot; ;uEme{er iiiooqq

Io ,oiu) (); lrlISiope o/oo 0.i1 C.69 10.70 0.72' 0 50,l

FigureRECOMMENDATIONS ANDCONCLUSIONRecommendations

diameters of the pipe can be viewin the appendix, including eachflood mr,p.

1) The morieiing approach can beused for the flooding proL,lems2) In order to gain more reliableresult, the ,modeling still needssome checks between tlre datafrom the simulation and data fromthe field (at the critical points).3) More alternatives such as addingother ponds for storage. la,ving

006

1) Some strategies are suggested to 6) The green pipes on the nrap shorv'mitigate the problems, yet the the proposed new diameter, bluemain attempt is to lower the pipes show the existin$ pipe'hydraulic gradient below the2) First, propose bigger diameter ofthe pipes in certain areas3) Second, build storage to flow the"flood" into the storage4) Third, make second line pipesfrom pint 29 to 13 across otherroute5) In this case, first option is chosen.Herewith the proposed new

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channels (using SOBEK-RR-CF-SF) can be done for finding themost effective and efficientsolution for the flooding Problem'REFERENCESChow, V.T., 1959, OPen ChonnelHydraulics' McGraw-Hiil, NewYork.Fei, W., 2004, Modeling ComPound-Channels with Sobek, Master ofScience thesis, LINESCO-IHE,Delft, The NetherlandsLinsley, Kohler, Paulitus, 1988, Hydrologtfor En gineers, Mc-Graw'Hill,New YorkSoemifio, C.D., 1995, Hidrologi Tefuik,Erlangga, Jakarta

Subramany4 K-, 1986, EngineeringHydrologt, Ivlc{raw-Hill, NewDelhiSulistiyowati, D, Rodriguez, R., 2005,Hydro informatics Teclmologt forAnatYsis of Flooding Problems,Modul 3Drainage Sewer

System, UNF,SCO-IHE, Delft, TheNetherlandsSuyono S., 1983, Hidrologi wtukPengairan, PradnYa Paramita,

JakartaWanielista M-, 1990, HYdralogt and

Woter gualitY Control, JohnWileY sons-Wijayanti, Y., 2000, Simulation of lestorui wqter sYSrcm in Flavo CitYusing Sabek ftft-SF Progrum,Master of Engineering thesis, IHEDelft, The Netherlands. .

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Numerical Simulation of Storm Water Sewer System With Sobek-RR-SF (Rainfall Runoff-sewer Flow). Yureana w Oki S Jurnal Skala vol 3 no 1 feb 2006 ISSN 1693-959x