nota kursus tahun 2006 - rekabentuk kolam takungan menggunakan wsma - 15-08-2006 to 17-08-2006

8/7/2019 NOTA KURSUS TAHUN 2006 - Rekabentuk Kolam Takungan Menggunakan WSMA - 15-08-2006 To 17-08-2006

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JABATAN P ENG AIRAN D A N SA LIRA N (JPS)KEMENT ERIAN SUMBER ASL I D AN ALAM SEKITAR (NRE)MALAYSIA

NOTA KUR SUS TAHUN 2006


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DETENTION POND COURSE(CONCEPT, DESIGN & CALCULATION)

15 - 17 OGOS 2006INS TITUT PEMBANGUNAN KOMPETENSI ,

IPS, KUALA LUMPUR

DISEDIAKAN OLEHMOHD YAHAYA B IN AHMAD PEng


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PRELIM INERIES POND DESIGN CONCEPT1. SITE SELECTION(a) Establish Land Owne~hip

structuresSecondary Outlet(Emergency Spillway)

PLAN

SECTION A-AFigure 20.1 Typical D ry Detention Basin Components

(6) Assess Proximity to Flood-prone Areasc Determineif site Size is Adequate(d) Evaluate Topography and Likelihood of Gravity Flow


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2. GENERAL DESIGN REQUIREMENTSOutlet Control(a) Primary OutletsPrimary outlets for detention basins shall be designed to reduce post-development peak flows to match pre-development peak flows for both the minor and m ajor system design storm ARI in accordance with Section 4.5.Design storm ARIs for the minor and major drainage systems shall be selected in accordance with Table 4.1.(6) Skcondary Outlets (Emergency Spi//wasfA hazard rating for the basin should be de termined and a secondary outlet design ARI selected in accordancewith the Federal Government or relevant State Government dam safety guidelines and ANCOLD (1986) andshall be designed to safely pass a m inimum design storm o f 100 year ARI through the basin.Bypass FlowsProvision should be made in a dry detention basin to bypass low flows through or around the basin. This isnecessary to ensure tha t the basin floor, particularly if it is grassed, is no t inundated by small storms orcontinually wetted by dry weather baseflow. The m inimum amoun t of bypass should be one half the1month ARI flow.3. DETENTION DESIGN CONCEPTSThe sizing of a detention facility requires an inflow hydrograph, a stage-storage curve, and a stage-dischargecurve (sometimes called a rating curve). Infl ow hydrographs for a range of design storm durations must berouted through the basin to determine the maximum storage volume and water level in the basincorresponding to the maximum allowable outflow rate.The design storm duration that will produce the maximum storage volume in a basin will vary depending oncatchment, rainfall, and basin outflow characteristics, and is typically somewhere between one and three timesthe peak flow time o f concentration for the basin catchment. The design storm duration that produces themaximum storage volume is called the c ritical duration.Inflow HydrographsVarious method can be use such as Time Area Method, Non Linear Resevoir Method, Kinematic Wave Method and RationalMethod Hydrograph Method.Stage-Storage Relationship ( Stage vs Storage )A stage-storage relationship defines the relationship between the depth of water and storage volume in thestorage facility. The volume of storage can be calculated by using simple geom etric formulas expressed as afunction of storage depth.

storage (Ip

Figure 20.2 Typical Stage-Storage Curve


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Stage-Discharge Relationship ( Stage vs Discharge)A stage-discharge curve defines the re lationsh ip between the storage w ater d epth and the discharge or ou fflowfrom a storage facility. A single composite stage-discharge curve should be deve loped 2foreach design stormoutlet arrangement, which req uires consideration of the stage and discharge rating relationship for each outletcomponent.

Figure 20.3 Com posite Stage-Discharge Curve

0 5 10 15 20 25 30Discharge (curnec)

Storage Discharge- Discharge Relationship( Storage Discharge Function vs Discharge)4. BASIN CONFIGURATIONClassificationAn embankment th at raises the water level a specified amoun t as defined by the appropriate dam safety group(generally 1.5 m t o 3 m or more above the usual mean low water height, when measured along thedownstream toe of the embankment to the em ergency spillway crest), is classified as a dam.Maximum Pond DepthThe m aximum pond depth w ithin the basin should not exceed 3.0 m under norm al operating conditions for themaximum design flow for which the primary outlets have been designed, i.e. the maximum design storm AR Iflow th at does no t cause the emergency spillway to operate under no rmal design conditions.Top WidthsMinimum recommended embankment top w idths are provided in Table 20.1.

Table 20.1 Minimum Recommended Top Wid th for Earthen Embankments (USDA, 1982)

Height of Embankment(m)

Under 33 to 4.5

Top Width(m >2.43.0


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Side SlopesFor ease of maintenance, the side slopes of a grassed earthen embankmen t and basin storage area should notbe steeper than 4(H ):l(V). However, to increase public safety and facilitate ease of mowing, side slopes of6(H): 1(V) (o r flatter) are recommended.BottomGradesThe floor of the basin shall be designed with a m inimum grade of l0/0 to provide positive drainage and minimisethe likelihood of ponding.FreeboardThe elevation of the top o f the settled emban kment shall be a minimum of 0.3 m above the water surface inthe detention basin when th e em ergency spillway is operating at m aximum design flow.5. PRIMARY OUTLET DESIGNPrimary outlets are designed for the planned release of wate r from a d etention basin. Basin outlets areordina rily uncontrolled (i.e. withou t gates or valves), and m ay be a single stage outlet structure or severaloutlet structures combined to provide multi-stage outlet control.

(a) Pipe or Box Culvert (d) Weir Overflow Spillway

(b) Riser Structure Cross-section(single and multi-level outlets)-. . . .. ... .-View from Downstream

(e) Slotted Outlet(c) Drop Inlet Pit(surcharge pit or culvert outlet)Figure 20.4 Typica l Deten tion Basin Primary outlet^

OrificesFor a single circular orifice, illustrated in Figure 0.5(a), the orifice flow can be determ ined using Equation 0.1.

where,Q = the orifice flow rate (m3/s)Cd = orifice discharge coefficient (0.40 - 0.62)A, = area of orifice (m2), ~r 3 4Do = orifice d iameter (rn)


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H, = effective head on the orifice measured from the centre of th e opening (m)g = acceleration due to gravity (9.81 m/s2)4

a) Free Fall

(b) Single (Submergd)

(c) MultpleFigure 20.5 Definition Sketch for Orifice Flow

Weirs(a) Sharp-Crested WeirsTypical sharp-crested weirs are illustrated in Figure 20.6. Equation 20.2 provides the discharge relationship forsharp-crested weirs with no end contractions (illustrated in Figure 20.6(a)).

where,Q = weir discharge (m3/s)

Cm= 1.81 + 0.22 (HIH,), sharp-crested weir discharge coefficientB = weir base width (rn)H = head above we ir crest excluding velocity head (m)


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(a) No end contractions (b ) With end contractions

(c) Section (d) SectionFigure 20.6 Sharp-C rested Weirs

(b) Broad-Crested WeirThe equation typically used for a broa d-crested weir is:

where,Q = weirdischarge (m3/s)CBCW= road-crested weir coefficientB = weir base width (m)H = effective head above weir cre st (m)

(c) V-Notch WeirThe discharge through a V-notch weir is shown in Figure 0.7 and can be calculated using:

Q = 1.38 tan ( ) Hwhere,Q = weir discharge (m3/s)6 = angle of V-notch (degrees)H = head on apex of V-notch (m)


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(d) Proportional WeirQ = 2.PIa0.' b ( H -q )

Section A-AFigure 20.7 V-Notch Weir

L 1where,Q = weir discharge (m3/s )H = head above horizontal sill (m)Dimensions a, b, x and y are as shown in F igure 20.8.

Figure 20.8 Proportiona l Weir Dimensions

CulvertsPipe or box culverts are often used as outlet structures for detention facilities. The design of these outlets canbe for either single or m ulti-stage discharges


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Erosion Protection(a) Primary Outlets(6) Downstream Waterway6. SECONDARY OUTLET DESIGNThe purpose of a secondary outlet (eme rgency spillway) is to provide a controlled overflow for flows in excessof the maximum design storm A R I for the storage facility.

flattening o f the downstream embank ment facearmouring the embankment crest and downstream faceusing regulated floodplain delineation an d occupancy res trictions downstream representative of conditionswithout the detention storageproviding extra waterway capacity downstreamusing a wide embankment crest such as is common with urban roads and streets (where rapid failureseldom occurs due to modest overtoppin g depths)using non-ero ding embankm ent material such as roller compacted concreteusing small tributary basins, where the rate and volume of discharge involved are limited, resulting inovertopping flows of sho rt duration and non-hazardous propor tions

Overflow W eirThe most common type of emergency spillway used is a broad-crested overflow weir cut through originalground ne xt to the embankm ent. The transverse cross-section of the weir cut is typically trapezoidal in shapefor ease of construction.

Q = C B H;.' (20.6)Where,Q = emergency spillway discharge (m 3/s)CSp= spillway discharge coefficien tB = emergency spillway base width (m)Hp = effective head on the spillway crest (m)The discharge coefficient CSp in Eq uation 20.6 varies as a fun ction o f spillway base width and effec tive head.Design values fo r CSpare provided in Design Chart 20.2.


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7. PUB LIC SAFETYRetarding basins should be provided with signs that clearly indicate their purpose and their potentialdanger during storms. Signs should be located such that they are clearly visible at public access pointsand at entrances and exits to outlet structures.. Gratings or trash racks may be used to help preven t thishappening. A pipe rail fence should be provided on steep or vertical drops such as headwalls andwingwalls at th e inlet and outlet t o a primary outlet structure to discourage public access.8. LANDSCAPINGAesthetics of th e finished facility is therefore extreme ly important. Wherever possible, designs shouldincorporate naturally shaped basins with landscaped banks, footpaths, and selective planting ofvegetation to help enrich the area and provide a focal point for surrounding development.9. OPERATION AND MAINTENANCE

ConsultationPlanned Maintenance and Insp ectionEffect of Design on Maintenance CostsGrassed Areas and Embankm entsWaterwaysPrimary OutletsSediment RemovalStructural Repairs and Replacement


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STORMPAY

Quick Start GuideVersion 1.0Feb 2006

PerundingAsnol Yahaya


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DevelopingA StormPay ProjectTo develop a model, the user must complete the following steps:

Create a new project.Calculating a Precipitation.The user must always start the storm pay and come back to main window after data input using ainput box on colour and view a result using a output box by click &?%.

Main windowThe user can refer Urban Stormwater Management Manual, MSMA (2000) for further detailand description when using a Storm Pay.Create a New Project

At How to use worksheet, createa new project by moving a mouse to a button box underInput in General information at Catchment as shown below.

Precipitation - - + - - - - - ~ - - - ~ domainstorm pay r e ~roposd.xk - ~ n p u t ! ~ l ) .Enter a "project title", "state", "nearest hydrology station" and "area of development" inGeneral Information at I n ~ u t orksheet as shown below.ProJecttile.t I- - - - POND 1State : 1 Perak 1 I t


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Calculating a PrecipitationIn calculating a precipitation, the user needs to:calculates a time of concentration

calculates a intensityselection of intensity, andcalculate a loss and excess rainfall

Time of concentrationAt How to use worksheet, before calculated a precipitation at selected duration, td, theuser must calculated tc pre and tc post by moving a mouse to a button boxunder Input inTime of concentrati~on tPrecipitation as shown below.

Enter a "length", "slope", "n manning", "area" and "wetted parameter" in Time ofConcentration at Input worksheet as shown below.

to,min-Length,m I 840 ISlope,%--nmanningP-- M,minLength,m

Either tc pre or tc post, to view the output, moving a mouse to a button box under Outputin time of concentration at Precipitation as shown below.

The output as shown in tcpre and tcpost worksheet.

IS6.01126

Slope, WP -nmanning-Area, A (m2]---.--

I---V--

-----. --Wetted parameter, P ml I 1


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IntensityAt How to use worksheet, to calculated a intensity at selected duration, td, for selectedsystem, the user can moving a mouse to a button box under Input in Intensity atPrecipitation as shown below.

Enter a "Fd", "AN at selected system", "a, b, c & d", and/ or "deduction factor" inIntensity at Input worksheet as shown below.

' For lessthan 2 ARC--+ 1 Deduction actor= 1The output as shown in rfall insity minorari, rfall insity majorari and rfall insityemergencyworksheet.Selection of intensityAt How to use worksheet, the user can moving a mouse to a button box under Input inIntensity and temporal pattern at Selection of Intensity as shown below.

At Intenct temp petrn worksheet, for selection of intensity, the user must related to tcpost. The selection of intensity must start from 0.5 tc post to 3 tc post. The value forselected tc and intensity for selected system must gain from rfall insity minorari, rfallinsity majorari and rfall insity emergency worksheet. For values and referred table fortemporal pattern, the user must refer to MSMA. Make sure the values representedselected tc (0.5 tc post to 3 tc post) as shown on Tables below.


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Table 13.81 emo oral patterns- west coas t of pemwx r m w i a I I i I i

FraGtion of Rainfa l l in Each lime Petiod I

Loss and excess rai~fallThe method used in calculating Loss and excess rainfall is Loss Method. At How to useworksheet, either for pre-development or post-development, at selected ART, the user cancalculated loss and excess rainfall by moving a mouse to a button box under Input in Lossand excess rainfall at Precipitation as shown below.

Enter a "initial losses", "% pervious", "& impervious7', and "% propotional loss" in loss& excess rainfall Input worksheet as shown below.

Propotionctl oss . % I 20 I I o IImpervious, X-.--- ---- . .- - 0 I \ so 'I "----Propotionaltoss.% 20 0 I


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1Fram summary hydrogroph, !-u -- I -i IL

mlMhodl ime keaMethod

A1

ARI P o r m d 0.5 tc t 2tc 3tc" MinorAR I tp [min] 25 25 40 &I.-

I O m31s) I 7.361 I4- IMax. vol. estimated [m'l I 83411 ---t

llreo for predm., ma

-

0.5 tc3461S

A2 1 3461 S

keo for portdew., mZtc

3461 .53461.5

0.5 1,3461 53461.5

- ----MajorARI- tinergency---. -- ---- ----

--------- - --

t,3461.53461.5

Max. vol. estimated [m')ti (min)tp [minl

F

ti [min]tp [min)Qo [m3/s]Max. vol. estimated (m3]

2 k3461.53461.5

744640,25

4025

8.2518627

3t,71923.0126730.0

55 .

5525

85

I

135251 40

8540

60

-

13560

I--- - ----- --- -


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pond parameter 1 I 1 I 1----- Stalt detention level 0.0 mS t a r t invert level i 31.00 m - i ---- Max.bund high 32.50 m/ Max.high when reachmax. volume 32.10 m I

numbercliameter

Area mmzdiameter

H0.000.100.200.30

20150

0.0217673.75

0.150.075

Ho0.0000.0250.1250.225

rnM

mmQ m3/s (basis)

0.0000.15303430.4mf


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I Time lndcx I Inflow l 1 Inflow l 1 Inflow l 1


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APPENDIX

0.0.1 Polynomial Approximation of IDF CurvesPolynom ial expressions in the form of Equation 0.1 have been fitted to the published IDF curves forthe 35 main citiesltowns in Malaysia.

= a+ b ln ( t ) + c(ln(t,l,I2 + d ( l t ~ ( t ) ) ~ (0.1)where,R4 = the average rainfall ntensity (mm/hr) for AR I and duration tR = average return interval(yti3n)t = duration (minutes)a to d are fmng constants dependent on ARI.

The design rainfall depth Pdfor a short duration d (minutes) is given by,pd =&I - F~ (P60 - 5 0 ) (0.2)

where Pso,PbO re the 30-minute and 60-minute duration rainfall depths respectively, obtained fromthe pu blished design curves. FD is the adjustment factor for storm durationEquation 0.2 should be used for durations less than 30 minutes. For durations between 15 and 30minutes, the results should be checked against the published IDF curves. The relationship is valid forany ARI within the range of 2 to 100 years.Note that Equation 0.2 is in terms of rainfall depth, not intensity. If intensity is required, such as forroof drainage, the depth Pd (mm ) is converted to an intensity I (mm /hr)'by dividing by the duration din hours:I , Pd

d (0.3)Table 0.1 Values of FDfor Equation 0.2

~ u r a t i o , P24h (, m) In West Coast East Coast(minutes) 120 150 All


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The following preliminary equations are recommended for calculating the 1,3,6-month and 1 yearARI rainfall intensities in the design storm, for all durations:

0.083 0.25 0.5where, ID , ID , ID and ' I ~ re the required 1,3,6-month and 1-year ARI rainfall intensities forany durationD, and 2 ~ Ds the 2-year ARI rainfall intensity for the same duration D, obtained from IDFcurves.

(a) Overland Flow TimeThe formula shown below, known as Friend's formula, shouldbe used to estimate overland sheet flowtimes. The formula was derived from previous work (Friend, 1954) in the form of a nomograph(Design Chart O.Error! Bookmark not defined.) for shallow sheet flow over a plane surface.

where,to = overland sheet flow travel time (minutes)L = overland sheet flow path length (m)n = Manning's roughness value for the surfaceS = slope of overland surface (Yo)Note : Values for Manning's 'n ' are given in Table 0.2.Some texts recommend an alternative equation, the Kinematic Wave Equation. However thistheoretical equation is only ,valid for uniform planar homogeneous flow. It is not recommended forpractical application.(b) Overland Flow Time over Multiple SegmentsWhere the characteristics of' segments of a sub-catchment are different in terms of land cover orsurface slope, the sub-catchment should be divided into these segments, and the calculated travel timesfor each combined.


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Figure 13.3 V a b d 'pplh or lppewith Tat& 13.3(source: HP 1,19821

Table 0.2 Values of Manning's 'n' for Overland Flow


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Surface TypeConcreteIAsphalt**Bare Sand**Bare Clay-Loam **(eroded)GravelledSurface**Packed Clay**Short Grass**Light Turf*Lawns*Dense Turf*Pasture*Dense Shrubberyand ForestLitter*

Manning n7ecommended Range0.01-0.0130.01 -0.06

0.012-0.033

0.012-0.030.02-0.040.10-0.200.15-0.250.20-0.300.30-0.400.30-0.400.35-0.50

* From Crawford and Linsley (1966) - obtained by calibration of Stanford Watershed Model.** From Engman (1986) by Kinematic wav e and storage analysis of m easured rainfall runoff data.

How ever, it is incorrect to simply add the values of tofor each segment as Equation 0.1 is based on theassumption that segments are independent of each other, i.e. flow d oes not enter a segment fiomupstream.Utilising Eq uation 0.1, the following method (Australian Rainfall & Runoff, 1998) for estimating thetotal overiand flow travel time for segmen ts in series is recomm ended. For two segments, termed Aand B (Figure 0.1):t~o ta l= t ~ ( b ) ~ B ( L ~ + L B ) ~ ( ~ ) (0.6a)

where,LA = length of flow for Segment ALB = length of flow for Segment 6

~ A W ) = time of flow calculated for Segment A overlength LAtBL..) =time for Segment B over the lengths indicated


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For each additional segment, the following time value should be added:t~ = ~~(LT~I )ti(Lrota1 - 4 ) (0.6b)

where,tadd = time increment for additional segmentLTotal = total length of flow, including the current segment iL j = length of flow for segmenti

t,( ...) = time for the segment i over the lengths indicated

Segment SegmentB

\ \ \ \ \ \ \

TravelTime

Figure 0.1 Overland Flow over Multiple SegmentsThis procedure must be applied iteratively because the travel time is itself a function of rainfallintensity.(c) Roof Drainage Flow TimeWh ile considerable uncertainty exists in relation to flow travel time on roofs, the time of flow in a lotdrainage system to the street drain, or rear o f lot drainage system is generally very small for residentiallots and may be adop ted as the minimum time of 5 minutes (Chapter 23). However, for largerresidential, comm ercial, and industrial developments the travel time m ay be longer than 5 minutes inwhich case it should be estimated using the procedures for pipe and/or channel flow a s appropriate.(d) Kerbed Gutter Flow TimeThe velocity of water flowing in kerbed gutters is affected by:

the roughness of the kerb, gutter and paved surfacethe cross-fall of the pavementthe longitudinal grade of the kerbed gutterthe flow carried in the kerbed gutter

The flow normally varies along the length of a kerbed gutter due to lateral surface inflows. Therefore,the flow velocity will also vary along the length of a gu tter. As the amou nt of gutter flow is notknown for the initial analysis of a sub-catchment, the flow velocity and hence the flow time cannot becalculated directly. An initial assessment of the kerbed gutter flow time must be made.An approximate kerbed gutter flow time can be estimated from Design Chart O.Error! Bookmark notdefined. or by the following empirical equation:


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where,t, = kerbed gutter flow time (minutes)L = length of kerbed gutter b w m)S = longitudinal grade of the kerbed gutter (%)Equation 0.2 should only be used for L < 100 metres. Kerbed gutter flow time is generally only asmall portion o f the time o f concentration for a catchment. The errors introduced by theseapproximate methods of calculation of the flow time result in only sm all errors in the time o fconcentration for a catchment, and hence high accuracy is not required.(e) Channel Flow TimeThe time stormwater takes .to flow along a open channel may be determ ined by dividing the length ofthe channel by the av erage velocity of the flow. The average velocity of the flow is calculated usingthe hyd raulic characteristics of the open channel.The M anning's Equation is recomm ended for this purpose:

1V = - 2 / 3 ~ 1 / 2n (0.8a)From which,

n.Lt,, =- 2 1 3 1 / 260 (0.8b)where,V = average velocity (m/s)n = Manning's roughness coefficientR = hydraulic radius (m)S = friction slope (m/m)L = length of reach (m)tch= travel time in the channel (minutes)Where an open channel has varying roughness or depth across its width it may be necessary tosectorise the flo w and determine the average velocity of the flow, to determine the flow time.(f) Pipe Flow TimeThe velocity V in a pipe running just full can be estimated from pipe flow charts such as those inChapter 25, Appendix 25.B where the flow, pipe diameter, roughness and pipe slope are known. Thetime o f flow through pipe, t , , s then g iven by:Lt - -P - v (0.9)where,L =: pipe length (m)V = average pipe velocity (m/.s)


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0.0.2 Time of Concentrationfor NaturalCatchment

For natural/landscaped catchmen ts and mixed flow paths the tim e of concentration can be found byuse of the Bransby-W illiams' Equation 0.1 0 (AR&R, 1987). In these cases the times for overland flowand ch annel or stream flow are included in the time calculated.Here the overland flow time including the travel time in natural channels is expressed as:

where,t = the time of concentration (minute)F = a conversion factor, 58.5 when area A is in km2,or 92.5 when area is in haL = length of flow path from catchment divide to outlet (km)A = catchment area (km2 or ha)S = slope of stream flow pa th (m/km)0.0.3 Ratknal Formula

The Rational Formu la is on e of the most frequently used urban hydrology m ethods in Malaysia. Itgives satisfactory results for sm all catchments only.The formula is:

where,Q, = yyear ARI peak flow (m3/s)C = dimensionless runoff coefficient''1, = yyear ARI average ra infall intensity over time of concentration, tc , mm/hr)A = drainage area (ha)


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Table 4.3 Design Storm ARIs for Urban Stormwater Systems

(See Note 1) Quantity

Type o f Development

Open Sp ace, Parks and AgriculturalLand in urban areas

Average R ecurrence Interval (ARI) ofDesign Storm (year)

Residential:Low densityMedium densityHigh density

Comm ercial, Business and Industrial- Other than CB DComm ercial, Business, Industrial inCentral Business District (CBD)areas of Large Cities

Quality

3 month ARI(for all typesofdevelopment1


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Table 14.4 Recommended Loss Models and Values for Hydrograph-

Condition[mperviousAreasPerviousAreas

Loss ModelInitial loss-Lossrate -Initial loss-proportionalloss, or -nitial loss-Lossrate,

-orton model

Initial loss: 1.5 mmRecommended Values

Loss rate: 0mrnkr-Initial loss: 10 mm

Initial loss: 10 mm for all soils(i) Sandy open structured soil(ii) Loam soil(iii) Clays, dense structured soil(iv) Clays subject to high shrinkage andin a cracked state at start of rain

~nitialnfiltration Capacity foA. DRY soils (little or no vegetation)Sandy soils: 125 mmihrLoam soils: 75 mmihrClay soils: 25 mmihrFor dense vegetation, multiply values given inA by 2B. MOIST soilsSoils which have drained but not dried out:divide values from A by 3Soils close to saturation: value close tosaturated hydraulic conductivitySoils partially dried out: divide values from Aby 1.5-2.5Recommended value of k is 4h r

Proportional Loss:20% of rainfall

Loss rate:10 - 25 mmhr3 - 10 mmhr0.5 - 3 m d h r4 - 6 mmihr

UltimateInfiltration Ratef c (mmhr), forHydrologic SoilGroup (see Note)A 10 - 7.5B 7.5 - 3.8C 3.8 - 1.3D 1.3 - 0

Note: Hydrological Soil Group corresponds to the classification given by the U.S. Soil ConservationService. Well drained sandy soils are "A"; poorly drained clayey soils are "D". The texture of thelayer of least hydraulic conductivity in the soil profile should be considered. Caution should be used inapplying values from the above table to sandy soils (GroupA). Source: XP-SWMM Manual (WP-Software, 1995).


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Table O.Al Coefficients for the IDF Equations for the Different Major Cities and Towns in Malaysia

State Location

I / Highland

Pahang Kuantan

Terengganu Kuala DungunIerengganu I KualaI Terengganu

(30 5 5 1000 min)

Data Period ARI(year) Coefficien ts of the IDF Polynomial1Equations I


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APPENDIX 0.A DESIGN TEMPORAL PATTERNSTable O.B1 Temp oral Patterns -W es t Coast of Peninsular Malaysia

n, 10min Duration

Duration(min)

10153060120180360

Time Period1 2 3

Time Period

No. ofTime

Periods236

12866

1 2 3 4 5 6 7 8 9 1 0 1 1 I 2Time Period

Fraction of Rainfall in Each Time P eriod0.570 0.430 -0.320 0.500 0.180 -0.160 0.250 0,330 0.090 0.110 0.060 -0.039 0.070 0.168 0.120 0.232 0.101 0.089 0.057 0.048 0.031 0.028 0.0170.030 0.119 0.310 0.208 0.090 0.119 0.094 0.030 -0.060 0.220 0.340 0.220 0.120 0.040 -0.320 0.410 0.110 0.080 0.050 0.030 -

180minute Duration I

1 2 3 4 5Time Period 1

l i me Pe r ~od1 2 1 4

120minute Durabon0.5 r

1 2 3 4 5 6 7 8Time Per~od

I 360 minute Duration

I 1 2 3 4 5 6lime Period


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No. of(min) Periods

120180360

10 min Duration

Table 0.B2 Temporal Patterns- East Coast of Peninsular Malaysia '

Fraction of Rainfall in Each Time Period

I 2Time Period

15 min Duratton

1 2 3Time Jer~od

60 minute Durat~on0.3 1

1 2 3 4 5 6 7 8 9 1 0 1 1 1 2Time Period

180minute Duration

1 2 3 4 5 6Time Period

(# these patterns can also be used in Sabah and

30 minute Duration


1 2 3 4 5 6 7 8Time Per~od

360 minute Duration

1 2 3 4 6l ime Period

ak, until local studies are carried out)


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CULVERT:

APPENDIX 27.A DESIGN FORM, CHARTSAND NOMOGRAPHS

I I H Conb-dhiornograph- COlXX* PipeCuIvertInlet Contrd Nomograph 8ox C U M 27-24-Irklet Corrtrd Nomograph - CormgatedMetal Pipe (CMP) Cuhrert 27-25Rielathe Discharge, V e l o g and HydraulicRadius in Part-full Pipe 27-26RowRelative Discharge, Velocity and Hydraulic Radius inPart-full Box 27-27Culvert FlawCsiticalDepth in a Circular Pipe 27-28-CriticalDepth ina Rectangular (Box) Sectjon 27-29Outkt Control Nomograph- Concrete PipeCulvert Rowing Fullwith 27-30n = 0.012 -OutfetControlNomograph- ConcreteBoxCutweft RowingFullwlth 27-31n = 0.012Outkt ControlNomograph - Cr#Ngated Metal Rpe (CMP) Flowing 27-32M I with n= 0.024-


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REKABENTUK KOLAM TAKUNGANMENGGUNAKAN MSMADari 15 Hingga 17 Ogos 2006

Di Institut Pembangunan Kom petensi JPS KLBahagian Latihan & Kem ajuan KerjayaJPS Malaysia


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DETENTION POND COURSE(CONCEPT, DESIGN & CALCULATION)

15 - 17OGOS 2006INSTITUT PEMBANGUNAN KOMPETENSI ,

IPS, KUALA LUMPUR

DISEDIAKAN OLEHMOHD YAHAYA B IN AHMAD PEng


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'RELIMINER IES POND DESIGN CONCEPT1. SITE SELECTION(a) Establish Land Owne/sh@

PLAN

SECTION A-AFigure 20.1 Typical Dry Detention Basin Components

(b) Assess Pro~inityo Flood-prone Areas(c) Determine if Site Size13Adequate(d) Evaluate Topography and Likelihood of Gr amFlow


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2. GENERAL DESIGN REQUIREMENTSOutlet Control(a) Primary OutletsPrimary outlets for detention basins shall be designed to reduce post-development peak flows to match pre-development peak flows for both the minor and major system design sto rm ARI in accordance with Section 4.5.Design storm ARIs for the minor and major drainage systems shall be selected in accordance with Table 4.1.(b) Secondary Outlets (Emergency Spillways)A hazard rating fo r the basin should be d eterm ined and a secondary outlet design ARI selected in accordancewith the Federal Government or relevant State Government dam safety guidelines and ANCOLD (1986) andshall be designed to safely pass a minim um design storm o f 100 year ART throu gh the basin.Bypass FlowsProvision should be made in a dry deten tion basin to bypass low flows through o r around the basin. This isnecessary to ensure tha t the basin floor, particu larly if it is grassed, is not inundated by small storms orcontinually wetted by dry weather baseflow. The minimum amount of bypass shouid be one half the1month ARI flow.3. DETENTION DESIGN CONCEPTSThe sizing o f a de tention facility requires an inflow hydrograph, a stage-storage curve, and a stage-dischargecurve (sometimes called a rating curve). Inf low hydrographs for a range of design storm durations must berouted through the basin to determine the maximum storage volume and water level in the basincorresponding to the maximum allowab le outflow rate.The design storm duration that will produce the maximum storage volume in a basin will vary depending oncatchment, rainfall, and basin oufflow characteristics, and is typically mewh here between one and thre e timesthe peak flow time of concentration for the basin catchment. The design storm duration tha t produces themaximum storage volume is called the critical duration.Inflow HydrographsVarious m ethod can be use such as Time Area M ethod, Non Linear Resevoir Method, Kinematic Wave M ethod and RationalMethod Hydrograph Method.Stage-Storage Relationship ( Stage vs Storage )A stage-storage relationship defines the relationship between the depth of water and storage volume in thestorage facility. The volume o f storage can be calculated by using simple geom etric formulas expressed as afunction of storage depth.

=rase (*Figure 20.2 Typical Stage-Storage Curve


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Stage-Discharge Relationship ( Stage vs Discharge)A stage-discharge curve defines the relationship between the storage water de pth and the discharge or oufflowfrom a storage facility. A single composite stage-discharge curve should be developed,for each design stormoutlet arrangement, which requires consideration of the stage and discharge rating relationship for each outletcomponent.

Figure 20.3 Composite Stage-Discharge Curve

Storage Discharge- Discharge Relationship ( Storage Discharge Functionvs Discharge)4. BAS IN CONFIGURATIONClassificationAn e mbankment that raises the water level a specified amount as defined by the appropriate dam safety group(generally 1.5 m t o 3 m or more above the usual mean low water height, when measured along thedownstream toe o f the em bankment to the emergency spillway crest), is classified as a dam.Maximum Pond DepthThe maximum p ond depth within the b asin should no t exceed 3.0 m under norm al operating conditions for themaximum design flow for which the primary outlets have been designed, i.e. th e maximum design storm ARIflow tha t does n ot cause the emergency spillway to operate under norm al design conditions.Top WidthsMinimum recommended embankment top widths are provided in Table 20.1.

Table 20.1 Minimum Recommended Top Wid th for Earthen Embankments (USDA, 1982)

Under 3


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Side SlopesFor ease of maintenance, the side slopes of a grassed earthen embankment and basin storage area should notbe steeper than 4(H):l(V). However, to increase public safety and facilitate ease of mowing, side slopes of6(H): 1(V) (or flatter) are recommended.BottomGradesThe floor of the basin shall be designed with a minimum grade of 1% to provide positive drainage and rninimisethe likelihood of ponding.FreeboardThe elevation of the top of the settled embankment shall be a minimum of 0.3 m above the water surface inthe detention basin when the emergency spillway is operating at maximum design flow.5. PRIMARY OUTLET DESIGNPrimary outlets are designed for the planned release of water from a detention basin. Basin outlets areordinarily uncontrolled (i.e. without gates or valves), and may be a single stage outlet structure or severaloutlet structures combined to provide multi-stage outlet control.

(a) Pipe or Box Culve rt (d) Weir Overflow Spillway

(b) Riser Structure Cross-section(single a nd m ulti-level ou tlets)

(c) Drop Inlet Pit(surcharge pit or culvert outlet)

-. . .. . :______.._..-

View from Downstream(e) Slotted Outlet

Figure 20.4 Typical Detention Basin Primary Outlets

OrificesFor a single circular orifice, illustrated in Figure O.S(a), the orifice flow can be determined using Equation 0.1.

where,Q = the orifice flow rate (m3/s)Cd = orifice discharge coefficient (0.40 - 0.62)A, = area of orifice (m2), n 0 8 4Do = orifice diameter (m)


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H, = effective head on the orifice measured from the centre of the opening (m)g = acceleration due to gravity (9.8 1 m/s2)

(a) Free Fall

(b) Single (Submergd)

(c) MultpleFigure 20.5 De finition Sketch for Orifice Flow

Weirs(a) Sharp-Crested WeirsTypical sharp-crested weirs are illus trated in Figure 20.6. Equation 20.2 provides the discharge relationship forsharp-crested weirs with no end contractions (illustrated in Figure 20.6(a)).

where,Q = weir discharge (m3/s)

CScw= 1.81 + 0.22 (H/H,), sharp-crested weir discharge coe fficien tB = weir base width (m)H = head above weir crest excluding velocity head (m)


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(a) No end contractions (b) With end contractions

(c) Section (d) SectionFigure 20.6 Sharp-Crested Weirs

(b) Broad-Crested WeirThe equation typically used for a broad -crested weir is:

Q =c- B (20.3)where,Q =

CBCW=B =H =

weir discharge (m3/s)broa d-crested weir coefficientweir base width (m)effective head above weir crest (rn)

(c) V-NotchWeirThe discharge throu gh a V-notch weir is shown in Figure 0.7 and can be calculated using:

Q = 1.38 tan ( ) Hwhere,Q = weir discharge (m3/s)B = angle of V-n otch (degrees)H = head on apex o f V-notch (rn)


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Section A-A

Figure 20.7 V-Notch Weir

(d) Proportional Weir

where,Q = weir discharge (m3/s)H = head above horizontal sill (m)Dimensions a, b, x and y are as shown in Figure 20.8.

Figure 20.8 Proportional Weir Dimensions

Culverts

Pipe or box culverts are often used as outlet structures for detention facilities. The design of these outlets canbe for either single or multi-stage discharges


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Erosion Protection(a) Primary Outlets(b) Downstream Waterway6. SECONDARY OUTLET DESIGNThe purpose of a secondary outlet (emergen cy spillway) is to p rovide a controlled ovefflow fo r flows in excessof the m aximum design storm AR I for the storage facility.

flattening o f the downstream embankment facearmouring the em bankment crest and down stream faceusing regulated floodplain delineation and occupancy restrictions downstream representative of conditionswithout the detention storageproviding extra waterway capacity down streamusing a wide embankment crest such as is common w ith urban roads and streets (where rapid failureseldom occurs due to modest overtoppin g depths)using non-erod ing embankm ent material such as ro ller compacted concreteusing small tributary basins, where the rate and volume of discharge involved are limited, resulting inovertopping flows of short duration and non-hazardous proportions

Overflow WeirThe most common type of emergency spillway used is a broad-crested overflow weir cut through originalground next to th e em bankment. The transverse cross-section of the weir cut is typically trapezoidal in shapefor ease of construction.

Q = C,, B H:.' (20.6)Where,Q = emergency spillway discharge (m3/s )CSP= spillway discharge co efficientB = emergency spillway base width (m )H, = effective head on the spillway crest (m)The discharge coefficient CSp in Equation 20.6 varies as a function o f spillway base width and effective head.Design values for CSpare provided in Design Chart 20.2.


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7. PUB LIC SAFETYRetarding basins should be provided with signs that clearly indicate their purpose and their potentialdanger during storms. Signs should be located such that they are clearly visible at public access pointsand at entrances and exits to outlet structures.. Gratings or trash racks may be used to help prevent thishappening. A pipe rail fence should be provided on steep or vertical drops such as headwalls andwingwalls a t the inlet and outlet to a p rimary outlet structure t o discourage public access.8. LANDSCAPINGAesthetics o f the finished facility is therefore extremely important. Wherever possible, designs shouldincorporate naturally shaped basins with landscaped banks, footpaths, and selective planting ofvegetation to help enrich the area and provide a focal point for surrounding development.9. OPERATION AND MAINTENANCE

ConsultationPlanned Maintenance and Ins pectionEffect of Design on Maintenance CostsGrassed Areas and EmbankmentsWaterwaysPrimary OutletsSediment RemovalStructura l Repairs and Replacement


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STORMPAY

Quick Start GuideVersion 1.0Feb 2006

PcrundingAsnol Yahaya


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DevelopingA Storm Pay ProjectTo develop a model, the user must complete the following steps:

Create a new project.Calculating a Precipitation.The user must always start the storm pay and come back to main window after data input using ainput box on colour and view a result using a output box by click -1,

Main windowThe user can refer Urban Stormwater Management Manual,MSMA (2000) for further detailand description when using a Storm Pay.Create a New Project

At How to use worksheet, create a new project by moving a mouse to a button box underInput in General information at Catchment as shown below.

. .Precipitation .+--+---- -+:Womainstorm pay new propcisal.xk,- Input!Al/Enter a "project title", "state", "nearest hydrology station" and "area of development" inGeneral Information at Input worksheet as shown below.


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Calculating a PrecipitationIn calculating a precipitation, the user needs to:calculates a time of concentrationcalculates a intensiwselection of intensity, andcalculate a loss and excess rainfallTime of concentrationAt How to use worlcsheet, before calculated a precipitation at selected duration, td, theuser must calculated tc pre and tc post by moving a mouse to a button boxunder Input inTime of concentration at Precipitationas shown below.

Enter a "length", "slope7', "n manning", "area" and "wetted parameter" in Time ofConcentration at Input worksheet as shown below.

nmanning

Slope, Xn manning I I I 0.011 IArea,A (m')-

Either tc pre or tc post, to view the output, moving a mouse to a button boxunder Outputin time of concentration atPrecipitationas shown below.

The output as shown in tcpre and tcpost worksheet.


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IntensityAt How to use worksheet, to calculated a intensity at selected duration, td, for selectedsystem, the user can moving a mouse to a button box under Input in Intensity atPrecipitation as shown below.

Enter a "Fd", "ARI at selected system", "a, b, c& d",and/ or "deduction factors' inIntensity at Input worksheet as shown below.

Forless than 2 ARC--+ 1 Deduction fuctor = 1 1 IThe output as shown in rfall insity minorari, rfall insity majorari and rfall insityemergencyworksh.eet.Selection of intensityAt How to use worksheet, the user can moving a mouse to a button box under Input inIntensity and temporal pattern at Selection of Intensity as shown below.

---5 F:bubUcdomain storm pay-new proposal.xk- ' i i c t emp petrn'At Intenct temp petrn worksheet, for selection of intensity, the user must related to tcpost. The selection of intensity must start from 0.5 tc post to 3 tc post. The value forselected tc and intensity for selected system must gain from rfall insity minorari, rfallinsity majorari and rfall insity emergencyworksheet. For values and referred table fortemporal pattern, the user must refer to MSMA. Make sure the values representedselected tc (0.5 tc post to 3 tc post) as shown on Tables below.


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T a b k 13.B1 Temporal patterns - West Coast of Pensvlclr Malaysia1 1 1 I 1 1 1 1b ct i o nof Rdmfall in Each ime Period

Loss and excessrainfall

The method used in calculating Loss and excess rainfall is Loss Method. At How to useworksheet, either for pre-development or post-development, at selected A N , the user cancalculated loss and excess rainfall by moving a mouse to a button box under Input in Lossand excess rainfall at Precipitation as shown below.

Enter a "initial losses", "% pervious", "& impervious", and "% propotional loss" in loss& excess rainfall Input worksheet as shown below.

Pervious, X- -- - 100Propotional loss, 96--- - -- ----- 20 --imperv~ous.X-- *-- --- - -- 0I 80 1Propotional kss , % M 0 I


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lllelhodTime keaMelhod

A1

Meo tor predev., n20.5tc 1 tc3461.5 1 3461.5

kea tw poddm.,m20.5 , 1 h. I 2t; I 3t,3461.5 1 3461.5 3461.5 1 71923.0


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I S t a r t invert level 1 I 31.001m 1bundhigh 1highwhen reachmax.vdvmetop surfacearea in 1

number

Area mm2 17613.75diameter

-- --"32.5032.1013818

Length,L

mmm2 I

76.WWidth,W I 1181.82

I 1


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APPENDIX

0.0.1 Polynomial Approximation of IDF CurvesPolynomial expressions in the form of Equation 0.1 have been fitted to the published IDF curves forthe 35 main citieshowns in Malaysia.ln(qt) = a+ b ln(t) +c(ln(tjy2 +d(ln(t)13 (0.1)

where,R& = the average rainfall intensity (mmfhr) for ARI and duration tR = average return interval (years)t = duration (minutes)a to d are fitting constants dependent onARI.

The design rainfall depth Pd for a short duration d (minutes) is given by,' d =40 ~ ( P6 0 - 4 0 ) (0.2)

where P30, P60 are the 30-minute and 60-minute duration rainfall depths respectively, obtained fromthe published design curves. FD is the adjustment factor for storm durationEquation 0.2 should be used for durations less than 30 minutes. For durations between 15 and 30minutes, the results should be checked against the published IDF curves. The relationship is valid foranyARI within the range of 2 to 100 years.Note that Equation 0.2 is in terms of rainfall depth, not intensity. If intensity is required, such as forroof drainage, the depthPd (mm) is converted to an intensityI (mm1hr)'by dividing by the duration din hours:

Table 0.1 Values of FD for Equation 0.2P24h (mm)

West Coast East Coast100 180


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The following preliminary equations are recommended for calculating the 1,3,6-month and 1 yearARI rainfall intensities in the design storm, for all durations:

0.083 0.25 0.5where, Z , I' , ID nd 'ZD are the required 1, 3, dmonth and 1-year ARI rainfall intensities forany durationD, and 2~~ is the 2-year ARI rainfall intensity for the same duration D, obtained from IDFcurves.

(a) Overland Flow TimeThe formula shown below, known as Friend's formula, shouldbe used to estimate overland sheet flowtimes. The formula was derived from previous work (Friend, 1954) in the form of a nomograph(Design Chart O.Error! Bookmark not defined.) for shallow sheet flow over a plane surface.

where,to = overland sheet flow travel t ime (minutes)L = overland sheet flow path length (rn)n = Manning's roughness value for the surfaceS = slope of overland surface(YO)Note : Values for Manning's 'n are given in Table 0.2.Some texts recommend an alternative equation, the Kinematic Wave Equation. However thistheoretical equation is only .valid for uniform planar homogeneous flow. It is not recommended forpractical application.(b) Overland Flow Time over Multiple SegmentsWhere the characteristics of segments of a sub-catchment are different in terms of land cover orsurface slope, the sub-catchment shouldbe divided into these segments, and the calculated travel timesfor each combined.


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figure 13.3 V h f 2 ~ mor uer?.withTable X3.3{source: HP 1,1982)

Table 0.2 Values of Manning's In' for Overland Flow


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Surface TypeConcreteIAsphalt**Bare Sand**Bare Clay-Loam**(eroded)GravelledSurface**Packed Clay**Short Grass**Light Turf?Lawns*Dense TurfFPasture*Dense Shrubberyand ForestLitter*

Recommended Range0.01-0.0130.0 1-0.06

0.012-0.033

0.012-0.030.02-0.040.10-0.200.15-0.250.20-0.300.30-0.400.30-0.400.35-0.50

* From Crawford and Linsley (1966) - obtained by calibration of Stanford Watershed Model.** From Engman (1986) by Kinematic wave and storage analysis of measured rainfall runoff data.

However, it is incorrect to simply add the values of tofor each segment as Equation 0.1 is based on theassumption that segments are independent of each other, i.e. flow does not enter a segment fromupstream.Utilising Equation 0.1, the following method (Australian Rainfall& Runoff, 1998) for estimating thetotal overland flow travel time for segments in series is recommended. For two segments, termedAand B (Figure 0.1):

trofd~= ~ A ( L ~ )~ B ( L ~ + ~ )B (LA ) (0.6a)where,

LA = length of flow for Segment ALB = length of flow for Segment 6

tNU)= time of flow calculated for Segment A overlength LAtBc..) time for Segment 6 ver the lengths indicated


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For each additional segmen t, the follow ing time v alue should be added:tadd = t i ( L w ) - i ( L , ~ a ,- 4 ) (0.6b)

where,t& = time increment for additi'onal segmentLTm = total length of flow, including the current segment iLi = length of flow for segment i

t i ( ..) = time for the segmenti ver the lengths indicated

Segment SegmentB\ \ \ \ \ \ \

Length b-~,+~-TravelTime

Figure0.1 Overland flow over Multiple SegmentsThis procedure must be applied iteratively because the travel time is itself a function of rainfallintensity.(c ) Roof DrainageFlow TimeWh ile considerable uncertainty exists in relation to flow travel time o n roofs, the time o f flow in a lotdrainage system to the street drain, or rear of lot drainage system is gene rally very sma ll for residentiallots and may be adopted as the minimum time of 5 minutes (Chapter 23). However, for largerresidential, comm ercial, and industrial developments the travel time may be longer than 5 minutes inwhich case it should be estimated using the procedures for pipe and/or channel flow as appropriate.(d) Kerbed Gutter Flow TimeThe velocity of water flowing in kerbed gutters is affected by:

the roughness of the kerb, gutter and paved surfacethe cross-fall of the pavementthe longitudinal grade of the kcrbed gutterthe flow carried in the kerbed gutter

The flow norm ally varies along the length of a kerbed gutter due to lateral surface inflows. Therefore,the flow velocity will also vary along the length of a gutter. As the amou nt of gutter flow is notknown for the initial analysisof a sub-catchmen t, the flow velocity and hence the flow time cannot becalculated directly. An initial assessment of the kerbed gutter flow time m ust be made.An approximate kerbed gutter flow time can be estimated from Design C hart O.Error!Bookmark notd e f i n d or by the follow ing empirical equation:


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where,t, = kerbed gutter flow time (m inutes)L = length of kerbed gutter flow (m)S = longitudinal grade of the kerbed gutter(%)Equation 0.2 should only be used for L < 100metres. Kerbed gutter flow time is generally only asmall portion of the time of conce ntration for a catchment. The errors introduced by theseapproximate methods of calculation of the flow time result in only sm all errors in the time ofconcentration for a catchment, and hence high accuracy is not required.(e) Channel Flow TimeTh e time stormwater takes to flow along a open channel may be determined by dividing the length ofthe channel by the av erage velocity of the flow. The average velocity of the flow is calculated usingthe hydraulic characteristics of the open channel.The M anning's Equation i s recomm ended for this purpose:

1V = - 2 / 3 ~ 1 / 2n (0.8a)

From which,t - "'L ~ 2 1 3 I 2* -60

where,V = average velocity (mls)n = Manning's roughness coefficientR = hydraulic radius (m)S = friction slope (m/m)L = length of reach (m)td, = travel time in the channef (minutes)Where an open channel has varying roughness or depth across its width it may be necessary tosectorise the flow and determ ine the average velocity of the flow, to determine the flow time.(f) Pipe Flow TimeThe velocity V in a pipe running just full can be estimated from pipe flow charts such a s those inChapter 25, Appendix 25.B where the flow, pipe diameter, roughness and pipe slope are known. Thetime of flow through pipe, t , , s then given by:

Lt,,=V (0.9)where,L = pipe length (m)V = average pipe velocity (mls)


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0.0.2 Time of Concentration for NaturalCatchment

For natural/landscaped catchments and mixed flow paths the tim e of concentration can be found byuse o f the Bransby-Williams' Equation 0.10 (AR&R, 1987). In these cases the times for overland flowand channel o r stream flow are included in the time calculated.Here the overland flow time including the travel time in natural channels is expressed as:

where,tc = the time of concentration (minute)F, = a conversion factor, 58.5 when area A is in krn2,or 92.5 when area is in haL = length of flow path from catchment divide to outlet (krn)A = catchment area (km2 r ha)S = slope of stream flow path (m/km)0.0.3 Rational Formula

Th e Rational Formula is one of the most frequently used urban hydrology methods in Malaysia. Itgives satisfactory results for small catchmen ts only.The formula is:

where,Qy = yyear ARI peak flow (m3/s)C = dimensionless runoff coefficientYIt yyear ARI average rainfall intensity over time of concentration, tc, mm/hr)A = drainage area (ha)


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Table 4.3 Design Storm ARIs For Urban StormwaterSystems

Type of Development

(See Note 1)

Open Space, Parlts and A griculturalLand in urban areas

Residential:Low densityMedium densityHigh density

Comm ercial, Business and Industrial- Other than CBDComm ercial, Business, Industrial inCentral Business District (CBD)areas of Large Cities

Average Recurrence Interval ( A N ) ofDesign Storm (year)

Quantity Quality

3month ARI(for all typesofdevelopment1

MinorSystem Major System(see Note 2 and3)


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Table 14.4 Recommended Loss Models and Values for Hydrograph

Condition[m~ervious4reasPerviousAreas

Loss ModelInitial loss-LossrateInitial loss-proportionalloss, orInitial loss-Lossrate,

Horton model

Initial loss: 1.5 mmRecommended Values

Loss rate: 0mmlhr

Initial loss: 10 mm

Initial loss: 10 mm for all soils

(i) Sandy open structured soil(ii) Loam soil(iii) Clays, dense structured soil(iv) Clays subject to high shrinkage and

in a cracked state at start of rainInitial Infiltration Capacity foA. DRY soils (little or no vegetation)Sandy soils: 125 mmhrLoam soils: 75 mm/hrClay soils: 25 mmhrFor dense vegetation, multiply values given inAby2B. MOIST soilsSoils which have drained but not dried out:divide values from A by 3Soils close to saturation: value close tosaturated hydraulic conductivitySoils partially dried out: divide values from Aby 1.5-2.5Recommended value of k is 4h r

Proportional Loss:200 of rainfall

Loss rate:

10 - 25 mmhr3 - 10 mmhr0.5 - 3 mmhr4 - 6 mmhr

UltimateInfiltration Ratefc (mmhr), forHydrologic SoilGroup (see Note)

Note: Hydrological Soil Group corresponds to the classification given by the U.S. Soil ConservationService. Well drained sandy soils are "A"; poorly drained clayey soils are "D". The texture of thelayer of least hydraulic conductivity in the soil profile should be considered. Caution should be used inapplying values from the above table to sandy soils (Group A). Source: XP-SWMM Manual (WP-Software, 1995).


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Table O.Al Coefficients for the IDF Equations for the Different Major Cities and Towns in Malaysia

State

Pahang

Terengganu

Terengganu

Location

Kaub

CameronHighland

Temerloh

Kuala Dungun

KualaTerengganu

(30 I t < 1000 min)

Data Period


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APPENDIX 0.A DESIGN TEMPORAL PATTERNSTable O.B1 Temporal Pa tterns - West Coast o f Pe ninsular Malaysia ,

0,6 10 min Durahon

Duration(min)10153060120180360

1 L

Time Period

15 min Duration

No. ofTimePeriods23612866

Time Period

Fraction of R ainfall in Each Time Period0.570 0.430 -0.320 0.500 0.180 -0.160 0.250 0.330 0.090 0.110 0.060 -0.039 0.070 0.168 0.120 0.232 0.101 0.089 0.057 0.048 0.031 0.028 0.0170.030 0.119 0.310 0.208 0.090 0.119 0.094 0.030 -0.060 0.220 0.340 0.220 0.120 0.040 -0.320 0.410 0.110 0.080 0.050 0.030 -

- -60 mlnute Duration

0.3 ,

1 2 3 4 5 6 7 8 9 1 0 1 1 1 2Time Period -

180 minute Duration I

1 2 3 4 5Trne Period 1

30 mlnute Duratton

0.4


120 minute Duration

1 2 3 4 5 6 7 8Time Pertod

360 minute Duration

1 2 3 4 5 6Tiwe Period


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Table 0.B2 Temporal Patterns - East Coast of Peninsular Malaysia '

10 min Duration I 1 15 mln Durat~on

Duration(min)10153060120180360

1 2 3 4 5 6 7 8 9 1 0 1 1 1 2Time Period

180minute Duration

No. ofTime

Periods23612866


Fraction of R ainfall in Each Time Period0.570 0.430 -0.320 0.500 0.180 -0.160 0.250 0.330 0.090 0.110 0.060 -0.039 0.070 0.168 0.120 0.232 0.101 0.089 0.057 0.048 0.031 0.028 0.0170.030 0.119 0310 0.208 0.090 0.119 0.094 0.030 -0.190 0.230 0.190 0.160 0.130 0.100 -0.290 0.200 0.160 0.120 0.140 0.090 -

30 minute Durahon

Time Perrod

1 2 3 4 5 6 7 8Time Period

1 360 minute Duration


(# these patterns can also be used in Sabah and Sarawak, until local studies are carried out)


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CULVERT:

APPENDIX 27A DESIGNFORM, CHARTSAND NOMOGRAPHS

1 27.2 1 Entrance~ o s s ~ o e f ~ c i e n t s 1 27-22

Ir~letWef Nomograph-Cormgated Metal Pipe (O IP) Culvert 27-25RelativeDischarge, Velodty and HydraulicRadius in Pwt-full Pipe 27-26

I -- -7.7 1 -Wative Discharge, Velodty and Hydraulic Radius in Part-full BoxC~ulwrt ow 27-2727.8

27.91 27.10 1 OutletCmtrd Nomograph -Corn& PipeCUMlowing Fullwithn = 0.012

aiticaiDepth ina Circular PipeOiticalDepth ina Rectangular(Box) Section

27-30

OutletContrd Normgraph- Cmm t e f3oxCuk r t Rowing Fullwithn = 0.012

27-28

27-29

27-3

Control Nwnograph-CormgatedMetal Rpe (CMP) flowingFullwith n = 0.024 27-32


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CASE STUDY . I_I- j-USING MSMA CONCEPT TOSOLVE FLOOD PROBLEMFORSG. KERAYONG -SRI JOHOR POND Lllu.lOlb- i-II-"" !

ik.Chin CbongWing

Penganhi P S Wayah Perukutwn

Klang River Basin

BanfirDiKg . Chemb w , Sun@ Kenyongp d aa ur rowJab" I(bng LIrm 4 'h


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PONDEFFECTOFTHE INFLOWAND OUTFLOW FLOW HYDROGRAPH

FLOOD HYDROGRAPH

Flow Distribution at Diversion Modelled by HECR4S

Elevation-Area-Storage Cur ves of Seri-Johor Pond

Diversion1 Inlet Works A I

- Doenion n o r kflood r l o r l g paadPond iolct and oullrl w o r k sOutlet channelOther ancillary works


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Bed level 30 50 rn.- < -- 18 m500mm rop

14 m Constriction across Sg K craj ong in R eference Design- Plan

Outlet Channel Works @ I

1 PREFER CO.YSTHI


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r*

Study ObjectivesI Physical Hyddraulie Model Study ITo determine effectiveness of reltrence (original)design in diverting the requisite proportion ofinflow to detention pondBased on test findings on reference design, torecommend design modifications where necessaryfor further testingTo determine final dimensions of inletconfiguration to achieve the desired diversionTo study the effects of a nearby DBKL drain, anda log boom, on the flood diversion

Test Series Carried Out

Test Series Carried Out

FINDINGSI M o d i f i e d De s i g n I1The design is able to divert over 170m3/s

flow to the diversion drain at the peakdischarge of 350 m3/sThe 9 rn constriction appears excessive toclient

FINDINGSReference Design

The design isnot able todivert> 70 11131s to th edetention pondModified Design 1

The design is able to divert over 170 mYs flow tothe diversion drain at the peak discharge of 350m31sNot in favour of a constriction located upstream ofLRT bridge crossing

F I X D I N G SModified Design 1x1

The design is able to divert about 170 m3/s tothe detention pond during peak flooddischarge of 3 50 m31s for both the n ose shape stestedFlood water starts to overflow into detent ~onpond when flood discharge exceeds about 35m3/sModified Design I1 1 is preferred for itswider 12 m constriction and con~p arativelybetter flo\v conditions.


94/96


95/96

PELBAGAI ISU LAIN I

I POND - Relocation OfTrees

Prov. SumI . UTILITIES 4LLOCATION -PENGAUHAN SETXNGGAN


96/96

,-DESIGN PEAK FLOW

nota kursus tahun 2006 - rekabentuk kolam takungan menggunakan wsma - 15-08-2006 to 17-08-2006

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