06 urban drainage - universiti sains malaysia
TRANSCRIPT
IntroductionLined DrainsComposite DrainsGrassed SwalePipe DrainsEngineered Waterways
ContentsContents
Introduction
Existing Drain
Rigid Boundary ChannelRigid Boundary Channel
Rigid Boundary ChannelRigid Boundary Channel(Dry Period)(Dry Period)
Trunk Drain During Dry Period
Rigid Boundary ChannelRigid Boundary Channel
Wet PeriodWet Period
Rigid Boundary ChannelRigid Boundary Channel
Trunk Drain - Wet Period Rigid Boundary ChannelRigid Boundary Channel
Feasibility Study On Drainage Improvement in PraiIndustrial Complex, Seberang Perai Tengah, Penang
Study Area
Legend:Primary DrainExisting Pump StationRailway
Pump House A
Pump House B
Existing Primary Drains
Legend:Primary DrainExisting Pump StationRailway
Pump House A
Pump House B
Existing Primary Drains
Legend:Primary DrainExisting Pump StationRailway
Pump House A
Pump House B
Existing Trunk Drains
Legend:Primary DrainExisting Pump StationRailway
Pump House A
Pump House B
Existing Trunk Drains
B-2EL-6B
T-6E
J-2A
Rubber Pitching :Rubber Pitching :Top Width = 30’ - 46’
Depth = 5’ – 13’
Rectangular :Rectangular :Width = 5’ – 8’
Depth = 16’
Feasibility Study and Detail Design of Flood Mitigation and Drainage Improvement in Taman Sentul, TamanSentul Jaya, Taman Pinang & Taman Mangga, Juru,
S.P.T, Penang
Study Area
TolJuru
Lebuhraya Utara-Selatan
ParitNo. 5
Perkampungan Juru
KawasanPerusaha
anRingan
Utara
TamanSentulJaya
Taman
Mangga
Taman
Sentul
Taman
Pinang
Precast Concrete Drain900mm
Precast Concrete Drain1200mm
Precast Concrete Covered Drain
1200mm
PrecastConcrete
Drain3000mm
Feasibility Study of Flood Mitigation and Drainage Improvement in Kampung Tersusun, Juru, Seberang
Perai Tengah, PenangStudy Area
Primary Drain
Secondary Drain
Trunk Drain
Natural Waterway
Parit No. 5
Sungai Juru
Existing Problems
Feasibility Study of Flood Mitigation and Drainage Improvement in Kampung Tersusun, Juru, Seberang
Perai Tengah, Penang
Flooding occurs along the roads of the study areas due to improper drainage design, where roadside drains are not
provided.
Flooding occurs along the roads of the study areas due to improper drainage design, where roadside drains are not
provided.
Normal conditionNormal condition Flood condition on 6th October 2003
Flood condition on 6th October 2003
Flooding occurs along the roads of the study areas due to improper drainage design, where roadside drains are not
provided.
Flooding occurs along the roads of the study areas due to improper drainage design, where roadside drains are not
provided.
Normal conditionNormal condition Flood condition on 6th October 2003
Flood condition on 6th October 2003
Flooding caused by lack of maintenance and undersized secondary drain.
Flooding caused by lack of maintenance and undersized secondary drain.
Normal conditionNormal condition Flood condition on 6th October 2003
Flood condition on 6th October 2003
Normal conditionNormal condition Flood condition on 6th October 2003
Flood condition on 6th October 2003
Flooding caused by overflow of trunk drain.
Flooding caused by overflow of trunk drain.
Open Drains Volume 10 (Chapter 26)
Design Criteria
(a) Grassed Swale
0.5 m
Drainage Reserve
0.5 m Design flow width + freeboardmin min
1.5 m minimum 1.0 m
Drainage Reserve
(b) Lined Open Drain
Reserve Width for Open Drain
21
321. SRnAQ =
Manning’s Equation
38
21
.
BS
nQBYv.s
Manning’s Roughness Coefficient, n (Design Chart 26.1)
0.0150.012Precast Masonry Blockwork
0.0180.012 Brickwork
0.0300.025Rock Riprap
0.0350.020Random stones in mortar or rubble masonry
0.0170.015Dressed stone in mortar
Stone Pitching
0.0180.013Off form finish
0.0150.011Trowelled finish
Concrete
MaximumMinimum
Suggested n valuesSurface Cover or Finish
Solution to Manning Equation for Lined Open Drains
Longitudinal Grade, S0 (%)
1
10
1 5
3
4
5
1 20.4
0.6
0.9
0.8
0.7
0.5
0.3
2 3 4
2
3
4
5
6
7
8
9
Des
ign
Flow
, QD
(m3 /s
)
Use 'vee' shaped section
501 1
504
14
1
Base width, B (m)
Swale reserve width, R (m)( including required freeboard )
y
Base width, B (m)
Flow depth, y (m)
1.5
1.5
0.1 0.90.5
Flow Depth, y (m)
0.2 0.3 0.4 0.6 0.7 0.8
1
0.01
0.5
0.1
3
0.005
0.05
2
Valu
e of
Q n
S 01/
2
0.15
Z = 5.5
Z = 6
Z = 5
Z = 4.5
Z = 4
Swale reserve width, R (m)( including required freeboard )
y
z1
z1
'Vee' shaped Section
Lined Drains Volume 10 (Chapter 26.3)
Design Criteria
Uncovered Open Lined Drain (Minor System – Chap. 26)
H max = 0.5 m
B = 0.5 – 1.0 m 1.5 m minimum1.0 m
Drainage Reserve Width
50 mm
Covered Open Lined Drain (Minor System – Chap. 26)
H = 0.5 m – 1.0 m
B = 0.5 – 1.0 m 1.5 m minimum1.0 m
Cover
Drainage Reserve Width
50 mm
To prevent sedimentation and vegetative growth
Min Average Flow Velocity = 0.6 m/s
Velocity Limitation (Minor System – Chap. 26.3.6)
To prevent Channel Surface Erosion
Max Average Flow Velocity = 4.0 m/s
Note: Average Flow Velocity > 2.0 m/s, drain provided with a handrail fence, or covered with solid or grated cover
Composite Drains Volume 10 (Chapter 26.4)
C
Design flow width + freeboard
14 min
Qminor
50 mm freeboard
4 min1
Grassed Section
Lined drain
Recommended Composite Drain
• Provided in locations subject to dry-weather base flows which would otherwise damage the invert of a grassed swale, or in areas with highly erodible soils.
•The lined drain section is provided at the drain invert to carry dry-weather base flows and minor flows up to a recommended limit of 50% of the 1 month ARI.
Grassed Swale Volume 10 (Chapter 26.2)
Constructed Swale
Perimeter Perimeter SwaleSwale
Bio-Ecological Drainage SystemUSM, Engineering Campus
Type CType C
Type BType B
Type AType A
Design Criteria
C
Design flow width + freeboard
4 min1 1
4 min
Qminor
(a) ' Vee' Shaped
300mm freeboard
15050
11
4 min14 min
Batter BatterBase
Qminor
Design flow width + freeboard
(b) Trapezoidal Shaped
C 300mm freeboard
Velocity Limitation (Minor System – Chap. 26.2.5)
Max Average Flow Velocity < 2.0 m/s
Freeboard (Minor System – Chap. 26.2.4)
Min freeboard of 50 mm above the design stormwater level
Manning’s Roughness Coefficient, n Design Chart 26.1
0.0500.035Tall grass cover
0.0350.030Short grass cover
Grassed Swales
MaximumMinimum
Suggested n valuesSurface Cover or Finish
Worked Example(Application of Bio-Ecological
Drainage System (BIOECODS) in Malaysia)
Perimeter Swale
Study Area – BIOECODS, USM Engineering Campus
Recommended Grassed Swale Cross-Sections: Side slope = 1:4 min (batter); 1:50 (base)
Figure 26.2
The average flow velocity in a grassed swale shall not exceed 2 m/s.
26.2.5
The depth of a grassed swale shall include a minimum freeboard of 50 mm above the design storm water level in the swale.
26.2.4
In new development areas, the edge of a grassed swale should generally be located 0.5 m from the road reserve or property boundary.
26.2.2
Design CriteriaReference
2.40m
3.60m
3.60m
a) Overland flow time:Overland sheet flow path length = 35mSlope of overland surface = (3.60-2.40)/35 = 3.5%Design Chart 14.1, overland flow time, to = 12 minute
b) Flow time in channel:
- Reach length of perimeter swale = 130m
- The estimated average velocity = 0.25m/s
- Flow time in ecological swale , td = (130/0.25)/60 = 8.7 minutes
c) Time of concentration
Time of concentration, tc = to + td = 12 + 8.7 = 20.7 minutesAssume : tc = 20 minit
d) Design Storm
Minor Storm : 10 year ARIMajor Storm : 50 year ARITable 13.A1 Lacation : Pulau Pinang and equation 13.2 for tc = 20 minute,
Table 13.A1 Coefficients for the IDF Equations for the Different Major Cities and Towns in Malaysia (30 ≤ t ≤ 1000 min)
0.0341-0.56102.24172.7512100
0.0335-0.54692.14562.842950
0.0286-0.47031.76893.325520
0.0241-0.40231.43933.727710
0.0180-0.32401.12843.95995
0.0118-0.23110.67294.514021951-1990
PenangPulauPinang
dcba
Coefficients of the IDF Polynomial EquationsARI (year)
Data Period
LocationState
0.000.000.000.000.0030
0.480.320.360.420.4720
0.740.540.620.720.8015
1.030.860.991.131.2810
1.391.401.621.852.085
All≥ 180150120≤ 100(minutes)
East CoastWest Coast
2P24h (mm)Duration
Table 13.3 Values of FD for Equation 13.3
Where, 10I30 = 3.7277 + (1.4393) [In(30)] + (-0.4023) [In(30)]2 + (0.0241) [In(30)]310I30 = 136.65 mm/hr
P30 = 136.65/2 = 68.32 mm
And, 10I60 = 3.7277 + (1.4393) [In(60)] + (-0.4023) [In(60)]2 + (0.0241) [In(60)]310I60 = 92.83 mm/hrP60 = 92.83/1 = 92.83 mm
32 ))t(ln(d))t(ln(c)tln(ba)Iln( tR +++=
Thus, P20 = 68.32 – (0.42) (92.83 - 68.32) = 56.80 mm
10I20 = 56.80 (60) / 20 = 170.41 mm/hr
(13.2)
)( 306030 PPFPP Dd −−= dPI d=(13.3) (13.4)
Minor Storm: 10 year ARI:
Where, 100I30 = 2.7512 + (2.2417) [In(30)] + (-0.5610) [In(30)]2 + (0.0341) [In(30)]3100I30 = 186.35 mm/hr
P30 = 186.35/2 = 93.17
And, 100I60 = 2.7512 + (2.2417) [In(60)] + (-0.5610) [In(60)]2 + (0.0341) [In(60)]3 100I60 = 129.75 mm/hr
P60 = 129.75 /1 = 129.75
32 ))t(ln(d))t(ln(c)tln(ba)Iln( tR +++=
Thus, P20 = 93.17 – 0.47 (129.75 - 93.17) = 75.99
100I20 = 75.99 (60) / 20 = 220.96 mm/hr
(13.2)
)( 306030 PPFPP Dd −−= dPI d=(13.3) (13.4)
Major Storm: 100 year ARI:
e) Runoff Coefficient
Design Chart 14.3 (Landscape: Category 7),
C for minor storm = 0.58I= 170.41 mm/hr
C for major storm = 0.67I= 220.96 mm/hr
1.0
Run
off
Coef
ficie
nt,
C
Rainfall Intensity, I (mm/hr)
0 10 20 30 40 50 60 70 80 90 100 110 120 130 140 150 160 170 180
0.9
0.8
0.7
0.6
0.5
0.4
0.3
0.2
0.1
0190 200
2
1
7
6
5
4
3
8Impervious Roofs, ConcreteCity Areas Full and Solidly Built Up
Urban Residential Fully Built Up with Limited Gardens
Surface Clay, Poor Paving, Sandstone RockCommercial & City Areas Closely Built Up
Semi Detached Houses on Bare Earth
Bare Earth, Earth with Sandstone Outcrops
Bare Loam, Suburban Residential with Gardens
Widely Detached Houses on Ordinary LoamSuburban Fully Built Upon Sand Strata
Park Lawns and Meadows
Cultivated Fields with Good GrowthSand Strata
8
7
6
5
4
3
2
1
*I = 200mm/hr, C = 0.63I = 400mm/hr, C = 0.90
(Pavement: Category 1),C for minor & major storm = 0.91
f) Average Runoff Coefficient
000,3600AIC t
R
Q ××=
g) Peak flow
By using Rational formula (equation 14.7)
Minor storm,Cavg = [(0.58x4600) + (0.91x1900)] / 6500 = 0.68
Major storm,Cavg = [(0.67x4600) + (0.91x1900)] / 6500 = 0.74
Qminor /2* = C.I.A/ (3600,000) (2) = 0.68 (170.41) (6500) / (3600,000) (2)= 0.10m3/s
Qmajor /2* = C.I.A/( 3600,000) (2) = 0.74 (220.96) (6500) / (3600,000) (2)= 0.15m3/s
* There are two perimeter swale in the catchment area to cater the peak flow.
∑∑
=
== m
i
i
m
i
ii
avg
A
AC
C
1
1
g) Perimeter Swale SizingLongitudinal slope = 1:1000; Side slope 1:6 (batter), 1:50 (base); Bottom width, B = 1.8m; Depth, D = 175mm; Manning’s, n = 0.035; Area, A = 0.50 m2,; Wetted Perimeter, P = 3.93m;Hydraulic radius, R = A/P = 0.13m;Average velocity, V = 0.23m/s (<2.0 m/s) …OKQ = 0.11m3/s (> Q10) ... OK
0.1460.240.144.230.604.200.20061.80.001
0.1130.230.133.930.503.900.17561.80.001
0.0840.210.113.620.413.600.15061.80.001
0.0600.190.103.320.323.300.12561.80.001
0.0400.170.083.020.243.000.10061.80.001
0.0240.140.062.710.172.700.07561.80.001
0.0120.110.042.410.112.400.05061.80.001
0.0040.070.022.100.052.100.02561.80.001
0.0000.000.001.800.001.800.00061.80.001
(cumec)(m/s)(m)(m)(sq.m)(m)(m)(m)(m)
QVRPATWDepth, DSide Slope, ZBWSLOPE
Freeboard = 300mm; Depth, D = 1200mm; Area, A = 11.64 m2;
Wetted Perimeter, P = 17.10m; Hydraulic radius, R = A/P = 0.68m;Average velocity, V = 0.27m/s (<2.0 m/s) …OKQ = 0.19m3/s (> Q100) ... OK
0.2760.290.185.150.955.100.27561.80.001
0.1910.270.164.540.714.500.22561.80.001
0.1460.240.144.230.604.200.20061.80.001
0.1130.230.133.930.503.900.17561.80.001
0.0840.210.113.620.413.600.15061.80.001
(cumec)(m/s)(m)(m)(sq.m)(m)(m)(m)(m)
QVRPATWDepth, DSide Slope, ZBWSLOPE
Pipe DrainsVolume 10 (Chapter 25)
Design Criteria
Table 25.5 Minimum Pipe Diameters
Diameter
450For a non-self draining underpass, the pipe shall be sized for 10 year ARI and shall not be less than
375Any other pipe
300Pipe draining a stormwater inlet and crossing a footpath alignment *
Diameter (mm)Application
Note: * 300 mm diameter pipes are permitted in this situation only, in order to provide more space in the footpath alignment for other utility services.
Minimum Design Service LifeStormwater pipelines shall be designed for a minimum effective service life of 50 years.
Pipe Grades
(a) Maximum Grade
Pipeline grades shall be chosen to limit the pipe full flow velocity to a value less than or equal to 6.0 m/s.
(b) Minimum Grades
Stormwater pipelines shall be designed and constructed to be self cleansing. The desirable minimum grade for pipelines shall be 1.0%.
An absolute minimum grade of 0.5% may be acceptable where steeper grades are not practical.
Table 25.7 Pipe Roughness Values (average condition)
0.060.011UPVC
0.150.013Fibre Reinforced Cement
0.30.013Spun Precast Concrete
k (mm)nPipe Material
Pipe Roughness Values
n = Manning roughness coefficientk = Pipe roughness height for Colebrook-White equation
Worked Example(Proposed Tuanku Heights Mixed Development of Daerah Seremban,
Negeri Sembilan)
System System Layout Layout
Forebay
Mini Wetland
RockBaffle
Community Detention Pond
Engineered Waterway
Lot
Pipe DrainEngineered WaterwayEcological Drain
Natural Waterway
SCHEMATIC LAYOUT OF NEW SCHEMATIC LAYOUT OF NEW DRAINAGE SYSTEM, TUANKU DRAINAGE SYSTEM, TUANKU
HEIGHTHEIGHT
Subcatchment : 1
Area = 6770m2
Qp1 = 144.39 l/s
k = 0.3 mmTable 25.7
n = 0.013Table 25.7
Minimum grade = 1.0%Sec. 25.3.3 (b)
Maximum Grade : Velocity < 6 m/s.Sec. 25.3.3 (a)
φmin = 375mmTable 25.5
Design CriteriaReference
Calculation for Underground Drain Pipes Sizing
From Design Chart 25.B3 (k = 0.3 mm),
With D = 375 mm
Hydraulic gradient 1 %
Q = 230 l/s (> Qp1 …OK)
V = 2 m/s (< 6m/s…OK)
(Major System)
Engineered WaterwaysVolume 11 (Chapter 28)
Engineered Waterways
H
W VariesVaries
Drainage Reserve Width
300 mm
Recommended Waterway Reservefor Maintenance Access
To prevent sedimentation and vegetative growth
Min Velocity = 0.8 m/s
To prevent Channel Surface Lining Erosion
Max Velocity = 4.0 m/s (Lined Channel / Low flow invert)
= 2.0 m/s (Floodways and Natural Waterway)
Minimum Longitudinal Slope
0.2 % - Lined Channel0.5 % - Grassed floodways and natural waterway
Suggested Values of ManningSuggested Values of Manning’’s s Roughness Coefficient, Roughness Coefficient, nn
0.1200.100Medium to dense
0.0500.040Scattered
Tree cover
0.1600.100Medium to dense
0.0700.050Scattered
Shrub cover
0.0500.035Tall grass
0.0350.030Short grass
Grass cover only
Grassed Floodways
MaximumMinimum
Suggested n valuesSurface Cover
Suggested Values of ManningSuggested Values of Manning’’s s Roughness Coefficient, Roughness Coefficient, nn
0.2000.110Dense growth of trees
0.1600.070Medium to dense brush
0.0800.040Light brush and trees
0.0500.030Long pasture grass, no brush
0.0350.025Short pasture grass, no brush
Overbank flow areas
0.1000.035Irregular and rough cross-section
0.0600.025Regular cross-section with no boulders or brush
Large streams
0.0700.030Steep mountain streams with gravel, cobbles, and boulders
0.0800.050Sluggish weedy reaches with deep pools
0.0450.035Clean, winding with some pools and shoals
0.0330.025Straight, uniform and clean
Small streams
Natural Channels
MaximumMinimum
Suggested n valuesSurface Cover
Suggested Values of ManningSuggested Values of Manning’’s s Roughness Coefficient, Roughness Coefficient, nn
0.0300.025Rock Riprap
0.0350.020Random stones in mortar or rubble masonry
0.0170.015Dressed stone in mortar
Stone Pitching
0.0250.020Unfinished
0.0250.018Trowelled, wavy
0.0230.016Trowelled, not wavy
Shotcrete
0.0180.013Off form finish
0.0150.011Trowelled finish
Concrete
Lined Channels and Low Flow Inverts
MaximumMinimum
Suggested n valuesSurface Cover
Suggested Values of ManningSuggested Values of Manning’’s s Roughness Coefficient, Roughness Coefficient, nn
0.0240.02014 mm stone
0.0190.0177 mm stone
Flush Seal Pavement
0.0170.015Rough
0.0140.012Smooth
Hotmix Pavement
0.0150.011Kerb & Gutter
Roadways
MaximumMinimum
Suggested n valuesSurface Cover
I. Composite Waterways(With Increased Capacity - Chap 28)
∑
∑
=
== m
i i
i
m
i i
ii
*
PAP
An
n
13/2
3/51
3/2
3/5
where,n* = equivalent Manning’s roughness coefficient for the whole
cross-sectionni = Manning's roughness coefficient for segment iAi = flow area of segment i (m2)P = wetted perimeter of segment i (m)m = total number of segments
(28.1)
Estimate the Overall Roughness Coefficient
II. Natural Waterways
To prevent Channel Erosion
Max Velocity = 2.0 m/s
or
Critical Velocity
Minimum Longitudinal Slope0.5 %
Velocity Limitation (Major System - Chap 28)
To prevent Channel Erosion
Max Velocity = 2.0 m/s
or
Critical Velocity
Minimum Longitudinal Slope0.5 %
Critical Velocities, (m/s) for various conduit materials
III. Grassed Floodways
6
1
6
1
15050
1
Batter BatterBase
C Low FlowProvision
Figure 28.3 Typical Grassed Floodway Cross-Section
Qmajor
Qminor
C Terracing
161
50
BatterTerrace Base
Figure 28.4 Typical Grassed Floodway Terracing
Low Flow Provision:Minimum capacity of 50% of the 1 month ARI flow.
Design Chart Design Chart 28.228.2
Des
ign
Flow
, (m
3 /s)
15
2025
3035
5055
60
4045
1.2
1.3
1.4
1.5
1.6
1.1
1.0
0.9
0.8
0.7
10
5
Floodway Base Width –Preliminary Estimate(Manning's n = 0.035,
Average Velocity = 2 m/s)
Worked Example(Application of Bio-Ecological
Drainage System (BIOECODS) in Malaysia)
Ecological Swale
Study Area – BIOECODS, USM Engineering Campus
Low flow inverts and pipes shall be sized for a minimum capacity of 50% of the 1 month ARI flow
28.10.4
Side slopes = 1:6 min (batter); 1:50 (base)Side slopes = 1:4 may be provided in special circumstance
28.10.2
Longitudinal grades shall be chosen such that the design storm average flow velocity will not exceed 2 m/s in grassed floodways and natural waterways
28.7.2
The minimum longitudinal grade for engineered waterways = 0.5% for grassed floodways and natural channels;Longitudinal grades shall not produce velocities less than 0.8 m/s if low flow inverts flowing full
28.7.1
The freeboard above the design storm water level shall be a minimum of 300 mm.
28.6
Minimum requirements for maintenance access = 3.7m (One side) and 1.0m (Other Side) for top width of waterway ≤ 6m or Both sides = 3.7m for top width of waterway > 6m
Table 28.1
Design CriteriaReference
a) Overland flow time:Overland sheet flow path length = 35mSlope of overland surface = (3.60-2.40)/35 = 3.5%Design Chart 14.1, overland flow time, to = 12 minute
b) Flow time in channel:
-Reach length of ecological swale = 920m
- Average velocity for ecological swale is given by Manning equation. The estimated average velocity = 0.35m/s
-Flow time in ecological swale , td = (920/0.35)/60 = 43.8 minutes
c) Time of concentration
Time of concentration, tc = to + td = 12 + 43.8 = 55.8 minutesAssume : tc = 56 minit
d) Design StormMinor Storm : 10 year ARIMajor Storm : 100 year ARITable 13.A1 Lacation : Pulau Pinang and equation 13.2 for tc = 56 minute,
Table 13.A1 Coefficients for the IDF Equations for the Different Major Cities and Towns in Malaysia (30 ≤ t ≤ 1000 min)
0.0341-0.56102.24172.7512100
0.0335-0.54692.14562.842950
0.0286-0.47031.76893.325520
0.0241-0.40231.43933.727710
0.0180-0.32401.12843.95995
0.0118-0.23110.67294.514021951-1990
PenangPulauPinang
dcba
Coefficients of the IDF Polynomial EquationsARI (year)
Data Period
LocationState
Minor Storm: 10 year ARI:
10I56 = 3.7277 + (1.4393) [In(56)] + (-0.4023) [In(56)]2 + (0.0241) [In(56)]310I56 = 96.99 mm/hr
Major Storm: 100 year ARI:
100I56 = 2.7512 + (2.2417) [In(56)] + (-0.4023) [In(56)]2 + (0.0241) [In(56)]3100I56 = 135.48 mm/hr
32 ))t(ln(d))t(ln(c)tln(ba)Iln( tR +++= (13.2)
e) Runoff CoefficientDesign Chart 14.3 (category 5),
Minor storm:(I=96.99mm/hr,)C for = 0.61
Minor storm:(I=135.48mm/hr,)C for = 0.70
1.0
Run
off
Coef
ficie
nt,
C
Rainfall Intensity, I (mm/hr)
0 10 20 30 40 50 60 70 80 90 100 110 120 130 140 150 160 170 180
0.9
0.8
0.7
0.6
0.5
0.4
0.3
0.2
0.1
0
190 200
2
1
7
6
5
4
3
8Impervious Roofs, ConcreteCity Areas Full and Solidly Built Up
Urban Residential Fully Built Up with Limited Gardens
Surface Clay, Poor Paving, Sandstone RockCommercial & City Areas Closely Built Up
Semi Detached Houses on Bare Earth
Bare Earth, Earth with Sandstone Outcrops
Bare Loam, Suburban Residential with Gardens
Widely Detached Houses on Ordinary LoamSuburban Fully Built Upon Sand Strata
Park Lawns and Meadows
Cultivated Fields with Good GrowthSand Strata
8
7
6
5
4
3
2
1
000,3600AIC t
R
Q ××=
Qminor = C.I.A/3600,000 = 0.61 (96.99) (256,000) / (3600,000) = 4.21m3/sQmajor = C.I.A/3600,000 = 0.70 (135.48) (256,000) / (3600,000) = 6.75m3/s
f) Peak flow
By using Rational formula (equation 14.7), peak flow for minor storm = 4.21 m3/s and peak flow for major storm = 6.75 m3/s
g) Ecological Swale SizingLongitudinal slope = 1:1000; Side slope 1:6 (batter), 1:50 (base); Bottom width, B = 2.5m; Depth, D = 900mm; Manning’s, n = 0.035; Area, A = 7.12 m2,; Wetted Perimeter, P = 13.46m;Hydraulic radius, R = A/P = 0.53m;Average velocity, V = 0.59m/s (<2.0 m/s) …OKQ = 4.21m3/s (= Q10) ... OK
5.3290.630.5814.678.5014.501.0062.50.001
4.1910.590.5313.457.1113.300.9062.50.001
3.2150.550.4812.235.8412.100.8062.50.001
2.3910.510.4311.024.6910.900.7062.50.001
1.7090.470.379.803.669.700.6062.50.001
1.1590.420.328.582.758.500.5062.50.001
0.7290.370.277.371.967.300.4062.50.001
0.4090.320.216.151.296.100.3062.50.001
0.1880.250.154.930.744.900.2062.50.001
0.0530.170.083.720.313.700.1062.50.001
0.0000.000.002.500.002.500.0062.50.001
(cumec)(m/s)(m)(m)(sq.m)(m)(m)(m)(m)
QVRPATWDepth, DSide
Slope, ZBWSLOPE
Freeboard = 300mm; Depth, D = 1200mm; Area, A = 11.64 m2;
Wetted Perimeter, P = 17.10m; Hydraulic radius, R = A/P = 0.68m;Average velocity, V = 0.70m/s (<2.0 m/s) …OKQ = 8.13m3/s (> Q100) ... OK
8.1280.700.6817.1011.6416.901.2062.50.001
5.3290.630.5814.678.5014.501.0062.50.001
4.1910.590.5313.457.1113.300.9062.50.001
2.3910.510.4311.024.6910.900.7062.50.001
1.7090.470.379.803.669.700.6062.50.001
1.1590.420.328.582.758.500.5062.50.001
0.7290.370.277.371.967.300.4062.50.001
0.4090.320.216.151.296.100.3062.50.001
0.0530.170.083.720.313.700.1062.50.001
0.0000.000.002.500.002.500.0062.50.001
(cumec)(m/s)(m)(m)(sq.m)(m)(m)(m)(m)
QVRPATWDepth,
DSide
Slope, ZBWSLOPE
Low Flow Provision: Design Capasity for 1 Month ARI
Design Storm : 2 year ARITable 13.A1 Lacation : Pulau Pinang and equation 13.2 for tc = 56 minute,
2I56 = 69.94 mm/hr
32 ))t(ln(d))t(ln(c)tln(ba)Iln( tR +++=
2I56 = 4.5140 + (0.6729) [In(54)] + (-0.2311) [In(54)]2 + (0.0118) [In(54)]3
1 month ARI rainfall intensity = 0.4x69.94 = 27.98 mm/hr
DD II 2083.0 4.0 ×= 13.5a
1.0
Run
off
Coef
ficie
nt,
C
Rainfall Intensity, I (mm/hr)
0 10 20 30 40 50 60 70 80 90 100 110 120 130 140 150 160 170 180
0.9
0.8
0.7
0.6
0.5
0.4
0.3
0.2
0.1
0
190 200
2
1
7
6
5
4
3
8Impervious Roofs, ConcreteCity Areas Full and Solidly Built Up
Urban Residential Fully Built Up with Limited Gardens
Surface Clay, Poor Paving, Sandstone RockCommercial & City Areas Closely Built Up
Semi Detached Houses on Bare Earth
Bare Earth, Earth with Sandstone Outcrops
Bare Loam, Suburban Residential with Gardens
Widely Detached Houses on Ordinary LoamSuburban Fully Built Upon Sand Strata
Park Lawns and Meadows
Cultivated Fields with Good GrowthSand Strata
8
7
6
5
4
3
2
1
e) Runoff CoefficientDesign Chart 14.3 (category 5), C for 1 month ARI = 0.30
360AIC t
R
Q ××=
f) Peak flowBy using Rational formula (equation 14.7), peak flow = 0.60 m3/s
Qlow flow = C.I.A/3600,000 = 0.30 (69.94) (256,000)
/ (3600,000) = 0.60m3/s
Ecological SwaleDrainage capacity for low flow = 0.30 m3/s.
Thus, no. of module needed = (0.60-0.30) / 0.038 = 8