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http://www.msmam.com 1
MSMA2-
WHAT CHANGES?
Presented By: Ir. Dr. Quek Keng Hong
*A BEM/CPD Endorsed Seminar (6 CPD Hours)
Venue: Jurutera Perunding Primareka Sdn Bhd
Organised By: Dr. Quek & Associates
Date: 9 March 2013 Time: 8:30 am-5:00 pm
http://www.msmam.com 2
Program for Today:
• Registration: 8:30 am
• 1st Session: 9:00 am- 10:30 am
• Morning Tea Break: 10:30 am to 11 am
• 2nd Session: 11:00 am-12:30 pm
• Lunch: 12:30 pm to 1:30 pm
• 3rd Session: 1:30 pm- 3:00 pm
• Afternoon Tea Break: 3:00 pm to 3:30 pm
• 4th Session: 3:30 pm- 5:00 pm
• Seminar Finish: 5:00 pm
http://www.msmam.com 3
Let’s Introduce Myself
• Ir. Dr. Quek Keng Hong
• Chairman of IEM WRTD 2003/4/5
• Professional engineer, member IEM
• Consultancy for 20+ years
• Training MSMA Workshops
• Principal of Dr. Quek & Associates
http://www.msmam.com 4
My Track Records: • Review of Bridges for Double Track from Rawang-
Ipoh- 2001. DRB-HICOM.
• Review of Culverts for Double Track from Rawang-Ipoh- 2001. DRB-HICOM.
• Hydrological and Hydraulic Design Double Track from Gemas-Kluang 2003/4. GAMUDA-MMC.
• Hydrological and Hydraulic Design Double Track from Kluang-JB- 2003/4. GAMUDA-MMC.
• Many infrastructural projects around the country.
• Expert witness for many court cases related to flooding.
http://www.msmam.com 5
Remember the Good Old Day?
• Planning and Design
Procedure No. 1
(PDP1) published by
D.I.D. in 1975.
• 242 pages
• 10 chapters
• ½ inch thick
http://www.msmam.com 6
Remember the
Not So Good Old Days?
• >1,100 pages
• 20 volumes
• 48 chapters
• 2 three-inch arch
folders
http://www.msmam.com 9
By the end of this Seminar…
• For a typical urban area like KL, if you
apply MSMA2, you can expect:
• ??% higher storm intensity.
• ??% higher peak discharges.
• ??% bigger OSD.
• ??% bigger wet/dry sediment basins.
http://www.msmam.com 10
Bonuses
• 4 spreadsheets were used in the case
studies:
• (1) IDF computation
• (2) Rational Method computation
• (3) OSD design computation, and
• (4) Wet and dry sediment basins design.
http://www.msmam.com 11
Extra Bonus
• Download spreadsheets from:
• http://seminar1.msmaware.com
http://www.msmam.com 13
Chapter 2: Changes in
MSMA 2000 & 2011
• 2.2.1 Layout of MSMA (2011)
• 2.2.2 Quantity Control Design Criteria
• 2.2.3 Design Storm Computation
• 2.2.4 Storm Temporal Pattern
• 2.2.5 Rational Formula
• 2.2.6 Changes in OSD Design Procedure
• 2.2.7 Detention Ponds
• 2.2.8 Time-Area Method
• 2.2.9 Quality Control Design Criteria
http://www.msmam.com 14
Chapter 2- Continued
• 2.2.10 Pollutant Reduction Targets
• 2.2.11 Pollutant Estimation
• 2.2.12 Sediment Basins
• 2.2.13 Gross Pollutant Traps
• 2.2.14 Water Quality Ponds
• 2.2.15 Erosion and Sediment Control
• 2.2.16 Rainwater Harvesting
• 2.2.17 Pipe Drain
• 2.2.18 Engineered Channel
http://www.msmam.com 15
2.2.1: Layout of MSMA (2011)
MSMA (2000) MSMA (2011) Part A: Introduction
Chapter 1: Malaysian Perspective Chapter 1- Design Acceptance Criteria
Chapter 2: Environment Processes Chapter 1- Design Acceptance Criteria
Chapter 3: Stormwater Management Chapter 1- Design Acceptance Criteria
Part B : Administration
Chapter 4: Design Acceptance Criteria Chapter 1- Design Acceptance Criteria
Chapter 5: Institutional and Legal Framework Chapter 1- Design Acceptance Criteria
Chapter 6: Authority Requirement and Documentation Chapter 1- Design Acceptance Criteria
Part C : Planning
Chapter 7: Planning Framework Chapter 1- Design Acceptance Criteria
Chapter 8: Strategic Planning Chapter 1- Design Acceptance Criteria
Chapter 9: Master Planning Chapter 1- Design Acceptance Criteria
Chapter 10: Choice of Management Chapter 1- Design Acceptance Criteria
Part D : Hydrology and Hydraulics
Chapter 11: Hydrologic Design Concepts Chapter 2- Quantity Design Fundamental
Chapter 12: Hydraulic Fundamentals Chapter 2- Quantity Design Fundamental
Chapter 13: Design Rainfall Chapter 2- Quantity Design Fundamental
Chapter 14: Flow Estimation and Routing Chapter 2- Quantity Design Fundamental
Chapter 15: Pollutant Estimation, Transport and Retention Chapter 3- Quality Design Fundamentals
Chapter 16: Stormwater System Design Chapter 2- Quantity Design Fundamental
Chapter 17: Computer Models and Softwares Chapter 2- Quantity Design Fundamental
Part E : Runoff Quantity Control
Chapter 18: Principle of Quantity Control Chapter 5- On-Site Detention/Chapter 7- Detention Pond
Chapter 19: On-site Detention Chapter 5- On-Site Detention
Chapter 20: Community and Regional Detention Chapter 7- Detention Pond
Chapter 21: On-site and Community Retention Chapter 8- Infiltration Facilities
Chapter 22: Regional Retention Chapter 8- Infiltration Facilities
Nil Chapter 6- Rainwater Harvesting
Part F : Runoff Conveyance
Chapter 23: Roof and Property Drainage Chapter 4- Roof and Property Drainage
Chapter 24: Stormwater Inlets Chapter 13- Pavement Drainage
Chapter 25: Pipe Drains Chapter 15- Pipe Drain
Chapter 26: Open Drains Chapter 14- Drains and Swales
Chapter 27: Culvert Chapter 18- Culvert
Chapter 28: Engineered Waterways Chapter 16- Engineered Channel
Chapter 29: Hydraulic Structures Chapter 20- Hydraulic Structures
Part G : Post Construction Runoff Quality Controls
Chapter 30: Stormwater Quality Monitoring Chapter 3- Quality Design Fundamentals
Chapter 31: Filtration Chapter 9- Bioretention System
Chapter 32: Infiltration Chapter 8- Infiltration Facilities
Chapter 33: Oil Separators Chapter 10- Gross Pollutant Traps
Chapter 34: Gross Pollutant Traps Chapter 10- Gross Pollutant Traps
Chapter 35: Constructed Ponds and Wetlands Chapter 11- Water Quality Ponds and Wetlands
Chapter 36: Housekeeping Practices Nil
Chapter 37: Community Education Nil
Part H : Construction Runoff Quality Controls
Chapter 38: Action to Control Erosion and Sediment Chapter 12- Erosion and Sediment Control
Chapter 39: Erosion and Sediment Control Measures Chapter 12- Erosion and Sediment Control
Chapter 40: Contractor Activity Control Measures Chapter 12- Erosion and Sediment Control
Chapter 41: Erosion and Sediment Control Plans Chapter 12- Erosion and Sediment Control
Part I : Special Application
Chapter 42: Landscaping Annex 1: Ecological Plants
Chapter 43: Riparian Vegetation and Watercourse Management Chapter 17- Bioengineered Channel
Chapter 44: Subsoil Drainage Nil
Chapter 45: Pumped Drainage Chapter 19- Pump and Tidal Gate
Chapter 46: Lowland, Tidal and Small Island Drainage Nil
Chapter 47: Hillside Drainage Nil
Chapter 48: Wet Weather Wastewater Overflows Nil
Nil Annex 2: Maintenance
Nil Annex 3: IDF Curves
Table 2.1:
Comparison
of the various
chapters in
MSMA
(2000, 2011).
http://www.msmam.com 16
2.2.2: Quantity Control
Design Criteria
Table 2.2 DESIGN STORM ARIs FOR URBAN STORMWATER SYSTEM ADOPTION
(MSMA, 2000) Source: Table 4.1 of MSMA (2000)
Type of Development Average Recurrence interval (ARI) of Design Storm (Year)
Quantity Quality
Minor System Major System
Open Space, Parks and Agricultural Land in urban
areas
1 Up to 100 3 month
A.R.I. (for
all types
of
developm
ent)
Residential:
- Low density 2 Up to 100
- Medium density 5 Up to 100
- High density 10 Up to 100
Commercial, Business and Industrial- Other than
CBD
5 Up to 100
Commercial, Business, Industrial in Central
Business District (CBD) areas of Large Cities
10 Up to 100
http://www.msmam.com 17
2.2.2: Quantity Control
Design Criteria
Table 2.3 DESIGN STORM ARI ADOPTION (MSMA, 2011)
Type of
Development
Minimum Average Recurrence
interval (ARI)
of Design Storm (Year)
Residential Minor
System
Major
System
-Bungalow and Semi-D 5 50
-Link Houses/Apartment 10 100
Commercial and
Business Centers
10 100
Industry 10 100
Sport Fields, Parks
and Agricultural
Land
2 20
Infrastructure/utility 5 100
Institutional
Building/Complex
10 100
http://www.msmam.com 18
2.2.3: Design Storm
Computation
• Equation (2.1) in MSMA (2000):
• Equation 2.2 of MSMA (2011):
http://www.msmam.com 19
2.2.4: Storm Temporal Pattern
• 5 regions
• Recommended Time Intervals
Storm Duration (minutes) Time Interval (minutes)
< 60 5
60-120 10
121-360 15
>360 30
http://www.msmam.com 21
2.2.5: Rational Formula
(Continued) Landuse Runoff Coefficient (C)
For Minor
System
(≤10 year
ARI)
For Major
System
(>10 year
ARI)
Residential
Bungalow
Semi-detached
Bungalow
Link and
Terrance House
Flat and
Apartment
Condominium
0.65
0.70
0.80
0.80
0.75
0.70
0.75
0.90
0.85
0.80
Commercial and
Business Centres
0.90 0.95
Industrial 0.90 0.95
Sport Fields, Park
and Agriculture
0.30 0.40
Open Spaces
Bare Soil (No
Cover)
Grass Cover
Bush Cover
Forest Cover
0.50
0.40
0.35
0.30
0.60
0.50
0.45
0.40
Roads and
Highways
0.95 0.95
Water Body
(Pond)
Detention Pond
(with outlet)
Retention Pond
(no outlet)
0.95
0.00
0.95
0.00
http://www.msmam.com 22
2.2.6: Changes in OSD
Design Procedure
• MSMA (2000)
• Permissible Site Discharge (PSD)
• Site Storage Requirement (SSR)
http://www.msmam.com 23
2.2.6: Changes in OSD
Design Procedure
• MSMA (2011) • Figure 5.A1 divides peninsula into 5 design regions.
• Table 5.A1 gives max PSD and min SSR for 5 regions in Pen
Malaysia.
• Table 5.A2: gives max PSD, min SSR and inlet values for major
towns in Pen Malaysia.
• Table 5.A3 gives the OSD volume, inlet size and outlet size for 5
regions in Pen Malaysia.
• Table 5.A4 gives the discharge and pipe diameter relationship for
low lying, mild and steep slopes.
http://www.msmam.com 24
2.2.6: Changes in OSD
Design Procedure (Continued)
• Table 2.6 OSD or Dry/Wet Detention
Pond in MSMA (2011)
Type of Storage Facility Limiting Area (ha)
Individual OSD ≤ 0.1
Community OSD >0.1, ≤5
Dry Detention Pond 5 to 10
Wet Detention Pond >10
http://www.msmam.com 25
2.2.7: Detention Ponds
• MSMA (2011) • Figure 2.1 Estimate of Pond Area for Planning Purpose
• (Figure 7.5 in MSMA, 2011)
http://www.msmam.com 27
2.2.8: Time-Area Method
• MSMA (2011)
Catchment
Condition
Initial loss
(mm)
Continuous
Loss (mm/hr)
Impervious 1.5 0
Pervious 10 (i) Sandy Soil: 10-25
mm/hr
(ii) Loam Soil: 3-10
mm/hr
(iii) Clay Soil: 0.5-3
mm/hr
http://www.msmam.com 28
2.2.9: Quality Control
Design Criteria
• MSMA (2000)
• Dry pond- retain 70% coarse sediments
>0.04 mm, 3/6 months for project </> 2 yr
• Wet pond- 75/80 percentile 5 day rainfall
events.
http://www.msmam.com 29
2.2.9: Quality Control
Design Criteria
• MSMA (2011)
• 50/40 mm rainfall for temporary/permanent
rainfall
Variables Criteria
Water Quality Volume Temporary BMPs- 50 mm of rainfall applied to
catchments draining to the BMPs.
Permanent BMPs- 40 mm of rainfall applied to
catchments draining to the BMPs.
Primary Outlet Sizing Based on the peak flow calculated from the 3
month ARI event.
Secondary Outlet
(Spillway) Sizing
As per the ARIs recommended in the
respective chapters of the individual BMPs.
http://www.msmam.com 30
2.2.10: Pollutant
Reduction Targets
• MSMA (2000)
• Pollutant Reduction Targets
Pollutant New
Development
Land
Redevelopment
(see note)
Drainage
System
Upgrading
Annual Average
Pollutant
Removal
Efficiency (%)
Reduction in
Annual Average
Pollutant Load
from Existing
Conditions (%)
Reduction in
Annual Average
Pollutant Load
from Existing
Conditions (%)
Floatables 90 90 30
Sediment 70 50 20
Suspended
Solids
60 40 20
Nitrogen 50 30 20
Phosphorus 50 30 20
http://www.msmam.com 31
2.2.10: Pollutant
Reduction Targets (Continued)
• MSMA (2011)
• Pollutant Reduction Targets
Pollutant Reduction Targets (%)
Floatables / Litters 90
Total Suspended Solids (TSS) 80
Total Nitrogen (TN) 50
Total Phosphorus (TP) 50
http://www.msmam.com 32
2.2.11: Pollutant Estimation
• MSMA (2011)
• Pollutant Load Formula
• Event Mean Concentration (Table 2.13)
http://www.msmam.com 34
2.2.12: Sediment Basins
• Dry Sediment Basin
• MSMA (2000)
• MSMA (2011)
Parameter Design Storm
(mth ARI)
Time of Concentration of Basin Catchment (min)
10 20 30 45 60
Surface Area
(m2/ha)
3 333 250 200 158 121
6 n/a 500 400 300 250
Total Volume
(m3/ha)
3 400 300 240 190 145
6 n/a 600 480 360 300
Parameter Time of Concentration of Basin
Catchment (min)
10 20 30 45 60
Surface Area (m2/ha) 333 250 200 158 121
Total Volume (m3/ha) 400 300 240 190 145
http://www.msmam.com 35
2.2.12: Sediment Basins
• Wet Sediment Basin
• MSMA (2000)
• MSMA (2011)
Parameter Site Runoff
Potential
Magnitude of Design Storm Event in mm
20 30 40 50 60
Settling Zone
Volume
(m3/ha)
Moderate-
high runoff
70 127 200 290 380
Very high
runoff
100 167 260 340 440
Total Volume
(m3/ha)
Moderate-
high runoff
105 190 300 435 570
Very high
runoff
150 250 390 510 660
Parameter Site Runoff
Potential
Magnitude of Design Storm Event in mm
20 30 40 50 60
Settling
Zone
Volume
(m3/ha)
Moderate-
high runoff
70 127 200 290 380
Very high
runoff
100 167 260 340 440
Total
Volume
(m3/ha)
Moderate-
high runoff
105 190 300 435 570
Very high
runoff
150 250 390 510 660
http://www.msmam.com 38
2.2.15: Erosion and
Sediment Control
• Universal Soil Loss Equation (USLE)
• Modified Universal Soil Loss Equation
(MUSLE)
http://www.msmam.com 39
2.2.16: Rainwater Harvesting
• Average Annual Rainwater Yield
• Tank size estimation
No. Name of Town Average Annual
Rainwater Yield
(m3)
1 Alor Star 103
2 Ipoh 99
3 Klang 107
4 Kuala Lumpur 116
5 Seremban 98
6 Melaka 100
7 Kluang 115
8 Johor Baru 128
9 Kota Baru 95
10 Kuala Terengganu 94
11 Kuantan 111
12 Kuching 156
13 Sibu 144
14 Bintulu 148
15 Kota Kinabalu 109
16 Sandakan 120
17 Tawau 89
http://www.msmam.com 41
2.2.18: Engineered Channel
• MSMA (2011)
• Design criteria for different types of
engineered channels
Channel Type Minimu
m
Freeboa
d (mm)
Minimu
m
Longitu
dinal
Grade
(%)
Maximum
Average
Flow
Velocity
(m/s)
Maxi
mum
Side
Slope
Natural channels 300 0.1 2 1V:3H
Grassed
channels
300 0.1 2 1V:3H
Soft lined
channels with
turf
reinforcements
mats (TRM)
300 0.1 4 1V:2H
Composite
channels
300 0.4 4 1V:1.5
H
Hard lined
channels
300 0.4 4 Vertic
al
http://www.msmam.com 43
Chapter 3: Case Studies
• 3.1.1: Case Study 1- Design A.R.I.
• 3.1.2: Case Study 2: Design Storm
• 3.1.3: Case Study 3: Design Discharge
Estimate using Rational Method
• 3.1.4: Case Study 4: On-Site Detention
• 3.1.5: Case Study 5: Sediment Basin Sizing
http://www.msmam.com 44
3.1.1: Case Study 1-
Design A.R.I.
• Changes in the design A.R.I. on rainfall intensities
is assessed.
• Using the design storm A.R.I. for the old and new
procedures, the rainfall intensities for both minor
and major systems are compared.
• The quantum of increase is assessed.
• The location of the study is in Sg. Batu, Kuala
Lumpur.
http://www.msmam.com 45
3.1.1: Case Study 1-
Design A.R.I. (Results)
• For medium density residential and commercial and city
area, the storm intensity has increased by up to 22% for
minor system for an A.R.I increase from 5 to 10 years
• And up to 33% for major system for an A.R.I increase
from 50 year to 100 years from MSMA (2000) to (2011).
• changes in the storm intensity is not only due to changes in
the A.R.I but also the higher IDF data in MSMA (2011).
• It is expected the same proportional increase in the design
discharge is observed.
http://www.msmam.com 46
3.1.2: Case Study 2-
Design Storm
• The design storm estimates are compared
using the IDF formulas from MSMA (2000)
& 2011 for Kualta Lumpur.
• The objective is to determine the changes in
design rainfall due to differences in the IDF
formulas.
http://www.msmam.com 47
3.1.2: Case Study 2-
Design Storm (Results)
• Durations of between 15 to 700 min, the IDF estimates
using MSMA (2011) were mostly higher than those
estimated using MSMA (2000).
• In the study, out of 14 stations, 10 of them (or 71%) were
higher than the MSMA (2000) curve, while the remaining
4 stations (or 29%) were lower than the first edition
estimates.
• Conclusion: design storms estimated based on MSMA
(2011) for Kuala Lumpur can be up to about 26% higher
than MSMA (2000) for duration below 700 minutes, for
71% of the stations.
http://www.msmam.com 48
3.1.2: Case Study 2-
Design Storm (Results)
• IDF (KL) ARI= 100 yr
1
10
100
1000
1 10 100 1000 10000
Rai
nfa
ll In
ten
sity
(m
m/h
r)
Storm Duration (min)
Comparison of Estimated Rainfall Intensity Frequency Duration Curves for Kuala Lumpur between MSMA 2000 & 2011 (A.R.I. =100 YR)
0 (MSMA 2000) 1 (MSMA 2011) 2 (MSMA 2011) 3 (MSMA 2011) 4 (MSMA 2011)
5 (MSMA 2011) 6 (MSMA 2011) 7 (MSMA 2011) 8 (MSMA 2011) 9 (MSMA 2011)
10 (MSMA 2011) 11 (MSMA 2011) 12 (MSMA 2011) 13 (MSMA 2011) 14 (MSMA 2011)
http://www.msmam.com 49
3.1.3: Case Study 3- Design
Discharge (Rational Method)
• The Rational Method for 1st and 2nd editions
are applied to a typical catchment and the
results compared.
• The changes in the design discharge due to
changes in the runoff coefficient C is
assessed.
• The study area is located in Sg. Batu, Kuala
Lumpur.
http://www.msmam.com 50
3.1.3: Case Study 3- Design
Discharge (Rational Method)
• For commercial and city area, the peak discharge from MSMA (2011)
is about 31% higher than the peak discharge from MSMA (2000). The
Q has increased from 16.9 to 22.1 m3/s. The C has increased from
0.905 to 0.95 while the storm intensity has increased from 224.3
mm/hr to 279.4.
• In conclusion, the peak discharge computed using the Rational Method
in MSMA (2011) is up to 31% higher than that in MSMA (2000).
• In general, it is concluded that 71% of the stations in Kuala Lumpur
will have up to 26% higher storm intensity and up to 31% higher peak
discharges for commercial and city area.
http://www.msmam.com 51
3.1.4: Case Study 4-
On-Site Detention
• Design of On-Site Detention (OSD)
facilities using MSMA (2000) and MSMA
(2011) for a proposed factory site in Sg
Batu, Kuala Lumpur.
http://www.msmam.com 52
3.1.4: Case Study 4-
On-Site Detention
• The result (Table 3.16) shows that for Kuala
Lumpur, the PSD using MSMA (2011) is
about 20% of that using MSMA (2000).
• For the SSR, the result shows that the figure
using MSMA (2011) is about 190% that
using MSMA (2000).
http://www.msmam.com 53
3.1.5: Case Study 5-
Sediment Basin Sizing
• Case Study: To design a dry sediment basin
for a construction site in Kuala Lumpur
using MSMA (2000) and (2011).
• Same catchement data.
http://www.msmam.com 54
3.1.5: Case Study 5-
Sediment Basin Sizing
• The dry sediment basin volume using MSMA (2011) is half of that
using MSMA (2000) for 6 month A.R.I design (for projects taking
more than two years) as MSMA (2011) does not cover 6 month A.R.I.
• The wet sediment basin volume was 65% higher using MSMA (2011)
compared to MSMA (2000) because of it was based on 50 mm of
rainfall for temporary BMP in MSMA (2011), compared to the 75th
percentile storm of 36.75 mm in MSMA (2000) which is lower.
• For locations where the 75th percentile 5-day storms are lower than 50
mm, it is expected the wet sedimentation basin volume will decrease
compared to MSMA (2000) using MSMA (2011).
http://www.msmam.com 55
Question: Spreadsheet
or Computer software?
• A dumb engineer is one who use computer
software blindly without understanding the
basic principles involved.
• A smart engineeer is one who understand
the basic principles involved and can apply
them in his design.
http://www.msmam.com 56
Advantages of Spreadsheets
1. Be a real PRO: Understand how to solve
problem from first principles!
2. Can be recycled!
3. Allows plotting easily.
4. Can output results easily.
5. Allows trials and error.
http://www.msmam.com 57
Examples of Spreadsheets
1.Computation of design storm
2.Computation of peak discharge
3.Reservoir routing
4.Design of detention basin
5.Design of sediment basin
6.Water surface profile computation
7.Culvert design procedure
8.Onsite Detention (OSD)
http://www.msmam.com 58
Example 1- Computation of
Design Storms (Workshop A)
• MSMAM uses a set of polynomial equations
for 35 major urban centres in Malaysia.
• PDP1 uses:
– IFD curves derived for 11 cities in P. Malaysia
– HP1 uses a set of ½, 2 & 24 hour isopleths of 2
and 20 year A.R.I. for Malaysia.
http://www.msmam.com 59
Example 2- Computation of
Peak Discharge (Workshop A)
• MSMAM uses:
– For area < 0.8 km2, Rational Method.
– For area > 0.8 km2,
• Time-Area Method
• Runoff-Routing Computer Models
• PDP1 uses:
– Modified Rational Method
http://www.msmam.com 60
Hydrograph Methods:
• Time-Area Method- Design method, spreadsheet. (Workshop 1)
• Runoff-Routing Computer Models (HEC-HMS)- Design and event simulation model, software can simulate changes in landuse, drains types, ponds, detention basins, etc.
• Use with HEC-RAS- powerful tool! (Workshop 2)
http://www.msmam.com 61
Example 3- Reservoir Routing
(Workshop B)
• MSMAM uses level-pool routing method.
• PDP1 uses a graphical procedure to
determine the maximum differential storage
based on the cumulative inflow and
outflow. Note:
MSMAM more accurate
PDP1 approximate
http://www.msmam.com 62
Example 4- Design of
Detention Basin (Workshop B) • MSMAM uses:
– Hydrograph method for inflow
– Level-pool routing through basin
– Can route inflow hydrograph through basin to get outflow hydrograph
• PDP1 uses:
– Modified Rational Method for inflow
– Graphical method of determining storage
– Cannot route hydrograph through basin
• MSMAM states that Post-Development Peak = Pre-Development Peak for major & minor storms
Note:
MSMAM computes
outflow hydrograph
from detention basin
http://www.msmam.com 63
Example 5- Design of
Sediment Basin (Workshop D)
• MSMAM uses:
– 3 or 6 month A.R.I for design storm < or > 2 yr
– Wet/dry sediment basin
– Storage volume related to storm charateristics
(Time of concentration and storm depth)
• PDP1 uses:
– empirical formula to determine storage volume
Note:
MSMAM- more rational
PDP1- more empirical
http://www.msmam.com 64
Example 6- Water Surface Profile
Computation (Workshop C)
• MSMAM:
– Recommends the use of HEC-RAS
– Steady state one dimensional open channel
hydraulics.
• PDP1:
– Unclear on this
– Backwater profile computation using standard step
method considered too difficult
– Manning Formula
Note:
HEC-RAS: Solution of energy equation.
Excellent free public domain software.
http://www.msmam.com 65
Example 7- Culvert Design
Procedure (Workshop B)
• MSMAM uses:
– SI units
– Different nomographs
– More entrance loss coefficients (outlet control)
• PDP1 uses:
– Imperial units
– Different nomographs
– Less entrance loss coefficients
Note:
MSMAM culvert formula wrong!
Eqn 27.4, 27.5
http://www.msmam.com 66
Topics Covered- Recap:
• In general, it is concluded that 71% of the
stations in Kuala Lumpur will have up to
26% higher storm intensity and up to 31%
higher peak discharges for commercial and
city area.
Upcoming Workshops
Workshop Day Content
Workshop A Day 1 Design storm, Rational Method, HP’s
Workshop A Day 2 Time-Area Method
Workshop B Day 1 Reservoir routing, detention basin
Workshop B Day 2 OSD, culvert design
Workshop C Day 1 Hydrologic Modelling using HEC-HMS
Workshop C Day 2 Hydraulic Modelling using HEC-RAS
Workshop D Day 1 Sediment Basins
Workshop D Day 2 Erosion and Sediment Control Plan (ESCP)
http://www.msmam.com 67
Upcoming Workshop
• 13th hands-on training workshop
• Date: 25 June- 4 July, 2013
• Location: C&S room, IEM
• To download registration form, type
http://workshop.msmam.com
• To download material in this Seminar:
• http://seminar1.msmaware.com
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