1. TECHNICAL GUIDE No.1
Estimation of Future Design Rainstorm under the Climate Change Scenario in Peninsular Malaysia
Research Centre for Water Resources & Climate Change
National Hydraulic Research Institute of Malaysia
Ministry of Natural Resources & Environment
Feb. 17, 2013
NAWMI, JPS

2. Part 2 : NAHRIM Tech. Guide No.1
Part 1 : HP1 (2010)
Part 2 : NAHRIM Tech. Guide No.1
Chap. 1 – 1.2 (problem state. &
1.3 (objective)
Chap. 2 – Approach & Methodology
Chap. 3 – Results & Findings
Part 3 : Chap. 4 - Worked Example

3. Part 1 : HP1 (2010) -1/3

4. Part 1 : HP1 (2010) -2/3
BEST FIT/ APPROPRIATE MODEL
Math. Formulation of at-Site IDF & Ungauged Site
Estimation of the Design Rainstorm T7 T8
3P-GPA/LMOM
3P-GEV/LMOM
2P-GPA/EXP/LMOM
2P-EV1/LMOM
2P-EV1/MOM
3P-GEV/OS-LSM

5. Total Nos. of Raingauges
Part 1 : HP1 (2010) -3/3
Total Nos. of Raingauges
Kauto
188
Dauto
Rauto
627
Pauto
Tauto
Aauto
Cauto
Bauto
Wauto
Jauto
Nauto
Mauto

7. Part 2 : NAHRIM Tech. Guide No.1
Part 1 : HP1 (2010)
Part 2 : NAHRIM Tech. Guide No.1
Chap. 1 – 1.2 (problem state. &
1.3 (objective)
Chap. 2 – Approach & Methodology
Chap. 3 – Results & Findings
Part 3 : Chap. 4 - Worked Example

8. Part 2 : NAHRIM Tech. Guide No.1

9. 1.1 Background: Climate Change Scenario
A study that has been carried out indicate a possible increase in inter-annual and intra-seasonal variability with increased hydrologic extremes (higher high flows and lower low flows) at various northern watersheds in the future ( );
The probability of increase in rainfall would lead to a raise in river flow of between 11% and 47% for Peninsular Malaysia with low flow reductions ranging from 31% to 93% for the central and southern regions (NAHRIM, 2006);
Parts of Malaysia may experience a decrease in return for extreme precipitation events and the possibility of more frequent floods as well as drought

10. 1.2 Problem Statement

11. HYDROLOGIC & HYDRAULIC DESIGN
To estimate water surface profile, platform level, size of hydraulic structure corresponding to any return period of occurrence or level of protection AVERAGE RECURRENCE INTERVAL (RETURN PERIOD)
HYDRO-METEOROLOGY DATA
HYDRAULIC STRUCTURES
WATERSHED – “MEDIUM - SYSTEM”
HYDROLOGY MODELING
HYDRAULIC MODELING

12. 1.3 Objective of Technical Guideline
To assist engineers, hydrologists and decision makers in designing, planning and developing water-related infrastructure under changing climatic conditions.
To introduce an approach of quantifying the scale of climatic change to surface water systems.
The main purpose of this guideline is to derive climate change factor (CCF)
CCF – defined as the ratio of the design rainfall for each of the future periods (time horizons) to the control periods of historical rainfall)
The objective of this guideline is to assist engineers, hydrologists and decision makers in designing, planning and developing water-related infrastructure under changing climatic conditions. The aim is to introduce an approach of quantifying the scale of climatic change to surface water systems, particularly due to variability and fluctuations in precipitation pattern, through the development of climate change factor and reformulation of the developed Intensity-Duration-Frequency relationship by Dept of Irrigation and Drainage for future conditions. The main purpose of this guideline is to derive climate change factor (CCF). CCF is defined as the ratio of the design rainfall for each of the future periods (time horizons) to the control periods (present rainfall).

13. Chap. 2: Approach & Methodology
Obtain observed annual maximum rainfall over various durations
Review, update & reformulate IDF relationships
(1970 – 2007)
Part 1
IDF formulation
STEP 1:
Obtain downscaled climate data projection
STEP 2:
Bias correction of downscaled data
Part 2
Statistical Downscaling Model: 18 GCMs
( )
STEP 3:
Derivation of CCF
Derivation of CCF
This flowchart depicts the methodology workflow of estimation and quantification of climate change impacts on floods.
The first part involves IDF formulation, while the second part continues with the derivation of CCF.
For IDF formulation, the observed annual maximum rainfall over various durations and return periods was obtained for selected rainfall stations. The IDF relationships were then reviewed, updated, and reformulated.
The second part, derivation of CCF, will be explained in detail in following slides.
There are three main elements in the derivation of CCF, which are [1] climate change projection by means of downscaling technique, [2] derivation of climate change ‘load’ factor, and [3] disaggregation of 1-day design rainfall to short duration and the formulation of future Intensity-Duration-Frequency (IDF) relationship.
Dynamic Downscaling Model: RegHCM-PM
( , )
STEP 4:
Disaggregation of 1-day design rainfall to short duration and reformulation of IDF Curves
STEP 5:
Rainfall-runoff modelling: Obtain future Qp

14. 2.3.2 - Derivation of Climate Change Factor (Pg.13)
defined as a ratio of the design rainfall for each of the future periods to the control periods (historical) for each time horizon.
STEP 1:
Work out current ( ) return levels of all rainfall events with return periods between 2 and 200-years from observed database rainfall data using GEV and EV1.
STEP 2:
Identify current return levels for 7 return periods (1 in 5, 10, 20, 25, 50, 100 and 200-year events) from STEP 1.
STEP 3:
Repeat STEP 1 using climate model data for the period and (control period) from the 18 GCMs and RegHCM-PM respectively.
STEP 4:
Repeat STEP 3 using climate model data for the periods (RegHCM-PM) & (GCMs)
STEP 5:
Calculate climate change load factors by dividing the return level for each of the future periods (STEP 4) by the return level for the control period (STEP 3), again for all of the return periods.
Eq. 28 (Pg.17)

15. 2.4 Incorporation of CCF and Historical at-Site IDF (Pg.14)
2.4.1 & 2.4.2
2.4.3
Eq. 30 (Pg.17)
Eq. 29 (Pg.17)

16. Chap. 3: Results & Findings
Table 3.1: At site 1 day Climate Change Factor (CCF) corresponding to Return Period in Peninsular Malaysia (Pg )
State
No.
Station ID
Station Name
Climate Change Factor, CCF
Return Period, T 2 5 10 20 25 50
100
200
Kedah 1
Ampang Pedu
1.05
1.08
1.09
1.10
1.11
1.12
1.13
Bt.27, Jln Baling
1.16
1.18
1.20
1.21
1.22
1.24
1.25 3
Bt.61, Jln Baling
1.19 4
Kedah Peak
1.14
1.26
1.27
1.29
1.31
1.33
Klinik Jeniang
1.15
1.17 6
Komp. Rmh Muda
1.34
1.38
1.41
1.44 7
Kuala Nerang
0.97
1.07
1.28 8
Padang Sanai
1.23 9
JPS Alor Setar
1.32
1.35

17. Table 3.2: At site 1-day Future IDF Parameter (λ’) corresponding to Return Period in Peninsular Malaysia (Pg )
State
No.
Station ID
Station Name
1-day λ'
Return Period, T 2 5 10 20 25 50
100
200
Kedah 1
Ampang Pedu
69.47
71.27
72.22
73.00
73.22
73.86
74.41
74.90
Bt.27, Jln Baling
58.55
60.64
61.84
62.86
63.16
64.04
64.84
65.56 3
Bt.61, Jln Baling
51.41
53.74
55.00
56.06
56.37
57.24
58.02
58.71 4
Kedah Peak
92.90
98.19
100.91
103.08
103.70
105.44
106.93
108.24
Klinik Jeniang
68.59
69.98
70.71
71.30
71.47
71.95
72.37
72.73 6
Komp Rmh Muda
60.25
64.83
67.41
69.61
70.27
72.14
73.83
75.37 7
Kuala Nerang
53.34
58.78
61.68
64.07
64.76
66.71
68.42
69.94 8
Padang Sanai
65.37
65.71
66.84
68.48
69.10
71.32
73.94
76.97 9
JPS Alor Setar
69.44
75.61
79.04
81.94
82.79
85.23
87.41
89.38

18. IDF Parameters – Baseline (Historical) & Future
State
Station ID
Station Name
Derived Parameters λ λ' κ θ η
Kedah
Bt. 27, Jalan Baling
52.40
64.84
0.172
0.104
0.788
Kedah Peak
81.58
106.93
0.200
0.437
0.719
Klinik Jeniang
59.79
72.37
0.165
0.203
0.791
Bt. 61, Jalan Baling
47.50
58.02
0.183
0.079
0.752
Setor JPS Alor Setar
64.83
87.41
0.168
0.346
0.800
Kompleks Rumah Muda
52.34
73.83
0.173
0.120
0.792
Kuala Nerang
54.85
68.42
0.174
0.250
0.810
Ampang Padu
66.10
74.41
0.177
0.284
0.842
Padang Sanai
60.33
73.94
0.193
0.249
0.829

19. 3.3 1 Day Climate Change Factor For Ungauged Sites (Pg. 27)
Fig. 3.1 – 3.8
(Pg )
Figure 3.1: 1 Day Climate Change Factor (CCF) – 2yrs ARI Figure 3.2: 1 Day Climate Change Factor (CCF) – 5yrs ARI Figure 3.3: 1 Day Climate Change Factor (CCF) – 10yrs ARI Figure 3.4: 1 Day Climate Change Factor (CCF) – 20yrs ARI Figure 3.5: 1 Day Climate Change Factor (CCF) – 25yrs ARI Figure 3.6: 1 Day Climate Change Factor (CCF) – 50yrs ARI Figure 3.7: 1 Day Climate Change Factor (CCF) – 100yrs ARI Figure 3.8: 1 Day Climate Change Factor (CCF) – 200yrs ARI

20. 3.4 LIMITATIONS OF GUIDELINE
The climate projection data used in the calculation of climate change factor in this study are averaged from 18 chosen GCMs. For this study, the emission scenario A1B from IPCC SRES is assumed. The A1B is a scenario in which the usage of all energy sources is evenly balanced. The dataset used in this analysis covers only two future periods from 2025 to 2050 and from 2046 to The climate change factors, CCF and modified λ, λ’ in this guideline are calculated for 1 day (24 hours) rainfall duration only.

21. Part 2 : NAHRIM Tech. Guide No.1
Part 1 : HP1 (2010)
Part 2 : NAHRIM Tech. Guide No.1
Chap. 1 – 1.2 (problem state. &
1.3 (objective)
Chap. 2 – Approach & Methodology
Chap. 3 – Results & Findings
Part 3 : Chap. 4 - Worked Example

22. Chap. 4 – Worked Example
(Pg.37-52)

24. DESIGNED FLOOD PEAKS – SG KEDAH
Example 6:
DESIGNED FLOOD PEAKS – SG KEDAH
Item
Time Horizon
Climate Change Factor (CCF)
1-Day Design Rainfall (mm)
Peak Discharges (Qp) 100-years ARI
Percentage Increase of Flood Magnitude
(%)
Climate Change Scenario Flood Magnitude, Qp (m3/s)
Climate Change Scenario Flood Magnitude Increment (m3/s)
Baseline -
241
2048 1
2020
1.05
245
2111 63
3.1 2
2030
1.09
257
2268
220
10.7 3
2040
1.14
268
2430
382
18.7 4
2050
1.19
280
2602
554
27.1 5
2060
1.25
293
2785
737
36.0
The design rainstorm for the basin is derived by means of Thiessen weight factor of all stations in the basin. The result is shown in this table. As shown in the last column, the 100-years ARI flood peaks (Qp) is projected to increase by 3.1% from 2048 m3/s baseline condition to 2111 m3/s in 2020 and up to 36% or 737m3/s in time horizon 2060.

25. Increment rate of rainfall
Increment rate of flow
737m3/s [598.1]
554m3/s [449.5]
382m3/s[310.5]
The rising flood peaks from the table are shown in this graph as a blue line. The green line shows the increasing rainfall, and the red line is the projected annual mean surface temperature for Malaysia.
220m3/s [179]
Increment rate of rainfall

26. ANALYSIS OUTCOME: WATER RESOURCES SECTOR
FLOOD MAPS– SG KEDAH
Time horizon
Area for flood depth (km2) m m
>1.2 m
Sum
Baseline
50.50
41.55
35.57
127.62
2020
51.24
43.91
37.92
133.06
2030
51.01
45.18
39.90
136.10
2040
50.51
46.86
42.00
139.36
2050
49.13
49.17
44.20
142.50
2060
48.16
50.00
46.95
145.10
These flood maps are generated by using Infoworks. These maps show the increasing projected flood extent in the future. Note that the table shows the increasing flood area calculated in ArcGIS. These maps can be used by economist to estimate the projected damage from future flood events.

27. terima kasih

28. TECH GUIDE No.2 – The Design Guide for Rainwater Harvesting System
25 Feb. 2014