technical guide no.1 estimation of future design rainstorm under the climate change scenario in...

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 MalaysiaMinistry of Natural Resources & Environment

Feb. 17, 2013

NAWMI, JPS

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

TASK 1 (T1) TASK 2 (T2) TASK 3 (T3) TASK 4 (T4)

Data Mining &Assembly

PD Series: Low &High Return

Period

AM Series: HighReturn Period

(>1yr)

Data:PD Series & AM

Series

3P-GPA or2P-GPA/EXP

3P-GEVor 2P-EV1

L-MOMENTS(LMOM)

METHODS OFMOMENT (MOM)

ONE-STEP LEASTSQUAREMETHOD

Choice of RainfallFreq. Model

Choice of Prob.Distribution

Method of ParameterEstimator

OUTLIER CHECKING

OPTIONAL forUNGAUGED

Part 1 : HP1 (2010) -1/3

ROBUSTNESSANALYSIS :

BIAS & RMSE

RANDOMNUMBER

ACCURACY :ROOT MEAN

SQUARE ERROR

GOODPERFORMANCE :

BIAS

BEST FIT/APPROPRIATE

MODEL

3P-GPA/LMOM3P-GEV/LMOM

2P-GPA/EXP/LMOM2P-EV1/LMOM2P-EV1/MOM

3P-GEV/OS-LSM

Estimation of theDesign Storm of Low

and High ReturnPeriod

TASK 5(T5)

Construction andFormulation of at-

site IDF Curve&

UNGAUGED SITE

TASK 6(T6)

T7T8T9

TASK 1 (T1) TASK 2 (T2) TASK 3 (T3) TASK 4 (T4)

BEST FIT/ APPROPRIATE

MODEL

3P-GPA/LMOM

3P-GEV/LMOM

2P-GPA/EXP/LMOM

2P-EV1/LMOM

2P-EV1/MOM

3P-GEV/OS-LSM

Estimation of the Design Rainstorm

Math. Formulation of

at-Site IDF & Ungauged Site

T7T8

Part 1 : HP1 (2010) -2/3

Dauto

Cauto

Jauto

Kauto

Rauto

Pauto

Aauto

Bauto

Wauto

Nauto Mauto

Tauto

Total Nos. of Raingauges

188

627

Part 1 : HP1 (2010) -3/3

Rainfall Intensity Duration Frequency CurveSite 3117070@Pusat Penyelidikan JPS Ampang, Selangor

1.0

10.0

100.0

1000.0

0.1 1 10 100Duration (hr)

Rai

nfa

ll In

ten

sity

(m

m/h

r)

2 5 10 20 50 100

0.25 155.1 177.7 196.9 218.2 249.9 276.90.5 103.8 118.9 131.8 146.0 167.2 185.31 64.6 74.0 82.0 90.8 104.1 115.33 27.9 31.9 35.4 39.2 44.9 49.76 15.9 18.2 20.2 22.4 25.7 28.412 9.0 10.3 11.4 12.7 14.5 16.124 5.1 5.8 6.4 7.1 8.2 9.048 2.8 3.3 3.6 4.0 4.6 5.172 2.0 2.3 2.6 2.9 3.3 3.6

Duration (hr)

Yearly Return Period

8372.0

1481.0

1559.0

8094.66

d

TI 100

50201052

Part 2 : NAHRIM Tech. Guide No.1

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 (2025-2050);

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

1.1 Background: Climate Change Scenario

1.2 Problem Statement

HYDROLOGIC & HYDRAULIC DESIGNTo 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)

810920:123001 8701 9001 9301 9601 9901 0201 YYYMM

A A

A site 5229436 SG. NERUS at KG. BUKIT,TERENGGANU Stage m

Start Time: Finish Time:

Lower Value: Upper Value:

810920 1230011040427 123700

6.00 16.00

Data units /pixel: Horizontal=5.00days Vertical=0.021mData units /pixel: Horizontal=5.00days Vertical=0.021m

710630:0800 8001 8601 9201 9801 YYMMA A

A site 5328044 KG. SG. TONG at TERENGGANU Rain mm/day (Total=94149)

Start Time: Finish Time:

Lower Value: Upper Value:

710630 0800001050131 090000

0.0 410.0

Data units /pixel: Horizontal=8.0days Vertical=0.84mmData units /pixel: Horizontal=8.0days Vertical=0.84mm

HYDRO-METEOROLOGY

DATAHYDRAULIC

STRUCTURES

Kg Guntung

Luar

Kg Che Salmah

Bdr Permaisuri

Kg Seladang

Kg K Guntung

Sg Tarum [7.97km]

Sg Setiu [5.48km]

Sg Setiu [8.6km]

Sg Tarum [8.7km]

Sg Setiu [11.11km]

Sg Tarum 9.5km]

Sg Setiu [4.34km]

Sg Setiu [9.48km]

Sg Lirim [13.16km]

Sg Lirim [8.70km]

Sg Setiu [14.55km]

Sg Ima Putih [12.38km]

Sg Pelung [9.3km]

Sg Pancur Merah [10.40km]

Sg Cakah Dua [11.00km]

Sg Guntung [13.86km

WATERSHED – “MEDIUM - SYSTEM”

HYDROLOGY MODELING

HYDRAULIC MODELING

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)

1.3 Objective of Technical Guideline

STEP 3:Derivation of CCF

STEP 4:Disaggregation of 1-day design rainfall to short duration and reformulation of IDF Curves

STEP 5:Rainfall-runoff modelling:

Obtain future Qp

STEP 1:Obtain downscaled climate

data projection

Statistical Downscaling Model: 18 GCMs

(2046-2065)

Statistical Downscaling Model: 18 GCMs

(2046-2065)

Dynamic Downscaling Model: RegHCM-PM

(2025-2034, 2041-2050)

Dynamic Downscaling Model: RegHCM-PM

(2025-2034, 2041-2050)

STEP 2:Bias correction of downscaled

data

Chap. 2: Approach & Methodology

Part 1

Part 2

IDF formulation

Derivation of CCF

STEP 1:Work out current (1971-2007) 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

1981-2000 and 1984-1993 (control period) from the 18 GCMs and RegHCM-PM respectively.

STEP 4:Repeat STEP 3 using climate model data for the periods

2025-2050 (RegHCM-PM) & 2046-2065 (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.

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.

Eq. 28 (Pg.17)

2.4 Incorporation of CCF and Historical at-Site IDF (Pg.14)

Eq. 30 (Pg.17) Eq. 29 (Pg.17)

2.4.32.4.1 & 2.4.2

Chap. 3: Results & Findings

Table 3.1: At site 1 day Climate Change Factor (CCF) corresponding to Return Period in Peninsular Malaysia (Pg. 20-23)

State No. Station ID Station Name

Climate Change Factor, CCF

Return Period, T

2 5 10 20 25 50 100 200

Kedah

1 6207032 Ampang Pedu 1.05 1.08 1.09 1.10 1.11 1.12 1.13 1.13

2 5507076 Bt.27, Jln Baling 1.12 1.16 1.18 1.20 1.21 1.22 1.24 1.25

3 5808001 Bt.61, Jln Baling 1.08 1.13 1.16 1.18 1.19 1.21 1.22 1.24

4 5704055 Kedah Peak 1.14 1.20 1.24 1.26 1.27 1.29 1.31 1.33

5 5806066 Klinik Jeniang 1.15 1.17 1.18 1.19 1.20 1.20 1.21 1.22

6 6108001 Komp. Rmh Muda 1.15 1.24 1.29 1.33 1.34 1.38 1.41 1.44

7 6206035 Kuala Nerang 0.97 1.07 1.13 1.17 1.18 1.22 1.25 1.28

8 6306031 Padang Sanai 1.08 1.09 1.11 1.14 1.15 1.18 1.23 1.28

9 6103047 JPS Alor Setar 1.07 1.17 1.22 1.26 1.28 1.32 1.35 1.38

State No. Station ID Station Name

1-day λ'

Return Period, T

2 5 10 20 25 50 100 200

Kedah

1 6207032 Ampang Pedu 69.47 71.27 72.22 73.00 73.22 73.86 74.41 74.90

2 5507076 Bt.27, Jln Baling 58.55 60.64 61.84 62.86 63.16 64.04 64.84 65.56

3 5808001 Bt.61, Jln Baling 51.41 53.74 55.00 56.06 56.37 57.24 58.02 58.71

4 5704055 Kedah Peak 92.90 98.19 100.91 103.08 103.70 105.44 106.93 108.24

5 5806066 Klinik Jeniang 68.59 69.98 70.71 71.30 71.47 71.95 72.37 72.73

6 6108001 Komp Rmh Muda 60.25 64.83 67.41 69.61 70.27 72.14 73.83 75.37

7 6206035 Kuala Nerang 53.34 58.78 61.68 64.07 64.76 66.71 68.42 69.94

8 6306031 Padang Sanai 65.37 65.71 66.84 68.48 69.10 71.32 73.94 76.97

9 6103047 JPS Alor Setar 69.44 75.61 79.04 81.94 82.79 85.23 87.41 89.38

Table 3.2: At site 1-day Future IDF Parameter (λ’) corresponding to Return Period in Peninsular Malaysia (Pg. 23-26)

IDF Parameters – Baseline (Historical) & Future

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

3.3 1 Day Climate Change Factor For Ungauged Sites (Pg. 27)

Fig. 3.1 – 3.8(Pg. 28-32)

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 2065. The climate change factors, CCF and modified λ, λ’ in this guideline are calculated for 1 day (24 hours) rainfall duration only.

Chap. 4 – Worked Example

(Pg.37-52)

Example 6: DESIGNED FLOOD PEAKS – SG KEDAH

ItemTime

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

Increment rate of rainfall

Increment rate of flow

220m3/s [179]

382m3/s[310.5]

554m3/s [449.5]

737m3/s [598.1]

ANALYSIS OUTCOME: WATER RESOURCES SECTOR

FLOOD MAPS– SG KEDAH

Time horizon

Area for flood depth (km2)

0.01 - 0.5 m

0.5 - 1.2 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

terima kasih

TECH GUIDE No.2 – The Design Guide for

Rainwater Harvesting System

25 Feb. 2014

technical guide no.1 estimation of future design rainstorm under the climate change scenario in...

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