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
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TECHNICAL GUIDE No.1 Estimation of Future Design Rainstorm under the Climate Change Scenario in Peninsular Malaysia Research Centre for Water Resources.
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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
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)
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.
Part 1 : HP1 (2010) Part 2 : NAHRIM Tech. Guide No.1