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

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

Part 1 : HP1 (2010) -1/3

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

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

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

Part 2 : NAHRIM Tech. Guide No.1

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 (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

1.2 Problem Statement

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

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).

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 (2046-2065) 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 (2025-2034, 2041-2050) STEP 4: Disaggregation of 1-day design rainfall to short duration and reformulation of IDF Curves STEP 5: Rainfall-runoff modelling: Obtain future Qp

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 (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.   Eq. 28 (Pg.17)

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)

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 5507076 Bt.27, Jln Baling 1.16 1.18 1.20 1.21 1.22 1.24 1.25 3 5808001 Bt.61, Jln Baling 1.19 4 5704055 Kedah Peak 1.14 1.26 1.27 1.29 1.31 1.33 5806066 Klinik Jeniang 1.15 1.17 6 6108001 Komp. Rmh Muda 1.34 1.38 1.41 1.44 7 6206035 Kuala Nerang 0.97 1.07 1.28 8 6306031 Padang Sanai 1.23 9 6103047 JPS Alor Setar 1.32 1.35

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

IDF Parameters – Baseline (Historical) & Future State Station ID Station Name Derived Parameters λ λ' κ θ η Kedah 5507076 Bt. 27, Jalan Baling 52.40 64.84 0.172 0.104 0.788 5704055 Kedah Peak 81.58 106.93 0.200 0.437 0.719 5806066 Klinik Jeniang 59.79 72.37 0.165 0.203 0.791 5808001 Bt. 61, Jalan Baling 47.50 58.02 0.183 0.079 0.752 6103047 Setor JPS Alor Setar 64.83 87.41 0.168 0.346 0.800 6108001 Kompleks Rumah Muda 52.34 73.83 0.173 0.120 0.792 6206035 Kuala Nerang 54.85 68.42 0.174 0.250 0.810 6207032 Ampang Padu 66.10 74.41 0.177 0.284 0.842 6306031 Padang Sanai 60.33 73.94 0.193 0.249 0.829  

3.3 1 Day Climate Change Factor For Ungauged Sites (Pg. 27) Fig. 3.1 – 3.8 (Pg. 28-32) 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

3.4 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 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

Chap. 4 – Worked Example (Pg.37-52)

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.

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

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 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.

terima kasih

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