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TECHNICAL GUIDE No.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.

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TECHNICAL GUIDE No.1

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

  6. 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

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

  8. 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

  9. 1.2 Problem Statement

  10. 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) HYDROLOGY MODELING HYDRAULIC MODELING HYDRO-METEOROLOGY DATA WATERSHED – “MEDIUM - SYSTEM” HYDRAULIC STRUCTURES

  11. 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)

  12. Chap. 2: Approach & Methodology Part 1 IDF formulation STEP 1: Obtain downscaled climate data projection STEP 2: Bias correction of downscaled data Part 2 STEP 3: Derivation of CCF Statistical Downscaling Model: 18 GCMs (2046-2065) Derivation of CCF STEP 4: Disaggregation of 1-day design rainfall to short duration and reformulation of IDF Curves Dynamic Downscaling Model: RegHCM-PM (2025-2034, 2041-2050) STEP 5: Rainfall-runoff modelling: Obtain future Qp

  13. 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)

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

  15. 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)

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

  17. IDF Parameters – Baseline (Historical) & Future

  18. 3.3 1 Day Climate Change Factor For Ungauged Sites (Pg. 27) 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 Fig. 3.1 – 3.8 (Pg. 28-32)

  19. 3.4LIMITATIONS 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.

  20. 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

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

  22. Example 6: DESIGNED FLOOD PEAKS – SG KEDAH

  23. Increment rate of flow 737m3/s [598.1] 554m3/s [449.5] 382m3/s[310.5] 220m3/s [179] Increment rate of rainfall

  24. ANALYSIS OUTCOME: WATER RESOURCES SECTOR FLOOD MAPS– SG KEDAH

  25. terima kasih

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

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