Pilbara rfa ea presentation v3.2 1

1,062 views
989 views

Published on

0 Comments
0 Likes
Statistics
Notes
  • Be the first to comment

  • Be the first to like this

No Downloads
Views
Total views
1,062
On SlideShare
0
From Embeds
0
Number of Embeds
0
Actions
Shares
0
Downloads
16
Comments
0
Likes
0
Embeds 0
No embeds

No notes for slide

Pilbara rfa ea presentation v3.2 1

  1. 1. Pilbara Region Flood Frequency Free Powerpoint TemplatesAnalysis ReviewBy Jim Davies and Edwin YipJDA Date: Free Powerpoint Templates 12 November 2012 Page 1
  2. 2. Outline of the Presentation Free Powerpoint Templates• Introduction• Study Area and Flow Data• Methodology and Results• Conclusions Page 2
  3. 3. Outline of the Presentation Free Powerpoint Templates• Introduction• Study Area and Flow Data• Methodology and Results• Conclusions Page 3
  4. 4. Outline of the Presentation Free Powerpoint Templates• Introduction – Background – Previous Studies – Scope of this Study – Source of Information Page 4
  5. 5. Introduction Free Powerpoint TemplatesBackground•Regional method is for ungauged catchment floodestimation•Frequency analysis is estimation of how often aspecified event will occur•Extreme environmental event such as floods, havesevere consequences for society Page 5
  6. 6. Introduction Free Powerpoint TemplatesBackground (Cont.)•Couple of advance statistical techniques weredeveloped since the last two decades after thepublication of ARR1987, –L-moments were introduced in 1990’s.•The aim of this study is to review the ARR1987Index-flood Method of Pilbara utilizing:- –advance statistical techniques, and –flow measurement records up to 2012 Page 6
  7. 7. Introduction Free Powerpoint TemplatesPrevious StudiesEstimation of design peak discharge for ungauged catchments:• 1972 US Bulletin 17 – LPIII• 1975 UK Flood Studies Report – GEV• 1987 Australia AR&R – LPIII• 1997 “Regional Frequency Analysis” – Complete Procedure by Hosking & Wallis - L moments - Screening of Data - Regions - Choice of Distribution - Estimation of Frequency Page 7
  8. 8. Introduction Free Powerpoint TemplatesRegions defined in ARR198725 years out of date now Pilbara Region Gascoyne Region (firm recommendations of design discharges were not made in ARR1987)Pilbara Region + Gascoyne Region= Drainage Division 7 Page 8
  9. 9. Introduction Free Powerpoint TemplatesPilbara Index-flood Method (ARR1987)•was developed utilizing 13 stream gaugingstations in Pilbara Region•Methodology – Annual Exceedance Series – Log-Normal distribution (assumed the generalised skew coefficient was zero) – Method of Product-Moments – All 13 catchments to form one Pilbara region Page 9
  10. 10. Introduction Free Powerpoint TemplatesPilbara Index-flood Method (ARR1987)(Cont.)•Frequency Factors are depending on: – Catchment Area – ARIs ARI 2 yrs 5 yrs 10 yrs 20 yrs 50 yrs Area Frequency Factors (km2) 1 0.55 1.00 1.58 2.40 3.90 10 0.52 1.00 1.70 2.77 4.90 100 0.50 1.00 1.81 3.20 6.30 1,000 0.48 1.00 1.94 3.70 7.90 10,000 0.46 1.00 2.08 4.25 9.90 Page 10
  11. 11. Introduction Free Powerpoint TemplatesPilbara Index-flood Method (ARR1987)(Cont.)•Index-flood: – Design Discharge of 5-year ARI [m3/s] Q5 = 6.73 x 10-4 A0.72 P1.51•Parameters in Design Discharge Equation: – Catchment factor: Catchment Area (A) [km2] – Climatic factor: Average Annual Rainfall Depth over the Catchment Area (P) [mm] Page 11
  12. 12. Introduction Free Powerpoint TemplatesL-Moments (Hosking & Wallis, 1997)• Sample moment statistics especially skewness and Kurtosis not reliable (biased) as algebraically bounded.• “L-moments” are linear combinations of order statistics – less subject to bias. Page 12
  13. 13. Introduction Free Powerpoint TemplatesSoftware•R-Project –with L-moments Packages “lmom” and “lmomRFA”•The R-Project and L-moment Packages are freelyavailable –Website: http://www.r-project.org/•J. R. M. Hosking is the developer and maintainer ofthe L-moment Packages Page 13
  14. 14. Introduction Free Powerpoint TemplatesEA AR&R Revision Projects: Project 5“Regional Flood Methods”Stage 2 ReportPS/S2/015June 2012By University Of Western SydneyTo test generic techniques for all Australia(WA Contributors: JR, NC, LP, MP, JG) Page 14
  15. 15. Introduction Free Powerpoint TemplatesProject 5 Stage 2 Report June 2012,General:• RFFA methods preferred to PRM• QRT and PRT perform similarly• PRT preferred due to smoothness• ROI outperforms fixed regions• RFFA requires only area and design rainfall intensity data (easy and simple)• Arid and semi-arid regions have insufficient data for RFFA; recommends simplified RFFA (4 regions)• Trends will be analyzed in Stage III (expected to be adjustment of ARI’s Page 15
  16. 16. Introduction Free Powerpoint TemplatesProject 5 Stage 2 Report June 2012Western Australia Specific –146 catchments (gauging stations) •Kimberley: 14 stations •Pilbara: 12 stations •South West: 120 stations –Area Range 0.1 to 7,405 km2 Page 16
  17. 17. Introduction Free Powerpoint TemplatesProject 5 Stage 2 Report June 2012• Pilbara Region 0.1 to 1,000 km2• Fixed region (all 12 stations)• QRT Q2, Q5, Q10, Q20, Q50, Q100 – Function of Catchment Area and Rainfall Intensity• PRT M, S, G – Function of Catchment Area, Rainfall Intensity, forest area, and stream density Page 17
  18. 18. Introduction Free Powerpoint TemplatesProject 5 Stage 2 Report June 2012 Flow records from 12 gauging stations in Drainage Division 7 were selected and analyzed in “ARR Revision Projects - Project 5 Regional Flood Methods Stage II” Source: Rahman, A., Haddad, K., Zaman, M., Ishak, E., Kuczera, G. and Weinmann, P. E. (2012). Regional flood methods for Australia, ARR Revision Project 5 Stage 2 Report, Engineers Australia, Report No. P5/S2/015 Page 18
  19. 19. Introduction Free Powerpoint TemplatesScope of this Study•To develop design equations for Index-flood (Q5)to estimate design peak discharges for ungaugedcatchments –utilizing the updated stream flow measurement records•To review the frequency factors of ARR1987 Index-flood method to Pilbara –utilizing the updated stream flow measurement records –utilizing advance statistical techniques Page 19
  20. 20. Introduction Free Powerpoint TemplatesScope of this Study (Cont.)•To compare the design discharges between thisstudy and other studies –ARR1987 –“Design Flood Estimation in Western Australia” by David Flavell (2012) (Flavell 2012) –“ARR Revision Projects - Project 5 Regional Flood Methods Stage II” by Ataur Rahman and others (2012) (ARR P5 S2) Page 20
  21. 21. Introduction Free Powerpoint TemplatesSource of Information•Department of Water – Daily maximum flow measurement records – Location of stream gauging stations•Bureau of Meteorology – Average Annual Rainfall Depth•ARR1987 – Design Rainfall Intensity Page 21
  22. 22. Outline of the Presentation Free Powerpoint Templates• Introduction• Study Area and Flow Data• Methodology and Results• Conclusions Page 22
  23. 23. Study Area and Flow Data Free Powerpoint Templates Page 23
  24. 24. Study Area and Flow Data Free Powerpoint TemplatesStudy Area•Whole Drainage Division 7 (i.e. Division of IndianOcean) including 10 River Basins as listed follow:- – Greenough River (701), – Murchison River (702), – Wooramel River (703) , – Gascoyne River (704), – Lyndon-Minilya Rivers (705), – Ashburton River (706), – Onslow Coast (707), – Fortescue River (708), – Port Hedland Coast (709), and – De Grey River (710) Page 24
  25. 25. Study Area and Flow Data Free Powerpoint Templates 709 - Port Hedland Coast 707 - Onslow Coast 710 - De Grey River 705 - Lyndon-Minilya Rivers 708 - Fortescue River 706 - Ashburton River 704 - Gascoyne River703 - Wooramel River 702 - Murchison River- Selected Stations (60) 701 - Greenough River Page 25
  26. 26. Study Area and Flow Data Free Powerpoint Templates World Maximum Flood Maximum Floods in Pilbara Region Yule River (1975) Ashburton River (1997) Sherlock River (1971) Fortescue River (2004) Nullagine River (2002) Robe River (2009) Sherlock River (1984) Portland River (1984) Source: Flavell, D. 2012, “Design flood estimation in Western Australia”, Australian Journal of Water Resources, Vol. 16, No. 1, pp. 1-20, http://dx.doi.org/10.7158/W11-865.2012.16.1 . Page 26
  27. 27. Study Area and Flow Data Free Powerpoint Templates Catchment Gauging Rank River Area (km2) Station No. 1 (largest) 86,777 Murchison River 702001 2 74,432 Gascoyne River 704139 3 71,387 Ashburton River 706003 4 71,212 Gascoyne River 704193 5 69,278 Gascoyne River 704194 6 50,007 De Grey River 710003 7 43,098 Ashburton River 706209 8 34,775 Gascoyne River 704195 9 29,752 Fortescue River 708006 10 19,613 Lyons River 704196 Page 27
  28. 28. Study Area and Flow Data Free Powerpoint Templates Catchment Gauging Rank River Area (km2) Station No. 51 198 Sthn Fortescue River 708004 52 174 Robe River 707001 53 128 Tanberry Creek 709006 54 78 Sherlock River 709009 55 77 Five Mile Creek 710002 56 50 Harding River 709002 57 49 Harding River 709007 58 41 Kanjenjie Creek Trib. 708009 59 34 Buller River 701006 Nokanena Brook 60 (smallest) 0.13 701601 Catch Page 28
  29. 29. Study Area and Flow Data Free Powerpoint TemplatesDesign Rainfall Intensity 35from ARR1987 [mm/hr](1hour duration, 2-years ARI) 30 27.5 25 22.5 20 18 16 20 Page 29
  30. 30. Study Area and Flow Data Free Powerpoint TemplatesDoW Hydrographic Work – Rating Curve•“Water Depth” vs “Flow Discharge” derivationusing discharge measurement and HEC-RASmodelling•See paper in AHA Conference 2010 Perth by:- –Michael Harris and Leith Bowyer –Ross Doherty Page 30
  31. 31. Study Area and Flow Data Free Powerpoint Templates Ashburton River Page 31
  32. 32. Study Area and Flow Data Free Powerpoint Templates Ashburton River Page 32
  33. 33. Study Area and Flow Data Free Powerpoint TemplatesMaitland River Page 33
  34. 34. Study Area and Flow Data Free Powerpoint TemplatesMaitland River Page 34
  35. 35. Outline of the Presentation Free Powerpoint Templates• Introduction• Study Area and Flow Data• Methodology and Results• Conclusions Page 35
  36. 36. Methodology and Results Free Powerpoint TemplatesMethodology - For Extreme Discharges1)Extract the AM series of stations in study area from flowmeasurement data of DoW – The quality of the measurement records were reviewed, poor quality records were discarded – The data in AM series was reviewed to ensure no two sequent data is due to same storm event – Only the stations with AM series containing at least 10 years of data are selected in this study (60 out of 90 stream gauging stations were selected in this study) Page 36
  37. 37. Methodology and Results Free Powerpoint TemplatesMethodology - For Extreme Discharges (Cont.)2)Divided 3 hydrological regions according tocatchment areas, the 3 regions are (after Hosking and Wallis(1997)):- –Small Area Region (19 gauging stations) – “S”: • catchment area ≤ 1,000 km2 –Medium Area Region (25 gauging stations) – “M”: • 1,000 km2 < catchment area ≤ 10,000 km2 –Large Area Region (16 gauging stations) – “L”: • catchment area > 10,000 km2 Page 37
  38. 38. Methodology and Results Free Powerpoint TemplatesHosking and Wallis (1997), page 180“Nonetheless, we emphatically reject the possibility ofperforming regional frequency analysis with the entireset of sites being treated as a single region. The mainreason is that the theory and practice of hydrologyimply that the frequency distribution is likely to dependon the drainage area of the basin. Regional frequencyanalysis should therefore be applied only to regionswhose basins cover a fairly small range of drainagearea.” Page 38
  39. 39. Methodology and Results Free Powerpoint TemplatesHosking and Wallis (1997), page 180“A further point is that in regional frequency analysisthere is little to be gained by using regions containingmore than about 20 sites. A reasonable starting pointfor regional frequency analysis would therefore be asubdivision of the set of sites, according to theirdrainage areas, into groups of not much more than 20.” Page 39
  40. 40. Methodology and Results Free Powerpoint TemplatesMethodology - For Extreme Discharges (Cont.)3)Sub-divide regions “S”, “M”, and “L” according to their statisticalhomogeneity, – Gauging stations with H-statistic < 2.0 were considered that they could belong to same sub-region – The number of stations in each sub-regions should not be much more than 20 – discordance test based on L-moment ratios was performed to ensure no existence of discordancy dataset in sub-regions (sub-regions S1 to S3; M1 to M3; L1 to L3; were formed) Page 40
  41. 41. Methodology and Results Free Powerpoint TemplatesMethodology - For Extreme Discharges (Cont.)4)Best-fitted frequency distribution for each sub-regions – The best-fitted frequency distribution was considered to be the one with the smallest absolute value of Z-statistic – Candidate frequency distributions are:- • Generalized Logistic, • Generalized Extreme Value, • Generalized Normal, • Pearson Type III, and • Generalized Pareto Page 41
  42. 42. Methodology and Results Free Powerpoint Templates Best-fitted Selected Sub-Region H-Statistic Distribution Gauging Name (< 2.0) (Z-Statistic) Stations (close to 0) 706207*, 709002, 709006, 709007, Pearson Type III S-1 1.326 709009, 709010, (0.108) 710004 701003, 701004, Generalized S-2 701005, 701006, 1.733 Logistic 701601, 704002 (-0.350) 704001, 704003, Generalized S-3 704004, 707001, 1.682 Pareto 708009, 708227 (1.384) * see later plot Page 42
  43. 43. Methodology and Results Free Powerpoint Templates Best-fitted Selected Sub-Region H-Statistic Distribution Gauging Name (< 2.0) (Z-Statistic) Stations (close to 0) 703001, 705001, Generalized 705002, 707005, M-1 710001, 710204, 0.520 Pareto 710229 (2.826) 701007, 701008, 701009, 701010, 701013, 701014, Generalized M-2 707002, 707004, 0.931 Logistic 708001, 708011, (-0.172) 708013, 708014, 708016 709001, 709003, Pearson Type III M-3 709004, 709005, 0.010 (0.671) 709008 Page 43
  44. 44. Methodology and Results Free Powerpoint Templates Best-fitted Selected Sub-Region H-Statistic Distribution Gauging Name (< 2.0) (Z-Statistic) Stations (close to 0) 701002, 701011, Pearson Type III L-1 701012, 702001, 0.548 703002 (0.024) 704139, 704193, Generalized 704195, 704196, L-2 706003, 706209, 0.855 Pareto 710003 (-0.260) 708002, 708003, Pearson Type III L-3 708015, 708223 1.195 (0.998) Page 44
  45. 45. Methodology and Results Free Powerpoint TemplatesMethodology - For Extreme Discharges (Cont.)5)Estimate parameters of each selectedstation for their best-fitted frequencydistribution6)Estimate the extreme discharges (QY, Y =2-, 5-, 10-, 20-, 50-, 100-year ARI) of everystations in each sub-regions Page 45
  46. 46. Methodology and Results Free Powerpoint Templates Page 46
  47. 47. Methodology and Results Free Powerpoint TemplatesMethodology - For Frequency Factors7)Define the peak discharge in 5-year ARI (i.e. Q5)as the “index-flood”, in regions “S”, “M”, and “L”8)Make the peak discharges dimensionless bydividing them by Q5, (i.e. QY / Q5)9)Calculate different Frequency Factors for differentARIs in each region, – “Frequency Factor” is the mean of [QY / Q5] over all stations and in regions S, M, and L Page 47
  48. 48. Methodology and Results Free Powerpoint Templates Medium Area Region Small Area Region Large Area Region Page 48
  49. 49. Methodology and Results Free Powerpoint TemplatesMethodology - For Design Discharge Equation (Q5)10)Catchment factors and climate factors for eachselected station:- –Catchment Area (A) [km2] –Average Annual Rainfall Depth (P) over the catchment area between year 1946 to year 2005 [mm/year] –Design Rainfall Intensity (IDuration, ARI) over catchment area [mm/hr] of ARI 2- and 50-year (1hr, 12hrs, 72hrs) Page 49
  50. 50. Methodology and Results Free Powerpoint TemplatesMethodology - For Design Discharge Equation (Q5)(Cont.)11)Develop design discharge equation for Design Discharges of5-year ARI (Q5) in regions S, M & L using catchment factorsand climate factors, – Stepwise Variable Selection and Multiple Variables Linear Least Square Regression were performed – The reasonability and simplicity of the design discharge equation are considered – The number of climate and catchment factors kept to a minimum, they should also be easy to obtain by end-users. Page 50
  51. 51. Methodology and Results Free Powerpoint TemplatesResults (Cont.)For Small Size Region(i.e. catchment area ≤ 1,000 km2)Design Discharge Equation: Q5 = 8.26*10-9 A0.703 I1hr,2yrs5.798Frequency Factors: ARI 2 yrs 5 yrs 10 yrs 20 yrs 50 yrs 100 yrs FF 0.34 1.00 1.64 2.43 3.84 5.37 Page 51
  52. 52. Methodology and Results Free Powerpoint TemplatesDesign Equation of Q5 in “ARR Revision Projects -Project 5 Regional Flood Methods Stage II”ln(Q5) = 3.90 + 0.48 [ln(A) – 4.71] + 7.20 [ln(I12hrs, 2yrs) – 1.47]=> Q5 = 1.30x10-4 A0.48 I12hrs,2yrs7.20 Page 52
  53. 53. Methodology and Results Free Powerpoint TemplatesResults (Cont.)For Medium Size Region(i.e. 1,000 km2 < catchment area ≤ 10,000 km2)Design Discharge Equation: Q5 = 2.72*10-7 A0.797 I1hr, 50yrs3.506Frequency Factors: ARI 2 yrs 5 yrs 10 yrs 20 yrs 50 yrs 100 yrs FF 0.33 1.00 1.71 2.67 4.59 6.87 Page 53
  54. 54. Methodology and Results Free Powerpoint TemplatesResults (Cont.)For Large Size Region(i.e. catchment area > 10,000 km2)Design Discharge Equation: Q5 = 4.26*10-6 A0.783 I1hr, 50yrs2.815Frequency Factors: ARI 2 yrs 5 yrs 10 yrs 20 yrs 50 yrs 100 yrs FF 0.27 1.00 1.76 2.64 3.98 5.13 Page 54
  55. 55. Methodology and Results Free Powerpoint Templates Page 55
  56. 56. Methodology and Results Free Powerpoint Templates Page 56
  57. 57. Methodology and Results Free Powerpoint Templates Page 57
  58. 58. Methodology and Results Free Powerpoint Templates Page 58
  59. 59. Methodology and Results Free Powerpoint Templates Page 59
  60. 60. Outline of the Presentation Free Powerpoint Templates• Introduction• Study Area and Flow Data• Methodology and Results• Conclusions Page 60
  61. 61. Conclusions Free Powerpoint TemplatesConclusions•Design discharges from JDA 2012 can beapplied to whole Drainage Division 7 – ARR1987 and Flavell 2012 cannot generate satisfactory design discharges in Gascoyne Region – Doubt about equations from ARR P5 S2 can be applied in river basin 702, 703, 705, and 710 • No stations were selected at those river basins in the equations development Page 61
  62. 62. Conclusions Free Powerpoint TemplatesConclusions (Cont.)•Design discharges from JDA 2012 canbe applied to a wide range ofcatchment area – ARR P5 S2 cannot generate satisfactory design discharges in large catchment area • Stations with maximum catchment area of 1,000 km2 were selected • The catchment areas in Pilbara are large in particular in downstream areas, say as large as 80,000 km2 Page 62
  63. 63. Conclusions Free Powerpoint TemplatesConclusions (Cont.)•The design equations of JDA 2012 is simple andeasy to apply, – only catchment area and design rainfall intensity are required in the design discharge equations – The parameters are easy to obtain Page 63
  64. 64. Conclusions Free Powerpoint TemplatesConclusions (Cont.)•ARR 1987 often over estimated the data (exceptriver basins 709, 710) Page 64
  65. 65. Study Area and Flow Data Free Powerpoint Templates 709 - Port Hedland Coast 707 - Onslow Coast 710 - De Grey River 705 - Lyndon-Minilya Rivers 708 - Fortescue River 706 - Ashburton River 704 - Gascoyne River703 - Wooramel River 702 - Murchison River - Selected Stations (60) 701 - Greenough River Page 65
  66. 66. Conclusions Free Powerpoint TemplatesConclusions (Cont.)•Flavell (2012) may mis-represent due to changesto measured DoW Flow Data Page 66
  67. 67. Conclusions Free Powerpoint TemplatesConclusions (Cont.)•Method will need recalibrate for revised IFD,published at H&WR Symposium November 2012 Page 67
  68. 68. Free Powerpoint TemplatesEnd of Presentation Page 68

×