The Beleaguered Figure 15

Transcription

1 The Beleaguered Figure 15 TFMA 2015 Fall Technical Summit After the Floods: Texas Rising Craig Loftin, PE, CFM US Weather Bureau Technical Paper No. 40, Figure 15 Village Creek Watershed 1

2 100-Year 30-Minute Rainfall (Inches) 100-Year 1-Hour Rainfall (Inches) 100-Year 2-Hour Rainfall (Inches) 2

3 100-Year 3-Hour Rainfall (Inches) 100-Year 6-Hour Rainfall (Inches) 100-Year 12-Hour Rainfall (Inches) 3

4 100-Year 24-Hour Rainfall (Inches) 100-Year 30-Minute Rainfall (Inches) 100-Year 1-Hour Rainfall (Inches) 4

5 100-Year 2-Hour Rainfall (Inches) 100-Year 3-Hour Rainfall (Inches) 100-Year 6-Hour Rainfall (Inches) 5

6 100-Year 12-Hour Rainfall (Inches) 100-Year 24-Hour Rainfall (Inches) Dallas TP-40 Data 6

7 Dallas TP-40 Data USGS Water Resources Investigations Report USGS Water Resources Investigations Report

8 USGS Water Resources Investigations Report Location Parameter 15-Minute Duration Location Parameter 30-Minute Duration 8

9 Location Parameter 60-Minute Duration Location Parameter 1-Hour Duration Location Parameter 2-Hour Duration 9

10 Location Parameter 3-Hour Duration Location Parameter 6-Hour Duration Location Parameter 12-Hour Duration 10

11 Location Parameter 24-Hour Duration Location Parameter 1-Day Duration Scale Parameter 15-Minute Duration 11

12 Scale Parameter 30-Minute Duration Scale Parameter 60-Minute Duration Scale Parameter 1-Hour Duration 12

13 Scale Parameter 2-Hour Duration Scale Parameter 3-Hour Duration Scale Parameter 6-Hour Duration 13

14 Scale Parameter 12-Hour Duration Scale Parameter 24-Hour Duration Scale Parameter 1-Day Duration 14

15 Shape Parameter 15-Minute Duration Shape Parameter 30-Minute Duration Shape Parameter 60-Minute Duration 15

16 Shape Parameter 1-Hour Duration Shape Parameter 2-Hour Duration Shape Parameter 3-Hour Duration 16

17 Shape Parameter 6-Hour Duration Shape Parameter 12-Hour Duration Shape Parameter 24-Hour Duration 17

18 USGS Scientific Investigations Report USGS Scientific Investigations Report USGS Scientific Investigations Report

19 USGS Scientific Investigations Report Depth of Precipitation, 100-Year Storm 15-Minute Duration Depth of Precipitation, 100-Year Storm 30-Minute Duration 19

20 Depth of Precipitation, 100-Year Storm 1-Hour Duration Depth of Precipitation, 100-Year Storm 2-Hour Duration Depth of Precipitation, 100-Year Storm 3-Hour Duration 20

21 Depth of Precipitation, 100-Year Storm 6-Hour Duration Depth of Precipitation, 100-Year Storm 12-Hour Duration Depth of Precipitation, 100-Year Storm 12-Hour Duration 21

22 Depth of Precipitation, 100-Year Storm 1-Day Duration Depth of Precipitation, 100-Year Storm 2-Day Duration Depth of Precipitation, 100-Year Storm 3-Day Duration 22

23 Depth of Precipitation, 100-Year Storm 5-Day Duration Depth of Precipitation, 100-Year Storm 3-Day Duration NOAA Technical Memorandum NWS HYDRO-35 23

24 2-Year 60-Minute Precipitation (inches) 100-Year 60-Minute Precipitation (inches) 2-Year 5-Minute Precipitation (inches) 24

25 100-Year 5-Minute Precipitation (inches) 2-Year 15-Minute Precipitation (inches) 100-Year 15-Minute Precipitation (inches) 25

26 HYDRO-35 Data at Dallas HYDRO-35 Data at Dallas Spliced and Adjusted Results at Dallas 26

27 Spliced and Adjusted Results at Dallas Expanded Results at Dallas Expanded Results at Dallas 27

28 Mass Curve Redistributed Mass Curve Distributed Storm (5-minute time step) 28

29 Distributed Storm (15-minute time step) Distributed Storm (30-minute time step) Distributed Storm (1-hour time step) 29

30 Distributed Storm (2-hour time step) Distributed Storm (3-hour time step) Distributed Storm (6-hour time step) 30

31 Distributed Storm (12-hour time step) Distributed Storm (24-hour time step) NUDALLAS/SWFHYD Precipitation Inputs 31

32 HEC-1 Precipitation Inputs HEC-HMS Precipitation Inputs HEC-HMS Precipitation Inputs 32

33 HEC-1 and HEC-HMS Point to Areal Depth Conversion HEC-1 and HEC-HMS Area Reduction Factor (ARF) Improved fit by adding an area multiplier per duration 33

34 Weather Bureau Technical Paper No. 40 Weather Bureau Technical Paper No. 29, Part 1 The Ohio Valley WB TP-29, Part 1 The Ohio Valley Sources of Rainfall Data 34

35 WB TP-29, Part 1 The Ohio Valley ARF Curves and Map of Dense Networks WB TP-29, Part 1 The Ohio Valley Example Computation of ARF WB TP-29, Part 1 The Ohio Valley Network Area, Subdivision, and Limitations 35

36 WB TP-29, Part 1 The Ohio Valley Duration a major Parameter but Depth not a Parameter WB TP-29, Part 1 The Ohio Valley Need for Judgment and Basis of ARF Curves Weather Bureau Technical Paper No. 29, Part 2 Southeastern US 36

37 WB TP-29, Part 2 Southeastern US Sources of Rainfall Data WB TP-29, Part 2 Southeastern US Map of Nationwide Dense Networks WB TP-29, Part 2 Southeastern US Nationwide Dense Network Statistics 37

38 WB TP-29, Part 2 Southeastern US ARF Curves WB TP-29, Part 2 Southeastern US Example Computation of ARF WB TP-29, Part 2 Southeastern US Discussion of various Area-Depth Relationships 38

39 US Weather Bureau Technical Paper No. 40, Figure 15 NOAA Technical Report NWS 24 NOAA Technical Report NWS 24 2-Year Depth-Area Ratios at Chicago 39

40 NOAA Technical Report NWS Year Depth-Area Ratios at Chicago NOAA Technical Report NWS 24 Extended 2-Year Depth-Area Ratios at Chicago NOAA Technical Report NWS 24 Commentary on Nature of Classical ARFs 40

41 USGS Water Resources Investigations Report USGS Water Resources Investigations Report USGS Water Resources Investigations Report

42 USGS Water Resources Investigations Report Frequency Considerations USGS Water Resources Investigations Report Empirical Depth-Distance Relations for Austin, Dallas, Houston USGS Water Resources Investigations Report ARFs for 1-Day Design Storms at Austin, Dallas, Houston 42

43 USGS Water Resources Investigations Report Observation re. applicability relative to watershed TOC. Journal of Hydrology Article: Precipitation areal-reduction factor estimation using an annual-maxima centered approach TX Transportation Inst. at A&M Report : Calculation of Areal Reduction Factors Using NEXRAD Precipitation Estimates 43

44 TX Transportation Inst. at A&M Report : Calculation of Areal Reduction Factors Using NEXRAD Precipitation Estimates TTI at A&M Report ARF-Area Plot for Region 4, Storm Duration of 24 Hours TTI at A&M Report ARF-Area Plots for Region 4, Storm Duration of 24 Hours 44

45 % of Total Depth 10/4/2015 TTI at A&M Report Comparison with Former Studies TTI at A&M Report Comparison or ARF-Area curves to those from other studies USACE SWF Upper Trinity River Basin research Figure 15 Extension (All Storms - 24 Hour) 100% HEC-1/HEC-HMS Equation 90% 80% 70% 60% Proposed Extension Curve 50% 1981 Area-Depth 40% 30% 20% 10% 0% Area in Sq. Mi. 45

46 % of Total Depth % of Total Depth % of Total Depth 10/4/2015 USACE SWF Upper Trinity River Basin research 100% Figure 15 Extension (All Storms - 24 Hour) HEC-1/HEC-HMS Equation 90% Proposed Extension Curve 80% 70% 1981 Area-Depth Curve 60% 50% 40% 30% 20% 10% 0% Area in Sq. Mi. USACE SWF Upper Trinity River Basin research 1.00 Figure 15 Extension (All Storms - 6 Hour) 0.90 HEC-1/HEC-HMS Equation Oct Proposed Extension Curve 1981 Area-Depth Curve HEC-1 Proposed Extension Curve Area in Sq. Mi. USACE SWF Upper Trinity River Basin research 1.00 Figure 15 Extension (All Storms - 6 Hour) HEC-1/HEC-HMS Equation Proposed Extension Curve Area-Depth Curve 10-Oct HEC Proposed Extension Curve Area in Sq. Mi. 46

47 % of Total Depth % of Total Depth 10/4/2015 USACE SWF Upper Trinity River Basin research 1.00 Figure 15 Extension (All Storms - 1 Hour) HEC-1/HEC-HMS Equation HEC-1/ HEC-HMS Equation 10-Oct Area-Depth Curve Area in Sq. Mi. USACE SWF Upper Trinity River Basin research 1.00 Figure 15 Extension (All Storms - 1 Hour) HEC-1/HEC-HMS Equation Area-Depth Curve HEC-1/ HEC-HMS Equation 10-Oct Area in Sq. Mi. USACE SWF Upper Trinity River Basin research 47

48 USACE SWF Upper Trinity River Basin research US Weather Bureau Technical Paper No. 40, Figure 15 The Changing Paradigm for Configuring Hypothetical Storms - more robust use of recorded storm events as proxies - attempts to define specific frequencies for those events - potential use of bracketed durations - attempts to establish appropriate/consistent ARFs - attempts to optimize elliptical storm position 48

49 USACE SWF Upper Trinity River Basin research USACE SWF Upper Trinity River Basin research In this presenter s view, with regards to the NFIP Consistency has greater net value than does perceived accuracy. We should strive to let our truly meaningful technical experiences gained over time be our primary guide. 49

50 Questions and Discussion 50