The Beleaguered Figure 15 TFMA 2015 Fall Technical Summit After the Floods: Texas Rising

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

100-Year 30-Minute Rainfall (Inches)

100-Year 1-Hour Rainfall (Inches)

100-Year 2-Hour Rainfall (Inches)

100-Year 3-Hour Rainfall (Inches)

100-Year 6-Hour Rainfall (Inches)

100-Year 12-Hour Rainfall (Inches)

100-Year 24-Hour Rainfall (Inches)

100-Year 30-Minute Rainfall (Inches)

100-Year 1-Hour Rainfall (Inches)

100-Year 2-Hour Rainfall (Inches)

100-Year 3-Hour Rainfall (Inches)

100-Year 6-Hour Rainfall (Inches)

100-Year 12-Hour Rainfall (Inches)

100-Year 24-Hour Rainfall (Inches)

Dallas TP-40 Data

USGS Water Resources Investigations Report 98-4044

Location Parameter 15-Minute Duration

Location Parameter 30-Minute Duration

Location Parameter 60-Minute Duration

Location Parameter 1-Hour Duration

Location Parameter 2-Hour Duration

Location Parameter 3-Hour Duration

Location Parameter 6-Hour Duration

Location Parameter 12-Hour Duration

Location Parameter 24-Hour Duration

Location Parameter 1-Day Duration

Scale Parameter 15-Minute Duration

Scale Parameter 30-Minute Duration

Scale Parameter 60-Minute Duration

Scale Parameter 1-Hour Duration

Scale Parameter 2-Hour Duration

Scale Parameter 3-Hour Duration

Scale Parameter 6-Hour Duration

Scale Parameter 12-Hour Duration

Scale Parameter 24-Hour Duration

Scale Parameter 1-Day Duration

Shape Parameter 15-Minute Duration

Shape Parameter 30-Minute Duration

Shape Parameter 60-Minute Duration

Shape Parameter 1-Hour Duration

Shape Parameter 2-Hour Duration

Shape Parameter 3-Hour Duration

Shape Parameter 6-Hour Duration

Shape Parameter 12-Hour Duration

Shape Parameter 24-Hour Duration

USGS Scientific Investigations Report 2004-5041

Depth of Precipitation, 100-Year Storm 15-Minute Duration

Depth of Precipitation, 100-Year Storm 30-Minute Duration

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

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

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

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

Depth of Precipitation, 100-Year Storm 5-Day Duration

Depth of Precipitation, 100-Year Storm 3-Day Duration

NOAA Technical Memorandum NWS HYDRO-35

2-Year 60-Minute Precipitation (inches)

100-Year 60-Minute Precipitation (inches)

2-Year 5-Minute Precipitation (inches)

100-Year 5-Minute Precipitation (inches)

2-Year 15-Minute Precipitation (inches)

100-Year 15-Minute Precipitation (inches)

HYDRO-35 Data at Dallas

Spliced and Adjusted Results at Dallas

Expanded Results at Dallas

Mass Curve

Redistributed Mass Curve

Distributed Storm (5-minute time step)

Distributed Storm (15-minute time step)

Distributed Storm (30-minute time step)

Distributed Storm (1-hour time step)

Distributed Storm (2-hour time step)

Distributed Storm (3-hour time step)

Distributed Storm (6-hour time step)

Distributed Storm (12-hour time step)

Distributed Storm (24-hour time step)

NUDALLAS/SWFHYD Precipitation Inputs

HEC-1 Precipitation Inputs

HEC-HMS Precipitation Inputs

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

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

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

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

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

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

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

NOAA Technical Report NWS 24 100-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

USGS Water Resources Investigations Report 99-4267

USGS Water Resources Investigations Report 99-4267 Frequency Considerations

USGS Water Resources Investigations Report 99-4267 Empirical Depth-Distance Relations for Austin, Dallas, Houston

USGS Water Resources Investigations Report 99-4267 ARFs for 1-Day Design Storms at Austin, Dallas, Houston

USGS Water Resources Investigations Report 99-4267 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 0-4642-3: Calculation of Areal Reduction Factors Using NEXRAD Precipitation Estimates

TTI at A&M Report 0-4642 ARF-Area Plot for Region 4, Storm Duration of 24 Hours

TTI at A&M Report 0-4642 ARF-Area Plots for Region 4, Storm Duration of 24 Hours

TTI at A&M Report 0-4642 Comparison with Former Studies

TTI at A&M Report 0-4642 Comparison or ARF-Area curves to those from other studies

% of Total Depth 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% 40% 1981 Area-Depth 30% 20% 10% 0% 0 1000 2000 3000 4000 5000 6000 7000 8000 9000 10000 Area in Sq. Mi.

% of Total Depth 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% 0 100 200 300 400 500 600 700 800 900 1000 Area in Sq. Mi.

% of Total Depth USACE SWF Upper Trinity River Basin research 1.00 0.90 Figure 15 Extension (All Storms - 6 Hour) HEC-1/HEC-HMS Equation 0.80 0.70 0.60 10-Oct 1981 0.50 0.40 0.30 Proposed Extension Curve 1981 Area-Depth Curve HEC-1 Proposed Extension Curve 0.20 0.10 0.00 0 1000 2000 3000 4000 5000 6000 7000 8000 9000 10000 Area in Sq. Mi.

% of Total Depth USACE SWF Upper Trinity River Basin research 1.00 0.90 Figure 15 Extension (All Storms - 6 Hour) HEC-1/HEC-HMS Equation 0.80 Proposed Extension Curve 0.70 0.60 0.50 0.40 1981 Area-Depth Curve 10-Oct 1981 HEC-1 Proposed Extension Curve 0.30 0.20 0.10 0.00 0 100 200 300 400 500 600 700 800 900 1000 Area in Sq. Mi.

% of Total Depth USACE SWF Upper Trinity River Basin research 1.00 Figure 15 Extension (All Storms - 1 Hour) 0.90 0.80 HEC-1/HEC-HMS Equation 0.70 0.60 0.50 0.40 HEC-1/ HEC-HMS Equation 10-Oct 1981 0.30 1981 Area-Depth Curve 0.20 0.10 0.00 0 1000 2000 3000 4000 5000 6000 7000 8000 9000 10000 Area in Sq. Mi.

% of Total Depth USACE SWF Upper Trinity River Basin research 1.00 Figure 15 Extension (All Storms - 1 Hour) 0.90 0.80 HEC-1/HEC-HMS Equation 0.70 0.60 0.50 0.40 1981 Area-Depth Curve HEC-1/ HEC-HMS Equation 10-Oct 1981 0.30 0.20 0.10 0.00 0 100 200 300 400 500 600 700 800 900 1000 Area in Sq. Mi.

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

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.

Questions and Discussion