Hydrology, Hydraulics and Hydrometeorology of in the Eastern United States

Baltimore Jim Smith Ecosystem Princeton University Study LTER Outline and Themes

How does the 100 year vary over the eastern US?

Complex Terrain

Central Appalachians Land – Ocean Urban Environment

Basin Scale: “3 Floods”

Warm Season Thunderstorm Systems – Smethport PA July 1942 Tropical Cyclones – Hurricane Agnes, June 1972 Winter/Spring Extratropical Systems – March 1936

Extreme Floods and Tropical Cyclones

Hurricane Isabel 18 September 2003

Annual Flood Peak Discharge South Fork Shenandoah River Drainage Area: 1640 mi2 Record Length: 78 Years

10 Year Flood: 47,500 cfs 100 Year Flood: 130,000 cfs Tropical Cyclones and Annual Flood Peaks

572 USGS Streamflow Stations.

More than 75 year record length.

NOAA Atlantic Hurricane Data Base (HURDAT). Isabel Rainfall (mm) – Weather Isabel Rainfall (mm) – HydroNEXRAD Research and Forecasting (WRF) Rainfall Observations Model. “Envelope Curve”: Flood Peaks in the Eastern US Thunderstorm Frequency – Catastrophic Floods – Complex Terrain

Rapidan Storm – 27 June 1995 Rapidan Storm WRF Simulation

“19 July” Storms

Smethport PA 19 July 1942 30.8 inches – 4 Hours

19 July 1996

1889 Rockport WVA 1942 Smethport PA 1977 Johnstown PA 1996 Redbank Creek, PA Moores Run, June 13, 2003 Flood Frequency – Charlotte NC Storm total rainfall (mm)

Storm Total Lightning (CG Storm -2 Total strikes km ) (mm)

7 July 2004 - Flood of Record in Dead Run Storm total rainfall (mm) 7 July 2004 Yellow – July 7 Inundation Area Light blue – FEMA 500-yr Floodplain Dark blue – FEMA 100-yr Floodplain

Life Cycle of Warm Season Thunderstorm Systems:

1) Initiation over Blue Ridge. 2) Propagation over Piedmont. 3) Interaction with urban environment and land – circulation systems.

CG lightning strikes on 13 June 2003; color coding indicates time (hour) of occurrence. Summary and Conclusions

* Tropical cyclones control extreme flooding in much of the eastern US; there is pronounced spatial heterogeneity in flooding. * Mountainous terrain (orographic mechanisms) plays a central role in the extreme flood of the eastern US. * Thunderstorm systems in mountainous terrain of the eastern US have produced some of the largest rainfall accumulations in the world for time intervals less than 6 hours. * Envelope curve of flood peak magnitudes for the eastern US includes numerous urban floods with relatively short return intervals. * “Climatology” of urban floods is directly linked to the climatology of warm season thunderstorm systems.

Weather Research and Forecasting Model - 7 July 2004 Simulations

Conclusions from WRF Model Simulations

HydroNEXRAD Convergence-induced Storm Total Rain “spin-up” along Blue Ridge Chesapeake Bay “thermal boundary” plays important role in evolution of storm system “Urban Canopy” has important impacts on storm evolution No “UHI” effect Aerosol effects – suppression, enhancement or redistribution. WRF Storm Total Rainfall (mm) PA

NJ

DE

VA

Baisman Run at Broadmoor !.

!. Gwynns Falls near Delight

Gwynns Falls at Villa Nova !. !. Moores Run at Dead Run at Franklintown !. Radecke Ave

Gwynns Falls at Washington Blvd !. Baltimore City

0 2.5 5 10 15 20 Kilometers CG Lightning Strikes on July 7, 2004

Initiation along Blue Ridge, propagation over Piedmont, interaction with urban environment and land - water boundaries (Chesapeake Bay)

Storm Total LightningStorm Total(CG -2 strikesLightning km ) Storm Strikes km-2 Total Rain (mm)

•Return interval of rainfall accumulations over Dead Run: < 10 years at 15 minutes; > 300 years at 120 minutes.

Storm Evolution: 1845 - 2115 UTC on 7 July 2004 Evolution of Storm Elements on 7 July 2004