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Hurricane Agnes


Agnes began as a tropical disturbance off the coast of the Yucatan Peninsula in Mexico on 14 June 1972. As the disturbance moved northward, it strengthened and became a tropical storm on 16 June.

By 19 June, Agnes became a hurricane. Agnes made initial landfall along the Florida pan handle on 19 June. Agnes then proceeded through Georgia, South Carolina and North Carolina before she moved back over the Atlantic off the North Carolina coast on 21 June,

After regaining strength over the Atlantic, she made landfall again over southeastern New York on 22 June and moved westward in an arc over southern New York into north-central Pennsylvania. She became nearly stationary over Pennsylvania by morning of 23 June, but was soon absorbed by a low-pressure system that slowly drifted northeastward from Pennsylvania into New York.

Rainfall Amounts

Rainfall from 20-25 June over the Mid-Atlantic region ranged from 2-3 inches in the extreme upper basins of the Potomac and North Branch Susquehanna Rivers to 18 inches near Shamokin, Pennsylvania, in the Main Stem Susquehanna River basin. An average of 6-10 inches of rain fell over the Mid-Atlantic region.

Preceding Rainfall

In the three weeks preceding the arrival of Agnes, Pennsylvania as a whole had received 2 to 3 inches of rain, thus greatly increasing the runoff potential of Agnes.

Flooding

The most impressive aspect of the 1972 floods was their widespread nature, resulting in extremely rare floods on major rivers and streams. The flood recurrence frequency in many locations exceeded 100 years, most notably on the Susquehanna River downstream of Waverly, New York, and on the Potomac River, downstream from Point of Rocks, Maryland.

Here's a look of the flooding, basin by basin:


Delaware River Basin

The worst flooding occurred in the Schuylkill River basin. Flood peaks in excess of 100 year recurrence frequency levels were observed at many sites along the Schuylkill. Major flooding also occurred on the tributaries of the Schuylkill, primarily on the Tulpehocken, French and Perkiomen Creeks. Elsewhere in southeastern Pennsylvania, significant flooding occurred on the Brandywine Creek.

In the rest of the Delaware River basin, flooding was only minor.

A file containing stage data of the Delaware River basin can be found here.


Susquehanna River Basin

The Agnes flood remains the greatest flooding event known in the Susquehanna River basin in regards to both the area affected and the magnitude of the flood flow. Only the extreme upper headwaters escaped disastrous flooding.

Main Stem Susquehanna

Flooding along the Susquehanna above Binghamton, New York was only minor. However, flood flows increased greatly downstream to Waverly, New York, which had a 40 year flood. The points along the Susquehanna River from the mouth of the Chemung River down to the Chesapeake Bay experienced the worst flooding since 1784, the earliest known records. Peak flows were often 1.5 times greater than the previous know maximum flood.

Susquehanna River Tributaries

Some of the worst flooding occurred in the Chemung River and its principal tributaries, the Tioga, Canisteo, and Cohocton Rivers. Floods with greater than 100 year recurrence frequency level occurred at almost every point in the basin. The peak flows were reduced somewhat in the Canisteo River by the Arkport and Almond Reservoirs, but record floods were still observed downstream of these dams.

Flooding on the West Branch of the Susquehanna River was reduced somewhat by flood-control reservoirs, but the lower reaches of the West Branch still experienced record high peak flows. It was estimated that the flood peak at Williamsport, Pennsylvania, would have been up to 4 feet higherif it had not been for the reservoirs. Major flooding was also observed on all tributaries downstream of the West Branch Susquehanna River down to the Juniata River.

The Juniata River basin experienced significant flooding, but it was lessened by flood-control reservoirs, in particular, an unfinished Raystown Lake reservoir.

A file containing stage data of the Susquehanna River basin can be found here.


Potomac River Basin

Above Hancock, Maryland, no unusual flooding was observed. Most of the flooding occurred in tributaries of the Potomac River downstream of the Shenandoah River. In the tributaries on the north side of the Potomac River, from the Conococheague Creek at Fairview, Maryland down to Rock Creek at Washington, DC, floods in excess of the 100 year frequency level were observed. In the tributaries along the south side of the Potomac River, severe flooding occurred at most locations in West Virginia and Virginia from just west of Winchester, Virginia, and artinsburg, West Virginia, to Alexandria and Quantico, Virginia. Peak flows in some of the larger streams ranged from two to six times greater than the previous known maximum.

A file containing stage data of the Potomac River basin can be found here.


Rappahannock River Basin

Flooding in the Rappahannock River basin was less severe in comparison to the Potomac River to its north and the James River to its south. any points in the basin had flooding with a 50 year recurrence frequency and often were at the third highest levels on record.

A file containing stage data of the Rappahannock River basin can be found here.


James River Basin

The James River basin was also hit very hard by Agnes, especially tragic since devastating floods caused by the remnants of Hurricane Camille occurred only three years before. Flooding along the James River downstream of Lynchburg, Virginia was the worst known since at least 1870. Flooding along the main stem of the James River ranged from 25 to 100 year recurrence frequency levels in the upper portions to well over 100 year recurrence frequency levels downstream from Lynchburg, Virginia. The flow at Richmond, Virginia, was 50% greater than during the peak of the 1969 Camille flood.

In the headwater tributaries, severe flooding occurred along streams in the vicinity of Covington, New Castle and Catawba, Virginia. Recurrence frequencys in this area ranged from 50 to over 100 years. Flooding in the tributaries between Buchanan, Virginia, and Scottsville, Virginia were extensive, but not record breaking. In contrast, flooding in the tributaries between Scottsville, Virginia, and Cartersville, Virginia, were generally the greatest on record. The largest tributary in this stretch, the Rivanna River, exceeded 100 year flood recurrence frequency levels at many sites.

The Appomattox River, just to the south of the James, experienced record breaking flooding upstream from Mattoax, Virginia. Sites above this point experienced flooding greater than the 100 year recurrence frequency level. Below this point, flow contribution from the tributaries lessened, resulting in the attenuation of the flood peak at it traveled down to Farmville, Virginia, where it was only two-thirds of the flow that was observed at Mattoax, Virginia.

A file containing stage data of the James River basin can be found here.


The Damage

Hurricane Agnes was the costliest natural disaster in the United States at that time. Damage was estimated at $3.1 billion and 117 deaths were reported. Hardest hit was Pennsylvania, with $2.1 billion in damages and 48 deaths, making Hurricane Agnes the worst natural disaster ever to hit the state. The damage over Pennsylvania was so extreme, the entire state was declared a disaster area by President Richard Nixon.

The state-by-state breakdown is as follows:

State Damage (1972 Dollars) Deaths
Pennsylvania $2,119,269,000 48
New York 702,502,000 24
Virginia 125,987,000 13
Maryland 110,186,000 19
New Jersey 15,000,000 1
Florida 8,243,000 9
West Virginia 7,753,000 0
Ohio 6,818,000 0
North Carolina 6,558,380 2
Georgia 205,000 0
South Carolina 50,000 0
Delaware Light 1
TOTAL $3,102,571,380 117

References

Hurricane Agnes Rainfall and Floods, June-July 1972: United States Geological Survey Professional Paper 924, Bailey, J.F., J.L. Patterson, USGS, and J.L.H. Paulhus, NWS. U.S. Geological Survey: Washington, DC. 1975.

Water Resources Bulletin No. 9: Hydrologic Data of the June 1972 Flood in Pennsylvania Miller, R. Adam. Pennsylvania Department of Environmental Resources: Harrisburg, PA. August 1974.

Tropical Storm Agnes June 1972: Post Flood Report Volume I, eteorology and Hydrology Gannett, Flemming, Corddry and Carpenter, Engineers. U.S. Army Corps of Engineers: Baltimore, MD. November, 1974.

 

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