Northeastern Section - 36th Annual Meeting (March 12-14, 2001)

Paper No. 3
Presentation Time: 8:30 AM-12:00 PM

RECORD OF FLOODING ON THE MOHAWK RIVER FROM 1634 TO 2000 BASED ON HISTORICAL ARCHIVES


JOHNSTON, Sarah A. and GARVER, John I., Geology Department, Union College, Schenectady, NY 12308-2311, johnstos@union.edu

We have attempted to reconstruct a chronology of ~350 years of flooding on the Mohawk River in eastern NY using historical records. This record, which consists of over 30 floods, was constructed through examination of newspapers, and other historical documents. Usefulness of historical accounts varies, and become increasing reliable through time. From1634 to 1663 the record is poor and less reliable from 1664 to 1771. From 1772 to 1823 the record is fair, but common and well-archived newspapers result in a very good record from 1824 to 1910. From 1910 to 2000 the record is excellent and most accounts provide for stage, discharge, and weather details. Stage elevations in Schenectady are fairly reliable from 1832 to 2000. Flooding of the Mohawk River includes "free-water" flood events and "break-up" events. Free-water flood events commonly occur in late summer and early fall, during peak hurricane season and are associated with significant precipitation. Break-up events are caused by rising temperatures, melting snow, and/or heavy rains in the winter and early spring. Ice jams accompany break-up events in the majority of the large-scale flooding events (>4.6 m stage elevation in Schenectady). Despite probable gaps in the archived record, the worst flooding occurred between1869 to 1914, where stages >4.6 m were reached eight times in a span of 45 years. This period concluded with the great flood of 1914, the most devastating event recorded; flood stage in Schenectady was 7.1 m, about 1 m higher than all others on record. This period was wetter and cooler but deforestation also probably exacerbated flooding during this time. Since the 1914 event, there has been a decline in the frequency and magnitude of flooding in Schenectady.