Lab 5 Binghamton Flood Frequency 23
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Binghamton University *
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116
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Geology
Date
Dec 6, 2023
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12
Uploaded by EarlChimpanzee972
Geology 116, Fall 2023
Name ______
Kyra Hooshi_
__________________
Lab 5: The Binghamton Storms and Floods of 2006 and 2011
In June 2006 and September 2011, Binghamton suffered from the two largest floods of record.
While flood records are incomplete prior to the establishment in 1913 of a river gauging station
on the Susquehanna River at Conklin, NY, just upstream of Binghamton, other historical records
indicate that these two floods were the highest river levels recorded at the city of Binghamton,
surpassing the previous record flood of 1936 as well as other historical floods in 1865 and 1846.
The 2006 and 2011 floods were caused by major storms, but different styles of storm. The first
part of this exercise asks you to gather data on the magnitude and nature of the storm events.
The second part of the lab asks you to evaluate the differences in flood size in the Binghamton
area by looking at maps of the flooded areas. The final part of the lab asks you to compare the
two large main-river floods, consider why they were different (and similar), and consider why
intense thunderstorms in November 2016 didn’t produce the same kind of flooding.
Part 1. Learning about major storms
The
National Weather Service Binghamton
weather station website is a good hunting ground for
information about past weather events. Some of their descriptions of past severe weather
events are listed under flooding; this is true of all three events you’ll look at. These events are
also summarized on a website from a joint
Cornell-NWS project
(look at the Local Case Studies
for the year in question). These two sources will provide you with sufficient information to
answer the following questions. In addition, if you’re willing to read a scientific paper on the
two big floods, you’ll find an article by Gitro and others in the Lab section of the course
Brightspace page. The abstract (summary) of the paper is included in this “handout”.
June 2006 storm
1.
What was the nature of the storm in June 2006 that produced major flooding in the
Binghamton area? What kind of front(s) contributed to the rainfall?
Tropical moisture and a stalled cold front combined to produce flash flooding and river flooding
along portions of the Upper Susquehanna River, Delaware River, and Chenango River Basins in
central New York and northeast Pennsylvania in June 2006. A stalled cold front contributed to
the rainfall and mass flooding that resulted.
2.
What was the duration and intensity of the rainfall event? Where was the most intense
rainfall? Note this carefully; it is important for considering differences among the storm
events.
The rainfall event lasted for 3 days in total, producing heavy rainfall at a high intensity. The most
intense rainfall hit the Susquehanna and Chenango rivers.
3.
What were the antecedent conditions, and how did they contribute to the effect of the main
storm?
The antecedent conditions contributing to the effect of the main storm were factors such as
the tropical moisture streaming northwards over a front stalled out over New York State.
There were several weather factors that contributed to the flooding over the weekend.
Over the Atlantic Ocean, the Bermuda High stalled just west of the Appalachian Mountains.
November 2006 storm
In November 2006 there was another set of storms that had a different character and result.
4.
What was the nature of the November 2006 storm(s)? What kind of front(s) contributed?
Heavy rainfall and damaging winds contributed to the flooding of the Binghamton area in
November 2006. The heavy rainfall that endured due to the storm led to flash flooding in that
particular area. What started out as a cold front then moved towards the Great Lakes of
Tennessee, with the greatest amount of rainfall estimated to occur with a low-pressure storm.
5.
What was the duration and intensity of the rainfall? Where was the most intense rainfall?
The storm lasted from November 16th to November 17th of 2006. The total amount of
rainfall in the Binghamton area was approximately 3.0012 to 3.500 inches. Near Jim Thorpe,
PA, and just north of Binghamton were the areas hit by the most intense rainfall.
The next big storm to investigate occurred in September 2011 (in fact, during the second week
of classes that fall). Back to the National Weather Service and Cornell sites to gather data on
this storm.
6.
What was the nature of the September 2011 storm?
The nature of this storm was a tropical one which stalled on the 8th causing the September
2011 storm to cause major flooding. Also, the flooding that occurred was attributed to and
driven by the hurricane’s high moisture content.
7.
What was the duration and intensity of the rainfall? Where was the most intense rainfall?
The total rainfall lasted for two days from 11/6 to 11/7. A recorded amount of 11-12 inches on
the PA-NY border, and between Oswego and Binghamton on the border is where there was the
most intense rainfall occurring primarily south between the two on the perimeter.
8.
What were the antecedent conditions, and how did they contribute to the effect of the main
storm?
In the lead-up to September 11th, Tropical Storm Lee moved northward from the southern
Appalachians on the 6th to the middle Atlantic states on the 7th (before stalling on the 8th).
Besides the moisture from Lee (with the front system crossing the Ohio Valley and the Great
Lakes), additional moisture from Hurricane Katia also contributed as it moved north along the
east coast with Lee's remnants.
Part 2. Floods of 2006 and 2011.
The two big storms of June 2006 and September 2011 produced widespread regional flooding
on the Susquehanna and other rivers, whereas the November 2006 event was characterized by
flash flooding of smaller streams.
9.
Describe the extent and type of flooding that occurred during the November 2006 storm.
Where was the most severe flooding, and how did it correspond to the location(s) of most
severe rainfall?
As a storm system moved across the northeast part of the country on November 16 and 17
of 2006, it brought heavy rains and damaging winds to parts of Central NY and Northeast
Pennsylvania. The heavy rainfall resulted in several flash floods across that area. Although
the floods themselves weren't as devastating individually as the one from June of the same
year, their combined destructiveness caused a high level of gradual property and health
damage. However, the rainfall itself, which caused the flash floods, was much more intense
than what Chenango and Delaware faced during June.
The Susquehanna River Floods of 2006 and 2011.
To get a better handle on the extent of flooding that occurred in these two events, and how
they compared, you can use the reports from the above-mentioned sites. In addition, the
Broome County GIS Website shows the extent of flooding in 2006 and 2011 in the Triple Cities
area (see figures on following pages).
10. Describe areas in Johnson City and adjacent areas north and south of the Susquehanna
River that were flooded in 2006. Note any major landmarks and/or roads that were
underwater.
●
Susquehanna floodwater covering Route 41 near Afton, NY.
●
Susquehanna floodwater over County Road 26 in Nineveh, NY.
●
The Chenango and Unadilla Rivers and Oneida Creek were among the other high-rising
waterways
●
Chenango driving range and Chenango bridge
11. Were these same areas flooded again in 2011? Were more areas flooded? Were some areas
that were flooded in 2006 flooded less severely?
The September 2011 flood was severely worse than the one in 2006, as it was significantly more
devastating in proportion.
The same areas were hit like the Susquehanna River (bordering Downtown Binghamton), and
the Chenango River, but these areas were flooded to a much greater extent, setting records
after the flooding from the 2006 storm. It was recorded to be half a foot higher than the
previous high mark in 2006.
Part 3. Comparison and Conclusions
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The main floods of 2006 and 2011 were the two biggest floods that the Triple Cities area has
experienced in recorded history. What was similar about the storms and the subsequent
floods? What was different? Did pre-existing conditions play a similar or different role? How
important were the location and amount of highest precipitation during these storms? In
conclusion, what conditions led the 2011 flood to be larger?
The storms in both 2006 and 2011 hit the same areas. As a result of the 2006 storm, inundation
modeling to help develop efficient plans to help offset the devastating effects on the
infrastructure and affected populations in these areas in subsequent storms to come (near the
Chenango and Susquehanna Rivers). The main notable difference between the two storms was
the intensity of the September 2011 flood compared to the 2006 storm, which was much less
intense yet still damaging. Both the tropical moisture moving northwards and global warming
were the main pre-existing conditions that played a similar role in contributing to the nature of
both the 2006 and 2011 floods.
2006 Flood map, Johnson City/Endwell/Vestal
B
2011 Flood map, Johnson City/Endwell/Vestal area
Part 4. Assessing Effect of the Binghamton Floods of 2006 and 2011 on Flood Frequency
In the analysis of flood frequency, whether for scientific predictions, flood insurance
assessment, or other purposes, one of the more challenging issues is how to deal with
extremely large historical floods. The basic question: if a particular flood is significantly larger
than any other historical event, should it be considered as part of the data used in computing
the potential for future large floods, or should it not be included in the calculation because it is
an “outlier”? In this part of the exercise, you’ll examine this question by looking at how much
change the inclusion (or not) of the largest historical events would have on predicting the size of
the 1% exceedance flood.
One of the lingering questions about these two floods is, how rare were they? Should they be
incorporated into flood frequency assessments in order to estimate the size of the 100-year
flood and floodplain, as required by law? The Federal Emergency Management Agency has
been revising floodplain maps of the Binghamton area (as well as other areas all over the US) in
light of the recent flood history. They incorporated the 2006 flood directly into their initial
calculations and likely will include the 2011 flood as well.
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As a current resident of the Binghamton area, you may well feel it is worth doing the flood
assessment as correctly as possible. On the one hand, you wouldn’t want the flood hazard to
be
under
estimated, as this would lead to a false sense of security. On the other hand, you
wouldn’t want the flood hazard to be
over
estimated, as this would needlessly require some
people to purchase (fairly expensive) flood insurance.
For this part of the assignment, you will review the implications of including the 2006 and 2011
floods in the flood frequency analyses and decide whether you think including these data points
is appropriate.
1.
The accompanying graphs show the flood frequency relationships for the gaging station
in Conklin (a) excluding and (b) including the 2006 and 2011 floods in the computation.
In both cases, estimate the recurrence interval that would be assigned to the 2006 and
2011 floods (follow the example provided for the Vestal gaging station). The peak
discharge of the June 2006 flood at Conklin was estimated to have been 78,400 cubic
feet per second (cfs); the peak discharge of the Sept 2011 flood was 72,100 cfs.
2.
Compute the 100-year flood for each graph.
3.
Turn in: your graphs to show the recurrence intervals for the Conklin site; a table that
compares the 100-year flood computed with and without the 2006 and 2011 floods
used in the data set and the recurrence intervals of the 2006 and 2011 floods with and
without that floods used in the data set (i.e. from graphs 2 and 3); a short discussion of
how different the results are; and whether and why you believe one or the other sets of
values is more useful in guiding flood hazard assessment.
Recurrence interval =
x 100
1
𝐸????????? ?𝑟????𝑖𝑙𝑖𝑡? Recurrence interval of a 100 years = 1% probability of it occurring again after the next 100 years
Example: 1/.75 x 100 = 133 years (rate at which the 100 yr flood will occur)
Take the value of the peak discharge for the flood (in this case, 116,000 cfs), and draw a
horizontal line for that value to where it intersects the best-fit curve (the horizontal blue line in
the figure above). Then draw a vertical line down to the x-axis to estimate the exceedance
probability (the vertical blue line in the figure above). Recall that the recurrence interval is
(1/exceedance probability) x 100. In this case the 2006 event has an estimated return period of
around 150 years. The two dashed red lines, by the way, show the confidence limits in the
estimate:, worth knowing, but not something you need to estimate for this assignment.
Including 2006/2011 Floods:
Conklin, NY, flood frequency plot using all data including 2006 and 2011 floods. Vertical axis is
Annual Peak Discharge in cubic feet per second; graph has been stretched and truncated so that
scale is similar to second graph below.
Excluding 2006/2011 Floods:
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Conklin, NY, flood-frequency analysis excluding the 2006 and 2011 floods from the analysis.
You’ll need to plot where the 2006 flood would show up on this graph and estimate its
recurrence interval, following the guidelines from the Vestal example on the previous page.
Including 2006/2011 flood
data
Excluding 2006/2011 flood
data
2006 Flood Recurrence
interval
143 years
333 years
2011 Flood Recurrence
interval
90 years
200 years
100 year flood annual peak
discharge
70,000 cfs
65,000 cfs
The expected recurrence for both floods varies greatly between graphs that include and exclude
them as data points because of the mapping of the recurrence interval. 190 years separate the
two graphs for the expected recurrence interval of the 2006 flood, with more years expected in
the model excluding it. When the 2011 flood is excluded from the model, it would take 200
years for the flood to recur over the course of 90 years. The difference shown here is lower, with
110 years. The peak flow rates for each model in the case of a flood event occurring every 100
years are 70,000 cfs for the model that includes the two major floods and 65,000 cfs for the
model that excludes them.
Considering the substantial time gap of more than a century between the recurrence
intervals of the two floods in the two models, determining which is more reliable for
flood hazard assessment poses a challenge. Nevertheless, the first model, which
incorporates both floods as data points and still demonstrates a recurrence interval of
nearly a century, might be the preferable choice. A century is not too distant, and
adopting this model wouldn't result in a preparedness gap of over three centuries, even
in light of the 2006 flood events.
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