Analysis of Precipitation Variability and Meteorological
Drought in the Apalachicola-Chattahoochee-Flint River Basin
Department of Meteorology
Florida State University
Tallahassee FL 32306-4520
Supervising Professor: Paul H. Ruscher
The water flowing through Apalachicola-Chattahoochee-Flint River (ACF) River
basin is used by several cities, industries, and farms, and for wastewater dilution,
navigation for barge traffic, recreational boating and fishing, wildlife conservation and
power generation. Droughts result in adverse effects for water users in this basin. For
example, the drought of 1980-1981 caused a reduction in hydroelectric power generation,
the curtailment of navigation, reduced lake levels for recreation, and restrictions on lawn
watering and other water uses, according to U. S. Army Corps of Engineer reports.
Besides, recent water-use conflicts between the states over which the ACF River Basin
flows have made clear how important it is to monitor weather effects on stream levels.
This study collects and analyzes cooperative and first-order precipitation
observations of stations within the ACF river basin in order to assess significant droughts
experienced in the past. Observed and replaced missing data went all the way back to
1895, giving the study a long period of time to analyze precipitation climatology. The
main emphasis will be to describe the ACF river basin’s precipitation patterns for the last
century. This includes a climatology definition or normal annual precipitation value for
each station in the basin from 1931 to 1980. The final result will show how these stations
patterns differ or relate throughout the basin. We hope to gain a perspective on the
frequency and nature of drought in the ACF basin, in order to help inform the debate and
controversy about water use. In summary, basin-wide prolonged droughts of several
years duration are frequent and are likely to significantly affect long-term decisions
regarding water allocations in the region. There are serious political and legal
repercussions that will soon be discussed in Federal courts that will affect users in three
states, as well as stakeholders in industries along the Gulf of Mexico coast.
The Apalachicola-Chattahoochee-Flint (ACF) River basin covers approximately
50,800 km2 (United States Army Corps of Engineers [USACE] 1984) and drains parts of
Alabama, Florida and Georgia. Most of the Chattahoochee and Flint River basin
(headwaters) are contained in Georgia, north of Lake Sydney Lanier. They stretch south
to Florida to form the Apalachicola River, which discharges its waters into the Gulf of
Mexico (Figure 1). The water flowing through the ACF River basin is used by several
cities, industries, and farms, and for wastewater dilution, navigation for barge traffic,
recreational boating and fishing, wildlife conservation and power generation. (Marella et
al. 1993; Figure 2)
As the ACF river basin’s streams flows to the south, they cross the boundaries of
different climate regions, created by the National Climatic Data Center. These
boundaries are used to group and study different climatic variables such as temperature,
rainfall and humidity, and then determine averages, minimums and maximums, and
declare any weather extremes, such as droughts, for these areas.
Droughts adversely affect water users in this basin. For example, the drought of
1980-1981 caused a marked reduction in hydroelectric power generation, the curtailment
of navigation, reduced lake levels for recreation, and restrictions on lawn watering and
other water uses (USACE 1984). Besides, recent water-use conflicts between the states
(Yates 2003) through which the ACF River Basin flows have made clear how important
it is to monitor weather effects on stream levels. Water allocation rights between states
and stakeholders are now issues before Federal courts, in one of the first major disputes
of this kind in the eastern United States.
The purpose of this study is to examine the frequency of meteorological drought
(using historical precipitation data) for the ACF basin. Rainfall data have been recorded
for 108 years through different agencies and cooperative observers throughout Florida,
Georgia and Alabama. The National Weather Service stations and cooperative observer
stations have made their information available to the public through the National Climatic
Data Center (NCDC). For this study, monthly precipitation data for the past hundred
years have been retrieved for the stations in the ACF Basin. Other information and data
about stream flow, river basin boundaries and pertinent material have been obtained
through the studies and databases of the U.S. Geological Survey (USGS).
This study collects and analyzes cooperative and first-order precipitation
observations within the ACF River basin in order to assess significant droughts
experienced in the past. Observed data spanned 1895 through 2002, providing a long
period of record. We hope to gain a perspective on the frequency and nature of
meteorological drought in the ACF basin, in order to help inform the debate and
controversy about water use.
Our reference climatology for the calculation of anomalies and departures from
normal was made using data from 1931 to 1980, the period that had the best dataset in
terms of small amounts of missing data. The entire dataset was analyzed using a 50-year
climatology because we wished to use a longer period than the traditional 30 years here;
however, 1931 also marks the beginning of the time when many stations have easily
retrievable data from NCDC in the same format. Precipitation distribution charts were
made for each station to find what type of distribution they had. Another set of charts was
prepared for the precipitation anomalies, defined as the departure from our 50-year
climatology for each station. Other statistical figures, like standard deviation and
normalized values, similar to a precipitation index, were calculated to help organize and
analyze the dataset. The 10th, 25th and 50th percentiles of observed annual total events
were calculated, and they were used to determine the degree of drought intensity.
Because the distributions did not illustrate normal distribution signatures, we will use the
median and measures of spread to define drought, rather than just a certain standard
deviation below the mean.
We seek to define how dry any year was compared to our long-term climatology.
These calculations identify drought occurrences and separate those events that have
relatively longer and more intense dry conditions from the shorter, less intense ones. Our
study defines prolonged meteorological drought periods as those of three or more
consecutive years of precipitation that is below normal, that also had at least one year
with precipitation measured below the 25th percentile for that station. This threshold was
used because we first want to determine how common are these prolonged droughts,
especially those with at least one particularly dry year, and if these prolonged events have
any notable time and space distribution over the river basin.
These prolonged droughts, with one or more very dry years included among
several dry years in a row, tend to have a different type of impact on many agricultural
and economical aspects than shorter, episodic, annual droughts. This is because longer
droughts would require a greater logistical plan of action to avoid larger economic losses
and to be able to recover from them faster than short droughts would. There is more
likelihood of substantial impact on agriculture, recreation, fisheries, forest health (and fire
danger), and water quality due to low water levels and low soil moisture values during
these times. Also, people affected the most by these events probably have shaped their
decision making according to the empirical knowledge of climate they have acquired
over the years. They might have established agricultural and management practices
according to the climate for the past 20 or 30 years (or even much shorter periods of
time), but without knowing how much the weather could or has changed over the past
decade compared to previous decades. It might be helpful to either corroborate their
practices or alert them for any possible changes in the climate of the river basin.
II. Chattahoochee-Apalachicola-Flint river basin under study
Because of its location, many important urban and agricultural areas take
advantage of the waters in the ACF drainage basin to provide power generation, irrigation
and waste disposal. For this reason, there have been several important studies conducted
on this river basin. A few have served as sources of information for the river basin’s
physiography presented in this paper. Some of the previous studies and papers deal with
environmental issues, and concentrate on studying the different environmental settings
throughout the basin; others have studied the river basin’s water flow and discharge.
They take only a general look at precipitation data; their main focus takes into account a
broad band of aspects that diminish their attention on studying rainfall.
The Apalachicola-Chattahoochee-Flint Rivers drain approximately 50,800 km2 in
Georgia, Alabama and Florida (Figure 3). The Chattahoochee River is born in northern
Georgia, and it flows 430 miles towards the South, serving as a boundary line between
Georgia and Alabama. The Flint River originates south of Atlanta and travels 350 miles
through part of the state before it joins its waters with the Chattahoochee River (Couch et
al., cited 2004). Because of rainfall distributions, the average annual discharge from the
Chattahoochee River exceeds that of the Flint River. The Chattahoochee River also
makes a greater contribution to peak flows in the Apalachicola River than the Flint River.
However, during extremely dry periods, the greater flow contribution comes from the
Flint River, whose base flow is sustained by ground water discharges (Elder et al. 1988).
It is estimated that aquifer discharges to the Chattahoochee River are one-fifth of the
amount that aquifers discharge to the Flint River (Torak et al. 1991). Then, they drain
their waters into Lake Seminole, which in turn feeds the Apalachicola River. The
Apalachicola River crosses a short extension of 106 miles over northern Florida before it
sheds its waters in Apalachicola Bay and the Gulf of Mexico (Couch et al., cited 2004).
Eighty percent of the Apalachicola River’s flow is contributed by the Chattahoochee and
Flint River, 11 percent by the Chipola River and less than 10 percent from ground water
and overland flow (Elder et al. 1988). Some recent preliminary work suggests that the
past 25 years have suffered frequent periods of very low flow (Figure 4) (Light 2004,
unpublished data). It is also important to mention that other factors such as agriculture
and urban population growth might be having a greater influence in these low flow
events, and that they might have a greater influence on these dry conditions than lack of
rainfall does (Leitman et al. 2003).
III. Description of methodology
Data were collected from the cooperative and first-order observation stations
within the Chattahoochee-Flint-Apalachicola river basin from NCDC, which amounted to
a total of 122 stations. However, few stations had consistent observations throughout a
long period of time, but some had information that went back up to the 1890’s. This long
period of record, even with its inconsistencies in data completeness, still provides
valuable information, which may be used to analyze the river basin’s climatology.
In the selection process, the only stations kept for the study were those that had at
least 30 years of complete data. Of the 122 stations present on the original dataset, only
50 stations complied with the minimum. As was mentioned before, many of these
selected stations had data that went back to the 1890’s, but these years outside the 30
minimum had gaps of one or more (partial or full) years throughout their records.
Because of these data gaps, it was necessary to create a way of filling the missing data by
using those stations that had valid data around that area (of course radar estimates are not
available for most of our study period). Then, a method for completing the desired
longer period of record using complex interpolation techniques was required.
A helpful tool developed by the Spatial Climate Analysis Service at Oregon State
University was used to complete the few years that made some stations’ data inconsistent
throughout time. This tool is a computer model called PRISM (Parameter-elevation
Regression on Independent Slopes Model). PRISM is a knowledge-based system that
uses point data, a high-resolution digital elevation model (DEM), and many other
geographic data sets to generate gridded estimates of monthly and event-based climatic
parameters (Daly et al. 2004). PRISM has been used extensively to map precipitation,
dew point, and minimum and maximum temperature over the United States, Canada,
China and other countries (USDA-NRCS 1998, Daly et al. 2004). The method used by
this software was strongly appealing and parallel to the study’s plan for completing the
data, because it “can provide time series of spatially distributed precipitation for a variety
of watersheds and drainages at time intervals ranging from years to single events, serving
as high quality input” (Daly et al. 2004). Another appeal for using the model was that
part of its data came from the same cooperative observer stations used by this study.
Overall, the reliability of the model has undergone extensive evaluation ever since
it became available, and it has been used for hydrological modeling and related scientific
studies. Several of our stations where chosen to test the model’s ability to create
interpolations that closely resembled real observations, and some of these are shown in
Figure 5. The program appeared to very reliably replace missing data with realistic
values in a very consistent manner, so the PRISM program was used to fill in missing
observed data, when monthly accumulations were missing from the NCDC dataset.
More details can be found on the PRISM software’s web page which address is indicated
in the references page (Oregon State University 2004).
The most reliable period of observations occurred between the 1930’s and 1980’s.
For this reason, our normal climatological values were calculated using the 50 years
between 1931 and 1980 (Figure 6). In particular, many stations had reliable data
beginning in 1931 in common formats.
First, the climatological normal or mean values were calculated using data within
the 50-year range, together with the standard deviation. The precipitation anomalies were
then graphed by calculating how many standard deviations, above or below normal, the
total annual precipitation was for a station on each given year (Figure 7). The normal
values would help distinguish dry periods from wetter ones at the same time that it would
make dry year trends easier to spot.
The entire set of plots are available on a web site at
http://yankee.met.fsu.edu/~ruscher/ACF/. The next step was to calculate different
percentiles for the stations. The 10th, 25th and 50th percentiles were calculated, and lower
decile and lower quartile were used as initial criteria for determining significantly dry
years. Determining drought periods just using the 10th percentile would not necessarily
account for all years that could have been dry enough to have a major impact on the river
basin, and any several year-long droughts that might have had a significant impact as
well. The 25th percentile appeared to be a more acceptable threshold to use for
determining multiple years of drought by cutting out below-normal-precipitation years
that were too close to climatological average, while maintaining yearlong drier periods.
The next step of this study was to analyze how many stations were in a drought
period for each year. This would show if there is any pattern to the drought distribution
in the river basin and if different stations coincide with similar drought periods.
Furthermore, this classification would tell how recurrent were basin-wide and regional
droughts for the last one hundred years. Years that had a large number of stations
recording values below the chosen percentile will also be pointed out in this study.
V. Significant Droughts
Table I summarizes groups of drought periods by the number of stations that
suffered drought conditions. The 10th percentile and 25th percentile were calculated here
to demonstrate the viability of our chosen threshold. At the lower decile, a large number
Table I: Years with the number of stations recording below the 10th and 25th percentile values,
respectively, based on the sample size of 50 stations in the ACF Basin.
Year Total Stations Total stations
below 10th percentile below 25th percentile
1899 16 50
1904 21 50
1910 15 50
1921 19 50
1925 18 50
1927 20 49
1931 20 50
1933 14 48
1935 10 42
1938 18 48
1941 11 44
1950 15 49
1954 20 50
1955 17 47
1968 18 47
1981 13 46
1986 12 46
1990 9 45
1999 16 48
2000 19 49
*Boldface font indicates years which fall outside multiple-year drought periods
of years are present in which there do not appear to be basin-wide impacts (based on the
number of stations meeting the harsh threshold). The lower quartile, however, appears to
adequately represent the idea of basin-wide drought, as evidenced by the large number of
years in which all stations are in rainfall deficits. Therefore we adopt the 25th percentile
as the threshold that must be met at least once during a multiyear period to define a
prolonged drought; that is at least one of three consecutive years must have an annual
precipitation value which is no more than the 25th percentile. A more robust statistical
threshold could be applied to more adequately address questions regarding objective
thresholds appropriate for defining meteorological drought here. Based on this chosen
threshold, the major droughts are indicated in Table II. A statistical summary for all 50
stations used in this study is shown in Table III at the end of this document.
Table II. Periods of time classified by percentage of stations (N) under 3-year long
droughts (or longer)
N < 25% of river basin 25% < N <50% 50% < N < 75 % of river basin
1902-1904 1908-1910 1895-1899
1913-1918 1930-1935 1949-1952
1924-1926 1954-1956 1984-1988
Of the 108 years in the study, a total of 51 years are represented in the table above
as part of notable dry periods covering at least part of the ACF basin. There were four
drought periods from 1895 to 2002 in which at least one year had most of the river basin
area experiencing drought conditions (the last column in Table II). The first such drought
period began in 1895 (which is also the first year of data), in a drought that had more than
half of the selected stations in drought conditions. That is, the recorded values for a
station were below the 25th percentile. They concentrated over the northern and central
region. In 1897, 40 stations (out of 50) showed to be part of a three yearlong drought
event. The drought extent decreased the next year, by recording above the 10th percentile
total annual precipitation for all the river basin stations. Less than half of the selected
stations showed a continued drought event for the following year, concentrating mainly
on the southern regions before it faded on 1900 (Figure 8).
The second drought period under this category occurred between 1949 and 1952.
Three years of selected stations with no-drought conditions preceded the year of 1949.
More than half of the stations suffered drought conditions that year, all evenly spread
throughout the river basin, and a quarter of the stations recorded total precipitation below
the 10th percentile for that year. The two following years suffered a river-basin extended
drought. Then, in 1952, only 25 percent of the stations experienced another year of
below normal rainfall, while the rest suffered drought for two of the next three years. A
year later, half of the river basin suffered another 3-year drought, while the rest suffered
two more years of drought out of three.
The third drought period happened between 1984 and 1988. The two first years
of the event had more than half of the stations under the dry spell before most of the
entire basin stations fell under this condition. These stations were initially concentrated
mainly on the central region of the basin, with no stations either in Florida or the northern
part of the Georgia basin in drought conditions, according to the study definition. In
1986, 44 stations suffered the dry conditions, and in 1987 and 1988, forty-three stations
were still under the dry spell.
The fourth period lasted from 1998 to 2001. Three of these four years had most
of the river’s drainage area suffering smaller-than-normal amounts of precipitation, and
more than half the basin in 2001 before drought anomalies disappeared. In 1998, only a
quarter of the basin’s stations experienced dry conditions. In 2002, only half of the
stations continued to have lower than normal annual precipitation. During this time (in
September 1999), Lake Jackson, a lake in Tallahassee in an enclosed basin covering
1,658 ha (4,097 acres), drained completely overnight into one of several karst sinkholes,
an event which has occurred throughout modern history during many of these dry spells
in the neighboring ACF Basin, since at least 1907. The drawdowns or drainings from
1907-1911, in the 1930s, 1950s, 1980s, and the present one all related quite closely to the
drought periods for the ACF Basin (Table II), suggesting a profound meteorological
reason for the drawdowns of this significant body of water, with historical excellent bass
fishing and recreation (Tucker 2003). The lake slowly began filling but emptied again in
2002, and still remains approximately 1.5 m below normal levels, which makes several
areas of the lakebed still dry, apparently the longest dry period for the lake since 1911.
A few other periods of apparent drought did not meet the same threshold as the
prior periods, but they are notable, so they will be summarized here. The northern region
experienced very dry conditions from 1933 to 1935, with the former holding dry
conditions for the entire basin (Figure 9). The drought from 1954-1956 had at least half
of the studied stations under a multiple-year drought. The first two years of this period
were the driest of all. They had nearly all their stations in below-normal conditions, and
at least 17 stations were below the 10th percentile ever recorded for each year. The whole
decade seemed to be one of the driest, as it experienced two drought periods.
The 1902-1904 drought was a northern region drought, although the entire river
basin experienced dry conditions in 1904. The 1908-1910 drought affected the southern
region of the basin (Figure 10). The year 1910 was dry below the 25th percentile for the
entire basin with 15 stations recording the first under-the-lower-decile values of the
century. The central parts of the basin experienced one of the longest dry periods from
1913 to 1918. The years 1913, 1914 and 1916 affected the entire region, but very few
stations had recorded total annual precipitation below the lower decile value. The 1924-
1927 drought affected the northern region. The years 1925 and 1927 brought the dry
spell to the entire basin. This drought period has a slightly larger number of stations
(about 5 to 6 more stations) under this condition than during 1902-1904. The 1938-1941
period of time had the stations on the northern region experience 4 years of dry
conditions. The years 1938 and 1941 affected most of the basin (Figure 11). The years
1958 and 1960 were the harshest for the basin when 39 and 34 of the stations experienced
dry conditions. The 1967-1969-drought period affected mostly the basin’s central region
stations. Once again, the 1958-1960 period brought dryness to the northern regions.
The longest drought period found during the period 1895-2002 lasted 6 years,
from 1913 to 1918. There were two droughts that lasted 5 years (1895-1899, 1984-1988)
and 4 that lasted four years (1999-2002 being the most recent one). There were about
twenty-three years that had at least 90 percent of the basin under dry conditions in the
108-year period of record. The maximum number of stations reporting below the lower
decile for a given year was 21. The decade of the 1950s was the driest, followed by the
1930s by having at least 50 percent of the basin’s region under dry conditions for almost
all of the 10 years. The 1970s was the least dry decade with just one year having more
than 75 percent of the basin under the dry spell, followed by the 1990s.
The Apalachicola-Chattahoochee-Flint river basin is an important part of the
socioeconomic structure of Georgia’s, Alabama’s and Florida’s urban population,
agricultural and power generation economy. They take advantage of the river’s stream
flow to carry some of the most basic and important activities of any modern population.
It has been demonstrated that the sources of water for the streams differ for each river.
The Flint River, with a smaller flow, is more stable throughout the year because it has
ground water feeding its mainstream, while the Chattahoochee River depends more on
precipitation runoff. The Chattahoochee River possesses a much larger stream flow and
has a greater contribution on the peaks recorded by the Apalachicola River. Mainly fed
by the upstream rivers, the Apalachicola River also benefits from aquifer waters and
other aquifer-fed affluent waters that flow into it. This way, it is possible to visualize that
the Chattahoochee River will be affected the most by rainfall variability.
Long-term droughts will not have an immediate effect on groundwater fed rivers,
but they would significantly hurt the Chattahoochee River at first, and most likely the
Apalachicola River, too. Prolonged droughts will also affect groundwater fed rivers like
the Flint because its aquifers will not be able to recharge their water tables were a drought
event to last long enough. Florida is very dependent on reliable water flows in the
Apalachicola River, in particular, and the river established some record low flows (Figure
12) during the most recent drought (USGS 2004). These low flows are serious
impediments to any multi-state agreements that might solve water use allocations, and in
fact, the ACF Basin water allocation formulas are likely to be resolved by the Federal
courts, the first time this will have occurred for the United States east of the Mississippi
River for a large multi-state river basin.
With this study, it has been determined that the river basin has suffered from
several multiple-year-long droughts throughout the last century, sometimes even having
two events within the same decade. These periods of dryness can have a localized pattern
to them. For example, the 1902-1904 drought affected most of the basin’s northern
region, and with it, most of the Chattahoochee and Flint headwaters. Other droughts, like
the 1913-1918 drought mostly affected the central region of the basin.
There is no obvious pattern for the return of drought periods, except
acknowledging they can happen within just one year from the other. It can also be said
that droughts have not lasted more than 6 years for any particular area, usually no longer
than two consecutive years for the entire basin, and that the likelihood of these type of
long term events is small. This assumption can be made if we take the first year used for
this study as the beginning of the first drought. Otherwise, this drought could have been
another of the longest recorded droughts in the ACF river basin. Years with extreme
events tend to be peaks of a drought period, although a few years have been recorded as
stand alone drought years. Two examples of this are the 1931 and 1981 droughts, which
experienced 20 and 13 stations, respectively, under the lower decile values, with the rest
of the basin under the 25th percentile values.
It is tempting to compare return periods of these droughts with other quasi-
periodic events, such as was already done for the Lake Jackson drawdowns. It is well
known, for example, that the cool phase of the El Niño-Southern Oscillation (ENSO)
known as La Niña, is generally associated with drier than normal conditions in the
southeastern United States (Green et al. 1997). In comparing our drought years from
Table II to published La Niña years from the FSU Center for Ocean-Atmosphere
Prediction Studies (COAPS, cited 2004; data are classified beginning in 1900), we find
the connection somewhat plausible, with 29.4% (15 out of 51) of our dry years (from
Table II) also occurring during La Niña. Dry years also corresponded with seven El Niño
events (13.7%), while the remaining dry years were associated with neutral years.
Curiously, while none of the four prolonged extreme drought periods corresponded to La
Niña, two of the three droughts which affected between 1/4 and 1/2 of the basin matched
exactly prolonged La Niña periods (1908-1910 and 1954-1956). In addition, the years
1998 and 1999, half of the most recent devastating prolonged drought, were both La Niña
years. Further study of this relationship is suggested, given that long-term droughts are
generally longer than La Niña events, which will usually be preceded and followed by
neutral years, if not El Niño (warm phase).
We have demonstrated that the Apalachicola-Chattahoochee-Flint river basin is
susceptible to multiple year droughts, and droughts receiving precipitation below the 10th
and 25th percentile that last up to three or more years have happen rather frequently.
Extremes can also happen during years that are not part of multiple years of drought.
This variability makes it difficult to estimate a single plan of action for these events, and
it is difficult to rely on the recurrence of certain patterns. As the generally wetter 1970s
and 1990s show, it can be an entire decade before another multiple-year drought occurs.
No decision-making can rely on the increased wetness of a decade, for this characteristic
may not last in the next one. There are also many ways to define drought, in
meteorological and non-meteorological terms. Future studies of both physical and
sociological aspects of water use are recommended to resolve the issue of water supply
for the important ACF river basin.
Acknowledgements: Sincere gratitude to my honor's thesis committee members, Dr.
Henry Fuelberg and Dr. Sergio Fagherazzi for being a part of my honors thesis defense.
Thanks also to the departmental faculty committee, whose members provided some very
helpful comments to improve the manuscript. Special thanks to my family, that even
though far away from where I’ve worked and studied, always gave me moral support to
continue my pursuits, including this little project. We thank the Spatial Climate Analysis
Service at Oregon State University for permission to use the PRISM software, and thank
USGS for the use of their unpublished data. And last, but not least, my thanks to Dr. Paul
Ruscher, for all the time dedicated and the trust he put in me in doing this project.
COAPS, cited 2004: ENSO Index According to JMA SSTA (1868-present). Retrieved
online June 2004, from the Center for Ocean-Atmosphere Prediction Studies, at
Florida State University, from
Couch, Carol A., et al., cited 2004: Influences of Environmental Settings on Aquatic
Ecosystems in the Apalachicola-Chattahoochee-Flint Basin. U.S. Geological
Survey Water-Resources Investigations Report 95-4278.
Daly, C., Gibson, W.P., M. Doggett, J. Smith, and G. Taylor. 2004. Up-to-date monthly
climate maps for the conterminous United States. Proc., 14th AMS Conf. on
Applied Climatology, 84th AMS Annual Meeting Combined Preprints, Amer.
Meteorological Soc., Seattle, WA, January 13-16, 2004, Paper P5.1, CD-ROM.
Green, P. M., D. M. Legler, C. J. Miranda V., and J. J. O'Brien, 1997: The North
American climate patterns associated with the El-Niño-Southern Oscillation.
Unpublished manuscript, COAPS Report Series 97-1, Center for Ocean-
Atmosphere Prediction Studies, Florida State University, Tallahassee. Available
online at http://www.coaps.fsu.edu/lib/booklet/.
Light, Helen. 2004. Increase in frequency and duration of very low flows (graph) USGS.
Marella, Richard L., Fanning, Julia L. and Mooty, Will S., 1993: Estimated Use of Water
in the Apalachicola-Chattahoochee-Flint River basin during 1990 with State
Summaries from 1970 to 1990, U.S. Department of Interior, WRI 93-4084
Tallahassee, Florida, pg 1-58
Torak, L.J., Davis G.D., Herndon, J.G., and Strain, 1991: Geohydrology and evaluation
of water-resource potential of the Upper Floridan aquifer in the Albany area,
southwestern Georgia: U.S. Geological Survey Open-File Report 91-52, 85 p.
Tucker, T., 2003: "Fate of Famed Florida Lakes Remains Uncertain", Bassmaster April
2003, retrieved online June 2004 from ESPN.COM at
U.S.G.S., 2003a: National Water Quality Assessment (NAWQA) Program's
Apalachicola-Chattahoochee-Flint (ACF) River basin study Home Page. U.S.
Geological Survey. [Available online at
U.S.G.S., 2003b: Water Watch, Current water resources conditions. U.S. Geological
Survey. [Available online at http://ga.water.usgs.gov/nawqa/index.html]
U.S. Army Corps of Engineers, (U.S.A.C.E.) 1984: Water assessment for the
Apalachicola-Chattahoochee-Flint River Basin (Main Report): Mobile, U.S.
Army Corps of Engineers Executive Summary, v. 1, 88 p.
Yates L., Oliver, cited 2003: Water Wars in Drought-Ridden Southeast. [Available
online at http://abcnews.go.com/sections/us/DailyNews/water000811.html]
McKee, Thomas B., Doesken, Nolan J., and others, cited 2003: A History of drought in
Colorado Lessons learned and what lies ahead., Colorado Climate Center,
Colorado State University, Atmospheric Science Department [Available online at
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Estimation, [Available online at
X. Other Data Sources
National Climatic Data Center. Collection of Cooperative Observer Station’s Monthly
Precipitation, Temperature data. http://www.ncdc.noaa.gov/oa/ncdc.html
“Spatial Climate Analysis Service, Oregon State University,
http://www.ocs.oregonstate.edu/prism/, created 10 March 2004.”
Table III. Statistical summary of the 50 stations in the ACF river basin
Climo Value (1931-2002) Normal (1895-2002) Standard
Station hundredths of an inch hundredths of an inch 10 th
25th 50th Deviation
10422 5521.63 5409.50 4349.40 4835.25 5306.500 913.68
12372 5322.06 5351.74 4254.00 4780.50 5189.500 948.17
12730 5094.65 5098.10 4199.70 4565.50 4979.500 814.65
14502 5492.00 5431.50 4458.60 4835.50 5382.000 859.74
14884 5330.53 5265.79 4126.00 4723.00 5253.500 903.73
15439 5282.57 5196.89 4348.40 4600.25 5124.000 869.28
16129 5459.41 5395.38 4405.60 4823.75 5332.000 890.04
18438 5297.10 5327.90 4117.90 4842.25 5252.500 927.86
80211 5293.53 5335.98 3991.80 4598.00 5181.500 1217.31
85372 5605.24 5663.12 4552.60 5018.00 5606.500 922.29
87424 5496.39 5505.41 4176.60 4794.75 5418.000 996.23
87429 5612.00 5575.57 4284.20 4877.50 5613.500 1089.37
89566 6696.35 6492.79 5221.70 5711.00 6240.000 1239.19
90140 4919.33 5147.29 4021.60 4316.00 4905.000 889.91
90219 5047.75 5112.72 4166.80 4548.00 5016.000 791.86
90253 4901.88 4878.07 3844.70 4355.25 4793.000 890.66
90451 4839.61 4861.03 4004.40 4396.25 4808.000 754.72
90581 5177.35 5117.18 3947.70 4466.25 5036.000 969.96
90979 5467.39 5373.60 4099.60 4661.00 5253.500 999.62
91372 4900.33 4899.17 4016.40 4323.25 4746.500 788.61
91463 5189.45 5167.15 4010.90 4598.00 5186.500 973.74
91500 5084.53 5119.54 4011.50 4430.50 5034.000 871.21
91640 5222.39 5187.44 4156.00 4527.50 5166.500 843.55
92006 6514.16 6191.32 5045.70 5795.50 6403.000 974.53
92166 5007.78 5228.72 3808.40 4336.00 4767.500 866.65
92198 4988.71 4802.04 3976.00 4318.00 4733.000 771.19
92266 4539.80 4538.52 3560.60 4094.50 4463.500 811.65
92450 5131.39 4959.43 4023.60 4587.75 5024.000 929.35
92475 6287.45 6069.16 5033.90 5531.00 6368.500 1035.81
92485 5183.76 5570.37 4251.50 4743.50 5371.000 871.62
92570 5039.80 5075.00 3869.80 4416.25 4895.500 871.13
92578 5932.59 5649.40 4733.00 5341.50 5913.000 980.23
93147 5407.06 5638.68 4360.50 4906.50 5463.000 862.44
93271 5084.16 5076.09 4006.90 4333.50 4804.000 857.28
93516 5365.96 5274.13 4083.30 4747.50 5237.500 945.20
93570 5233.71 5122.38 4195.30 4688.75 5081.500 793.89
93621 5486.55 5430.21 4371.00 4904.00 5551.000 902.44
93936 5122.82 5139.93 4065.80 4344.00 4827.500 865.26
94700 4983.69 4930.31 3916.10 4299.50 4831.000 876.89
94949 5319.24 5105.02 4163.80 4596.75 5126.000 868.29
95979 4683.16 4814.14 3738.70 4004.50 4406.000 790.85
96043 5333.67 4993.79 4064.20 4702.00 5324.500 921.04
96335 5198.00 5201.16 4102.20 4605.75 5182.500 880.92
96407 5149.57 5142.70 4235.70 4567.25 5196.000 841.08
97087 4836.18 5019.72 3869.90 4367.75 4729.000 814.30
97201 4978.53 4861.73 3867.20 4319.50 4807.000 842.37
98535 5247.67 4861.08 3865.90 4332.50 4816.500 954.67
98661 4973.16 4943.75 3981.80 4309.00 4751.000 782.12
99291 5241.18 5087.00 4193.40 4597.75 5074.500 848.74
99506 5088.75 4966.22 4033.40 4449.00 4814.500 781.45
Climo Value (1931-2002) Normal (1895-2002) Standard
Station hundredths of an inch hundredths of an inch Percentile Deviation
Table III continued.