Preface to Flood.
Floods Happen.
by Bill Wells, Reese Library, Augusta State University. 2006.
“The Savannah River is a stream bold in all of its
features,” wrote Augusta, Georgia ’s 1914 weather bureau officer-in-charge Eugene D. Emigh.[1]
The Savannah River is formed by the union of the Seneca and Tugaloo Rivers some one hundred miles above Augusta and has its cultural and physical ties to both Georgia and South Carolina. Emigh wrote, for its size, the Savannah is a “restless river” with
intermittent stretches of water “rushing over the granite bed” and “resting in placid
pools.” Overall the river made a rapid passage to Augusta with a
257-foot drop over the sixty-four miles immediately preceding Augusta. The
last “rapids” are about six miles above Augusta but once past the city the river
turns into a slow, meandering course to the sea.
Part of the river’s rush to Augusta is the up-state
topography. The “catchment” area above Augusta entails a geological formation of
the Piedmont
Plateau with its foundations of granite and gneiss. The elevation of the plateau ranges from 200 feet above sea level in the
east to 1000 feet in the west. Further north, the mountains reach 2000 feet
with some well beyond. All the height, combined with hard surfaces, made natural
runways for water run-off. At that time, the only factor preventing larger
run-off was the dense forests of the 7,294 square mile watershed. The
denseness of the forest acted to absorb the moisture through the roots or by evaporation. The concern was the large deforestation for agricultural
purposes. Emigh cited that the watershed above Augusta shrank during the 1859
to 1912 period from 70% to 19%. The result was by 1909 only 25% of the
catchment area remained forested. A positive factor of the period was during
the peak rainfall periods of January, February, March, and April the land was
being plowed for new crops and this plowed land was “ideal” for rainfall
storage.
The ideal river height level for the Savannah River was 20
feet. This level afforded water transportation as well as allowing logging
companies to float logs out the swampy regions south of Augusta. River water
would not enter Augusta until the 32-foot mark (pre-levee) and was not a real
danger to the businesses until the 34-foot mark. Emigh noted, “At 36 feet a
wide area of the business and residence sections is covered to depths of 1 to 3
feet.”
It was held that water run-off was caused by two causes.
Primary was direct falling rain and secondary a gradual supply from
saturated soil or from the forest floor. It was more common in cultivated lands
following a slow but steady rainfall. Emigh argued this was truer for long
rivers, but the short span of the upper Savannah River “freshets” came from the
delayed flow when one rain supersaturates the soil and is followed by another
rain a few days later. This combination of rapid run-off and soil saturation presented the greatest
possibility of flooding. However, by 1914 the number of days the Savannah
River, at Augusta, was above the 20-foot mark increased with the “expansion of
agricultural and contraction of forest area.”[2] The theory that plowed ground would hold more water was shown that the forests were needed to help control run off as well.
Emigh’s study of rainfall versus river height produced
interesting comments. He concluded,
Starting
from the initial stages below 16 feet, the normal amount of rise in the
Savannah River at Augusta for each inch of rain in 24 hours over the catchment
area with the ground in moist condition is 8.5 feet. This remains true until
rain has brought the river to its 29-foot stage. Any surplus of water above
that necessary to cause a 29-foot stage has a value of about 3 feet for each
inch of rain.[3]
Year |
Rainfall, January-April |
Days of 20 feet or over. |
1903 |
24.6 |
23 |
1906 |
17.8 |
14 |
1908 |
19.8 |
24 |
1909 |
18.2 |
12 |
1912 |
25.2 |
25 |
Means |
21.1 |
20 |
| Emigh, 51. |
Interestingly, rises above the 34-foot level were negligible
with the greater rises occurring at the 16-foot level. He dismissed any
calculation of rainfall that would not bring the level to 20-feet and theorized
that it would take some twelve inches of rain during the first four months of
the year to bring the river to the 20-foot mark.
Unknowingly predicting the Flood of 1929, Emigh predicted,
“If precipitation be of short duration but great intensity, it occasions a high
stage that keeps the river above 20 feet for several days.” Rain, soil
saturation, or run-off was not the only considerations of Emigh. The “flashy”
nature of the river itself had to be included in the estimations.
The freshets of the Savannah River have a long history. The
greatest was the flood of 1796, reaching an average of 40 feet making it the
greatest pre-levee flood in the city’s history. The 1929 (post-levee) flood
marks the greatest in height, but the 1930 flood exceeded in volume of water
flowing past Augusta.
Table 2.--Annual
peak stages and discharges for the Savannah River at Augusta, Ga. (02197000) for the period 1796 - 1985 |
[ft, feet; ft3/s,
cubic feet per second] |
Water
year |
Date |
Stage
(ft) |
Discharge
(ft3/s) |
|
Water
year |
Date |
|
Stage
(ft) |
Discharge
(ft3/s) |
|
Water
year |
Date |
Stage
(ft) |
Discharge
(ft3/s) |
1 1796 |
Jan. 17 |
40 |
360,000 |
|
1909 |
June |
5 |
|
28.7 |
87,300 |
|
1947 |
Jan. |
22 |
23.97 |
86,000 |
1840 |
May 28 |
37.8 |
270,000 |
|
1910 |
Mar. |
2 |
|
26.4 |
69,800 |
|
1948 |
Feb. |
10 |
23.90 |
83,200 |
2 1852 |
Aug. 29 |
37.4 |
250,000 |
|
1911 |
Apr. |
14 |
|
19.1 |
32,800 |
|
1949 |
Nov. |
30 |
26.61 |
154,000 |
3 1864 |
Jan. 1 |
34.9 |
185,000 |
|
1912 |
Mar. |
17 |
|
36.8 |
234,000 |
|
1950 |
Oct. |
9 |
20.10 |
32,500 |
1865 |
Jan. 11 |
36.9 |
240,000 |
|
1913 |
Mar. |
16 |
|
35.1 |
156,000 |
|
1951 |
Oct. |
22 |
22.32 |
46,300 |
1876 |
Dec. 30 |
28.6 |
86,400 |
|
1914 |
Dec. |
31 |
|
24.3 |
48,000 |
|
61952 |
Mar. |
6 |
21.53 |
39,300 |
1877 |
Apr. 14 |
31.4 |
119,000 |
|
1915 |
Jan. |
20 |
|
28.2 |
61,000 |
|
1953 |
May |
8 |
20.80 |
35,200 |
1878 |
Nov. 23 |
23.5 |
51,500 |
|
1916 |
Feb. |
3 |
|
31.0 |
82,400 |
|
1954 |
Mar. |
30 |
17.39 |
25,500 |
1879 |
Aug. 3 |
22.0 |
44,000 |
|
1917 |
Mar. |
6 |
|
29.2 |
68,000 |
|
1955 |
Apr. |
15 |
16.77 |
23,900 |
1880 |
Dec. 16 |
30.1 |
102,000 |
|
1918 |
Jan. |
30 |
|
25.5 |
45,500 |
|
1956 |
Apr. |
12 |
14.70 |
18,600 |
1881 |
Mar. 18 |
32.2 |
130,000 |
|
1919 |
Dec. |
24 |
|
35.0 |
128,000 |
|
1957 |
May |
7 |
14.08 |
18,000 |
1882 |
Sept.12 |
29.3 |
93,300 |
|
1920 |
Dec. |
11 |
|
35.4 |
133,000 |
|
1958 |
Apr. |
18 |
22.91 |
66,300 |
1883 |
Jan. 22 |
30.8 |
111,000 |
|
1921 |
Feb. |
11 |
|
35.1 |
129,000 |
|
1959 |
June |
8 |
18.65 |
28,500 |
1884 |
Apr. 16 |
28.0 |
81,000 |
|
1922 |
Feb. |
16 |
|
32.0 |
92,000 |
|
1960 |
Feb. |
14 |
20.58 |
34,900 |
1885 |
Jan. 26 |
27.5 |
77,000 |
|
1923 |
Feb. |
28 |
|
28.0 |
59,700 |
|
'1961 |
Apr. |
2 |
20.56 |
34,800 |
1886 |
May 21 |
32.5 |
135,000 |
|
1924 |
Sept.22 |
|
28.0 |
59,700 |
|
1962 |
Jan. |
9 |
20.09 |
32,500 |
1887 |
July 31 |
34.5 |
173,000 |
|
1925 |
Jan. |
20 |
|
36.5 |
150,000 |
|
1963 |
Mar. |
23 |
19.52 |
31,300 |
1888 |
Sept-11 |
38.7 |
303,000 |
|
1926 |
Jan. |
20 |
|
27.3 |
55,300 |
|
1964 |
Apr. |
9 |
24.16 |
87,100 |
1889 |
Feb. 19 |
33.3 |
149,000 |
|
1927 |
Dec. |
30 |
|
24.0 |
39,000 |
|
1965 |
Dec. |
27 |
20.62 |
34,600 |
1890 |
Feb. 27 |
22.9 |
48,500 |
|
1928 |
Aug. |
17 |
|
40.4 |
226,000 |
|
1966 |
Mar. |
6 |
21.50 |
39,300 |
1891 |
Mar. 10 |
35.5 |
197,000 |
|
1929 |
Sept |
27 |
|
46.3 |
343,000 |
|
1967 |
Aug. |
25 |
18.10 |
26,500 |
1892 |
Jan. 20 |
32.8 |
140,000 |
|
1930 |
Oct. |
2 |
|
45.1 |
350,000 |
|
1968 |
Jan. |
12 |
20.94 |
35,900 |
1893 |
Feb. 14 |
25.0 |
60,000 |
|
1931 |
Nov. |
17 |
|
19.9 |
26,100 |
|
1969 |
Apr. |
21 |
22.24 |
45,600 |
1894 |
Aug. 7 |
24.0 |
54,000 |
|
1932 |
Jan. |
9 |
|
30.4 |
93,800 |
|
1970 |
Apr. |
1 |
17.68 |
25,200 |
1895 |
Jan. 11 |
30.4 |
106,000 |
|
1933 |
Oct. |
18 |
|
30.3 |
92,600 |
|
1971 |
Mar. |
5 |
23.30 |
63,900 |
1896 |
July 10 |
30.5 |
107,000 |
|
1934 |
Mar. |
5 |
|
28.5 |
73,200 |
|
1972 |
Jan. |
20 |
20.36 |
33,700 |
1897 |
Apr. 6 |
29.3 |
93,300 |
|
1935 |
Mar. |
15 |
|
27.4 |
63,700 |
|
1973 |
Apr. |
8 |
21.63 |
40,200 |
1898 |
Sept. 2 |
31.3 |
117,000 |
|
1936 |
Apr. |
8 |
|
41.2 |
258,000 |
|
1974 |
Feb. |
23 |
20.13 |
32,900 |
1899 |
Feb. 8 |
31.0 |
113,000 |
|
1937 |
Jan. |
4 |
|
30.1 |
91,400 |
|
1975 |
Mar. |
25 |
22.24 |
45,600 |
1900 |
Feb. 15 |
32.7 |
138,000 |
|
1938 |
Oct. |
21 |
|
30.1 |
91,400 |
|
1976 |
June |
5 |
20.27 |
33,300 |
1901 |
Apr. 4 |
31.8 |
124,000 |
|
1939 |
'Mar. |
2 |
3 |
24.10 |
90,900 |
|
1977 |
Apr. |
7 |
20.50 |
34,200 |
1902 |
Mar. 1 |
34.6 |
175,000 |
|
1940 |
Aug. |
15 |
|
29.40 |
239,000 |
|
1978 |
Jan. |
26 |
21.98 |
43,100 |
1903 |
Feb. 9 |
33.2 |
147,000 |
|
1941 |
July |
8 |
|
22.89 |
53,300 |
|
1979 |
Feb. |
27 |
21.13 |
37,300 |
1904 |
Aug. 10 |
25.5 |
63,000 |
|
1942 |
Mar. |
23 |
|
24.56 |
105,000 |
|
1980 |
Mar. |
31 |
22.33 |
47,200 |
1905 |
Feb. 14 |
25.8 |
64,800 |
|
1943 |
Jan. |
20 |
|
25.10 |
117,000 |
|
1981 |
Feb. |
12 |
14.70 |
17,700 |
1906 |
Jan. 5 |
29.6 |
96,600 |
|
1944 |
Mar. |
22 |
|
25.53 |
128,000 |
|
1982 |
Jan. |
2 |
19.39 |
30,700 |
1907 |
Oct. 5 |
23.6 |
52,000 |
|
1945 |
Apr. |
27 |
|
23.16 |
64,000 |
|
61983 |
Apr. |
10 |
23.21 |
66,100 |
1908 |
Aug. 27 |
38.8 |
307,000 |
|
1946 |
Jan. |
9 |
|
24.43 |
97,200 |
|
1984 |
Mar. |
5 |
20.35 |
34,000 |
|
|
|
|
|
|
|
|
|
|
|
|
1985 |
Feb. |
7 |
17.89 |
25,700 |
Note: |
1 Flood of January 17, 1796, reached a stage of about 40 feet
(at site and datum of
Fifth Street gage), marked by local residents; discharge approximately
360,000 ft3/s, by slope conveyance study. Little information exists and
the data are considered approximate. Data furnished by the U.S. Army
Corps of Engineers. |
|
2 A horizontal line
in "Water year" column indicates
discontinuous record. |
|
3 U.S. House of
Representatives Document No. 64. |
|
4 Lines
across the "Date" and "Discharge" columns indicate a change in the site that significantly affects the
stage-discharge relation. |
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5 A line across the "Stage" column indicates a change in gage datum and means that the stages above and below the
line are not comparable. |
|
6 Filling of Thurmond Lake began in December 1951.
7 Filling of
Hartwell Lake began in February 1961. |
|
8 Filling of
Russell Lake began in October 1984. |
|
Source: Curtis L.
Sanders, Jr., Harold E. Kubik, Joseph T. Hoke, Jr., and William H. Kirby, Flood
Frequency of the Savannah River at Augusta, Georgia. U. S. Geological Survey, Columbia, S. C., 1990. |
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Anthony J. Gotvald, hydrologist for the USGS Georgia Water Science Center explains how river height is determined
in 2006,
“When a streamgage is
first installed, we set the gage-height to some arbitrary value. But, we try to
set this gage-height value high enough so that we don't get negative
gage-heights. We then tie this gage-height to a local benchmark in order to
determine the gage datum. So by adding the gage datum to the gage-height, you
get the water surface elevation above the National Geodetic Vertical Datum of
1929 (NGVD29).”
He then provides an example. “The gage datum for
0219700 Savannah River at Augusta, GA is 96.58 feet above NGVD29. . . . For the
October [19]29 flood at 02197000, the gage-height peaked at a value of 45.10
feet. By adding the 96.58 feet gage
datum to that reading, you get a water surface elevation of 141.68 feet
above NGVD29.” [4]
Although Eugene Emigh provides no physical reference for his
gage, the 5th Street Bridge had been used in previous floods.[5] This structure would be the most likely guide
because it would have been the limit of steam vessel navigation and just
upstream from Augusta’s port facility and steam boat landings and was used
locally for the 1888 flood until the river washed the bridge away.
The 1888 freshet was the largest since 1796 and in the
interim the populace of Augusta had grown complacent. Only the 1840 and 1865
floods reached the city proper and nearly all memory of these disappeared. The
1888 flood was a reminder of what the Savannah River could do if unchecked.
This flood did open flooding for scientific study. In 1892, the River and
Flood Service of the Weather Bureau was established to provide some warning of
dangerous high water. Nevertheless, as Emigh would mention later, the Savannah being a “flashy” river prone to very sudden rising, any gage readings would be of
no use and, as future weather forecasters would claim, there is nothing certain
about the weather. However, averages could be built with carefully acquired
information. This information can be useful and fairly accurate when
predicting normal circumstances if there is enough time to analyze the
computations and give warnings. The computations were gleaned from less than
a dozen reporting stations upstream from Augusta. From these the rise in river
stages upstream could be translated into river height at Augusta.

The floods of 1888 to 1929 were, as Emigh noted, from storms
dumping huge amounts of rain in a short period. Most were statewide storms
effecting nearly all the river systems of Georgia. The 1929 flood was an
extreme example of sudden and terrific rainfall.
Emigh’s prediction of a high intensity storm came during his
tenure at Augusta. With the simple description of “Hurricane No. 2,” this
Caribbean Sea storm reached modern Category 4 standards packing 120 MPH winds
from September 26 to 27. By October 2nd, the storm reached Augusta, GA., under the meteorological heading of “extra tropical storm” with 40 MPH winds
as it caused extreme rainfall. The storm had followed the Fall Line across the
State and hovered at 33.50N 81.00W for most of the day. (Augusta sits at 33.47N
81.95W) No one could have predicted the effects of the storm. Fortunately,
the Savannah River levee had been constructed after decades of debate. The levee was built to
48-feet and at one point the river reached 47.4 feet on the levee. The result
was this wall prevented flooding waters from destroying Augusta, but the same levee also
forced the water higher and into North Augusta and Hamburg, South Carolina.
The latter had taken the brunt of all previous floods and this last freshet was one cause for the end
to the small town.
;
In the current era, the three dams constructed up river from Augusta,
Hartwell Dam, Richard B. Russell Dam and J. Strom Thurmond (formerly Clarks
Hill) Dam offer protection from flooding damage to Georgia and South Carolina. The latter dam regulates and limits, to a degree, flooding
problems. Although Stevens Creek Dam, built in 1916, functions as a
“run-of-the-river,” reservoir it has no impact on flooding in Augusta. It was this dam that the cubic feet per second of flowing water was calculated
in 1929.
There remains a potential for dangerous flowing in Augusta, GA, and the city together with the U. S. Army Corps of Engineers (USACE) has made plans for disaster control from possible future floods. Part of this plan is a
proposed map of the possible
flooding caused by a break in the J. Strom Thurmond (Clarks Hill) Dam has
been drawn by the USACE.
Although the Savannah River has not overflowed its banks at
Augusta since the construction of the levee system and the
construction of the three upriver dams, there have been local floods in the
Rae’s and Rocky Creek sections as well as the 1990 flooding from heavy and
intense rain fall.
The low lying areas will always have the potential of
flooding. This is why knowing the history of former floods will serve as
warnings and preparatory lessons for the future. This web site is a reminder
of the clarity of the past and how the future can be as murky and “flashy” as
the Savannah River during a flood.
[1] Eugene D. Emigh, “Freshets of the Savannah River and the Forecasting of High
Water at Augusta, Ga.,” Monthly Weather Review, (January 1914), 46.
(Hereafter, Emigh).
[4] Email from Anthony J. Gotvald to author August 14, 2006.
[5] Curtis L. Sanders, Jr., Harold E. Kubik, Joseph T. Hoke, Jr., and William H.
Kirby, Flood Frequency of the Savannah River at Augusta, Georgia. U. S. Geological Survey, Columbia, S. C., 1990.,.10. Sanders et al notes the gage on
the 5th Street Bridge was read from one to four times a day.
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Reese Library
Augusta State University
4500 Walton Way
Augusta, Georgia 30904
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