DRAINAGE OF BLACK AND BOGGY SWAMPS, S. C. 
15 
IMPROVEMENTS IN BLACK SWAMP WATERSHED. 
The watershed area of Black Swamp is comparatively fiat, except 
the lower or southern portion, which is more rolling, with a good fall 
toward the swamp. A large part of the flat land is under cultiva- 
tion, while the remainder is mostly flat bays and ponds with a thick 
covering of bushes and trees. 
The swamp or wet land along this stream is 100 to 300 feet wide 
for the first few miles below the source, then 400 to 600 feet for a few 
miles, and finally reaches 800 to 1,000 feet width at the lower end. 
There is no well-defined channel, and during wet seasons the entire 
swamp is covered with water several feet deep. The growth in this 
swamp is a thick, tangled mass of vines, briars, canes, and bushes, with 
a fairly heavy growth of timber. The total fall is 79 feet, quite 
sufficient to give good drainage to these lands, and for the greater 
portion of the swamp it is quite uniform, as may be seen from the 
profile (fig. 3). It varies from 12.5 feet per mile at the upper end to 
1.3 feet per mile for a short distance at the lower end. 
The proposed improvements on Black Swamp consist, as shown in 
figures 2 and 3, of a dredge ditch starting at the Southern Railway 
just south of Furman and continuing down the swamp until overflow 
water from the Savannah River is encountered. This will require 
a ditch about 10 miles long. The depth should be 7 feet, with side 
slopes of J to 1. The ditch should start with a 14-foot bottom width, 
increasing to 30 feet. At the lower end the estimated capacity of 
the ditch is less than the calculated run-off, and consequently some 
flooding is to be expected. No harm will result from this, however, 
as the lower end of the swamp will be flooded by exteme high water 
in the Savannah River, and the lands bordering the swamp lie 15 to 20 
feet above its level and have good natural drainage. The table 
below summarizes the data and computations for the Black Swamp 
ditch. 
Table 2. — Data and computations for Black Swamp ditch. 
Side slop 
is of ditch 
I to 1.) 
Station. 
Com- 
puted 
velocity. 
Watershed. 
Com- 
Depth. 
Bottom 
width. 
Fall. 
puted 
ditch 
From— 
To— 
Area. 
Run-off. 
capacity. 
Feet per 
Feet per 
Feet per 
Cu.ft. 
Cu.ft. 
Feet. 
Feet. 
foot. 
mile. 
second. 
Acres. 
per sec. 
per sec. 
00 
80 
102 
169 
180 
240 
80 
102- 
169 
180 
240 
299 
1 
7 
7 
7 
7 
7 
14 
14 
14 
14 
14 
14 
0. 00237 
. 00200 
.00200 
. 00200 
.00127 
.00127 
12.51 
10.56 
10.56 
10.56 
6.71 
6.71 
2,000 
2,175 
3,575 
7,050 
7,850 
10, 775 
4.55 
4.55 
555 
555 
453 
299 
320 
7 
14 
.00127 
6.71 
4.55 
12, 600 
529 * 
555 
320 
339 
7 
16 
.00095 
5.02 
4.1 
12, 9C0 
542 
580 
339 
407 
7 
20 
. 00095 
5.02 
4.3 
16,650 
7G0 
710 
407 
432 
7 
22 
. 00095 
5.02 
4.35 
17, 425 
732 
/ (O 
432 
460 
7 
22 
. 00095 
5.02 
4.35 
, -L7,925 
753 
lib 
460 
526 
7 
30 
. 00023 
1.31 
2.4 
18,500 
777 
565 
