RECLAIMING OVEEFLOWED LANDS IN MISSISSIPPI. 27 
RELIEF DITCH. 
A relief ditch was then laid out in such a manner that two separate 
channels could be maintained the entire length of the bottom below 
Bywy Creek. Owing to construction limitations the maximum 
section of this ditch was designed with a bottom width of 100 feet 
and a depth of flow of 13 feet. With this ditch and with the river 
channel cleared, the run-off, as computed by the ditch formula, 
could be cared for above the mouth of Poplar Creek; but from this 
point downstream it is believed that the relief obtained would not 
justify the expenditure. The estimated cost of this plan, including 
the construction of the ditch and the clearing of the old channel, 
amounted to $27 per acre of land benefited. 
LEVEE AND FLOODWAY PLAN. 
Preliminary computations were then made on a system of protection 
consisting of levees and floodways. The necessary widths of river 
floodway and heights of levees were determined. Interior drainage 
was provided for by ditches with outlets through floodgates to the 
river channel. The results obtained show that while the cost of the 
complete system will be high, considering present land values and 
economic conditions in the district, yet portions of the valley can be 
reclaimed at a reasonable cost even at the present time, and the 
remainder can be reclaimed at a later date as conditions justify. 
Plans and estimates were therefore made along the lines just de- 
scribed; these are discussed in some detail in the following pages. 
PROPOSED PLAN. 
The general plan as proposed for the drainage of the Big Black 
Kiver bottoms consists of: 
(1) The construction of a main ditch and of the necessary laterals 
at the upper end of the valley. 
(2) The construction of levees. 
(3) The clearing of a floodway through the bottoms, including 
the present river channel. 
(4) Provision for interior drainage by the construction of ditches 
and the clearing of present channels. 
The proximity of the river channel to the bluffs or higher land at 
frequent intervals and the entrance of tributaries into the bottoms 
divide the overflowed land into natural drainage units. From the 
Ma thistcn- Walthall Road to Cox Ferry 36 drainage districts have 
been planned. These districts, as well as the drainage improvements 
recommended, are clearly shown on the accompanying maps and 
profiles (figs. 10-12, in pocket at end of bulletin).^ 
1 For index map to figure 10, see figure 2. 
