CONTROL OF ROAD EROSION

Controlling erosion on public roads is an important problem. Measurements in this area indicate that 7 percent of the total quantity of modern sediment that has accumulated to date on flood plains had

PLATE 15.-A white oak upland hardwood stand in Marshall County. Fire protection and forest management will restore forest stands to a condition of producing income rather than flood run-off.

its origin in soil losses from roads (pl. 16). Erosion also increases costs of road upkeep because of the continual need for maintenance. Although most Federal-aid highways are currently receiving erosion-control treatments as a practical means of reducing maintenance costs, the greater part of the public roads, especially those

maintained by the counties, are without adequate protection. Omitting uneroding highways which traverse comparatively level areas such as flood plains and the flatwoods area, there are approximately 4,950 miles of public roads in the Coldwater, Yocona, Yalobusha, and Bluff units which are urgently in need of stabilization measures.22 These include 1,517 miles of graded, drained, and surfaced roads and 3,433 miles of unsurfaced roads of lower construction standards.

PLATE 16.-Present eroded road banks contribute enormous quantities of soil to stream systems and are a constant source of costs to local and State governments.

Treatment will consist mainly of establishing suitable vegetal cover on all raw back slopes, fill embankments, and road berns, and stabilizing roadside and lead-out ditches with vegetation and supplemental structures. Highly effective techniques have been developed locally for controlling this type of erosion and the on-site value of this work fully justifies its being undertaken in the interests of reducing maintenance costs (pl. 17). However, these measures are relatively costly and will not be accomplished readily without special assistance; potential contributions of this work to flood and sediment control dictate that Federal and State agencies finance a substantial portion of the corrective program.

Costs of treatment range from $354 to $508 per mile depending on the class of road and varying with the physiographic area. In the brown loam and clay hills, costs vary from $387 to $508 per mile; in the deep loess, where treatments involve less movement of earth, estimated costs will range from $354 to $475. When adequately installed, maintenance of the measures will entail no special expense. Installing erosion-control measures on public roads will cost more than $2,000,000 (table 13). At least 40 percent of the cost or $825,000 should be met from Federal funds with the State and counties supplying the remainder. If additional Federal funds are needed to

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implement these measures, an amount totaling perhaps 65 percent of the cost can be justified on the basis of the contribution of this work to off-site public benefits. Treatment of approximately 65 miles of road within the Coffeeville land-utilization project in the Yalobusha area is properly a Federal responsibility and would be financed entirely from Federal funds.

TABLE 13.-Cost of installing erosion-control measures on public roads in the watershed

PLATE 17.-A roadbank in Marshall County that has been stabilized by the methods recommended for use

over the entire watershed.

THE PROGRAM SUMMARIZED

Installation of the recommended program involves comprehensive and integrated treatment of 2,353,000 acres or 80 percent of all rural lands in the Coldwater, Yocona, Yalobusha, and Bluff units exclusive of areas purchased by the United States Engineer Department for flood-control reservoirs. The program will require 20 years to complete, although certain measures can be installed fully during the first 5 years.

The proposed schedule of work as outlined in table 14 involves (1) public acquisition of 730,000 acres of submarginal lands as an implementing measure to facilitate flood-control treatments; (2) establishment of an effective fire-control system to protect more than 12 million acres of public and private forest lands, including those in reservoir areas and in noncooperating private ownership; (3) reforestation of 170,000 acres of submarginal lands, including about 47,000 acres of gullied land requiring special erosion-control measures; (4) timbermanagement measures on 1,176,000 acres of existing and proposed forest lands, including 532,000 acres to remain in private ownership; (5) soil- and water-conserving measures on 269,000 acres of cropland through the adoption of improved cropping practices and the construction of terraces; (6) construction and maintenance of 382 miles of diversion terraces to protect croplands against damaging run-off from adjacent areas; (7) establishment of perennial vegetation on 54,000 acres of critically eroding cropland intermingled with and endangering other arable lands; (8) treatment of 407,000 acres of existing and proposed pasture lands through such measures as contour furrowing, fertilizing, seeding and planting, establishment of erosion control structures, fencing, and general maintenance; and (9) treatment of 4,950 miles of public roads to eliminate an important source of sedi

ment.

Execution of such a program is predicated on utilizing all lands according to their highest potential uses commensurate with floodcontrol objectives and hence involves not only changes in management but also numerous adjustments in the use of all participating lands (table 15). In the future, cultivated land will aggregate about 704,000 acres, a reduction of 101,000 from the gross acreage presently in crops. The forest acreage will be increased by more than 282,000 acres to a total of 1,176,000 acres, the increase coming largely through the conversion of extensive areas of worn-out open lands to forest use; less than 10,000 acres of existing forest lands are suitable for conversion to cropland or pasture. There will be a net increase in pasture. land amounting to about 14,000 acres, the proposed future acreage totaling about 445,000 acres. Only 64 percent of the proposed pasture acreage is presently in pasture use, the remainder being largely in cultivation or idle. The latter conversions will more than offset the large acreage of pasture land which in the future must be shifted to forest use or to a lesser extent to cultivation.