Damage from sedimentation.

Nearly 20 percent of the uplands, or about 633,000 acres, are subject to several types of damage from flood-borne sediment. Sediment from the uplands is also causing damage on 113,000 acres of land in the delta. These cumulative damages are measured by changes in land productivity which are caused by deposition of sediment on flood-plain lands (pl. 8), by swamping of land as a result of deposition which interferes with drainage, and by channel filling which contributes to the overflow (pl. 9). An additional damage is caused by sediment reducing the storage capacity of flood-control reservoirs. Under present watershed conditions, infertile sediment is being flushed into the valleys at a rate of about 89,000,000 tons or 44,000 acre-feet annually. This is increasing.

TABLE 5.-Summary of property damages caused by the flood of Apr. 8, 19421

Had soils and other watershed resources been properly handled, the net productivity of the 746,000 acres of flood plain subject to damage by sedimentation would now be about $13.30 per acre annually. Actually, the present net productivity of the average flood-plain acre is only $5.70, and it will decrease still farther in the future if erosion of the uplands is not checked. The present value of this future damage, expressed as an annual equivalent, amounts to $737,803 (table 7).

10

The Engineer Department plans four flood-control reservoirs in the watershed. The Arkabutla (under construction), Enid (proposed), and New Grenada (proposed) are in the area under survey. The sediment transported into these reservoirs under present land-use practices in time will impair their flood-storage capacity to the point where additional expenditures will be necessary for effective operation. Table 6 indicates the extent of this damage.

The average annual value of the damages that will be suffered by reservoirs in the future is $12,376.11

PLATE 9. A channel completely plugged with sand in Marshall County. Such a condition necessitates frequent re-elevation of railroad fills; it also causes more frequent flooding or even swamping of adjacent flood plains which are lower than the stream channel.

1 Time at which additional expenditures will be necessary.

? In period of years indicated and point at which structural alterations will be necessary.

3 Annual payment necessary to provide funds for improvement at the time needed.

10 The fourth, Sardis Reservoir, is completed on the Little Tallahatchie River and is discussed in the

Little Tallahatchie Survey Report, H. Doc. 892, 77th Cong., 2d sess.

11 Annual payment necessary to provide funds for improvement at the time needed.

Indirect damage.

Floodwaters and flood-borne sediment cause many indirect damages that cannot be readily appraised. Virtually every flood to some extent interrupts the normal course of business, especially where transportation is disrupted. The farmer loses when a flood delays his operations for several days or weeks; the transportation companies and individual travelers lose time and incur extra costs when highways are inundated or bridges are washed out; merchants and processors lose business when transportation facilities are damaged; and other similar types of losses are experienced throughout the watershed and adjacent area. In the aggregate, these indirect losses may be greater than the direct losses; here they are conservatively estimated to be at least one-fourth the direct losses, or $637,398.

Damage not evaluated.

In order to appraise flood damages adequately, it would be necessary to determine the effects of floods on human health; on plant and animal life; on business, not only local but country-wide; on both interstate and intrastate transportation; on recreational assets, existing and potential; and on the morale of people who undergo these damages. A loss to farming enterprises affects all associated business and professions and results in lower purchasing power and reduced commerce. Occasional sickness and disease caused by or related to floods requires extra medical expenditures and loss in productive time. Insects associated with flooding weaken and sometimes kill work stock. Frequent flooding prevents recreational development, and especially in areas such as this where recreational opportunities are especially needed to combat frustration brought on by low standards of living. Occasionally floods directly affect fishing and hunting, thereby curtailing important sources of food and desirable forms of recreation. Loss of life by floods, although infrequent in this particular watershed, represents an intangible loss to society which cannot be overlooked. Losses in net incomes affect morale by lowered living standards and the inability of the people to provide such things as educational and church facilities. Although all such intangible damages cannot be measured monetarily, they must be given due weight in analyzing the effect of floods on the watershed economy.

Summary of damages.

In the Yazoo watershed the computed damages amount to $3,186,988 annually, of which 56 percent is caused by floodwater, 24 percent by sediment, and 20 percent represents the indirect effects of both floodwater and sedimentation (table 7).

TABLE 7.-Summary of average annual flood damages, Yazoo watershed

1 Damage attributable to run-off from the upland areas.

2 Damage to agricultural property is included with "property" rather than with "agricultural." 3 Based on anticipated future decline in productivity, assuming productivity declines for 200 years and then stabilizes at that level.

CHAPTER III. THE REMEDIAL PROGRAM

The analysis of flood problems and their causes, as outlined in the preceding chapter, clearly indicates the need for a comprehensive program of land treatments in aid of flood control in most of the Yazoo River watershed, exclusive of the Delta unit. The same program is required no less urgently in order to stabilize and restore an agricultural economy which will dwindle to still more meager levels of living unless exploitative practices are corrected.

In developing a land program in aid of flood control, the general objective is to reduce run-off and erosion to a practical minimum by improving the cover on all nonarable lands and by adopting methods of tillage and land management which furnish optimum protection to croplands. However, these general aims must take into account the practical limitations of converting all lands to a use or condition affording maximum restraints to waterflow. In this particular area, economic considerations dictate that as much land as possible be utilized for agriculture. As treatment for flood-control purposes entails rather drastic changes in cropping practices, remedial plans must be worked out for individual farm holdings and insofar as possible adapted to the economic needs and financial means of the owner. Few if any landowners in this area can entirely finance the cost of such a flood-control program. Some public assistance is therefore prerequisite to achieving any large-scale treatment of farm lands. including those generally well suited to sustained production under present ownership. On the other hand, thousands of acres are too impoverished to be rehabilitated under any practical plan of farm management. For these areas, public ownership and treatment afford the only practical solution.

In line with these guiding principles, a comprehensive, unified, landimprovement program has been developed for the Yazoo Basin. Although the primary purpose of this plan of action is to prevent or alleviate flood damages on valley lands not protected by existing or proposed works of the United States Engineer Department, the measures will function just as effectively in conserving water and soil