Table 1. --Furrowing costs and 80-year sediment reduction by hydrologic types 



Hydrologic 

 type 



Total 

 treatment 

 cost 



: Sediment : 

 : reduction : 



Cost/AI 



Cumulative 

 cost 



: Cumulative 

 : sediment 

 : reduction 





Dn 7 1 ny^<^ 



Ai^yp —ini^hps 



Do !■ tars 



Do 1 "Lars 



Acyp —7 yi^hes 



J Km 



75 



27.91 



2 . 69 



75 



28 



9B 



120 



20.36 



5.98 



195 



48 



9A 



195 



30.20 



6. 45 



390 



78 



4L 



450 



36.67 



12.27 



840 



115 



IE 



1,200 



85. 77 



13.99 



2 ,040 



201 



IXX 



6,345 



441 . 27 



14.38 



8,385 



642 



6N 



345 



23. 84 



14. 47 



8, 730 



666 



4H 



450 



30 . 83 



14.60 



9 ,180 



697 



4D 



11 ,970 



659 . 72 



18. 14 



21,150 



1 , 357 



IF 



1 , 170 



59 .50 



19.66 



22 ,320 



1 ,416 



4P 



300 



14.23 



21.08 



22 ,620 



1 ,430 



1-0 



7,545 



289 . 18 



26. 10 



30 ,165 



1,719 



1CB2 



150 



5. 72 



26.22 



30 ,315 



1 ,725 



4F 



75 



2.55 



29 .41 



30 ,390 



1,728 



IP 



450 



15.10 



29.80 



30,840 



1,743 



1CB3 



825 



16.52 



49.94 



31,665 



1,759 



1F3 



975 



14.50 



67.24 



32,640 



1,774 



lYY 



150 



1.65 



90.91 



32,790 



1,776 



4K 



1,545 



16.63 



92.90 



34,335 



1,792 



4E 



1,095 



10.23 



107.04 



35,430 



1,802 



4C 



2,325 



17.48 



133.01 



37,755 



1,819 



5E 



225 











37,980 



1,819 



For the hydrologic types on which furrowing was appropriate, ranking the types in 

 ascending order of cost of achieving an acre-inch of sediment reduction, the total cost 

 of treatment, and the total sediment reduction can be cumulatively added (table 1) to 

 provide a total cost-sediment reduction curve (fig. 1). By spending $1,000, about 125 

 acre-inches of sediment can be kept out of the reservoir. For an additional $1,000, 

 another 75 acre-inches can be stopped. Each additional Si, 000 results in less and less 

 sediment reduction until finally, after about a $35,000 expenditure, there is virtually 

 no additional sediment reduction achieved regardless of how much money is spent. Even 

 understanding the relationship between costs and expected treatment response gives no 

 indication as to whether any level of expenditure is worth the money. Such an under- 

 standing can, however, keep the managers out of the area of obvious foolish spending. 



For purposes of determining a budget, the planner-manager must come to a decision 

 as to how far to go in treatments once it has been determined that the stabilization 

 and rehabilitation goals have been set and achievement has been judged feasible. IVhere 

 the marginal cost of a particular treatment exceeds the estimated benefits from the 

 treatment, or where total costs for the treatment become excessive, less expensive 

 means for reducing sediment delivery or erosion should be sought. This could mean 

 evaluating other treatments on a particular area, the same treatment on other areas, or 

 sediment removal schedules. KTiere the prescription approach to stabilization is used, 

 the marginal cost, and total cost data, must be used to indicate the point beyond which 

 additional spending is inefficient. 



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