1961 



110 



— 100 

 E 



80 



60 - 



40 



20 



1962 



1963 



DATE (Years) 



| 1964 | 1965 



1966 



Road fill failure in one watershed 



Period of logging 



1967 



- 1 ,600 



- 1,500 



- 1,400 



- 1,300 Q 

 UJ 

 CO 



r- 1,200 CC 



-1,100 w 



Q 



I— 1 ,000 



h 900 

 800 

 h 700 



500 

 400 

 - 300 

 200 

 \- 100 



D 

 Z 

 < 

 X 

 H 

 CC 



UJ 



< 

 UJ 

 CC 



600 fj 



in 



"I 1 1 1 1 1 — ~ — r 1 t r~ 



200 400 600 800 1,000 1,200 1,400 1,600 1,800 2,000 2,200 



ELAPSED TIME (Days) 



Figure 6 .--Sediment production over time from surface erosion on jammer roads. 



Intuitively, one can visualize how bare, unprotected material in a road prism 

 could be subject to extremely high surface erosion immediately after construction. 

 However, in time, the more erodible materials are removed and vegetation and litter 

 begin to accumulate; this causes a decrease in surface erosion rates. Research data 

 elsewhere suggest time trends in sediment production from road erosion (Rice and Wallis 

 1962; Reinhart and others 1963; Haupt and Kidd 1965; Vice and others 1969; Fredriksen 

 1970). In our study, sediment production rates had decreased progressively to zero 

 prior to the 1964-65 measurement period. In subsequent measurement periods these 

 ratios exhibited considerable fluctuations; ranging from zero to about 100 times 

 greater in roaded areas than on undisturbed lands (fig. 6). Recent studies (Anderson 



9 



