Figure 21. Low forediine topography typical of reach C (17 October 1976). 



During th.e 4-year study period, the most noticeable change in reach C oc- 

 curred to the inland dunes in the northern part of the reach. Because of the 

 easy access and the rolling topography, the area has become popular with four- 

 wheel drive enthusiasts. The air photos clearly document a widening of the 

 trails and an increase in the number of roads across the dimes. A ground photo 

 of the area is shown in Figure 22. No attempt was made to determine if the in- 

 creased use of the area had an effect on the rate of bluff recession. The area 

 has recently been closed to vehicular traffic (C.L. Kureth, The Traverse Groiq), 

 Ann Arbor, Michigan, personal communication, 1979). 



Data were taken from the air photos at about 1-year intervals between 15 

 April 1971 and 23 November 1974. The results of the bluff recession rate and 

 average beach width computations are shown in Figure 23. The shift from accre- 

 tion to recession occurs between stations 15 and 16 with the bluff or foredune 

 being stable or accreting south of station 15. The average rate of accretion 

 for stations to 16 was 2.0 meters per year; the remaining stations retreated 

 3.2 meters per year, the lowest rate for any of the reaches. The rate of shore- 

 line change over the 4 years was an almost constant -3.7 meters per year, though 

 the rate was lovrest at the ends of the reach. 



Although measurements of beach width are of questionable accuracy due to 

 the difficulty in establishing a repeatable landward bound, the beach width 

 data (Fig. 23) correlate well with the bluff recession rates. In general, 

 where the beach was wide, the dune or bluff line either stabilized or accreted; 

 where the beach was narrow, the dunes retreated. During October 1973 to Novem- 

 ber 1974, the beach width averaged 5.6 meters and was fairly constant along the 



37 



