A COMPUTER SIMULATION ANALYSIS OF CARRYING CAPACITY OF A RIVER RECREATION SYSTEM

An operations research-based method of defining the carrying capacity of resource-based recreation systems was developed in conjunction with a computer simulation study of whitewater boating on the Youghiogheny River in Ohiopyle State Park, Pennsylvania. The system includes 6.5 miles of river, with one launch area, two exit points, five major rapids, one recreational stop, and four user populations.;Travel times varied widely. Commercial groups took the longest but varied the least. Private raft groups were fastest, on the average, while hard-boat groups were intermediate but varied the most. Correlation analysis showed that groups tended to move at a consistent pace, whether slow or fast.;The critical system variable was the time lapse between boats entering the rapids. It varied among rapids and among user populations. The inter-entry times could be described by the Weibull distribution in some cases and by the exponential in others.;Private raft groups were increased to give total use levels of 1,500, 1,700, 2,000, 2,500, and 3,000 user-days; a sample of 10 simulations was run at each level. In one experiment, representing unregulated growth, added groups were concentrated in the peak periods; in the second, representing scheduled launches, they were spread uniformly over a longer period. In the first experiment, congestion at the rapids increased only gradually up to 2,000 user-days but increased rapidly beyond 2,000. The second indicated that scheduled launches would decrease congestion.;Field observations on three peak-use days indicated that private groups launch independently at rates that vary with time and among populations. Commercial groups are limited to 12 per day, one launching each half hour. Observed total daily use was 1,256 on August 30, 1975; 1,710 on July 31, 1976; and 1,420 on August 1, 1976. Private group sizes were distributed geometrically and ranged from 1 to 25 boats. Commercial groups were limited to 20 boats and 80 persons.;Recommendations of a daily limit of 2,000 users and a limit of 50 private boats in any 1-hour period were implemented in 1978 and remain in force today.